BiologyQ1–88 of 121 questions
Page 1 of 2 · English
1
BiologyMediumMCQAIPMT · 1989
The Linnaeus system of plant classification is:
A
Artificial
B
Natural
C
Phylogenetic
D
None of the above
Solution
(A) The Linnaeus system of classification is considered $Artificial$ because it is based on only one or two morphological characters of plants,such as the number of stamens and carpels,rather than considering the entire range of plant characteristics or evolutionary relationships.
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2
BiologyEasyMCQAIPMT · 1989
The habitat of $E. coli$ is
A
Water
B
Colon
C
Soil
D
Organic food
Solution
(B) $E. coli$ (Escherichia coli) is a type of bacterium that normally lives in the intestines of people and animals.
It is a primary inhabitant of the human colon (large intestine),where it helps in the production of Vitamin $K$ and Vitamin $B$ complex.
Therefore,the correct habitat among the given options is the colon.
It is a primary inhabitant of the human colon (large intestine),where it helps in the production of Vitamin $K$ and Vitamin $B$ complex.
Therefore,the correct habitat among the given options is the colon.
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3
BiologyEasyMCQAIPMT · 1989
The causal organism for African sleeping sickness is
A
Trypanosoma cruzi
B
$T$. rhodesiense
C
$T$. tangela
D
$T$. gambiense
Solution
(D) African sleeping sickness, also known as Human African Trypanosomiasis, is caused by protozoan parasites of the genus $Trypanosoma$.
Specifically, there are two subspecies that cause this disease in humans: $Trypanosoma \text{ } brucei \text{ } gambiense$ and $Trypanosoma \text{ } brucei \text{ } rhodesiense$.
Since both $T. \text{ } rhodesiense$ and $T. \text{ } gambiense$ are causative agents, and in many standard biology contexts, $T. \text{ } gambiense$ is the most frequently cited answer for the chronic form, but both are correct. Given the options, $T. \text{ } gambiense$ is the classic textbook answer for the primary causal organism.
Specifically, there are two subspecies that cause this disease in humans: $Trypanosoma \text{ } brucei \text{ } gambiense$ and $Trypanosoma \text{ } brucei \text{ } rhodesiense$.
Since both $T. \text{ } rhodesiense$ and $T. \text{ } gambiense$ are causative agents, and in many standard biology contexts, $T. \text{ } gambiense$ is the most frequently cited answer for the chronic form, but both are correct. Given the options, $T. \text{ } gambiense$ is the classic textbook answer for the primary causal organism.
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4
BiologyEasyMCQAIPMT · 1989
Lichens indicate $SO_2$ pollution because they
A
Show association between algae and fungi
B
Grow faster than others
C
Are sensitive to $SO_2$
D
Flourish in $SO_2$ rich environment
Solution
(C) Lichens are highly sensitive to air pollution,particularly to higher $SO_2$ concentrations in the atmosphere.
This $SO_2$ causes plasmolysis of algal cells and converts the chlorophyll of algae into pheophytin by removing the magnesium $(Mg)$ ion.
This process results in chlorosis and the eventual death of the lichen.
This $SO_2$ causes plasmolysis of algal cells and converts the chlorophyll of algae into pheophytin by removing the magnesium $(Mg)$ ion.
This process results in chlorosis and the eventual death of the lichen.
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5
BiologyMediumMCQAIPMT · 1989
Selaginella has a character of evolutionary importance. That character is
A
Ligule
B
Seed
C
Heterospory
D
Strobilus
Solution
(C) $Selaginella$ is a pteridophyte that exhibits heterospory,which means it produces two different types of spores: microspores and megaspores. This phenomenon is considered a significant evolutionary precursor to the seed habit found in higher plants (spermatophytes). Therefore,heterospory is the key character of evolutionary importance in $Selaginella$.
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6
BiologyMediumMCQAIPMT · 1989
Which of the following structures in $Pinus$ are haploid?
A
Megaspore,integument,root
B
Endosperm,megaspore,pollen grain
C
Pollen grain,leaf,root
D
Megaspore,endosperm,embryo
Solution
(B) In $Pinus$,the endosperm is a haploid $(n)$ tissue formed before fertilization. The megaspore mother cell undergoes meiosis to form a linear tetrad of haploid megaspores. The pollen grain (microspore) represents the first stage of the male gametophyte and is also haploid $(n)$. Therefore,endosperm,megaspore,and pollen grain are all haploid structures.
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7
BiologyMediumMCQAIPMT · 1989
When the sperms of $Funaria$ and $Pteris$ are put together near the archegonia of $Pteris$,only the sperms of $Pteris$ readily enter the archegonia and reach the egg. The reason being that
A
Sperms of $Funaria$ are killed when mixed with sperms of $Pteris$
B
Archegonia of $Pteris$ secrete a substance which repels sperms of $Funaria$
C
Archegonia of $Pteris$ secrete a chemical substance which attracts sperms of $Pteris$ chemotactically
D
Sperms of $Funaria$ are less motile
Solution
(C) The correct answer is $C$.
In bryophytes and pteridophytes,fertilization is dependent on water.
The movement of male gametes (antherozoids) towards the archegonia is a chemotactic response.
Archegonia of $Pteris$ secrete specific chemical substances,primarily malic acid,which act as a chemoattractant.
This chemical specifically attracts the sperms of $Pteris$ through chemotaxis,ensuring species-specific fertilization.
In bryophytes and pteridophytes,fertilization is dependent on water.
The movement of male gametes (antherozoids) towards the archegonia is a chemotactic response.
Archegonia of $Pteris$ secrete specific chemical substances,primarily malic acid,which act as a chemoattractant.
This chemical specifically attracts the sperms of $Pteris$ through chemotaxis,ensuring species-specific fertilization.
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8
BiologyMediumMCQAIPMT · 1989
Transfer of $Taenia$ to the secondary host occurs as:
A
Onchosphere
B
Cysticercus
C
Morula
D
Egg
Solution
(A) The life cycle of $Taenia$ $solium$ involves two hosts. The primary host is human,and the secondary or intermediate host is the pig. The transfer of $Taenia$ to the secondary host occurs when the pig ingests food or water contaminated with the eggs of $Taenia$. Inside the intestine of the pig,the embryo (onchosphere) is released from the eggshell. This onchosphere then penetrates the intestinal wall to reach the muscles,where it develops into the cysticercus larva.
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9
BiologyEasyMCQAIPMT · 1989
Earthworms are:
A
Useful
B
Harmful
C
More useful than harmful
D
More harmful
Solution
(C) Earthworms are known as the $ \text{'friends of farmers'} $ because they improve soil fertility by burrowing, which aerates the soil, and by producing vermicompost through the decomposition of organic matter. While they may occasionally damage delicate seedlings, their overall contribution to agriculture is overwhelmingly positive. Therefore, they are considered more useful than harmful.
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10
BiologyEasyMCQAIPMT · 1989
The flight muscles of birds are attached to:
A
Clavicle
B
Coracoid
C
Keel of sternum
D
Scapula
Solution
(C) In birds,the $sternum$ (breastbone) is modified into a large,plate-like structure called the $keel$ (or $carina$).
This $keel$ provides a large surface area for the attachment of powerful flight muscles,specifically the $pectoralis$ and $supracoracoideus$ muscles,which are essential for the flapping movement of wings during flight.
This $keel$ provides a large surface area for the attachment of powerful flight muscles,specifically the $pectoralis$ and $supracoracoideus$ muscles,which are essential for the flapping movement of wings during flight.
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11
BiologyEasyMCQAIPMT · 1989
The only poisonous mammal is:
A
Ornithorhynchus
B
Echidna
C
Guinea pig
D
Snake
Solution
(A) The correct answer is $Ornithorhynchus$ (also known as the Platypus).
Male platypuses have spurs on their hind limbs that are connected to venom glands,which they use for defense or during mating competition.
$Echidna$ is a monotreme but is not venomous.
$Guinea$ $pig$ is a rodent and is not venomous.
$Snake$ is a reptile,not a mammal.
Male platypuses have spurs on their hind limbs that are connected to venom glands,which they use for defense or during mating competition.
$Echidna$ is a monotreme but is not venomous.
$Guinea$ $pig$ is a rodent and is not venomous.
$Snake$ is a reptile,not a mammal.
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12
BiologyEasyMCQAIPMT · 1989
Compound apocarpous gynoecium is found in
A
Lily
B
Hollyhock
C
Lotus/Ranunculus
D
Pumpkin
Solution
(C) An apocarpous gynoecium is one in which the carpels are free from each other. When there are multiple free carpels,it is referred to as a multicarpellary apocarpous gynoecium. Examples of plants exhibiting this condition include $Lotus$ and $Ranunculus$.
