BiologyQ51–147 of 213 questions
Page 2 of 3 · English
51
BiologyEasyMCQAIPMT · 1999
To which of the following families do folic acid and pantothenic acid belong?
A
Vitamin $K$
B
Vitamin $A$
C
Vitamin $C$
D
Vitamin $B$ complex
Solution
(D) Folic acid is known as Vitamin $B_9$ and pantothenic acid is known as Vitamin $B_5$.
Both of these vitamins are water-soluble and are essential components of the Vitamin $B$ complex group.
Therefore,they belong to the Vitamin $B$ complex family.
Both of these vitamins are water-soluble and are essential components of the Vitamin $B$ complex group.
Therefore,they belong to the Vitamin $B$ complex family.
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52
BiologyEasyMCQAIPMT · 1999
An average man needs approximately
A
$2900$ Kcal energy/day
B
$500$ Kcal energy/day
C
$1000$ Kcal energy/day
D
$2000$ Kcal energy/day
Solution
(A) An average adult male requires approximately $2900-3000$ Kcal of energy per day to maintain his basal metabolic rate and daily physical activities.
In comparison,a child of about $15$ years requires approximately $2500$ Kcal,and an infant of $4-6$ years requires about $1500$ Kcal per day.
Therefore,among the given options,$2900$ Kcal is the most appropriate value for an average man.
In comparison,a child of about $15$ years requires approximately $2500$ Kcal,and an infant of $4-6$ years requires about $1500$ Kcal per day.
Therefore,among the given options,$2900$ Kcal is the most appropriate value for an average man.
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53
BiologyEasyMCQAIPMT · 1999
Which of the following is required for the conversion of trypsinogen into trypsin?
A
$HCl$
B
Enterokinase
C
Lipase
D
Zymase
Solution
(B) Trypsinogen is an inactive enzyme (zymogen) secreted by the pancreas into the small intestine.
It is converted into its active form,trypsin,by an enzyme called enterokinase (also known as enteropeptidase).
Enterokinase is secreted by the intestinal mucosa.
Therefore,the correct option is $B$.
It is converted into its active form,trypsin,by an enzyme called enterokinase (also known as enteropeptidase).
Enterokinase is secreted by the intestinal mucosa.
Therefore,the correct option is $B$.
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54
BiologyEasyMCQAIPMT · 1999
Which of the following carries glucose from the digestive tract to the liver?
A
Hepatic artery
B
Pulmonary vein
C
Hepatic portal vein
D
Renal portal system
Solution
(C) The $Hepatic portal vein$ carries blood from the digestive tract to the liver.
This blood is rich in absorbed nutrients such as glucose and amino acids, which are transported directly to the liver for processing, storage, or distribution to the rest of the body.
This blood is rich in absorbed nutrients such as glucose and amino acids, which are transported directly to the liver for processing, storage, or distribution to the rest of the body.
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55
BiologyMediumMCQAIPMT · 1999
The respiratory centre in the brain which controls inspiration and expiration is situated in
A
Medulla oblongata
B
Cerebellum
C
Hypothalamus
D
Pericardium
Solution
(A) Breathing is regulated by specialized centers in the brainstem.
$1$. The respiratory rhythm center is primarily located in the medulla oblongata region of the brain.
$2$. This center is responsible for the regulation of the respiratory rhythm,specifically controlling inspiration and expiration.
$3$. Additionally,a pneumotaxic center present in the pons region of the brain can moderate the functions of the respiratory rhythm center.
$4$. Therefore,the primary control for inspiration and expiration is situated in the medulla oblongata.
$1$. The respiratory rhythm center is primarily located in the medulla oblongata region of the brain.
$2$. This center is responsible for the regulation of the respiratory rhythm,specifically controlling inspiration and expiration.
$3$. Additionally,a pneumotaxic center present in the pons region of the brain can moderate the functions of the respiratory rhythm center.
$4$. Therefore,the primary control for inspiration and expiration is situated in the medulla oblongata.
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56
BiologyMediumMCQAIPMT · 1999
Heartbeat can be initiated by
A
Sino-atrial node
B
Atrio-ventricular node
C
Sodium ion
D
Purkinje's fibres
Solution
(A) The human heart is myogenic,meaning the heartbeat is initiated by specialized cardiac muscle cells. The $Sino-atrial$ $node$ $(SAN)$,also known as the pacemaker,is located in the right atrium. It generates action potentials that initiate the heartbeat,making it the primary pacemaker of the heart.
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57
BiologyMediumMCQAIPMT · 1999
The thickening and hardening of the walls of arteries is called:
A
Arthritis
B
Aneurysm
C
Arteriosclerosis
D
Both $(a)$ and $(b)$
Solution
(C) The correct answer is $(c)$.
Arteriosclerosis refers to the thickening,hardening,and loss of elasticity of the arterial walls.
Atherosclerosis is a specific type of arteriosclerosis characterized by the deposition of fatty substances,especially cholesterol and triglycerides,in the tunica interna and smooth muscle of medium-sized and large arteries.
Arteriosclerosis refers to the thickening,hardening,and loss of elasticity of the arterial walls.
Atherosclerosis is a specific type of arteriosclerosis characterized by the deposition of fatty substances,especially cholesterol and triglycerides,in the tunica interna and smooth muscle of medium-sized and large arteries.
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58
BiologyMediumMCQAIPMT · 1999
Which of the following carries glucose from the digestive tract to the liver?
A
Hepatic artery
B
Hepatic portal vein
C
Pulmonary vein
D
None of these
Solution
(B) The $Hepatic$ $portal$ $vein$ is a unique vascular connection that exists between the digestive tract and the liver.
It carries blood rich in absorbed nutrients,such as glucose and amino acids,directly from the intestine to the liver for processing,storage,or distribution before the blood enters the systemic circulation.
It carries blood rich in absorbed nutrients,such as glucose and amino acids,directly from the intestine to the liver for processing,storage,or distribution before the blood enters the systemic circulation.
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59
BiologyMediumMCQAIPMT · 1999
Aquatic reptiles are
A
Ammonotelic
B
Ureotelic over land
C
Ureotelic
D
Ureotelic in water
Solution
(C) The correct answer is $C$.
Most reptiles,including aquatic ones,are ureotelic.
Ureotelic animals are those that excrete nitrogenous waste primarily in the form of urea.
While some aquatic animals like bony fishes are ammonotelic,reptiles (including aquatic species like sea turtles) generally excrete urea to conserve water or as a metabolic adaptation.
Most reptiles,including aquatic ones,are ureotelic.
Ureotelic animals are those that excrete nitrogenous waste primarily in the form of urea.
While some aquatic animals like bony fishes are ammonotelic,reptiles (including aquatic species like sea turtles) generally excrete urea to conserve water or as a metabolic adaptation.
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60
BiologyMediumMCQAIPMT · 1999
Articulation of the atlas with the axis is an example of
A
Hinge joint
B
Ball and socket joint
C
Gliding joint
D
Pivot joint
Solution
(D) The articulation between the atlas ($C1$ vertebra) and the axis ($C2$ vertebra) allows for the rotation of the head.
This specific type of synovial joint,where one bone rotates around a central axis provided by another bone,is known as a pivot joint.
Therefore,the correct option is $D$.
This specific type of synovial joint,where one bone rotates around a central axis provided by another bone,is known as a pivot joint.
Therefore,the correct option is $D$.
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61
BiologyMediumMCQAIPMT · 1999
The function of the sympathetic nervous system is to
A
Decrease heart rate
B
Increase heart rate
C
Contract respiratory organs
D
Secrete saliva
Solution
(B) The sympathetic nervous system is part of the autonomic nervous system that prepares the body for 'fight or flight' responses.
It releases neurotransmitters like norepinephrine which act on the sinoatrial $(SA)$ node of the heart.
This stimulation leads to an increase in the heart rate and the force of ventricular contraction to ensure adequate blood supply to tissues during stress.
Conversely,the parasympathetic nervous system decreases the heart rate.
It releases neurotransmitters like norepinephrine which act on the sinoatrial $(SA)$ node of the heart.
This stimulation leads to an increase in the heart rate and the force of ventricular contraction to ensure adequate blood supply to tissues during stress.
Conversely,the parasympathetic nervous system decreases the heart rate.
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62
BiologyEasyMCQAIPMT · 1999
Which cranial nerve has the highest number of branches?
A
Trigeminal
B
Facial nerve
C
Vagus nerve
D
None of these
Solution
(C) The $Vagus$ nerve (Cranial nerve $X$) is the longest and most complex cranial nerve, possessing the most extensive distribution and the highest number of branches.
Its primary branches include:
$(i)$ Superior laryngeal nerve
$(ii)$ Recurrent laryngeal nerve
$(iii)$ Cardiac branches
$(iv)$ Pulmonary branches
$(v)$ Esophageal branches
It provides parasympathetic innervation to the heart, lungs, and digestive tract.
Its primary branches include:
$(i)$ Superior laryngeal nerve
$(ii)$ Recurrent laryngeal nerve
$(iii)$ Cardiac branches
$(iv)$ Pulmonary branches
$(v)$ Esophageal branches
It provides parasympathetic innervation to the heart, lungs, and digestive tract.
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63
BiologyMediumMCQAIPMT · 1999
Gonadotrophic hormones are produced in the
A
Posterior part of thyroid
B
Adrenal cortex
C
Adenohypophysis of pituitary
D
Interstitial cells of testis
Solution
(C) Gonadotrophic hormones,specifically $FSH$ (Follicle Stimulating Hormone) and $LH$ (Luteinizing Hormone),are produced and secreted by the anterior lobe of the pituitary gland,which is known as the $adenohypophysis$.
These hormones play a crucial role in regulating the reproductive functions of the gonads (testes and ovaries).
These hormones play a crucial role in regulating the reproductive functions of the gonads (testes and ovaries).
