BiologyQ1–17 of 17 questions
Page 1 of 1 · English
1
BiologyMediumMCQAIIMS · 1990
The first act in taxonomy is
A
Description
B
Identification
C
Naming
D
Classification
Solution
(B) The correct answer is $B$. Identification is the first step in taxonomy,which involves determining the correct identity of an organism and placing it in its proper taxonomic category based on its characteristics.
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2
BiologyMediumMCQAIIMS · 1990
The symbiotic association of fungi and algae is called
A
Lichen
B
Mycorrhiza
C
Both $(A)$ and $(B)$
D
Mycoplasma
Solution
(A) The symbiotic association between fungi and algae is known as a $Lichen$. In this relationship,the algal component is called $phycobiont$ and the fungal component is called $mycobiont$. They live in a mutually beneficial association where the algae prepare food through photosynthesis,and the fungi provide protection,anchorage,and absorption of minerals and water for the algae. $Mycorrhiza$,on the other hand,is a symbiotic association between fungi and the roots of higher plants.
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3
BiologyMediumMCQAIIMS · 1990
The walls of sclerenchyma are:
A
Rigid
B
Lignified
C
Pectinised
D
Suberised
Solution
(B) The correct answer is $B$.
Sclerenchyma cells possess hard and extremely thick secondary cell walls due to the uniform deposition of lignin.
Lignin is a complex polymer that provides structural support and mechanical strength to the plant.
Sclerenchyma cells possess hard and extremely thick secondary cell walls due to the uniform deposition of lignin.
Lignin is a complex polymer that provides structural support and mechanical strength to the plant.
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4
BiologyMediumMCQAIIMS · 1990
Collenchyma differs from parenchyma in having
A
Living protoplasm
B
Cellulose walls
C
Vacuoles
D
Pectin deposits at corners
Solution
(D) Collenchyma is a type of simple permanent tissue that provides mechanical support to young stems and petioles.
Unlike parenchyma,which has uniformly thin cell walls made of cellulose,collenchyma cells are characterized by localized thickenings of the cell wall at the corners.
These thickenings are primarily composed of pectin,hemicellulose,and cellulose.
Therefore,the presence of pectin deposits at the corners is the distinguishing feature of collenchyma compared to parenchyma.
Unlike parenchyma,which has uniformly thin cell walls made of cellulose,collenchyma cells are characterized by localized thickenings of the cell wall at the corners.
These thickenings are primarily composed of pectin,hemicellulose,and cellulose.
Therefore,the presence of pectin deposits at the corners is the distinguishing feature of collenchyma compared to parenchyma.
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5
BiologyEasyMCQAIIMS · 1990
When a coenzyme is combined with an apoenzyme,it is called:
A
Cofactor
B
Holoenzyme
C
Substrate-enzyme complex
D
Vitamin $A$
Solution
(B) Enzymes are composed of one or several polypeptide chains. However,there are a number of cases in which non-protein constituents called cofactors are bound to the enzyme to make the enzyme catalytically active.
In these instances,the protein portion of the enzyme is called the apoenzyme.
When the non-protein part (cofactor) is bound to the apoenzyme,the complete,catalytically active enzyme is called the holoenzyme.
Coenzymes are a specific type of cofactor that are organic compounds,often derived from vitamins.
In these instances,the protein portion of the enzyme is called the apoenzyme.
When the non-protein part (cofactor) is bound to the apoenzyme,the complete,catalytically active enzyme is called the holoenzyme.
Coenzymes are a specific type of cofactor that are organic compounds,often derived from vitamins.
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6
BiologyMediumMCQAIIMS · 1990
When a plant cell is placed in a solution which is hypotonic to the cell sap,which of the following conditions will not apply?
A
The water potential of the cell sap will rise
B
The suction pressure of the cell sap will fail
C
The cell will become turgid
D
The wall pressure of the cell will fail
Solution
(D) When a plant cell is placed in a hypotonic solution,water enters the cell through endosmosis.
As water enters,the cell sap becomes more dilute,causing its water potential to increase.
The cell expands and exerts turgor pressure against the cell wall,making the cell turgid.