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13
BiologyMediumMCQAIPMT · 1989
Sieve tubes are better suited for translocation,because
A
Possess broader lumen and perforated cross walls
B
Are broader than long
C
Possess bordered pits
D
Possess no end walls
Solution
(A) Sieve tubes are specialized cells in the phloem tissue of angiosperms that are responsible for the translocation of food (sugars).
They are better suited for this function because they possess a broader lumen,which reduces resistance to the flow of sap,and perforated cross walls known as sieve plates,which facilitate the movement of materials between adjacent sieve tube elements.
They are better suited for this function because they possess a broader lumen,which reduces resistance to the flow of sap,and perforated cross walls known as sieve plates,which facilitate the movement of materials between adjacent sieve tube elements.
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14
BiologyMediumMCQAIPMT · 1989
Ligaments and tendons are:
A
Connective tissue
B
Muscular tissue
C
Fibrous connective tissue
D
Skeletal tissue
Solution
(C) Ligaments and tendons are specialized types of dense connective tissues. Specifically,they are classified as fibrous connective tissues. Ligaments are composed of yellow elastic fibers,which allow for flexibility,while tendons are composed of white collagen fibers,which provide high tensile strength to connect muscles to bones.
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15
BiologyMediumMCQAIPMT · 1989
The mineral present in the red pigment of vertebrate blood is:
A
Magnesium
B
Iron
C
Copper
D
Calcium
Solution
(B) The red pigment in vertebrate blood is $Hemoglobin$.
$Hemoglobin$ is a conjugated protein consisting of a protein part called $Globin$ and a prosthetic group called $Heme$.
$Heme$ is an iron-porphyrin complex, which means it contains an $Iron$ $(Fe^{2+})$ ion at its center.
This $Iron$ ion is responsible for the binding of $Oxygen$ and gives blood its characteristic red color.
$Hemoglobin$ is a conjugated protein consisting of a protein part called $Globin$ and a prosthetic group called $Heme$.
$Heme$ is an iron-porphyrin complex, which means it contains an $Iron$ $(Fe^{2+})$ ion at its center.
This $Iron$ ion is responsible for the binding of $Oxygen$ and gives blood its characteristic red color.
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16
BiologyEasyMCQAIPMT · 1989
Nerve cells originate from which embryonic layer?
A
Ectoderm
B
Mesoderm
C
Both of these
D
Endoderm
Solution
(A) The entire nervous system,including nerve cells,originates from the ectoderm during embryonic development.
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17
BiologyMediumMCQAIPMT · 1989
Nucleoproteins in a cell are synthesized in
A
Outside the nucleolus
B
Nucleoplasm
C
Nuclear membrane
D
Nucleolus
Solution
(D) Nucleoproteins are proteins that are associated with nucleic acids ($DNA$ or $RNA$).
Ribosomal proteins are synthesized in the cytoplasm and are transported into the nucleolus.
Inside the nucleolus,these proteins combine with ribosomal $RNA$ $(rRNA)$ to form ribosomal subunits.
Therefore,the assembly and synthesis of nucleoprotein complexes,specifically ribosomes,occur within the nucleolus.
Ribosomal proteins are synthesized in the cytoplasm and are transported into the nucleolus.
Inside the nucleolus,these proteins combine with ribosomal $RNA$ $(rRNA)$ to form ribosomal subunits.
Therefore,the assembly and synthesis of nucleoprotein complexes,specifically ribosomes,occur within the nucleolus.
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18
BiologyMediumMCQAIPMT · 1989
Which of the following is not a part of the enzyme but activates the enzyme?
A
$K^+$
B
$Zn^{2+}$
C
$Mg^{2+}$
D
$Mn^{2+}$
Solution
(A) Cofactors are non-protein chemical compounds or metallic ions that are required for an enzyme's activity.
$K^+$ (Potassium ion) is a monovalent cation that acts as an activator for several enzymes,such as $DNA$ polymerase and pyruvate kinase,but it is not considered a structural part of the enzyme molecule itself.
In contrast,$Zn^{2+}$,$Mg^{2+}$,and $Mn^{2+}$ often act as prosthetic groups or metal ion cofactors that are tightly bound to the enzyme structure.
$K^+$ (Potassium ion) is a monovalent cation that acts as an activator for several enzymes,such as $DNA$ polymerase and pyruvate kinase,but it is not considered a structural part of the enzyme molecule itself.
In contrast,$Zn^{2+}$,$Mg^{2+}$,and $Mn^{2+}$ often act as prosthetic groups or metal ion cofactors that are tightly bound to the enzyme structure.
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19
BiologyMediumMCQAIPMT · 1989
In the terrestrial habitat,which of the following factors affect temperature and rainfall conditions?
A
Translocation
B
Transformation
C
Thermo-denaturation
D
Transpiration
Solution
(D) Transpiration is the process of water movement through a plant and its evaporation from aerial parts,such as leaves,stems,and flowers.
On a large scale,forests contribute significantly to the atmospheric moisture content through transpiration.
This released water vapor influences local humidity,cloud formation,and rainfall patterns.
Consequently,transpiration plays a crucial role in regulating the temperature and rainfall conditions within terrestrial habitats.
On a large scale,forests contribute significantly to the atmospheric moisture content through transpiration.
This released water vapor influences local humidity,cloud formation,and rainfall patterns.
Consequently,transpiration plays a crucial role in regulating the temperature and rainfall conditions within terrestrial habitats.
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20
BiologyMediumMCQAIPMT · 1989
Which of the following is an essential mineral element that is not a constituent of any enzyme but stimulates the activity of many enzymes?
A
$Zn$
B
$Mg$
C
$Mn$
D
$K$
Solution
(D) The correct answer is $D$. Potassium $(K^+)$ is an essential macronutrient for plants. Unlike many other mineral elements that act as cofactors or structural components of enzymes,potassium does not become a permanent constituent of any enzyme molecule. Instead,it acts as an activator for more than $40$ enzymes involved in critical metabolic processes such as phosphorylation,photosynthesis,starch synthesis,respiration,and the synthesis of chlorophyll,$DNA$,and proteins.
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21
BiologyMediumMCQAIPMT · 1989
The possible resource of phosphorus ions and nitrogen ions in soil generally get depleted because they are usually found as
A
Positively charged ions
B
Negatively charged ions
C
$A$ disproportionate mixture of negatively charged ions
D
Particles carrying no charge
Solution
(B) Plants absorb phosphorus from the soil primarily in the form of phosphate ions,specifically $H_2PO_4^-$ and $HPO_4^{2-}$.
Nitrogen is absorbed by plants primarily in the form of nitrate ions $(NO_3^-)$.
Since soil particles are generally negatively charged,they tend to repel these negatively charged ions,preventing them from binding strongly to the soil surface.
Consequently,these ions are easily leached away by water,leading to their depletion in the soil.
Nitrogen is absorbed by plants primarily in the form of nitrate ions $(NO_3^-)$.
Since soil particles are generally negatively charged,they tend to repel these negatively charged ions,preventing them from binding strongly to the soil surface.
Consequently,these ions are easily leached away by water,leading to their depletion in the soil.
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22
BiologyMediumMCQAIPMT · 1989
In $C_4$ plants,the Calvin cycle occurs in
A
Stroma of bundle sheath chloroplast
B
Mesophyll chloroplast
C
Grana of bundle sheath chloroplast
D
Does not occur as $CO_2$ is fixed mainly by $PEP$ and no $CO_2$ is left for Calvin cycle
Solution
(A) In $C_4$ plants,the process of photosynthesis is divided between two types of cells: mesophyll cells and bundle sheath cells.
$1$. The initial fixation of $CO_2$ occurs in the mesophyll cells,where $PEP$ carboxylase fixes $CO_2$ into a $4$-carbon compound (oxaloacetic acid).
$2$. This $4$-carbon compound is transported to the bundle sheath cells.
$3$. In the bundle sheath cells,the $4$-carbon compound is broken down to release $CO_2$,which then enters the Calvin cycle.
$4$. Therefore,the Calvin cycle specifically takes place in the stroma of the bundle sheath chloroplasts.
$1$. The initial fixation of $CO_2$ occurs in the mesophyll cells,where $PEP$ carboxylase fixes $CO_2$ into a $4$-carbon compound (oxaloacetic acid).
$2$. This $4$-carbon compound is transported to the bundle sheath cells.
$3$. In the bundle sheath cells,the $4$-carbon compound is broken down to release $CO_2$,which then enters the Calvin cycle.
$4$. Therefore,the Calvin cycle specifically takes place in the stroma of the bundle sheath chloroplasts.