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64
BiologyMediumMCQAIPMT · 1999
Diabetes mellitus is primarily caused by:
A
$Na^+$ deficiency
B
Hormonal deficiency
C
Enzyme deficiency
D
Iodine deficiency
Solution
(B) Diabetes mellitus is a metabolic disorder characterized by high blood glucose levels (hyperglycemia). It is primarily caused by a deficiency or ineffective action of the hormone insulin,which is secreted by the beta cells of the Islets of Langerhans in the pancreas. Therefore,it is classified as a hormonal deficiency.
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65
BiologyMediumMCQAIPMT · 1999
Which part of the body secretes the hormone secretin?
A
Ileum
B
Duodenum
C
Stomach
D
Oesophagus
Solution
(B) The hormone $Secretin$ is secreted by the $S$-cells located in the mucosal lining of the $Duodenum$.
It is released in response to the low $pH$ (acidity) of the chyme entering the small intestine from the stomach.
$Secretin$ stimulates the pancreas to secrete water and bicarbonate ions into the small intestine to neutralize the acidic chyme.
It is released in response to the low $pH$ (acidity) of the chyme entering the small intestine from the stomach.
$Secretin$ stimulates the pancreas to secrete water and bicarbonate ions into the small intestine to neutralize the acidic chyme.
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66
BiologyMediumMCQAIPMT · 1999
The problem due to $Rh$ factor arises when the blood of two individuals ($Rh^+$ and $Rh^-$) mix up in which of the following conditions?
A
In a test tube
B
Through transfusion
C
During pregnancy
D
$Both (b)$ and $(c)$
Solution
(D) The $Rh$ incompatibility problem arises when $Rh^-$ blood is exposed to $Rh^+$ blood.
$1$. Through transfusion: If an $Rh^-$ individual receives $Rh^+$ blood, their immune system produces anti-$Rh$ antibodies.
$2$. During pregnancy: If an $Rh^-$ mother carries an $Rh^+$ fetus, fetal blood may mix with maternal blood during delivery, causing the mother to develop anti-$Rh$ antibodies, which can affect subsequent $Rh^+$ pregnancies (Erythroblastosis fetalis).
Mixing in a test tube is a controlled laboratory procedure and does not represent a physiological 'problem' in the context of clinical pathology.
$1$. Through transfusion: If an $Rh^-$ individual receives $Rh^+$ blood, their immune system produces anti-$Rh$ antibodies.
$2$. During pregnancy: If an $Rh^-$ mother carries an $Rh^+$ fetus, fetal blood may mix with maternal blood during delivery, causing the mother to develop anti-$Rh$ antibodies, which can affect subsequent $Rh^+$ pregnancies (Erythroblastosis fetalis).
Mixing in a test tube is a controlled laboratory procedure and does not represent a physiological 'problem' in the context of clinical pathology.
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67
BiologyEasyMCQAIPMT · 1999
Which of the following is the use of lichens in the context of pollution?
A
They treat polluted water.
B
They act as bioindicators of pollution.
C
They promote pollution.
D
Lichens are not related to pollution.
Solution
(B) Lichens are symbiotic associations between algae and fungi. They are highly sensitive to atmospheric pollutants,particularly sulfur dioxide $(SO_2)$. Because they do not grow in polluted areas,they serve as excellent bioindicators for air quality and pollution levels.
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68
BiologyMediumMCQAIPMT · 1999
The blood calcium level is lowered by the deficiency of
A
both calcitonin and parathormone
B
calcitonin
C
parathormone
D
thyroxine
Solution
(C) $Parathormone$ $(PTH)$ is secreted by the chief cells of the parathyroid gland and plays a crucial role in regulating calcium and phosphate metabolism.
It increases blood calcium levels by promoting calcium absorption from the intestine,enhancing calcium reabsorption from the renal tubules of the kidneys,and stimulating bone resorption.
Therefore,a deficiency of $Parathormone$ leads to a decrease in blood calcium levels,a condition known as hypocalcemia.
It increases blood calcium levels by promoting calcium absorption from the intestine,enhancing calcium reabsorption from the renal tubules of the kidneys,and stimulating bone resorption.
Therefore,a deficiency of $Parathormone$ leads to a decrease in blood calcium levels,a condition known as hypocalcemia.
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69
BiologyMediumMCQAIPMT · 1999
In photosynthetic bacteria,pigments are present in ..........
A
Leucoplasts
B
Chloroplasts
C
Chromoplasts
D
Chromatophores
Solution
(D) Photosynthetic bacteria are prokaryotic organisms that lack membrane-bound organelles like chloroplasts.
Instead,they possess specialized membranous structures called $Chromatophores$ that extend into the cytoplasm.
These $Chromatophores$ contain the pigments necessary for photosynthesis,allowing the bacteria to capture light energy.
Instead,they possess specialized membranous structures called $Chromatophores$ that extend into the cytoplasm.
These $Chromatophores$ contain the pigments necessary for photosynthesis,allowing the bacteria to capture light energy.
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70
BiologyEasyMCQAIPMT · 1999
Which of the following describes the use of lichens in relation to pollution?
A
Lichens are not related to pollution.
B
They are biological indicators of pollution.
C
They treat polluted water.
D
They increase pollution.
Solution
(B) Lichens are symbiotic associations between algae and fungi. They are highly sensitive to atmospheric pollutants,especially sulfur dioxide $(SO_2)$. Because they do not grow in polluted areas,they are widely used as biological indicators of air pollution.
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71
BiologyMediumMCQAIPMT · 1999
Which of the following plants are vascular but seedless?
A
Algae
B
Bryophytes
C
Pteridophytes
D
Gymnosperms
Solution
(C) The plant kingdom is classified based on the presence or absence of vascular tissues and seeds.
$1$. Algae and Bryophytes are non-vascular plants (thallophytes and bryophytes).
$2$. Pteridophytes are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$) but they do not produce seeds; they reproduce via spores.
$3$. Gymnosperms and Angiosperms are vascular plants that produce seeds.
Therefore,Pteridophytes are the correct group of plants that are vascular but seedless.
$1$. Algae and Bryophytes are non-vascular plants (thallophytes and bryophytes).
$2$. Pteridophytes are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$) but they do not produce seeds; they reproduce via spores.
$3$. Gymnosperms and Angiosperms are vascular plants that produce seeds.
Therefore,Pteridophytes are the correct group of plants that are vascular but seedless.
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72
BiologyMediumMCQAIPMT · 1999
Which of the following is true for $Bryophytes$?
A
They possess archegonia.
B
They contain chloroplasts.
C
They are thalloid.
D
All of the above.
Solution
(D) $Bryophytes$ are known as the amphibians of the plant kingdom. The following statements are true for them:
$1$. They possess $archegonia$ as the female sex organ.
$2$. They are photosynthetic organisms,hence they contain $chloroplasts$.
$3$. Their plant body is $thalloid$,meaning it is not differentiated into true roots,stems,or leaves.
Therefore,all the given statements are correct,and the correct option is $D$.
$1$. They possess $archegonia$ as the female sex organ.
$2$. They are photosynthetic organisms,hence they contain $chloroplasts$.
$3$. Their plant body is $thalloid$,meaning it is not differentiated into true roots,stems,or leaves.
Therefore,all the given statements are correct,and the correct option is $D$.
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73
BiologyMediumMCQAIPMT · 1999
Bryophytes possess:
A
$A$ long-lived sporophytic phase.
B
$A$ dominant sporophytic phase that is parasitic.
C
$A$ dominant gametophytic phase that produces spores.
D
$A$ small sporophytic phase that is parasitic on the gametophyte.
Solution
(D) In $Bryophytes$,the main plant body is a haploid gametophyte $(n)$,which is dominant and independent. The sporophyte $(2n)$ is multicellular and dependent on the gametophyte for its nutrition. Therefore,the sporophyte is considered parasitic on the gametophyte. Thus,the correct statement is that they possess a small sporophytic phase that is parasitic on the gametophyte.
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74
BiologyEasyMCQAIPMT · 1999
Dichotomous branching is found in ...........
A
Ferns
B
Funaria
C
Liverworts
D
Marchantia
Solution
(D) Dichotomous branching is a type of branching where the apical meristem divides into two equal branches. This pattern is characteristic of the thallus of liverworts,specifically $Marchantia$. In $Marchantia$,the thallus is dorsiventrally flattened and exhibits this distinct dichotomous branching pattern.
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75
BiologyEasyMCQAIPMT · 1999
The antherozoids of $Funaria$ are ....
A
Aflagellate
B
Biflagellate
C
Multiflagellate
D
Uniflagellate
Solution
(B) $Funaria$ is a genus of mosses belonging to the division $Bryophyta$.
In bryophytes,the male gametes are known as antherozoids.
These antherozoids are comma-shaped and possess two flagella at the anterior end,which helps them swim in water to reach the archegonium.
Therefore,they are described as biflagellate.
In bryophytes,the male gametes are known as antherozoids.
These antherozoids are comma-shaped and possess two flagella at the anterior end,which helps them swim in water to reach the archegonium.
Therefore,they are described as biflagellate.
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76
BiologyEasyMCQAIPMT · 1999
In the sporangium of $..........$,a specialized structure called columella is found.
A
$Ulothrix$
B
$Rhizopus$
C
$Spirogyra$
D
None of the above
Solution
(B) The columella is a sterile,dome-shaped structure found inside the sporangium of certain fungi,particularly in the order $Mucorales$.
$Rhizopus$,commonly known as the bread mold,belongs to this group.
In $Rhizopus$,the sporangium contains a central,sterile,dome-shaped portion known as the columella,which provides support and helps in the dispersal of spores.
$Rhizopus$,commonly known as the bread mold,belongs to this group.
In $Rhizopus$,the sporangium contains a central,sterile,dome-shaped portion known as the columella,which provides support and helps in the dispersal of spores.
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77
BiologyMediumMCQAIPMT · 1999
Which of the following is $NOT$ found in birds?