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23
BiologyMediumMCQAIPMT · 1989
Which of the following statements is incorrect?
A
Stomatal opening is influenced by many factors and potassium ions.
B
All enzymes are proteins,but all proteins are not enzymes.
C
All angiosperms have seeds,but all seed-bearing plants are not angiosperms.
D
Factors that affect respiration influence photosynthesis,but the reverse is not possible.
Solution
(D) . Stomatal opening is indeed regulated by various environmental factors and the influx of $K^+$ ions.
$B$. While most enzymes are proteins (ribozymes being the exception),not all proteins function as enzymes.
$C$. All angiosperms are seed-bearing,but gymnosperms are also seed-bearing plants,making the statement correct.
$D$. This statement is incorrect. Factors that affect respiration (like temperature,$CO_2$ concentration,and $O_2$ availability) also significantly influence photosynthesis,and vice versa. Both processes are metabolically linked and influenced by similar environmental parameters.
$B$. While most enzymes are proteins (ribozymes being the exception),not all proteins function as enzymes.
$C$. All angiosperms are seed-bearing,but gymnosperms are also seed-bearing plants,making the statement correct.
$D$. This statement is incorrect. Factors that affect respiration (like temperature,$CO_2$ concentration,and $O_2$ availability) also significantly influence photosynthesis,and vice versa. Both processes are metabolically linked and influenced by similar environmental parameters.
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24
BiologyMediumMCQAIPMT · 1989
Leaf fall can be prevented by
A
Florigen
B
Auxin
C
Cytokinins
D
Abscisic acid
Solution
(C) Cytokinins are plant hormones that promote cell division and delay the process of senescence (aging) in plant tissues. By delaying senescence,cytokinins effectively prevent or delay the abscission of leaves,thereby preventing leaf fall.
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25
BiologyMediumMCQAIPMT · 1989
Which of the following hormones can replace vernalization?
A
Auxin
B
Ethylene
C
Gibberellins
D
Cytokinins
Solution
(C) The physiological stimulus of vernalization is known as vernalin.
It has been observed that the application of $Gibberellins$ can replace the requirement of cold treatment (vernalization) to induce flowering in many plants.
Therefore,$Gibberellins$ can effectively substitute for the vernalization process.
It has been observed that the application of $Gibberellins$ can replace the requirement of cold treatment (vernalization) to induce flowering in many plants.
Therefore,$Gibberellins$ can effectively substitute for the vernalization process.
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26
BiologyMediumMCQAIPMT · 1989
Mowing a grass lawn facilitates better maintenance primarily owing to:
A
Removal of apical dominance and promotion of lateral meristem
B
Removal of apical dominance
C
Wounding which stimulates rapid regeneration
D
None of the above
Solution
(B) The correct answer is $B$.
In many plants,the apical bud inhibits the growth of lateral buds,a phenomenon known as apical dominance.
When a grass lawn is mowed,the apical buds are removed.
This removal eliminates the apical dominance,which allows the lateral buds to grow,resulting in a thicker and more uniform lawn.
In many plants,the apical bud inhibits the growth of lateral buds,a phenomenon known as apical dominance.
When a grass lawn is mowed,the apical buds are removed.
This removal eliminates the apical dominance,which allows the lateral buds to grow,resulting in a thicker and more uniform lawn.
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27
BiologyMediumMCQAIPMT · 1989
The tricuspid valve is present at the origin of
A
Carotid arch
B
Pulmonary arch
C
Truncus arteriosus
D
Systemic arch
Solution
(C) In the heart of amphibians and some reptiles,the $Truncus \ arteriosus$ is a large vessel that arises from the ventricle. The base of this vessel contains valves that prevent the backflow of blood. Specifically,the $Truncus \ arteriosus$ is guarded by spiral valves or tricuspid valves at its origin to regulate blood flow into the systemic and pulmonary arches.
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28
BiologyEasyMCQAIPMT · 1989
Which organ is considered as the "Graveyard of $RBCs$" where most of them are destroyed by macrophages?
A
Red bone marrow
B
Spleen
C
Kidney
D
Intestine
Solution
(B) The spleen is a bean-shaped organ that acts as a filter for the blood.
Old and damaged $RBCs$ are removed from the circulation and destroyed by macrophages through the process of phagocytosis.
Because of this function, the spleen is commonly referred to as the "Graveyard of $RBCs$".
Old and damaged $RBCs$ are removed from the circulation and destroyed by macrophages through the process of phagocytosis.
Because of this function, the spleen is commonly referred to as the "Graveyard of $RBCs$".
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29
BiologyMediumMCQAIPMT · 1989
Reabsorption of useful substances back into the blood from the filtrate in a nephron occurs in
A
Proximal convoluted tubule
B
Loop of Henle
C
Distal convoluted tubule
D
Collecting duct
Solution
(A) The $Proximal \text{ } Convoluted \text{ } Tubule$ $(PCT)$ is the primary site for the reabsorption of essential substances.
Approximately $100\%$ of glucose and amino acids, and $70-80\%$ of electrolytes and water from the filtrate are reabsorbed back into the blood in the $PCT$.
Approximately $100\%$ of glucose and amino acids, and $70-80\%$ of electrolytes and water from the filtrate are reabsorbed back into the blood in the $PCT$.
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30
BiologyEasyMCQAIPMT · 1989
The iter (cerebral aqueduct) is located:
A
In the third ventricle
B
In the second ventricle
C
Between the third and the fourth ventricles
D
In the lateral ventricles
Solution
(C) The iter,also known as the cerebral aqueduct or aqueduct of Sylvius,is a narrow canal that connects the third ventricle to the fourth ventricle of the brain.
It allows the flow of cerebrospinal fluid $(CSF)$ between these two ventricles.
It allows the flow of cerebrospinal fluid $(CSF)$ between these two ventricles.
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31
BiologyEasyMCQAIPMT · 1989
Which of the following cranial nerves plays an important role in regulating the heartbeat?
A
$IX$
B
$VII$
C
$X$
D
$VIII$
Solution
(C) The correct answer is $C$. The $X$ cranial nerve,also known as the Vagus nerve,plays a crucial role in regulating visceral functions. It controls visceral sensations and movements,including peristalsis,sound production,respiratory movements,and the regulation of the heartbeat by slowing it down.
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32
BiologyEasyMCQAIPMT · 1989
The sensitive layer of the eye is:
A
Sclerotic
B
Retina
C
Cornea
D
None of these
Solution
(B) The eye is composed of three layers. The outermost layer is the sclera,the middle layer is the choroid,and the innermost layer is the retina.
The retina is the light-sensitive layer of the eye that contains photoreceptor cells (rods and cones).
These cells convert light energy into electrical signals,which are then transmitted to the brain via the optic nerve.
Therefore,the retina is considered the sensitive layer of the eye.
The retina is the light-sensitive layer of the eye that contains photoreceptor cells (rods and cones).
These cells convert light energy into electrical signals,which are then transmitted to the brain via the optic nerve.
Therefore,the retina is considered the sensitive layer of the eye.
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33
BiologyMediumMCQAIPMT · 1989
During the course of development,cells in various regions of the embryo become variable in morphology and eventually perform diverse functions. This process is known as
A
Rearrangement
B
Differentiation
C
Metamorphosis
D
Organisation
Solution
(B) The process by which less specialized cells become more specialized in structure and function is called $Differentiation$.
During embryonic development,cells undergo specific changes to form different types of tissues and organs,allowing them to perform distinct physiological roles.
Therefore,the correct term for this developmental process is $Differentiation$.
During embryonic development,cells undergo specific changes to form different types of tissues and organs,allowing them to perform distinct physiological roles.
Therefore,the correct term for this developmental process is $Differentiation$.
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34
BiologyMediumMCQAIPMT · 1989
Compared to blood,our lymph has:
A
plasma without proteins
B
more $WBCs$ and no $RBCs$
C
more $RBCs$ and less $WBCs$
D
no plasma
Solution
(B) Lymph is a fluid connective tissue that is essentially blood plasma that has leaked out of the capillaries into the interstitial spaces.
It contains plasma and $WBCs$ (mainly lymphocytes) but lacks $RBCs$,platelets,and large plasma proteins.
Compared to blood,lymph has a higher concentration of $WBCs$ and is completely devoid of $RBCs$.
Therefore,the correct option is $B$.
It contains plasma and $WBCs$ (mainly lymphocytes) but lacks $RBCs$,platelets,and large plasma proteins.
Compared to blood,lymph has a higher concentration of $WBCs$ and is completely devoid of $RBCs$.
Therefore,the correct option is $B$.
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35
BiologyMediumMCQAIPMT · 1989
Trypanosoma belongs to the class ..........
A
Sarcodina
B
Flagellated
C
Ciliated
D
Sporozoan
Solution
(B) Trypanosoma is a parasitic protozoan that belongs to the class Flagellated (Mastigophora) protozoans.
These organisms are either free-living or parasitic and possess flagella for locomotion.
Trypanosoma is the causative agent of sleeping sickness.
These organisms are either free-living or parasitic and possess flagella for locomotion.
Trypanosoma is the causative agent of sleeping sickness.
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36
BiologyMediumMCQAIPMT · 1989
Lichens are indicators of $SO_2$ pollution because they are ........
A
symbiotic associations of algae and fungi.
B
growing faster than others.
C
sensitive to $SO_2$.
D
flourishing in $SO_2$ rich environments.
Solution
(C) Lichens are composite organisms consisting of a symbiotic association between algae (phycobiont) and fungi (mycobiont).
They are well-known as biological indicators of air pollution,specifically sulfur dioxide $(SO_2)$.
Lichens are highly sensitive to $SO_2$ and cannot grow in areas where the concentration of $SO_2$ is high.
Therefore,their absence in a particular area serves as an indicator of $SO_2$ pollution.
They are well-known as biological indicators of air pollution,specifically sulfur dioxide $(SO_2)$.
Lichens are highly sensitive to $SO_2$ and cannot grow in areas where the concentration of $SO_2$ is high.
Therefore,their absence in a particular area serves as an indicator of $SO_2$ pollution.
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37
BiologyMediumMCQAIPMT · 1989
In $Pinus$ (Gymnosperms),the haploid structures are .........
A
Megaspore,endosperm,and embryo
B
Megaspore,pollen grain,and endosperm
C
Megaspore,seed coat,and root
D
Pollen grain,leaf,and root
Solution
(B) In $Pinus$ (Gymnosperms),the life cycle involves a dominant sporophyte $(2n)$.
$1$. The $Megaspore$ $(n)$ is formed after meiosis in the megaspore mother cell.
$2$. The $Pollen$ $grain$ $(n)$ is the male gametophyte.
$3$. The $Endosperm$ $(n)$ in gymnosperms is a pre-fertilization tissue formed directly from the female gametophyte.
$4$. Embryo $(2n)$,seed coat $(2n)$,leaf $(2n)$,and root $(2n)$ are diploid structures.
Therefore,the correct combination of haploid structures is $Megaspore$,$pollen$ $grain$,and $endosperm$.
$1$. The $Megaspore$ $(n)$ is formed after meiosis in the megaspore mother cell.
$2$. The $Pollen$ $grain$ $(n)$ is the male gametophyte.
$3$. The $Endosperm$ $(n)$ in gymnosperms is a pre-fertilization tissue formed directly from the female gametophyte.
$4$. Embryo $(2n)$,seed coat $(2n)$,leaf $(2n)$,and root $(2n)$ are diploid structures.
Therefore,the correct combination of haploid structures is $Megaspore$,$pollen$ $grain$,and $endosperm$.
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38
BiologyMediumMCQAIPMT · 1989
Which of the following is an important evolutionary feature of $Selaginella$?
A
Heterospory
B
Rhizophore
C
Strobili
D
Ligule
Solution
(A) The most significant evolutionary feature of $Selaginella$ is $Heterospory$.
$Heterospory$ is the production of two types of spores: microspores and megaspores.
This phenomenon is considered a precursor to the seed habit in higher plants because it leads to the development of female gametophytes that are retained on the parent sporophyte for variable periods.
While $Rhizophore$,$Strobili$,and $Ligule$ are also characteristic features of $Selaginella$,$Heterospory$ is the most critical evolutionary advancement.
$Heterospory$ is the production of two types of spores: microspores and megaspores.
This phenomenon is considered a precursor to the seed habit in higher plants because it leads to the development of female gametophytes that are retained on the parent sporophyte for variable periods.
While $Rhizophore$,$Strobili$,and $Ligule$ are also characteristic features of $Selaginella$,$Heterospory$ is the most critical evolutionary advancement.
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39
BiologyMediumMCQAIPMT · 1989
In $Funaria$ and $Pteris$,both sperms are released near the archegonium of $Pteris$. Only $Pteris$ sperms enter the archegonium because:
A
$Pteris$ archegonium repels $Funaria$ sperms.
B
$Pteris$ sperms destroy $Funaria$ sperms.
C
$Funaria$ sperms are less motile.
D
$Pteris$ archegonium secretes chemicals that attract only $Pteris$ sperms.
Solution
(D) Fertilization in bryophytes and pteridophytes is dependent on water. In $Pteris$ (a pteridophyte),the archegonium secretes specific chemical substances (chemotaxis) that attract the male gametes (antherozoids) of its own species. This is a specific biological mechanism where the female sex organ recognizes and attracts only the compatible male gametes through chemical signaling. Therefore,even if $Funaria$ sperms are present,they are not attracted to the $Pteris$ archegonium.
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40
BiologyEasyMCQAIPMT · 1989
In birds,the wishbone is formed from the ...........
A
Pelvic girdle
B
Skull
C
Hind limb
D
Pectoral girdle/Clavicle
Solution
(D) In birds,the wishbone,also known as the furcula,is a forked bone found in the chest area. It is formed by the fusion of the two clavicles (collarbones) of the pectoral girdle. This structure provides structural support for the wings during flight.
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41
BiologyEasyMCQAIPMT · 1989
The flight muscles of birds are attached to the $..........$.
A
Clavicle
B
Sternum
C
Scapula
D
Coracoid
Solution
(B) In birds,the flight muscles (pectoral muscles) are very powerful and are attached to a large,keel-shaped extension of the sternum known as the $carina$ or $keel$. This structure provides a large surface area for the attachment of these muscles,which are essential for the flapping movement of wings during flight.
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42
BiologyEasyMCQAIPMT · 1989
The characteristic feature of Eutherians is ......
A
Hairy skin
B
True placenta
C
Ovoviviparous
D
Glandular skin
Solution
(B) Eutherians,also known as placental mammals,are characterized by the presence of a $True \ placenta$ (chorioallantoic placenta) which facilitates the exchange of nutrients,gases,and waste products between the mother and the developing fetus. This allows for a longer gestation period and more advanced development of the young before birth. Therefore,the correct option is $B$.
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43
BiologyMediumMCQAIPMT · 1989
In the secondary host,the transmission of $Taenia$ occurs in the form of:
A
Oncosphere
B
Cysticercus
C
Morula
D
Ovum
Solution
(A) The life cycle of $Taenia$ $solium$ (pork tapeworm) involves two hosts. The primary host is human,and the secondary (intermediate) host is the pig.
In the human intestine,the eggs are released and passed out with feces. When the pig (secondary host) ingests these eggs,the embryos (oncospheres) hatch and migrate to the muscles.
In the muscles of the pig,the oncosphere develops into a bladder-like larva known as $Cysticercus$ $cellulosae$ (also called bladder worm).
Therefore,the transmission of $Taenia$ to the secondary host occurs in the form of the oncosphere,which then develops into the $Cysticercus$ stage.
In the human intestine,the eggs are released and passed out with feces. When the pig (secondary host) ingests these eggs,the embryos (oncospheres) hatch and migrate to the muscles.
In the muscles of the pig,the oncosphere develops into a bladder-like larva known as $Cysticercus$ $cellulosae$ (also called bladder worm).
Therefore,the transmission of $Taenia$ to the secondary host occurs in the form of the oncosphere,which then develops into the $Cysticercus$ stage.
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44
BiologyEasyMCQAIPMT · 1989
In earthworms,photoreceptor structures are found on the .............
A
Clitellum
B
Many eyes
C
Dorsal surface
D
Lateral sides
Solution
(C) In earthworms $(Pheretima)$,there are no true eyes. However,they possess light-sensitive cells known as photoreceptors. These photoreceptors are primarily concentrated on the dorsal surface of the body,which allows the earthworm to detect light intensity and respond accordingly.
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45
BiologyEasyMCQAIPMT · 1989
Jellyfish belongs to the class $...$.
A
Hydrozoa
B
Scyphozoa
C
Anthozoa
D
None of these
Solution
(B) Jellyfish,scientifically known as $Aurelia$,belongs to the phylum $Cnidaria$ (or $Coelenterata$).
Within this phylum,the class $Scyphozoa$ is commonly referred to as the 'true jellyfish' class.
Members of the class $Hydrozoa$ include organisms like $Hydra$ and $Obelia$,while the class $Anthozoa$ includes corals and sea anemones.
Therefore,the correct classification for jellyfish is $Scyphozoa$.