A
Hind limbs
B
Pectoral girdle
C
Pelvic girdle
D
Forelimbs
Solution
(D) In birds $(Class-Aves)$,the forelimbs are modified into wings for flight. Therefore,they do not possess typical forelimbs as seen in other tetrapods. Instead,they have wings. Hind limbs are present and adapted for walking,swimming,or perching. Both pectoral and pelvic girdles are present to support the wings and hind limbs,respectively.
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78
BiologyEasyMCQAIPMT · 1999
The water vascular system is a characteristic feature of which of the following phyla?
A
Echinodermata
B
Platyhelminthes
C
Cnidaria
D
Porifera
Solution
(A) The water vascular system is a unique and characteristic feature of the phylum $Echinodermata$.
This system plays a crucial role in locomotion,capture and transport of food,and respiration.
While $Porifera$ (sponges) have a water canal system,it is distinct from the water vascular system of echinoderms.
Therefore,the correct option is $A$.
This system plays a crucial role in locomotion,capture and transport of food,and respiration.
While $Porifera$ (sponges) have a water canal system,it is distinct from the water vascular system of echinoderms.
Therefore,the correct option is $A$.
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79
BiologyEasyMCQAIPMT · 1999
Which plant produces haustorial roots?
A
Trapa
B
Orchid
C
Cuscuta
D
Podostemon
Solution
(C) Haustorial roots or parasitic roots are specialized roots found in parasitic plants that penetrate the host plant's tissues to absorb nutrients and water.
$Cuscuta$ (dodder) is a well-known total stem parasite that produces haustorial roots to derive nutrition from its host plant.
Therefore,the correct option is $C$.
$Cuscuta$ (dodder) is a well-known total stem parasite that produces haustorial roots to derive nutrition from its host plant.
Therefore,the correct option is $C$.
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80
BiologyEasyMCQAIPMT · 1999
The angiosperm that produces the largest flower is a ........
A
Total stem parasite
B
Partial stem parasite
C
Total root parasite
D
Partial root parasite
Solution
(C) The angiosperm that produces the largest flower is $Rafflesia$ $arnoldii$.
$Rafflesia$ is a genus of parasitic flowering plants.
It does not have visible leaves,stems,or roots,and it lives inside the host plant's tissue.
It absorbs nutrients from the host plant,specifically from the roots of the genus $Tetrastigma$.
Therefore,it is classified as a total root parasite.
$Rafflesia$ is a genus of parasitic flowering plants.
It does not have visible leaves,stems,or roots,and it lives inside the host plant's tissue.
It absorbs nutrients from the host plant,specifically from the roots of the genus $Tetrastigma$.
Therefore,it is classified as a total root parasite.
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81
BiologyMediumMCQAIPMT · 1999
Identify the type of placentation where the ovary is multicarpellary,unilocular,and ovules are borne on the periphery.
A
Axile placentation
B
Parietal placentation
C
Marginal placentation
D
Basal placentation
Solution
(B) In $Parietal$ $placentation$,the ovules develop on the inner wall of the ovary or on peripheral parts. The ovary is typically multicarpellary and unilocular (e.g.,in $Mustard$ and $Argemone$).
$1$. $Axile$ $placentation$: Ovules are attached to a central axis in a multilocular ovary.
$2$. $Marginal$ $placentation$: The placenta forms a ridge along the ventral suture of the ovary.
$3$. $Basal$ $placentation$: The placenta develops at the base of the ovary and a single ovule is attached to it.
$1$. $Axile$ $placentation$: Ovules are attached to a central axis in a multilocular ovary.
$2$. $Marginal$ $placentation$: The placenta forms a ridge along the ventral suture of the ovary.
$3$. $Basal$ $placentation$: The placenta develops at the base of the ovary and a single ovule is attached to it.
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82
BiologyEasyMCQAIPMT · 1999
Where are the Casparian strips found?
A
Epidermis
B
Endodermis
C
Pericycle
D
Phloem
Solution
(B) The Casparian strips are characteristic features of the endodermis in the roots of vascular plants.
These are bands of suberin-impregnated cell wall material that prevent the apoplastic movement of water and solutes into the vascular cylinder.
Therefore,the correct option is $B$.
These are bands of suberin-impregnated cell wall material that prevent the apoplastic movement of water and solutes into the vascular cylinder.
Therefore,the correct option is $B$.
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83
BiologyEasyMCQAIPMT · 1999
$DNA$ is primarily found in:
A
Nucleus
B
Cytoplasm
C
Both $(a)$ and $(b)$
D
Nucleolus
Solution
(A) $DNA$ (Deoxyribonucleic acid) is the genetic material of eukaryotic cells. It is primarily located within the nucleus,where it is organized into chromosomes. While small amounts of $DNA$ are also found in mitochondria and chloroplasts (which are organelles in the cytoplasm),the primary and most significant location for the bulk of cellular $DNA$ is the nucleus.
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84
BiologyMediumMCQAIPMT · 1999
Which organelles contain enzymes that convert fats into carbohydrates?
A
Liposomes
B
Golgi bodies
C
Microsomes
D
Glyoxysomes
Solution
(D) Glyoxysomes are specialized peroxisomes found in plants,particularly in the germinating seeds of oil-rich plants.
They contain enzymes for the glyoxylate cycle,which allows the conversion of stored fatty acids into carbohydrates (sugars) through gluconeogenesis.
This process provides the necessary energy and carbon skeletons for the growth of the embryo before it becomes photosynthetically active.
They contain enzymes for the glyoxylate cycle,which allows the conversion of stored fatty acids into carbohydrates (sugars) through gluconeogenesis.
This process provides the necessary energy and carbon skeletons for the growth of the embryo before it becomes photosynthetically active.
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85
BiologyEasyMCQAIPMT · 1999
Which of the following organelles is single-membrane bound?
A
Nucleus
B
Cell wall
C
Mitochondria
D
Sphaerosomes
Solution
(D) $1$. The $Nucleus$ and $Mitochondria$ are double-membrane bound organelles.
$2$. The $Cell wall$ is a non-membranous structure (it is a cell boundary).
$3$. $Sphaerosomes$ are small, spherical, single-membrane bound organelles found in plant cells, primarily involved in the storage and synthesis of lipids.
$2$. The $Cell wall$ is a non-membranous structure (it is a cell boundary).
$3$. $Sphaerosomes$ are small, spherical, single-membrane bound organelles found in plant cells, primarily involved in the storage and synthesis of lipids.
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86
BiologyEasyMCQAIPMT · 1999
Where does protein synthesis occur?
A
Ribosome
B
Mitochondria
C
Centrosome
D
Golgi apparatus
Solution
(A) Protein synthesis is the process by which cells make proteins.
In all living cells,the primary site for protein synthesis is the $Ribosome$.
Ribosomes are small,dense,granular structures composed of $RNA$ and proteins,which act as the machinery for translating $mRNA$ into polypeptide chains.
In all living cells,the primary site for protein synthesis is the $Ribosome$.
Ribosomes are small,dense,granular structures composed of $RNA$ and proteins,which act as the machinery for translating $mRNA$ into polypeptide chains.
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87
BiologyMediumMCQAIPMT · 1999
Aquatic reptiles are .......... .
A
Ureotelic
B
Ammonotelic
C
Ureotelic in water
D
Ureotelic on land
Solution
(B) The mode of excretion depends on the availability of water in the environment.
Ammonia is highly toxic and requires a large amount of water for its elimination.
Therefore,aquatic animals,including aquatic reptiles,are ammonotelic because they live in an environment where water is abundant,allowing them to easily excrete ammonia.
Ammonia is highly toxic and requires a large amount of water for its elimination.
Therefore,aquatic animals,including aquatic reptiles,are ammonotelic because they live in an environment where water is abundant,allowing them to easily excrete ammonia.
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88
BiologyMediumMCQAIPMT · 1999
Tendons are made up of .......
A
Adipose tissue
B
Modified white fibrous tissue
C
Areolar connective tissue
D
Yellow fibrous connective tissue
Solution
(B) Tendons are specialized dense regular connective tissues that connect skeletal muscles to bones.
They are primarily composed of collagen fibers arranged in parallel bundles.
These fibers are derived from white fibrous connective tissue,which provides high tensile strength and minimal flexibility,making them ideal for transmitting the force generated by muscle contraction to the bones.
They are primarily composed of collagen fibers arranged in parallel bundles.
These fibers are derived from white fibrous connective tissue,which provides high tensile strength and minimal flexibility,making them ideal for transmitting the force generated by muscle contraction to the bones.
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89
BiologyMediumMCQAIPMT · 1999
$A$ ligament is ............... .
A
Modified yellow elastic fibrous tissue
B
Inelastic white fibrous tissue
C
Loose connective tissue
D
None of the above
Solution
(A) ligament is a specialized type of dense connective tissue. It is primarily composed of yellow elastic fibers,which provide the necessary elasticity and strength to connect bones to other bones. Therefore,it is classified as a modified yellow elastic fibrous tissue.
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90
BiologyMediumMCQAIPMT · 1999
The respiratory rhythm center is located in the .......
A
Cerebellum
B
Medulla oblongata
C
Hypothalamus
D
Cerebrum
Solution
(B) The respiratory rhythm center is a specialized center primarily responsible for the regulation of respiration. It is located in the medulla region of the hindbrain. This center is primarily responsible for the regulation of respiratory rhythm.
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91
BiologyMediumMCQAIPMT · 1999
The gap between the axon of one neuron and the dendrite of another is called . . . . . . .
A
Junction point
B
Synapse
C
Joint
D
Continuous bridge
Solution
(B) $Synapse$ is the functional junction between two neurons. It consists of the presynaptic membrane (axon terminal of one neuron), the synaptic cleft (the gap), and the postsynaptic membrane (dendrite or cell body of another neuron). Therefore, the gap between the axon of one neuron and the dendrite of another is known as a $Synapse$.