Within this phylum,the class $Scyphozoa$ is commonly referred to as the 'true jellyfish' class.
Members of the class $Hydrozoa$ include organisms like $Hydra$ and $Obelia$,while the class $Anthozoa$ includes corals and sea anemones.
Therefore,the correct classification for jellyfish is $Scyphozoa$.
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46
BiologyMediumMCQAIPMT · 1989
Which of the following is a characteristic feature of $Phylum-Chordata$?
A
Pharyngeal gill slits
B
Operculum
C
Post-anal tail
D
Chitinous exoskeleton
Solution
(C) The fundamental characteristics of $Phylum-Chordata$ include the presence of a notochord,a dorsal hollow nerve cord,and a post-anal tail at some stage of their life cycle.
Among the given options,the post-anal tail is a unique diagnostic feature of chordates.
While pharyngeal gill slits are also a characteristic,the post-anal tail is a defining feature that distinguishes chordates from non-chordates.
Among the given options,the post-anal tail is a unique diagnostic feature of chordates.
While pharyngeal gill slits are also a characteristic,the post-anal tail is a defining feature that distinguishes chordates from non-chordates.
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47
BiologyMediumMCQAIPMT · 1989
The edible part of a mango is derived from the .......... .
A
Epicarp
B
Mesocarp
C
Endocarp
D
Pericarp and thalamus
Solution
(B) In mango (Mangifera indica),the fruit is a drupe.
It develops from a superior ovary and is one-seeded.
The fruit wall is differentiated into three layers: the outer thin epicarp,the middle fleshy edible mesocarp,and the inner stony hard endocarp.
Therefore,the edible part of the mango is the mesocarp.
It develops from a superior ovary and is one-seeded.
The fruit wall is differentiated into three layers: the outer thin epicarp,the middle fleshy edible mesocarp,and the inner stony hard endocarp.
Therefore,the edible part of the mango is the mesocarp.
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48
BiologyMediumMCQAIPMT · 1989
The floral formula of Tomato/Tobacco is ......
A
$\bigoplus \text{ } K_{4-5} C_{1+2+(2)} A_{10} G_{(2)}$
B
$\bigoplus \text{ } K_{2+2} C_4 A_{2+4} G_1$
C
$\bigoplus \text{ } P_2 A_3 G_1$
D
$\bigoplus \text{ } K_{(5)} C_{(5)} A_5 G_{(2)}$
Solution
(D) Tomato and Tobacco belong to the family $Solanaceae$.
The floral formula for the family $Solanaceae$ is represented as: $\bigoplus \text{ } K_{(5)} C_{(5)} A_5 G_{(2)}$.
- $\bigoplus$: Actinomorphic (radial symmetry).
- $K_{(5)}$: Calyx with $5$ sepals,gamosepalous (fused).
- $C_{(5)}$: Corolla with $5$ petals,gamopetalous (fused).
- $A_5$: Androecium with $5$ stamens,epipetalous.
- $G_{(2)}$: Gynoecium with $2$ carpels,syncarpous (fused),superior ovary.
The floral formula for the family $Solanaceae$ is represented as: $\bigoplus \text{ } K_{(5)} C_{(5)} A_5 G_{(2)}$.
- $\bigoplus$: Actinomorphic (radial symmetry).
- $K_{(5)}$: Calyx with $5$ sepals,gamosepalous (fused).
- $C_{(5)}$: Corolla with $5$ petals,gamopetalous (fused).
- $A_5$: Androecium with $5$ stamens,epipetalous.
- $G_{(2)}$: Gynoecium with $2$ carpels,syncarpous (fused),superior ovary.
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49
BiologyMediumMCQAIPMT · 1989
Which of the following is true regarding diffuse-porous and ring-porous wood?
A
Ring-porous wood conducts more water for a short duration.
B
Diffuse-porous wood conducts more water.
C
Ring-porous wood conducts more water during the time of need.
D
Diffuse-porous wood is less specialized but conducts water faster.
Solution
(C) In $Ring-porous$ wood, the vessels are significantly larger in the early wood compared to the late wood, which allows for a rapid and high volume of water conduction during the early spring when the plant's demand is high.
In $Diffuse-porous$ wood, the vessels are of uniform size throughout the growth ring, providing a steady but generally lower rate of water conduction compared to the peak capacity of $Ring-porous$ wood.
Therefore, $Ring-porous$ wood is considered more specialized for conducting large amounts of water during the period of high demand.
In $Diffuse-porous$ wood, the vessels are of uniform size throughout the growth ring, providing a steady but generally lower rate of water conduction compared to the peak capacity of $Ring-porous$ wood.
Therefore, $Ring-porous$ wood is considered more specialized for conducting large amounts of water during the period of high demand.
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50
BiologyMediumMCQAIPMT · 1989
The destruction of the protoplast is a primary requirement for which of the following important functions?
A
Transport of food
B
Transport of water
C
Absorption of water
D
Exchange of gases
Solution
(B) The destruction of the protoplast is a characteristic feature of the maturation of xylem tracheary elements,specifically vessel elements and tracheids.
These cells lose their protoplasm at maturity to become hollow,dead tubes,which allows them to efficiently transport water and minerals from the roots to the rest of the plant body.
Therefore,the destruction of the protoplast is a primary requirement for the transport of water.
These cells lose their protoplasm at maturity to become hollow,dead tubes,which allows them to efficiently transport water and minerals from the roots to the rest of the plant body.
Therefore,the destruction of the protoplast is a primary requirement for the transport of water.
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51
BiologyMediumMCQAIPMT · 1989
Malaria fever coincides with the liberation of
A
Cryptomerozoites
B
Metacryptomerozoites
C
Merozoites
D
Trophozoites
Solution
(C) The rupture of infected $R.B.Cs$ leads to the release of $Merozoites$ and a toxic substance called $Haemozoin$ into the blood.
$Haemozoin$ is responsible for the chills and high fever associated with malaria.
$Haemozoin$ is responsible for the chills and high fever associated with malaria.
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52
BiologyEasyMCQAIPMT · 1989
$A$ bite of the $Tse-tse$ fly may transmit which of the following to humans?
A
$Leishmania$ $donovani$
B
$Trypanosoma$ $gambiense$
C
$Entamoeba$ $histolytica$
D
$Plasmodium$ $vivax$
Solution
(B) The $Tse-tse$ fly ($Glossina$ species) acts as a vector for the protozoan parasite $Trypanosoma$ $gambiense$.
This parasite causes African Sleeping Sickness in humans.
$Leishmania$ $donovani$ is transmitted by the sandfly,$Entamoeba$ $histolytica$ is transmitted through contaminated food and water,and $Plasmodium$ $vivax$ is transmitted by the female $Anopheles$ mosquito.
This parasite causes African Sleeping Sickness in humans.
$Leishmania$ $donovani$ is transmitted by the sandfly,$Entamoeba$ $histolytica$ is transmitted through contaminated food and water,and $Plasmodium$ $vivax$ is transmitted by the female $Anopheles$ mosquito.
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53
BiologyMediumMCQAIPMT · 1989
The maximum evolution of oxygen is by which of the following producers of organic matter?
A
Great land area
B
Crops
C
Phytoplankton of sea
D
Forests
Solution
(C) The Earth's oxygen supply is primarily maintained by marine ecosystems.
Phytoplankton,which are microscopic marine plants,are the largest producers of organic matter in the biosphere.
They perform a significant portion of global photosynthesis,thereby contributing to the maximum evolution of oxygen in the atmosphere.
Phytoplankton,which are microscopic marine plants,are the largest producers of organic matter in the biosphere.
They perform a significant portion of global photosynthesis,thereby contributing to the maximum evolution of oxygen in the atmosphere.
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54
BiologyMediumMCQAIPMT · 1989
Which of the following is a correct statement?
A
Gametes are diploid.
B
Spores are invariably haploid.
C
Spores and gametes are invariably haploid.
D
Gametes are invariably haploid.
Solution
(B) In biological organisms,gametes are specialized cells produced for sexual reproduction. In many organisms,they are haploid $(n)$,but in some organisms (like certain algae or fungi),gametes can be produced by mitosis from haploid individuals,or in some cases,they may be diploid. However,spores are reproductive cells that are produced by meiosis in the sporophyte generation and are invariably haploid $(n)$. Therefore,the statement that spores are invariably haploid is the most accurate biological generalization among the options provided.
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55
BiologyMediumMCQAIPMT · 1989
Perisperm is
A
Degenerate part of synergids
B
Peripheral part of endosperm
C
Degenerate part of secondary nucleus
D
Remnant of nucellus
Solution
(D) Perisperm is the persistent,nutritive tissue derived from the nucellus that remains in the seed after fertilization. In some seeds,such as black pepper and beet,the nucellus is not completely consumed by the developing embryo and persists as a thin layer known as perisperm.
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56
BiologyMediumMCQAIPMT · 1989
Nucellar embryo is
A
Apomictic embryo
B
Amphimictic haploid
C
Adventitive embryony
D
Amphimictic diploid
Solution
(C) Nucellar embryony is a type of apomixis where the embryo develops directly from the diploid nucellar cells surrounding the embryo sac.
Since the nucellar cells are diploid $(2n)$ and they develop into an embryo without fertilization,this process is known as adventitive embryony.
Therefore,nucellar embryo is an example of adventitive embryony.
Since the nucellar cells are diploid $(2n)$ and they develop into an embryo without fertilization,this process is known as adventitive embryony.
Therefore,nucellar embryo is an example of adventitive embryony.
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57
BiologyMediumMCQAIPMT · 1989
Even after killing the generative cell with a laser beam,the pollen grain of a flowering plant germinates and produces a normal pollen tube because:
A
Laser beam stimulates pollen germination and pollen tube growth
B
The laser beam does not damage the region from which pollen tube emerges
C
The contents of killed generative cell permit germination and pollen tube growth
D
The vegetative cell has not been damaged
Solution
(D) mature pollen grain consists of two cells: the larger vegetative cell and the smaller generative cell.
The vegetative cell is responsible for the growth of the pollen tube,as it contains the necessary nutrients and cytoplasmic machinery for tube elongation.
The generative cell is responsible for producing the two male gametes through mitosis.
Since the vegetative cell remains intact after the laser treatment,it continues to function normally,allowing the pollen grain to germinate and form a pollen tube.
The vegetative cell is responsible for the growth of the pollen tube,as it contains the necessary nutrients and cytoplasmic machinery for tube elongation.
The generative cell is responsible for producing the two male gametes through mitosis.
Since the vegetative cell remains intact after the laser treatment,it continues to function normally,allowing the pollen grain to germinate and form a pollen tube.
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58
BiologyMediumMCQAIPMT · 1989
In the reproduction of a test-tube baby:
A
Fertilization is done outside the body.
B
The fetus is grown in a test tube.
C
Fertilization is done inside the body.
D
None of these.
Solution
(A) In the process of producing a test-tube baby,which is a form of $In$ $Vitro$ $Fertilization$ $(IVF)$,the fertilization of the egg by the sperm occurs outside the female's body in a laboratory setting (in a petri dish or test tube).
Once fertilization occurs and the zygote reaches the $8$-celled or $16$-celled stage,it is transferred into the uterus of the female for further development.
The fetus does not grow in a test tube; it grows inside the mother's uterus.
Once fertilization occurs and the zygote reaches the $8$-celled or $16$-celled stage,it is transferred into the uterus of the female for further development.
The fetus does not grow in a test tube; it grows inside the mother's uterus.
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59
BiologyMediumMCQAIPMT · 1989
When an albino female plant of maize is crossed with a normal green male plant,all plants in the progeny are albino because:
A
Plastids are inherited through maternal plants
B
Albinism is dominant over green character
C
The crossing results in structural changes in green plastids
D
Green plastids of male parents become mutated
Solution
(A) The inheritance of plastids in many plants,including maize,is governed by cytoplasmic inheritance (maternal inheritance).
Since plastids are inherited exclusively through the egg cell (maternal parent) and not through the pollen (male parent),the phenotype of the offspring is determined by the plastids present in the female parent.
In this case,the female parent is albino (lacking functional chloroplasts),so all offspring will inherit these defective plastids and appear albino,regardless of the green male parent's contribution.
Since plastids are inherited exclusively through the egg cell (maternal parent) and not through the pollen (male parent),the phenotype of the offspring is determined by the plastids present in the female parent.
In this case,the female parent is albino (lacking functional chloroplasts),so all offspring will inherit these defective plastids and appear albino,regardless of the green male parent's contribution.
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60
BiologyEasyMCQAIPMT · 1989
Haemophilia is:
A
$A$ type of mosquito lacking haemocoel
B
The royal disease
C
Faulty blood clotting
D
$(b)$ and $(c)$ both
Solution
(D) Haemophilia is a sex-linked recessive disorder in which the blood fails to clot properly due to the absence of specific clotting factors.
It is historically known as the 'royal disease' because it affected the descendants of Queen Victoria of England.
Therefore,both statements $(b)$ and $(c)$ are correct.
It is historically known as the 'royal disease' because it affected the descendants of Queen Victoria of England.
Therefore,both statements $(b)$ and $(c)$ are correct.
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61
BiologyMediumMCQAIPMT · 1989
In crop improvement programmes,haploids are of great importance because they
A
Are useful in studies on meiosis
B
Require only about half the amount of chemical fertilizers as compared to diploids
C
Give homozygous lines following diploidization
D
Grow better under adverse conditions
Solution
(C) Haploids contain only one set of chromosomes $(n)$.
When these haploids are treated with agents like colchicine,they undergo chromosome doubling (diploidization) to become completely homozygous $(2n)$.
This process is highly significant in plant breeding as it allows for the rapid production of pure lines (homozygous lines) in a single generation,bypassing the need for multiple generations of self-pollination.
When these haploids are treated with agents like colchicine,they undergo chromosome doubling (diploidization) to become completely homozygous $(2n)$.
This process is highly significant in plant breeding as it allows for the rapid production of pure lines (homozygous lines) in a single generation,bypassing the need for multiple generations of self-pollination.
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62
BiologyEasyMCQAIPMT · 1989
Kohler and Milstein developed biotechnology for the production of
A
Myelomas
B
Steroid conversion
C
Monoclonal antibodies
D
Immobilised enzymes
Solution
(C) In biotechnology,monoclonal antibodies $(Mabs)$ are specialized antibodies that are specific to only one type of antigen.
The concept of monoclonal antibodies was introduced by Georges Kohler and Cesar Milstein in $1974$.
The concept of monoclonal antibodies was introduced by Georges Kohler and Cesar Milstein in $1974$.
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63
BiologyMediumMCQAIPMT · 1989
Maximum contribution of $O_2$ is from
A
Phytoplankton
B
Grasslands
C
Herbs and shrubs
D
Dense forest
Solution
(A) The major source of $O_2$ liberation in the biosphere is the process of photosynthesis.
Approximately $90\%$ of the total global photosynthesis is carried out by phytoplankton present in oceans and aquatic ecosystems.
Therefore,phytoplankton are the primary contributors to the atmospheric oxygen supply.
Approximately $90\%$ of the total global photosynthesis is carried out by phytoplankton present in oceans and aquatic ecosystems.
Therefore,phytoplankton are the primary contributors to the atmospheric oxygen supply.
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64
BiologyEasyMCQAIPMT · 1989
Soil conservation is the process where
A
Sterile soil is converted to fertile soil
B
Soil is aerated
C
Soil erosion is allowed
D
Soil is protected against loss
Solution
(D) Soil conservation is a set of management strategies for the prevention of soil erosion and the degradation of the earth's soil surface. Its primary goal is to protect the soil against loss caused by natural factors like wind and water,or human activities like deforestation and overgrazing. Therefore,option $(d)$ is the correct answer.
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65
BiologyEasyMCQAIPMT · 1989
Soil conservation is
A
Conversion of sterile soil into fertile one
B
Aeration of soil
C
Erosion of soil
D
Protection against loss
Solution
(D) Soil conservation refers to the management and protection of soil to prevent its degradation,erosion,or loss of fertility.
It involves various strategies such as reforestation,terracing,and contour plowing to maintain the physical and chemical integrity of the soil.
Therefore,it is defined as the protection of soil against loss or degradation.
It involves various strategies such as reforestation,terracing,and contour plowing to maintain the physical and chemical integrity of the soil.
Therefore,it is defined as the protection of soil against loss or degradation.
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66
BiologyEasyMCQAIPMT · 1989
Greenhouse effect is primarily due to the presence of:
A
Ozone layer in the atmosphere
B
Infrared light reaching the earth
C
Moisture layer in the atmosphere
D
$CO_2$ layer in the atmosphere
Solution
(D) The greenhouse effect is a natural phenomenon that warms the earth's surface.
It is primarily caused by greenhouse gases that trap heat in the atmosphere.
Among these,$CO_2$ (carbon dioxide) is the most significant contributor,accounting for approximately $50\%$ of the increase in global temperature.
Other gases like chlorofluorocarbons (CFCs) contribute about $20\%$,while methane and nitrous oxide also play roles.