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92
BiologyMediumMCQAIPMT · 1999
Which of the following is considered the structural and functional unit of neural tissue?
A
Myelin sheath
B
Axon
C
Dendrite
D
Neuron
Solution
(D) The neural tissue is composed of neurons and neuroglial cells.
Neurons are the structural and functional units of the nervous system.
They are specialized cells that receive,process,and transmit information through electrical and chemical signals.
While axons,dendrites,and myelin sheaths are parts of a neuron,the entire cell itself is the fundamental unit.
Neurons are the structural and functional units of the nervous system.
They are specialized cells that receive,process,and transmit information through electrical and chemical signals.
While axons,dendrites,and myelin sheaths are parts of a neuron,the entire cell itself is the fundamental unit.
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93
BiologyEasyMCQAIPMT · 1999
Which cranial nerve has the largest number of branches?
A
Facial nerve
B
Trigeminal nerve
C
Vagus nerve
D
None of the above
Solution
(C) The $Vagus$ nerve (Cranial nerve $X$) is the longest and most widely distributed cranial nerve.
It originates from the medulla oblongata and extends down into the chest and abdomen.
It has the largest number of branches,providing parasympathetic innervation to the heart,lungs,and most of the digestive tract.
It originates from the medulla oblongata and extends down into the chest and abdomen.
It has the largest number of branches,providing parasympathetic innervation to the heart,lungs,and most of the digestive tract.
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94
BiologyMediumMCQAIPMT · 1999
Diabetes mellitus is caused by the deficiency of which of the following?
A
Iodine deficiency
B
Hormonal deficiency
C
$Na^+$ deficiency
D
Enzyme deficiency
Solution
(B) Diabetes mellitus is a metabolic disorder characterized by high blood glucose levels. It is primarily caused by the deficiency or ineffective action of the hormone $Insulin$,which is secreted by the $\beta$-cells of the Islets of Langerhans in the pancreas. Therefore,it is categorized as a hormonal deficiency.
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95
BiologyEasyMCQAIPMT · 1999
Gonadotropic hormones are produced by ...........
A
Interstitial cells of the testis
B
Adrenal cortex
C
Adenohypophysis of the pituitary
D
Posterior part of the thyroid
Solution
(C) Gonadotropic hormones,specifically $FSH$ (Follicle Stimulating Hormone) and $LH$ (Luteinizing Hormone),are secreted by the anterior lobe of the pituitary gland,which is known as the adenohypophysis.
These hormones play a crucial role in regulating the reproductive functions of the gonads (testes and ovaries).
These hormones play a crucial role in regulating the reproductive functions of the gonads (testes and ovaries).
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96
BiologyEasyMCQAIPMT · 1999
What is the term for the series of changes that occur from the larval stage to the adult stage after embryonic development?
A
Regeneration
B
Metamorphosis
C
Growth
D
Senescence
Solution
(B) The process of transformation from an immature form (larva) to an adult form in two or more distinct stages is known as $Metamorphosis$. This is commonly observed in insects like butterflies and frogs. $Regeneration$ is the ability to regrow lost body parts. $Growth$ refers to an increase in size or mass. $Senescence$ refers to the process of aging.
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97
BiologyMediumMCQAIPMT · 1999
Which of the following statements is incorrect regarding Cytochrome $P450$?
A
It contains iron.
B
It is a colored cell.
C
It plays an important role in metabolism.
D
It is an enzyme involved in oxidation-reduction reactions.
Solution
(B) Cytochrome $P450$ $(CYP)$ is a large and diverse superfamily of hemoproteins (proteins containing a heme cofactor with an iron atom).
They function as monooxygenases and are primarily involved in the metabolism of drugs,toxins,and endogenous compounds in the liver and other tissues.
They are enzymes involved in oxidation-reduction reactions.
The term 'Cytochrome' refers to a pigment-containing protein,not a 'colored cell'. Therefore,the statement that it is a 'colored cell' is incorrect.
They function as monooxygenases and are primarily involved in the metabolism of drugs,toxins,and endogenous compounds in the liver and other tissues.
They are enzymes involved in oxidation-reduction reactions.
The term 'Cytochrome' refers to a pigment-containing protein,not a 'colored cell'. Therefore,the statement that it is a 'colored cell' is incorrect.
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98
BiologyEasyMCQAIPMT · 1999
The water available to plants (roots) in the soil is known as:
A
Capillary water
B
Hygroscopic water
C
Gravitational water
D
Chemically bound water
Solution
(A) Plants absorb water from the soil primarily through their roots.
Soil water exists in various forms:
$1$. Gravitational water: This water drains away deep into the soil due to gravity and is generally unavailable to plants.
$2$. Hygroscopic water: This water is held tightly by soil particles and is not available to plants.
$3$. Chemically bound water: This water is part of the chemical structure of soil minerals and is unavailable.
$4$. Capillary water: This water is held in the capillary spaces between soil particles against the force of gravity. It is the form of water that is readily available for absorption by plant roots.
Therefore,the correct answer is $A$.
Soil water exists in various forms:
$1$. Gravitational water: This water drains away deep into the soil due to gravity and is generally unavailable to plants.
$2$. Hygroscopic water: This water is held tightly by soil particles and is not available to plants.
$3$. Chemically bound water: This water is part of the chemical structure of soil minerals and is unavailable.
$4$. Capillary water: This water is held in the capillary spaces between soil particles against the force of gravity. It is the form of water that is readily available for absorption by plant roots.
Therefore,the correct answer is $A$.
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99
BiologyEasyMCQAIPMT · 1999
In the Calvin cycle of $C_3$ plants,which molecule acts as the primary $CO_2$ acceptor?
A
Phosphoenolpyruvate $(PEP)$
B
Ribulose $1,5$-bisphosphate $(RuBP)$
C
Phosphoglyceric acid $(PGA)$
D
Ribulose monophosphate $(RMP)$
Solution
(B) In the Calvin cycle,which occurs in the stroma of chloroplasts,the primary $CO_2$ acceptor is a $5$-carbon ketose sugar called Ribulose $1,5$-bisphosphate $(RuBP)$.
This reaction is catalyzed by the enzyme Ribulose bisphosphate carboxylase-oxygenase $(RuBisCO)$.
$PEP$ is the primary $CO_2$ acceptor in $C_4$ plants,while $PGA$ is the first stable product of the Calvin cycle.
This reaction is catalyzed by the enzyme Ribulose bisphosphate carboxylase-oxygenase $(RuBisCO)$.
$PEP$ is the primary $CO_2$ acceptor in $C_4$ plants,while $PGA$ is the first stable product of the Calvin cycle.
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100
BiologyMediumMCQAIPMT · 1999
Which is the most abundant enzyme on Earth?
A
Catalase
B
RuBisCO
C
Nitrogenase
D
Invertase
Solution
(B) The enzyme $RuBisCO$ (Ribulose$-1,5-$bisphosphate carboxylase-oxygenase) is the most abundant protein and enzyme on Earth.
It plays a critical role in the Calvin cycle of photosynthesis,where it catalyzes the fixation of atmospheric $CO_2$ into organic compounds.
Because it is essential for the primary production of biomass in almost all plants,it is found in massive quantities in the chloroplasts of photosynthetic organisms.
It plays a critical role in the Calvin cycle of photosynthesis,where it catalyzes the fixation of atmospheric $CO_2$ into organic compounds.
Because it is essential for the primary production of biomass in almost all plants,it is found in massive quantities in the chloroplasts of photosynthetic organisms.
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101
BiologyEasyMCQAIPMT · 1999
$DDT$ is a
A
Non-biodegradable pollutant
B
Biodegradable pollutant
C
Antibiotics
D
None of the above
Solution
(A) $DDT$ (Dichlorodiphenyltrichloroethane) is a non-biodegradable pollutant.
These substances are persistent in the environment because they cannot be broken down naturally or by the metabolic activities of microorganisms.
Due to their chemical stability,they accumulate in the food chain and are not recycled back into the atmosphere or soil in a harmless form.
These substances are persistent in the environment because they cannot be broken down naturally or by the metabolic activities of microorganisms.
Due to their chemical stability,they accumulate in the food chain and are not recycled back into the atmosphere or soil in a harmless form.
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102
BiologyEasyMCQAIPMT · 1999
$PAN$ $(Peroxyacetyl \text{ nitrate})$ is an important constituent of photochemical smog. It is a
A
Primary pollutant
B
Secondary pollutant
C
Natural pollutant
D
Corollary pollutant
Solution
(B) $PAN$ is a secondary pollutant.
Pollutants that are formed by the chemical interaction of primary pollutants with atmospheric gases and moisture, often catalyzed by sunlight, are called secondary pollutants.
Since $PAN$ is produced in the atmosphere through the reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight, it is classified as a secondary pollutant.
Pollutants that are formed by the chemical interaction of primary pollutants with atmospheric gases and moisture, often catalyzed by sunlight, are called secondary pollutants.
Since $PAN$ is produced in the atmosphere through the reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight, it is classified as a secondary pollutant.
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103
BiologyMediumMCQAIPMT · 1999
The secondary pollutant that inhibits the Hill reaction is:
A
Sulphuric acid
B
Nitric acid
C
Peroxyacetyl nitrate $(PAN)$
D
Aldehydes
Solution
(C) The correct answer is $(C)$.
Peroxyacetyl nitrate $(PAN)$ is a secondary pollutant formed by the photochemical reaction of nitrogen oxides and hydrocarbons.
It is known to inhibit the Hill reaction,which is the light-dependent reaction of photosynthesis.
Specifically,$PAN$ interferes with the photolysis of water,thereby disrupting the electron transport chain and reducing the efficiency of photosynthesis in plants.
Peroxyacetyl nitrate $(PAN)$ is a secondary pollutant formed by the photochemical reaction of nitrogen oxides and hydrocarbons.
It is known to inhibit the Hill reaction,which is the light-dependent reaction of photosynthesis.