Therefore,the presence of a $CO_2$ layer in the atmosphere is the primary driver of the greenhouse effect.
It is primarily caused by greenhouse gases that trap heat in the atmosphere.
Among these,$CO_2$ (carbon dioxide) is the most significant contributor,accounting for approximately $50\%$ of the increase in global temperature.
Other gases like chlorofluorocarbons (CFCs) contribute about $20\%$,while methane and nitrous oxide also play roles.
Therefore,the presence of a $CO_2$ layer in the atmosphere is the primary driver of the greenhouse effect.
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67
BiologyMediumMCQAIPMT · 1989
Acid rain is caused by,or recent reports of acid rain in some industrial cities are due to the effect of atmospheric pollution by:
A
Excessive release of $CO_2$ by burning of fuels like wood and charcoal,cutting of forests and increased animal population.
B
Excessive release of $NO_2$ and $SO_2$ in the atmosphere by burning of fossil fuels.
C
Excessive release of $NH_3$ by industrial plants and coal gas.
D
Excessive release of $CO$ in the atmosphere by incomplete combustion of coke,charcoal and other carbonaceous fuels in the paucity of oxygen.
Solution
(B) . Acid rain is primarily caused by the emission of sulphur dioxide $(SO_2)$ and nitrogen oxides ($NO_x$,including $NO_2$) into the atmosphere.
These gases are released in large quantities due to the burning of fossil fuels in industries and vehicles.
When these gases react with water vapor in the atmosphere,they form sulphuric acid $(H_2SO_4)$ and nitric acid $(HNO_3)$.
These acids then fall to the earth along with rain,resulting in acid rain,which is harmful to aquatic life,soil,and buildings.
These gases are released in large quantities due to the burning of fossil fuels in industries and vehicles.
When these gases react with water vapor in the atmosphere,they form sulphuric acid $(H_2SO_4)$ and nitric acid $(HNO_3)$.
These acids then fall to the earth along with rain,resulting in acid rain,which is harmful to aquatic life,soil,and buildings.
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68
BiologyEasyMCQAIPMT · 1989
The cheapest high energy fruit crop of India is
A
Banana
B
Guava
C
Apple
D
Mango
Solution
(A) The correct answer is $A$.
Banana is considered the cheapest high-energy fruit crop in India.
It is a rich source of carbohydrates and provides a high amount of energy per unit weight compared to other common fruits.
Due to its year-round availability and affordability,it is often referred to as the 'poor man's apple'.
Banana is considered the cheapest high-energy fruit crop in India.
It is a rich source of carbohydrates and provides a high amount of energy per unit weight compared to other common fruits.
Due to its year-round availability and affordability,it is often referred to as the 'poor man's apple'.
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69
BiologyMediumMCQAIPMT · 1989
Which plant yields several utilizable products including fibre, oil, and animal food?
A
Sun hemp
B
Jute
C
Cotton
D
Sunflower
Solution
(C) The $Cotton$ plant $(Gossypium)$ is a versatile crop that yields several utilizable products.
$1$. Fibres are obtained from the seed surface (lint).
$2$. Fatty oil is extracted from the kernels.
$3$. The oil cake remaining after oil extraction is used as high-protein animal feed.
$4$. Additionally, it is used in the production of plastics, rayon, and explosives.
$1$. Fibres are obtained from the seed surface (lint).
$2$. Fatty oil is extracted from the kernels.
$3$. The oil cake remaining after oil extraction is used as high-protein animal feed.
$4$. Additionally, it is used in the production of plastics, rayon, and explosives.
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70
BiologyMediumMCQAIPMT · 1989
Fibres are obtained from
A
Xylem,phloem and sclerenchyma
B
Xylem,parenchyma and epidermis
C
Xylem,parenchyma and endodermis
D
Xylem,phloem,epidermis and sclerenchyma
Solution
(D) Fibres are structural components of plants that provide mechanical support and are used commercially. They are obtained from various plant tissues including xylem (wood fibres),phloem (bast fibres),epidermis (surface fibres like cotton),sclerenchyma,fruit walls (mesocarp),pericycle,and seed surfaces. Therefore,option $D$ is the most comprehensive choice among the given alternatives.
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71
BiologyMediumMCQAIPMT · 1989
Genetic erosion is due to
A
Deforestation
B
Shifting cultivation
C
Adoption of genetically uniform varieties
D
All the above
Solution
(D) Genetic erosion refers to the loss of genetic diversity within a species or population.
$1$. Deforestation leads to the destruction of natural habitats,causing the loss of wild relatives of crops and diverse plant species.
$2$. Shifting cultivation often involves clearing large areas of land,which can lead to the loss of local landraces and genetic variability.
$3$. The adoption of genetically uniform high-yielding varieties (HYVs) in modern agriculture replaces traditional,diverse landraces,leading to a significant reduction in the genetic pool of crops.
Therefore,all the mentioned factors contribute to genetic erosion.
$1$. Deforestation leads to the destruction of natural habitats,causing the loss of wild relatives of crops and diverse plant species.
$2$. Shifting cultivation often involves clearing large areas of land,which can lead to the loss of local landraces and genetic variability.
$3$. The adoption of genetically uniform high-yielding varieties (HYVs) in modern agriculture replaces traditional,diverse landraces,leading to a significant reduction in the genetic pool of crops.
Therefore,all the mentioned factors contribute to genetic erosion.
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72
BiologyMediumMCQAIPMT · 1989
Malaria fever is associated with the release of $..........$.
A
Cryptomerozoites
B
Metacryptomerozoites
C
Merozoites
D
Trophozoites
Solution
(C) Malaria fever is caused by the release of a toxic substance called $hemozoin$ into the blood. This substance is released when the $Plasmodium$ parasite completes its erythrocytic cycle (cycle in red blood cells) and ruptures the host's red blood cells to release the next generation of $merozoites$. Therefore,the periodic fever and chills associated with malaria are directly linked to the release of $merozoites$ and $hemozoin$ from the ruptured red blood cells.
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73
BiologyEasyMCQAIPMT · 1989
Which is the infectious stage of the malarial parasite $Plasmodium$ that enters the human body?
A
Merozoites
B
Sporozoites
C
Trophozoites
D
Minuta form
Solution
(B) The life cycle of $Plasmodium$ involves two hosts: humans and female $Anopheles$ mosquitoes.
When an infected female $Anopheles$ mosquito bites a human,it injects the $Plasmodium$ parasites in the form of $Sporozoites$ into the human bloodstream.
These $Sporozoites$ are the infectious stage of the parasite for humans.
They travel through the blood to the liver,where they infect liver cells and begin their asexual reproduction cycle.
When an infected female $Anopheles$ mosquito bites a human,it injects the $Plasmodium$ parasites in the form of $Sporozoites$ into the human bloodstream.
These $Sporozoites$ are the infectious stage of the parasite for humans.
They travel through the blood to the liver,where they infect liver cells and begin their asexual reproduction cycle.
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74
BiologyEasyMCQAIPMT · 1989
The vector for "Sleeping Sickness" is . . . . . . .
A
Housefly
B
Tsetse fly
C
Sand fly
D
Fruit fly
Solution
(B) Sleeping sickness, also known as African trypanosomiasis, is a parasitic disease caused by the protozoan $Trypanosoma \text{ } brucei$.
This parasite is transmitted to humans through the bite of an infected tsetse fly (genus $Glossina$).
Therefore, the tsetse fly acts as the biological vector for this disease.
This parasite is transmitted to humans through the bite of an infected tsetse fly (genus $Glossina$).
Therefore, the tsetse fly acts as the biological vector for this disease.
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75
BiologyEasyMCQAIPMT · 1989
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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76
BiologyMediumMCQAIPMT · 1989
The perisperm is a ..........
A
Haploid remnant
B
Diploid remnant
C
Haploid apomictic structure
D
Diploid apomictic structure
Solution
(B) In some seeds,such as black pepper and beet,remnants of the nucellus are persistent. This residual,persistent nucellus is known as the perisperm.
Since the nucellus is a part of the ovule and is composed of diploid maternal tissue $(2n)$,the perisperm is also diploid $(2n)$.
Since the nucellus is a part of the ovule and is composed of diploid maternal tissue $(2n)$,the perisperm is also diploid $(2n)$.
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77
BiologyMediumMCQAIPMT · 1989
What is the development of an organism from a female gamete or egg without fertilization called?
A
Apogamy
B
Polyembryony
C
Parthenocarpy
D
Parthenogenesis
Solution
(D) The development of an organism from an unfertilized female gamete or egg is known as $Parthenogenesis$.
$Apogamy$ refers to the development of an embryo from cells other than the egg cell (like synergids or antipodals).