Specifically,$PAN$ interferes with the photolysis of water,thereby disrupting the electron transport chain and reducing the efficiency of photosynthesis in plants.
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104
BiologyEasyMCQAIPMT · 1999
In $1984$,the Bhopal gas tragedy was caused due to the leakage of
A
Sodium monoxide
B
Sodium thiocyanate
C
Potassium isocyanate
D
Methyl isocyanate
Solution
(D) The Bhopal gas tragedy occurred on the night of $2-3$ December $1984$ at the Union Carbide India Limited $(UCIL)$ pesticide plant in Bhopal,Madhya Pradesh,India.
This disaster was caused by the accidental leakage of a highly toxic gas known as Methyl Isocyanate $(MIC)$,with the chemical formula $CH_3NCO$.
It is considered one of the world's worst industrial disasters,resulting in thousands of immediate deaths and long-term health complications for the local population.
This disaster was caused by the accidental leakage of a highly toxic gas known as Methyl Isocyanate $(MIC)$,with the chemical formula $CH_3NCO$.
It is considered one of the world's worst industrial disasters,resulting in thousands of immediate deaths and long-term health complications for the local population.
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105
BiologyEasyMCQAIPMT · 1999
Greenhouse effect refers to
A
Cooling of earth
B
Trapping of $UV$ rays
C
Production of cereals
D
Warming of earth
Solution
(D) The greenhouse effect is a natural process that warms the earth's surface.
When the sun's energy reaches the earth's atmosphere,some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
An increase in the concentration of greenhouse gases like $CO_2$,$CH_4$,$CFCs$,and $N_2O$ due to human activities has led to an enhanced greenhouse effect,which results in global warming or the warming of the earth.
When the sun's energy reaches the earth's atmosphere,some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
An increase in the concentration of greenhouse gases like $CO_2$,$CH_4$,$CFCs$,and $N_2O$ due to human activities has led to an enhanced greenhouse effect,which results in global warming or the warming of the earth.
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106
BiologyEasyMCQAIPMT · 1999
Which of the following is a pollution-related disorder?
A
Hypertension
B
Leprosy
C
Silicosis
D
Pneumoconiosis
Solution
(C) is the correct answer. Silicosis is an occupational respiratory disease caused by the inhalation of dust containing free silica or silicon dioxide. It is commonly observed in workers engaged in mining,pottery,ceramic industries,sandblasting,and construction industries.
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107
BiologyMediumMCQAIPMT · 1999
Which of the following organisms is likely to have the highest concentration of $D.D.T.$ in its body?
A
Herbivores
B
Carnivores
C
Top carnivores
D
Primary producers
Solution
(C) The phenomenon of increase in the concentration of non-biodegradable pollutants at successive trophic levels is known as $Biomagnification$.
$D.D.T.$ is a persistent, non-biodegradable chemical that accumulates in the fatty tissues of organisms.
As we move up the food chain, the concentration of $D.D.T.$ increases because each higher trophic level consumes a large number of organisms from the lower level, accumulating the toxin.
Therefore, the $Top$ carnivores (such as birds of prey or large fish) occupy the highest trophic level and accumulate the highest concentration of $D.D.T.$ in their bodies.
$D.D.T.$ is a persistent, non-biodegradable chemical that accumulates in the fatty tissues of organisms.
As we move up the food chain, the concentration of $D.D.T.$ increases because each higher trophic level consumes a large number of organisms from the lower level, accumulating the toxin.
Therefore, the $Top$ carnivores (such as birds of prey or large fish) occupy the highest trophic level and accumulate the highest concentration of $D.D.T.$ in their bodies.
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108
BiologyMediumMCQAIPMT · 1999
The technique by which "Dolly" the sheep was obtained is termed as
A
Cloning by gene transfer
B
Cloning by nuclear transfer
C
Cloning without the help of gametes
D
Cloning by tissue culture of somatic cells
Solution
(B) The correct answer is $B$.
"Dolly" the sheep was created using the technique of somatic cell nuclear transfer $(SCNT)$.
In this process, the nucleus from a somatic cell (udder cell) of a donor sheep was extracted and transferred into an enucleated egg cell (an egg cell from which the nucleus had been removed) of another sheep.
This reconstructed egg was then implanted into a surrogate mother, resulting in the birth of "Dolly", a genetic clone of the donor sheep.
"Dolly" the sheep was created using the technique of somatic cell nuclear transfer $(SCNT)$.
In this process, the nucleus from a somatic cell (udder cell) of a donor sheep was extracted and transferred into an enucleated egg cell (an egg cell from which the nucleus had been removed) of another sheep.
This reconstructed egg was then implanted into a surrogate mother, resulting in the birth of "Dolly", a genetic clone of the donor sheep.
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109
BiologyEasyMCQAIPMT · 1999
The ultrastructure of a cell can be best studied by:
A
Autoradiography
B
$X$-ray diffraction method
C
Phase contrast microscope
D
Electron microscope
Solution
(D) The ultrastructure refers to the detailed internal structure of cells and organelles that can only be resolved at very high magnification and resolution.
An electron microscope uses a beam of accelerated electrons as a source of illumination,which has a much shorter wavelength than visible light.
This allows for a significantly higher resolving power compared to light microscopes,making it the ideal tool for observing the ultrastructure of cellular components.
An electron microscope uses a beam of accelerated electrons as a source of illumination,which has a much shorter wavelength than visible light.
This allows for a significantly higher resolving power compared to light microscopes,making it the ideal tool for observing the ultrastructure of cellular components.
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110
BiologyMediumMCQAIPMT · 1999
If a colour blind woman marries a normal visioned man,their sons will be
A
all colour blind
B
all normal visioned
C
one-half colour blind and one-half normal
D
three-fourths colour blind and one-fourth normal
Solution
(A) Colour blindness is a recessive sex-linked trait caused by a gene on the $X$ chromosome.
Let $X^c$ represent the allele for colour blindness and $X$ represent the normal allele.
$A$ colour blind woman has the genotype $X^c X^c$.
$A$ normal visioned man has the genotype $XY$.
When they reproduce,the cross is $X^c X^c \times XY$.
The possible genotypes for the offspring are $X^c X$ (carrier daughters) and $X^c Y$ (colour blind sons).
Since all sons receive their $X$ chromosome from their mother,and the mother is colour blind $(X^c X^c)$,all sons will inherit the $X^c$ allele.
Therefore,all sons will be colour blind.
Let $X^c$ represent the allele for colour blindness and $X$ represent the normal allele.
$A$ colour blind woman has the genotype $X^c X^c$.
$A$ normal visioned man has the genotype $XY$.
When they reproduce,the cross is $X^c X^c \times XY$.
The possible genotypes for the offspring are $X^c X$ (carrier daughters) and $X^c Y$ (colour blind sons).
Since all sons receive their $X$ chromosome from their mother,and the mother is colour blind $(X^c X^c)$,all sons will inherit the $X^c$ allele.
Therefore,all sons will be colour blind.
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111
BiologyEasyMCQAIPMT · 1999
The fish used for the control of mosquitoes,known as the larvicidal fish,is ..............
A
Eel
B
Carp
C
Catfish
D
Gambusia
Solution
(D) The fish $Gambusia$ is widely known as the larvicidal fish.
It is used as a biological control agent to manage mosquito populations.
$Gambusia$ feeds on the larvae of mosquitoes,thereby preventing them from reaching the adult stage and reducing the spread of diseases like malaria and dengue.
It is used as a biological control agent to manage mosquito populations.
$Gambusia$ feeds on the larvae of mosquitoes,thereby preventing them from reaching the adult stage and reducing the spread of diseases like malaria and dengue.
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112
BiologyEasyMCQAIPMT · 1999
The edible part of the litchi fruit is:
A
Mesocarp
B
Fleshy aril
C
Endocarp
D
Pericarp
Solution
(B) The edible part of the litchi $(Litchi chinensis)$ is the fleshy,succulent outgrowth that develops from the base of the ovule,which is known as the aril.
Therefore,the correct option is $B$.
Therefore,the correct option is $B$.
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113
BiologyMediumMCQAIPMT · 1999
The eukaryotic genome is different from the prokaryotic genome because . . . . . . .
A
$DNA$ in prokaryotes is associated with histones.
B
Repetitive sequences are present in eukaryotes.
C
Genes in eukaryotes are organized as operons.
D
$DNA$ in prokaryotes is circular and single-stranded.
Solution
(B) The eukaryotic genome differs from the prokaryotic genome in several ways. One key difference is the presence of repetitive $DNA$ sequences in eukaryotes,which are largely absent or very rare in prokaryotes.
Regarding the other options:
$A$ is incorrect because histones are characteristic of eukaryotic $DNA$,not prokaryotic.
$C$ is incorrect because operons are a characteristic feature of prokaryotic gene regulation,not eukaryotic.
$D$ is incorrect because prokaryotic $DNA$ is circular but double-stranded,not single-stranded.
Regarding the other options:
$A$ is incorrect because histones are characteristic of eukaryotic $DNA$,not prokaryotic.
$C$ is incorrect because operons are a characteristic feature of prokaryotic gene regulation,not eukaryotic.
$D$ is incorrect because prokaryotic $DNA$ is circular but double-stranded,not single-stranded.
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114
BiologyMediumMCQAIPMT · 1999
The secretion of progesterone by the corpus luteum is initiated by:
A
Thyroxine
B
$LH$
C
$MSH$
D
Testosterone
Solution
(B) The corpus luteum is a temporary endocrine structure in female mammals that is involved in the production of relatively high levels of progesterone.
Its formation and the maintenance of its secretory function are primarily regulated by the Luteinizing Hormone $(LH)$,which is secreted by the anterior pituitary gland.
$LH$ stimulates the corpus luteum to produce progesterone,which is essential for maintaining the endometrium during pregnancy.
Its formation and the maintenance of its secretory function are primarily regulated by the Luteinizing Hormone $(LH)$,which is secreted by the anterior pituitary gland.
$LH$ stimulates the corpus luteum to produce progesterone,which is essential for maintaining the endometrium during pregnancy.
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115
BiologyMediumMCQAIPMT · 1999
Which of the following characteristics are typically observed in bird-pollinated flowers (ornithophily)?
A
Blue-colored flowers with nectar glands at the base of the petals.
B
Red and sweet-scented flowers containing nectar glands.
C
Bright red-colored flowers with a dense inflorescence.
D
White flowers that are highly fragrant.
Solution
(C) Bird-pollinated flowers,known as ornithophilous flowers,exhibit specific adaptations to attract birds.
$1$. Birds have a keen sense of color,particularly for bright colors like red,orange,and yellow.
$2$. These flowers are typically large,tubular,or funnel-shaped to accommodate the bird's beak.
$3$. They produce copious amounts of nectar to reward the pollinators.
$4$. Unlike insect-pollinated flowers,bird-pollinated flowers usually lack a strong scent,as birds have a poor sense of smell.
$5$. Therefore,bright red-colored flowers with a dense inflorescence are characteristic of bird pollination.
$1$. Birds have a keen sense of color,particularly for bright colors like red,orange,and yellow.
$2$. These flowers are typically large,tubular,or funnel-shaped to accommodate the bird's beak.
$3$. They produce copious amounts of nectar to reward the pollinators.
$4$. Unlike insect-pollinated flowers,bird-pollinated flowers usually lack a strong scent,as birds have a poor sense of smell.
$5$. Therefore,bright red-colored flowers with a dense inflorescence are characteristic of bird pollination.
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116
BiologyEasyMCQAIPMT · 1999
After ovulation, the Graafian follicle transforms into which of the following?
A
Corpus luteum
B
Corpus callosum
C
Corpus albicans
D
Corpus atretica
Solution
(A) After the process of ovulation, the ruptured Graafian follicle undergoes a transformation process called luteinization.
Under the influence of Luteinizing Hormone $(LH)$, the remaining follicular cells (granulosa and theca cells) differentiate into a glandular structure known as the $Corpus$ luteum.
The $Corpus$ luteum acts as an endocrine gland and secretes large amounts of progesterone, which is essential for maintaining the endometrium during a potential pregnancy.
Under the influence of Luteinizing Hormone $(LH)$, the remaining follicular cells (granulosa and theca cells) differentiate into a glandular structure known as the $Corpus$ luteum.
The $Corpus$ luteum acts as an endocrine gland and secretes large amounts of progesterone, which is essential for maintaining the endometrium during a potential pregnancy.
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117
BiologyEasyMCQAIPMT · 1999
What does the middle piece of a human sperm contain?
A
Mitochondria and centriole
B
Mitochondria only
C
Centriole only
D
Nucleus and mitochondria
Solution
(B) The human sperm is composed of a head,neck,middle piece,and tail.
The middle piece contains numerous mitochondria,which are arranged in a spiral pattern (often called the $Nebelkern$).
These mitochondria provide the energy required for the movement of the tail,which facilitates sperm motility.
While the neck contains the proximal and distal centrioles,the middle piece is specifically characterized by the presence of mitochondria.
The middle piece contains numerous mitochondria,which are arranged in a spiral pattern (often called the $Nebelkern$).
These mitochondria provide the energy required for the movement of the tail,which facilitates sperm motility.
While the neck contains the proximal and distal centrioles,the middle piece is specifically characterized by the presence of mitochondria.
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118
BiologyMediumMCQAIPMT · 1999
Contraceptive pills contain ......... .
A
Progesterone
B
$FSH$
C
$LH$
D
Both $(B)$ and $(C)$
Solution
(A) Contraceptive pills,commonly known as oral contraceptive pills (OCPs),are used to prevent pregnancy.
These pills typically contain either a combination of synthetic progesterone and estrogen or only progesterone (mini-pill).
Progesterone inhibits ovulation by suppressing the release of gonadotropins ($FSH$ and $LH$) from the anterior pituitary gland.
Therefore,the correct answer is Progesterone.
These pills typically contain either a combination of synthetic progesterone and estrogen or only progesterone (mini-pill).
Progesterone inhibits ovulation by suppressing the release of gonadotropins ($FSH$ and $LH$) from the anterior pituitary gland.
Therefore,the correct answer is Progesterone.
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119
BiologyMediumMCQAIPMT · 1999
When one pair of genes suppresses the effect of another pair,the phenomenon is known as:
A
Epistasis
B
Dominance
C
Mutation
D
None of the above
Solution
(A) Epistasis is a genetic interaction where the expression of one gene is modified or masked by the presence of one or more other genes.
In this phenomenon,the gene that suppresses the effect of another gene is called the epistatic gene,and the gene whose effect is suppressed is called the hypostatic gene.
Unlike dominance,which involves the interaction between alleles of the same gene,epistasis involves the interaction between different gene loci.
In this phenomenon,the gene that suppresses the effect of another gene is called the epistatic gene,and the gene whose effect is suppressed is called the hypostatic gene.
Unlike dominance,which involves the interaction between alleles of the same gene,epistasis involves the interaction between different gene loci.
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120
BiologyEasyMCQAIPMT · 1999
Which of the following are the main categories of genetic disorders?
A
Mendelian disorders
B
Chromosomal disorders
C
Both $A$ and $B$
D
None of the above
Solution
(C) Genetic disorders are broadly grouped into two categories:
$1$. Mendelian disorders: These are primarily determined by alteration or mutation in the single gene. Examples include Hemophilia,Cystic fibrosis,Sickle-cell anemia,etc.
$2$. Chromosomal disorders: These are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Examples include Down's syndrome,Klinefelter's syndrome,and Turner's syndrome.
Therefore,both $A$ and $B$ are correct categories.
$1$. Mendelian disorders: These are primarily determined by alteration or mutation in the single gene. Examples include Hemophilia,Cystic fibrosis,Sickle-cell anemia,etc.
$2$. Chromosomal disorders: These are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Examples include Down's syndrome,Klinefelter's syndrome,and Turner's syndrome.
Therefore,both $A$ and $B$ are correct categories.
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121
BiologyMediumMCQAIPMT · 1999
$A$ hemophilic man marries a normal woman. What will be the nature of their offspring?
A
All sons hemophilic
B
All normal
C
All daughters hemophilic
D
All hemophilic
Solution
(B) Hemophilia is an $X$-linked recessive disorder.
Let $X^H$ represent the normal allele and $X^h$ represent the hemophilic allele.
The genotype of the hemophilic man is $X^hY$ and the genotype of the normal woman is $X^HX^H$.
When they cross: $X^hY \times X^HX^H$.
The offspring genotypes will be $X^HX^h$ (carrier daughter) and $X^HY$ (normal son).
Since all daughters are carriers (phenotypically normal) and all sons are normal,all offspring are phenotypically normal.
Let $X^H$ represent the normal allele and $X^h$ represent the hemophilic allele.
The genotype of the hemophilic man is $X^hY$ and the genotype of the normal woman is $X^HX^H$.
When they cross: $X^hY \times X^HX^H$.
The offspring genotypes will be $X^HX^h$ (carrier daughter) and $X^HY$ (normal son).
Since all daughters are carriers (phenotypically normal) and all sons are normal,all offspring are phenotypically normal.
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122
BiologyMediumMCQAIPMT · 1999
What will be the phenotypic ratio of the offspring produced from the cross $Tt \times tt$?
A
$1 : 1$
B
$1 : 2 : 1$
C
$1 : 2$
D
$4 : 1$
Solution
(A) The cross $Tt \times tt$ is a test cross between a heterozygous dominant individual and a homozygous recessive individual.
When we perform the Punnett square for this cross:
- The gametes produced by $Tt$ are $T$ and $t$.
- The gametes produced by $tt$ are $t$ and $t$.
The resulting genotypes are $Tt, Tt, tt, tt$.
This results in $2$ tall $(Tt)$ and $2$ dwarf $(tt)$ offspring.
Therefore,the phenotypic ratio is $2 : 2$,which simplifies to $1 : 1$.
When we perform the Punnett square for this cross:
- The gametes produced by $Tt$ are $T$ and $t$.
- The gametes produced by $tt$ are $t$ and $t$.
The resulting genotypes are $Tt, Tt, tt, tt$.
This results in $2$ tall $(Tt)$ and $2$ dwarf $(tt)$ offspring.
Therefore,the phenotypic ratio is $2 : 2$,which simplifies to $1 : 1$.
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123
BiologyMediumMCQAIPMT · 1999
Which is the initiation codon for protein synthesis in eukaryotes?
A
$GUA$
B
$GCA$
C
$CCA$
D
$AUG$
Solution
(D) In protein synthesis,the process of translation begins with an initiation codon.
For both prokaryotes and eukaryotes,the codon $AUG$ serves as the initiation codon.
$AUG$ codes for the amino acid Methionine.
Therefore,the correct option is $D$.
For both prokaryotes and eukaryotes,the codon $AUG$ serves as the initiation codon.
$AUG$ codes for the amino acid Methionine.
Therefore,the correct option is $D$.
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124
BiologyMediumMCQAIPMT · 1999
In $DNA$,when the sequence is $AGCT$,what is the corresponding complementary strand sequence?
A
$ACGT$
B
$AGCT$
C
$TCGA$
D
All of the above
Solution
(C) According to the base-pairing rules of $DNA$ (Chargaff's rules),Adenine $(A)$ always pairs with Thymine $(T)$ and Guanine $(G)$ always pairs with Cytosine $(C)$.
Given the sequence $AGCT$ on one strand:
- $A$ pairs with $T$
- $G$ pairs with $C$
- $C$ pairs with $G$
- $T$ pairs with $A$
Therefore,the complementary sequence is $TCGA$.