$Polyembryony$ is the occurrence of more than one embryo in a seed.
$Parthenocarpy$ is the development of fruit without fertilization.
$Apogamy$ refers to the development of an embryo from cells other than the egg cell (like synergids or antipodals).
$Polyembryony$ is the occurrence of more than one embryo in a seed.
$Parthenocarpy$ is the development of fruit without fertilization.
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78
BiologyMediumMCQAIPMT · 1989
If the generative cell is destroyed by a laser,the pollen tube still forms. This is because:
A
The vegetative (tube) cell is not damaged.
B
The content of the dead generative cell stimulates pollen growth.
C
Laser rays stimulate the growth of the pollen tube.
D
The origin point of the pollen tube is not injured.
Solution
(A) In angiosperms,the pollen grain consists of two cells: the vegetative cell and the generative cell.
$1$. The vegetative cell (or tube cell) is responsible for the growth of the pollen tube.
$2$. The generative cell divides to form two male gametes.
$3$. Since the vegetative cell is responsible for the tube formation and elongation,destroying the generative cell with a laser does not prevent the formation of the pollen tube.
$1$. The vegetative cell (or tube cell) is responsible for the growth of the pollen tube.
$2$. The generative cell divides to form two male gametes.
$3$. Since the vegetative cell is responsible for the tube formation and elongation,destroying the generative cell with a laser does not prevent the formation of the pollen tube.
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79
BiologyMediumMCQAIPMT · 1989
The ovum is released from the ovary in the ............. stage.
A
Secondary oocyte stage
B
Primary oocyte stage
C
Ootid stage
D
Mature ovum stage
Solution
(A) During oogenesis, the primary oocyte undergoes meiosis-$I$ to form a secondary oocyte and a first polar body. The secondary oocyte then begins meiosis-$II$ but gets arrested at the metaphase-$II$ stage. It is in this $Secondary$ oocyte stage that the ovum is released from the ovary during ovulation.
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80
BiologyEasyMCQAIPMT · 1989
The human egg is ...
A
Alecithal
B
Microlecithal
C
Mesolecithal
D
Polylecithal
Solution
(A) The human egg (ovum) is classified as $Alecithal$ or $Microlecithal$ because it contains a very negligible or almost no amount of yolk. Since the human embryo receives nutrition from the mother through the placenta,the egg does not require a large amount of stored yolk.
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81
BiologyDifficultMCQAIPMT · 1989
Two genes '$a$' and '$b$' show $20\%$ recombination. What will be the proportion of gametes produced by a dihybrid $F_1$ individual with the genotype $++/ab$,derived from a cross between $++/++$ and $ab/ab$?
A
$++ \, 40\% : ab \, 40\% : a+ \, 10\% : +b \, 10\%$
B
$++ \, 50\% : ab \, 50\%$
C
$++ \, 40\% : ab \, 40\% : a+ \, 10\% : +b \, 10\%$
D
$++ \, 30\% : ab \, 30\% : a+ \, 20\% : +b \, 20\%$
Solution
(C) The recombination frequency is given as $20\%$.
This means the frequency of recombinant gametes ($a+$ and $+b$) is $20\%$ in total.
Since there are two types of recombinant gametes,each will be $20\% / 2 = 10\%$.
The parental gametes ($++$ and $ab$) will make up the remaining $100\% - 20\% = 80\%$.
Since there are two types of parental gametes,each will be $80\% / 2 = 40\%$.
Therefore,the proportions are: $++ = 40\%$,$ab = 40\%$,$a+ = 10\%$,and $+b = 10\%$.
Thus,the correct option is $C$.
This means the frequency of recombinant gametes ($a+$ and $+b$) is $20\%$ in total.
Since there are two types of recombinant gametes,each will be $20\% / 2 = 10\%$.
The parental gametes ($++$ and $ab$) will make up the remaining $100\% - 20\% = 80\%$.
Since there are two types of parental gametes,each will be $80\% / 2 = 40\%$.
Therefore,the proportions are: $++ = 40\%$,$ab = 40\%$,$a+ = 10\%$,and $+b = 10\%$.
Thus,the correct option is $C$.
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82
BiologyMediumMCQAIPMT · 1989
$DNA$ replication is .............
A
Conservative and discontinuous
B
Semi-conservative and semi-discontinuous
C
Semi-conservative and discontinuous
D
Conservative
Solution
(B) $DNA$ replication is described as semi-conservative because each new $DNA$ molecule consists of one parental strand and one newly synthesized strand.
Furthermore,it is semi-discontinuous because one strand (the leading strand) is synthesized continuously in the $5' \rightarrow 3'$ direction,while the other strand (the lagging strand) is synthesized in short fragments known as Okazaki fragments,which are later joined by $DNA$ ligase.
Furthermore,it is semi-discontinuous because one strand (the leading strand) is synthesized continuously in the $5' \rightarrow 3'$ direction,while the other strand (the lagging strand) is synthesized in short fragments known as Okazaki fragments,which are later joined by $DNA$ ligase.
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83
BiologyEasyMCQAIPMT · 1989
Who proposed the theory of inheritance of acquired characters?
A
Wallace
B
Lamarck
C
Darwin
D
de Vries
Solution
(B) The theory of inheritance of acquired characters,also known as Lamarckism,was proposed by Jean-Baptiste Lamarck.
According to this theory,organisms acquire traits during their lifetime due to the use or disuse of organs,and these acquired traits are passed on to their offspring.
According to this theory,organisms acquire traits during their lifetime due to the use or disuse of organs,and these acquired traits are passed on to their offspring.
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84
BiologyEasyMCQAIPMT · 1989
Who proposed the theory of continuity of germplasm?
A
de Vries
B
Weismann
C
Darwin
D
Lamarck
Solution
(B) The theory of continuity of germplasm was proposed by August Weismann.
According to this theory,the germplasm (reproductive cells) is passed from generation to generation,while the somatoplasm (body cells) is not inherited.
This theory effectively refuted the inheritance of acquired characters proposed by Lamarck.
According to this theory,the germplasm (reproductive cells) is passed from generation to generation,while the somatoplasm (body cells) is not inherited.
This theory effectively refuted the inheritance of acquired characters proposed by Lamarck.
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85
BiologyMediumMCQAIPMT · 1989
What is evolution?
A
Progressive development of a species
B
History of a species and its development with variations
C
History of a species
D
Development of a species
Solution
(B) Evolution is defined as the process of gradual change in the inherited characteristics of biological populations over successive generations. It involves the history of a species and its development through the accumulation of genetic variations over time,leading to the diversity of life we observe today.
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86
BiologyEasyMCQAIPMT · 1989
Who wrote the book 'Origin of Species'?
A
Oparin
B
Weismann
C
Lamarck
D
Darwin
Solution
(D) The book 'On the Origin of Species' was written by Charles Darwin. It was published on $24$ November $1859$. This landmark work introduced the scientific theory that populations evolve over the course of generations through a process of natural selection.
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87
BiologyMediumMCQAIPMT · 1989
In crop improvement programs,haploid varieties are important because they .
A
require half the nutrition.
B
help in the study of meiosis.
C
can grow well even in adverse conditions.
D
produce homozygous lines accurately.
Solution
(D) Haploid plants are produced through techniques like anther culture or pollen culture.
Since haploid plants contain only one set of chromosomes $(n)$,they are genetically unstable.
When these haploid plants are treated with colchicine,they undergo chromosome doubling to become diploid $(2n)$.
This process results in plants that are completely homozygous for all traits.
These homozygous lines are highly valuable in plant breeding programs for creating pure lines and developing hybrid varieties efficiently.
Since haploid plants contain only one set of chromosomes $(n)$,they are genetically unstable.
When these haploid plants are treated with colchicine,they undergo chromosome doubling to become diploid $(2n)$.
This process results in plants that are completely homozygous for all traits.
These homozygous lines are highly valuable in plant breeding programs for creating pure lines and developing hybrid varieties efficiently.
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88
BiologyMediumMCQAIPMT · 1989
The relationship between algae and fungi in a lichen is known as:
A
Mutualism
B
Parasitism
C
Commensalism
D
Protocooperation
Solution
(A) In a lichen,the algal component (phycobiont) and the fungal component (mycobiont) live in a symbiotic association called mutualism.
In this relationship,the algae provide food through photosynthesis,while the fungi provide protection,anchorage,and absorption of minerals and water for the algae.
Both organisms benefit from this association,which is the definition of mutualism.
In this relationship,the algae provide food through photosynthesis,while the fungi provide protection,anchorage,and absorption of minerals and water for the algae.
Both organisms benefit from this association,which is the definition of mutualism.
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