Given the sequence $AGCT$ on one strand:
- $A$ pairs with $T$
- $G$ pairs with $C$
- $C$ pairs with $G$
- $T$ pairs with $A$
Therefore,the complementary sequence is $TCGA$.
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125
BiologyMediumMCQAIPMT · 1999
The pneumococcus experiment proves that...
A
$DNA$ is the genetic material.
B
$RNA$ sometimes regulates the synthesis of $DNA$ and proteins.
C
Bacteria undergo binary fission.
D
Bacteria do not undergo sexual reproduction.
Solution
(A) The pneumococcus experiment,famously known as Griffith's transformation experiment,demonstrated that a 'transforming principle' from heat-killed virulent $S$-strain bacteria could transform non-virulent $R$-strain bacteria into virulent $S$-strain bacteria. Later,Avery,MacLeod,and McCarty identified this 'transforming principle' as $DNA$. This experiment provided the first strong evidence that $DNA$ is the genetic material.
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126
BiologyMediumMCQAIPMT · 1999
Antibodies are ........
A
Germs
B
Carbohydrates
C
Proteins
D
Lipids
Solution
(C) Antibodies,also known as immunoglobulins,are specialized $Y$-shaped proteins produced by the immune system in response to the presence of antigens (foreign substances like bacteria or viruses).
These proteins recognize and bind to specific antigens to neutralize them or mark them for destruction by other immune cells.
Therefore,antibodies are classified as proteins.
These proteins recognize and bind to specific antigens to neutralize them or mark them for destruction by other immune cells.
Therefore,antibodies are classified as proteins.
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127
BiologyMediumMCQAIPMT · 1999
Homologous organs are ............. .
A
Wings of insects and wings of bats
B
Gills of fish and lungs of rabbits
C
Flipper of whale and forelimbs of horse
D
Wings of grasshopper and wings of crow
Solution
(C) Homologous organs are those organs that have the same basic structural design and developmental origin but perform different functions.
These organs indicate divergent evolution.
The flipper of a whale and the forelimbs of a horse are homologous because they share the same skeletal structure (humerus,radius,ulna,carpals,metacarpals,and phalanges) despite being adapted for swimming and running,respectively.
In contrast,wings of insects and bats,or grasshoppers and crows,are analogous organs because they perform the same function (flight) but have different evolutionary origins.
These organs indicate divergent evolution.
The flipper of a whale and the forelimbs of a horse are homologous because they share the same skeletal structure (humerus,radius,ulna,carpals,metacarpals,and phalanges) despite being adapted for swimming and running,respectively.
In contrast,wings of insects and bats,or grasshoppers and crows,are analogous organs because they perform the same function (flight) but have different evolutionary origins.
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128
BiologyMediumMCQAIPMT · 1999
Darwin's finches provide an excellent example in the context of evolution. From which field did this evidence come?
A
Biogeography
B
Anatomy
C
Embryology
D
Paleontology
Solution
(A) Darwin's finches are a classic example of adaptive radiation observed in the Galapagos Islands.
This evidence is based on the geographical distribution of species,which is known as Biogeography.
Darwin observed that different species of finches evolved from a common ancestor to adapt to different ecological niches on the islands,demonstrating how geographical isolation leads to speciation.
This evidence is based on the geographical distribution of species,which is known as Biogeography.
Darwin observed that different species of finches evolved from a common ancestor to adapt to different ecological niches on the islands,demonstrating how geographical isolation leads to speciation.
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129
BiologyMediumMCQAIPMT · 1999
Koch's postulates are not applicable to which of the following?
A
Cholera
B
Leprosy
C
Tuberculosis
D
Diphtheria
Solution
(B) Koch's postulates are a set of criteria designed to establish a causative relationship between a microbe and a disease.
However, they cannot be applied to all pathogens.
Leprosy (caused by $Mycobacterium leprae$) is an example where Koch's postulates are not applicable because the causative agent cannot be grown in a cell-free culture medium (it is an obligate intracellular parasite).
Therefore, the correct answer is $B$.
However, they cannot be applied to all pathogens.
Leprosy (caused by $Mycobacterium leprae$) is an example where Koch's postulates are not applicable because the causative agent cannot be grown in a cell-free culture medium (it is an obligate intracellular parasite).
Therefore, the correct answer is $B$.
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130
BiologyMediumMCQAIPMT · 1999
Hybridoma cells are .....
A
Products of spore formation in bacteria
B
Hybrid cells produced from myeloma cells
C
Neurons of frogs
D
Cells containing oncogenes
Solution
(B) Hybridoma cells are created by the fusion of a specific antibody-producing $B$-cell (lymphocyte) and a myeloma cell (a type of cancer cell).
These hybrid cells combine the ability to produce a specific antibody (from the $B$-cell) with the ability to divide indefinitely in culture (from the myeloma cell).
Therefore,hybridoma cells are hybrid cells produced from myeloma cells.
These hybrid cells combine the ability to produce a specific antibody (from the $B$-cell) with the ability to divide indefinitely in culture (from the myeloma cell).
Therefore,hybridoma cells are hybrid cells produced from myeloma cells.
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131
BiologyEasyMCQAIPMT · 1999
New varieties of plants are produced by ..........
A
Selection and hybridization
B
Selection and introduction
C
Mutation and selection
D
Introduction and mutation
Solution
(A) Plant breeding is the purposeful manipulation of plant species in order to create desired plant types that are better suited for cultivation,give better yields,and are disease resistant. The primary methods used for plant breeding are selection and hybridization. Selection involves choosing plants with desirable traits,while hybridization involves crossing two genetically different individuals to combine their favorable traits.
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132
BiologyEasyMCQAIPMT · 1999
Which of the following is a biofertilizer reported to increase rice production by more than $50\%$?
A
Mycorrhiza
B
Azolla pinnata
C
Cyanobacteria
D
Legume-Rhizobium symbiosis
Solution
(B) $Azolla$ $pinnata$ is a small aquatic fern that has a symbiotic relationship with the nitrogen-fixing cyanobacterium $Anabaena$ $azollae$.
This fern is widely used as a biofertilizer in rice fields because it fixes atmospheric nitrogen and provides it to the rice plants.
Studies have shown that the use of $Azolla$ can increase rice production by more than $50\%$ due to the enrichment of soil nitrogen content.
This fern is widely used as a biofertilizer in rice fields because it fixes atmospheric nitrogen and provides it to the rice plants.
Studies have shown that the use of $Azolla$ can increase rice production by more than $50\%$ due to the enrichment of soil nitrogen content.
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133
BiologyEasyMCQAIPMT · 1999
Which aquatic fern is considered a very good biofertilizer?
A
Azolla
B
Pteridium
C
Salvinia
D
Marsilea
Solution
(A) $Azolla$ is a small aquatic fern that has a symbiotic relationship with the nitrogen-fixing cyanobacterium $Anabaena$ $azollae$.
This association allows $Azolla$ to fix atmospheric nitrogen,making it an excellent biofertilizer for rice paddies.
It is widely used in agriculture to increase soil fertility naturally.
This association allows $Azolla$ to fix atmospheric nitrogen,making it an excellent biofertilizer for rice paddies.
It is widely used in agriculture to increase soil fertility naturally.
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134
BiologyEasyMCQAIPMT · 1999
Which of the following is related to genetic engineering?
A
Mutation
B
Plasmid
C
Plastids
D
Heterosis
Solution
(B) Genetic engineering involves the manipulation of $DNA$ to alter the characteristics of an organism.
Plasmids are small,circular,double-stranded $DNA$ molecules that are distinct from a cell's chromosomal $DNA$.
They are extensively used as vectors in genetic engineering to carry foreign genes into host cells for cloning or expression.
Therefore,plasmids are fundamental tools in genetic engineering.
Plasmids are small,circular,double-stranded $DNA$ molecules that are distinct from a cell's chromosomal $DNA$.
They are extensively used as vectors in genetic engineering to carry foreign genes into host cells for cloning or expression.
Therefore,plasmids are fundamental tools in genetic engineering.
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135
BiologyMediumMCQAIPMT · 1999
In plasmid $DNA$,the regulation of the process of replication,other than the origin of replication,is controlled by:
A
Mitochondrial gene
B
Bacterial gene
C
Plasmid gene
D
None of the above
Solution
(C) In plasmid $DNA$,replication is initiated at the origin of replication $(ori)$.
However,the regulation of the replication process,such as copy number control,is governed by the genes present within the plasmid itself.
These genes encode proteins that interact with the $ori$ site to determine how many times the plasmid replicates within the host cell.
Therefore,the regulation is controlled by the plasmid gene.
However,the regulation of the replication process,such as copy number control,is governed by the genes present within the plasmid itself.
These genes encode proteins that interact with the $ori$ site to determine how many times the plasmid replicates within the host cell.
Therefore,the regulation is controlled by the plasmid gene.
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136
BiologyEasyMCQAIPMT · 1999
Which part of the world has the highest population density of species?
A
Temperate deciduous forests
B
Grasslands
C
Savannas
D
Tropical rainforests
Solution
(D) Tropical rainforests,such as the Amazon,are known for having the highest biodiversity and species density on Earth. This is due to the stable,warm climate and abundant rainfall throughout the year,which supports a vast array of flora and fauna.
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137
BiologyMediumMCQAIPMT · 1999
Which animals are most affected by changes in environmental temperature?
A
Homeotherms
B
Aquatic
C
Poikilotherms
D
Desert-dwelling
Solution
(C) Poikilotherms (ectotherms) are animals whose internal body temperature varies significantly with the ambient environmental temperature. Unlike homeotherms (endotherms) that maintain a constant body temperature through metabolic processes,poikilotherms lack such internal regulatory mechanisms. Therefore,their physiological processes and metabolic rates are directly influenced by external temperature fluctuations,making them the most affected group.
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138
BiologyMediumMCQAIPMT · 1999
What is the major drawback of $DDT$ as an insecticide?
A
It becomes ineffective after some time.
B
It is less effective than others.
C
It is not biodegradable in nature.
D
It is very expensive.
Solution
(C) $DDT$ (Dichlorodiphenyltrichloroethane) is a persistent organic pollutant.
It is not biodegradable,meaning it cannot be easily broken down by microorganisms in the environment.
Due to this property,it accumulates in the tissues of organisms and undergoes biomagnification through the food chain,causing long-term ecological damage.
It is not biodegradable,meaning it cannot be easily broken down by microorganisms in the environment.
Due to this property,it accumulates in the tissues of organisms and undergoes biomagnification through the food chain,causing long-term ecological damage.
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139
BiologyMediumMCQAIPMT · 1999
The transfer of energy from one trophic level to another occurs according to the second law of thermodynamics. What is the average efficiency of energy transfer from herbivores to carnivores (in $\%$)?
A
$5$
B
$10$
C
$25$
D
$50$
Solution
(B) According to the $10\%$ law of energy transfer in an ecosystem,proposed by $Lindeman$ $(1942)$,only about $10\%$ of the energy available at one trophic level is transferred to the next trophic level.
This occurs because a large portion of the energy is lost as heat during metabolic activities,as dictated by the second law of thermodynamics.
Therefore,when energy is transferred from herbivores (primary consumers) to carnivores (secondary consumers),the average efficiency of energy transfer is $10\%$.
This occurs because a large portion of the energy is lost as heat during metabolic activities,as dictated by the second law of thermodynamics.
Therefore,when energy is transferred from herbivores (primary consumers) to carnivores (secondary consumers),the average efficiency of energy transfer is $10\%$.
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140
BiologyMediumMCQAIPMT · 1999
In which of the following aquatic ecosystems is the maximum biomagnification observed?
A
Fishes
B
Phytoplankton
C
Birds
D
Zooplankton
Solution
(C) Biomagnification refers to the increase in concentration of non-biodegradable substances (like $DDT$ or mercury) at successive trophic levels in a food chain.
In an aquatic ecosystem, the food chain typically follows the sequence: $Phytoplankton \rightarrow Zooplankton \rightarrow Small \ fish \rightarrow Large \ fish \rightarrow Fish-eating \ birds$.
Since the concentration of the toxicant increases as we move to higher trophic levels, the organism at the highest trophic level will accumulate the maximum concentration.
Among the given options, fish-eating birds occupy the highest trophic level, hence they exhibit the maximum biomagnification.
In an aquatic ecosystem, the food chain typically follows the sequence: $Phytoplankton \rightarrow Zooplankton \rightarrow Small \ fish \rightarrow Large \ fish \rightarrow Fish-eating \ birds$.
Since the concentration of the toxicant increases as we move to higher trophic levels, the organism at the highest trophic level will accumulate the maximum concentration.
Among the given options, fish-eating birds occupy the highest trophic level, hence they exhibit the maximum biomagnification.
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141
BiologyMediumMCQAIPMT · 1999
Which of the following is responsible for the extinction of wildlife?
A
Habitat loss
B
Air and water pollution
C
Hunting for meat
D
All of the above
Solution
(D) The extinction of wildlife is caused by several anthropogenic factors.
$1$. Habitat loss and fragmentation is the most important cause driving animals and plants to extinction.
$2$. Pollution of air and water leads to the degradation of ecosystems,making them unsuitable for survival.
$3$. Over-exploitation,such as hunting for meat or trade,significantly reduces population sizes,leading to extinction.
Therefore,all the mentioned factors contribute to the loss of biodiversity and wildlife extinction.
$1$. Habitat loss and fragmentation is the most important cause driving animals and plants to extinction.
$2$. Pollution of air and water leads to the degradation of ecosystems,making them unsuitable for survival.
$3$. Over-exploitation,such as hunting for meat or trade,significantly reduces population sizes,leading to extinction.
Therefore,all the mentioned factors contribute to the loss of biodiversity and wildlife extinction.
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142
BiologyEasyMCQAIPMT · 1999
The Bhopal gas tragedy in $1984$ was caused by the leakage of ......... .
A
Potassium isocyanate
B
Sodium monoxide
C
Sodium thiocyanate
D
Methyl isocyanate
Solution
(D) The Bhopal gas tragedy,which occurred on the night of $2-3$ December $1984$,was a major industrial disaster.
It was caused by the accidental leakage of a highly toxic gas called Methyl Isocyanate $(MIC)$ from the Union Carbide India Limited $(UCIL)$ pesticide plant in Bhopal,Madhya Pradesh.
This gas leak resulted in the deaths of thousands of people and caused long-term health issues for many others.
Therefore,the correct option is $D$.
It was caused by the accidental leakage of a highly toxic gas called Methyl Isocyanate $(MIC)$ from the Union Carbide India Limited $(UCIL)$ pesticide plant in Bhopal,Madhya Pradesh.
This gas leak resulted in the deaths of thousands of people and caused long-term health issues for many others.
Therefore,the correct option is $D$.
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143
BiologyEasyMCQAIPMT · 1999
$DDT$ is a/an:
A
Non-biodegradable pollutant
B
Antibiotic
C
Biodegradable pollutant
D
Not a pollutant
Solution
(A) $DDT$ (Dichlorodiphenyltrichloroethane) is a synthetic organochlorine chemical compound.
It is highly stable and resistant to environmental degradation by microorganisms.
Because it cannot be broken down easily by natural biological processes,it accumulates in the environment and in the tissues of living organisms,a process known as biomagnification.
Therefore,it is classified as a non-biodegradable pollutant.
It is highly stable and resistant to environmental degradation by microorganisms.
Because it cannot be broken down easily by natural biological processes,it accumulates in the environment and in the tissues of living organisms,a process known as biomagnification.
Therefore,it is classified as a non-biodegradable pollutant.
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144
BiologyEasyMCQAIPMT · 1999
The greenhouse effect refers to:
A
Production of crops
B
Cooling of the Earth
C
Absorption of $UV$ rays
D
Keeping the Earth warm
Solution
(D) The greenhouse effect is a natural process that warms the Earth's surface.
When the Sun's energy reaches the Earth's atmosphere,some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
These gases,such as $CO_2$,$CH_4$,and water vapor,trap heat in the atmosphere,thereby maintaining the Earth's temperature at a level suitable for life.
Without this effect,the Earth would be too cold to support life as we know it.
When the Sun's energy reaches the Earth's atmosphere,some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
These gases,such as $CO_2$,$CH_4$,and water vapor,trap heat in the atmosphere,thereby maintaining the Earth's temperature at a level suitable for life.
Without this effect,the Earth would be too cold to support life as we know it.
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145
BiologyEasyMCQAIPMT · 1999
Which of the following is a secondary pollutant?
A
Aerosols
B
$CO$
C
$PAN$
D
$CO_2$
Solution
(C) secondary pollutant is not emitted directly into the atmosphere but forms when primary pollutants react in the atmosphere.
$PAN$ (Peroxyacetyl nitrate) is a classic example of a secondary pollutant formed by the photochemical reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight.
$CO$,$CO_2$,and aerosols are generally considered primary pollutants as they are emitted directly from sources.
$PAN$ (Peroxyacetyl nitrate) is a classic example of a secondary pollutant formed by the photochemical reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight.
$CO$,$CO_2$,and aerosols are generally considered primary pollutants as they are emitted directly from sources.
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146
BiologyMediumMCQAIPMT · 1999
Which of the following is a pollution-related disease?
A
Fluorosis
B
Leprosy
C
Pneumoconiosis
D
Silicosis
Solution
(A) Pollution-related diseases are caused by the presence of harmful substances in the environment.
$1$. Fluorosis is caused by excessive intake of fluoride in drinking water.
$2$. Pneumoconiosis and Silicosis are occupational lung diseases caused by the inhalation of dust particles (like silica) in industrial environments.
However,in the context of general environmental pollution,$Fluorosis$ is a classic example of a disease caused by water pollution.
$Leprosy$ is an infectious disease caused by the bacterium $Mycobacterium leprae$ and is not caused by environmental pollution.
Since both $Fluorosis$ and $Silicosis$ are pollution-related,$Fluorosis$ is often cited in environmental studies as a primary water pollution-related disease.
$1$. Fluorosis is caused by excessive intake of fluoride in drinking water.
$2$. Pneumoconiosis and Silicosis are occupational lung diseases caused by the inhalation of dust particles (like silica) in industrial environments.
However,in the context of general environmental pollution,$Fluorosis$ is a classic example of a disease caused by water pollution.
$Leprosy$ is an infectious disease caused by the bacterium $Mycobacterium leprae$ and is not caused by environmental pollution.
Since both $Fluorosis$ and $Silicosis$ are pollution-related,$Fluorosis$ is often cited in environmental studies as a primary water pollution-related disease.
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147
BiologyEasyMCQAIPMT · 1999
Which part of the world has a high density of organisms?
A
Deciduous forests
B
Grasslands
C
Tropical rain forests
D
Savannahs
Solution
(C) Tropical rain forests have a high density of organisms.
Tropical rain forests are mainly found in Central America,South America,the Congo River basin of Africa,and South East Asia.
In this biome,rainfall and warmth are abundant,leading to luxuriant plant growth.
This biome possesses more than half of the world's flora and fauna.
Productivity is very high,and the diversity of life is so immense that a single hectare of forest may contain $200$ species of trees.
Approximately $70-80\%$ of all insects and $80-85\%$ of all birds are known to inhabit tropical rain forests.
Tropical rain forests are mainly found in Central America,South America,the Congo River basin of Africa,and South East Asia.
In this biome,rainfall and warmth are abundant,leading to luxuriant plant growth.
This biome possesses more than half of the world's flora and fauna.
Productivity is very high,and the diversity of life is so immense that a single hectare of forest may contain $200$ species of trees.
Approximately $70-80\%$ of all insects and $80-85\%$ of all birds are known to inhabit tropical rain forests.
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