Consequently,the suction pressure (or diffusion pressure deficit) decreases as the cell becomes fully turgid.
However,the wall pressure is the pressure exerted by the cell wall against the expanding protoplast,which increases as the cell becomes turgid.
Therefore,the statement that 'the wall pressure of the cell will fail' is incorrect.
As water enters,the cell sap becomes more dilute,causing its water potential to increase.
The cell expands and exerts turgor pressure against the cell wall,making the cell turgid.
Consequently,the suction pressure (or diffusion pressure deficit) decreases as the cell becomes fully turgid.
However,the wall pressure is the pressure exerted by the cell wall against the expanding protoplast,which increases as the cell becomes turgid.
Therefore,the statement that 'the wall pressure of the cell will fail' is incorrect.
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7
BiologyEasyMCQAIIMS · 1990
The transfer of minerals from top soil to sub soil through soil water is called
A
Transpiration
B
Conduction
C
Percolation
D
Leaching
Solution
(D) The process by which mineral salts dissolved in the soil solution move downwards through the soil profile along with percolating (gravitational) water is known as leaching.
This phenomenon occurs because water moves through the soil pores due to gravity,carrying dissolved nutrients with it.
Leaching is particularly significant for anions,which are less strongly held by soil particles compared to cations.
Therefore,the correct option is $D$.
This phenomenon occurs because water moves through the soil pores due to gravity,carrying dissolved nutrients with it.
Leaching is particularly significant for anions,which are less strongly held by soil particles compared to cations.
Therefore,the correct option is $D$.
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8
BiologyMediumMCQAIIMS · 1990
Intact chloroplasts from green leaves can be isolated by using:
A
Acetone
B
Ethanol
C
Alcohol
D
Sugar solution
Solution
(D) To isolate intact chloroplasts from green leaves,an isotonic or hypertonic solution is required to maintain the structural integrity of the organelle.
Acetone,ethanol,and alcohol are organic solvents that dissolve the lipid bilayer of the chloroplast membrane,causing the organelle to rupture.
$A$ sugar solution (such as sucrose) provides an osmotic environment that prevents the chloroplast from bursting,allowing for the isolation of intact organelles.
Acetone,ethanol,and alcohol are organic solvents that dissolve the lipid bilayer of the chloroplast membrane,causing the organelle to rupture.
$A$ sugar solution (such as sucrose) provides an osmotic environment that prevents the chloroplast from bursting,allowing for the isolation of intact organelles.
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9
BiologyMediumMCQAIIMS · 1990
In the hexose monophosphate shunt ($HMP$ shunt),the number of $CO_2$ molecules evolved is:
A
Same as in glycolysis
B
Less than glycolysis
C
More than glycolysis
D
Much lesser than glycolysis
Solution
(C) In the process of glycolysis,there is no evolution of $CO_2$ molecules. Glycolysis involves the breakdown of glucose into two molecules of pyruvate without the release of carbon dioxide. In contrast,the hexose monophosphate $(HMP)$ shunt,also known as the pentose phosphate pathway,involves the oxidative decarboxylation of glucose$-6-$phosphate,which results in the release of $CO_2$ molecules. Therefore,the number of $CO_2$ molecules evolved in the $HMP$ shunt is more than in glycolysis.
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10
BiologyMediumMCQAIIMS · 1990
Leaf fall occurs when the abscission layer is formed due to a change in the content of:
A
Auxin increases
B
Auxin decreases
C
Abscisic acid decreases
D
Gibberellic acid decreases
Solution
(B) Auxin inhibits the abscission of leaves and fruits. The abscission layer is formed when the concentration of auxin in the leaf petiole falls below a critical minimum level,which triggers the enzymatic degradation of the cell walls in the abscission zone.
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11
BiologyMediumMCQAIIMS · 1990
Parthenocarpy is induced by
A
$ABA$
B
Auxins
C
Zeatin
D
Cytokinin
Solution
(B) Parthenocarpy is the development of fruit without fertilization.
Auxins are plant hormones that can induce parthenocarpy in many plants.
When auxins are applied to unfertilized ovaries,they stimulate the ovary to develop into a fruit,bypassing the need for fertilization.
Auxins are plant hormones that can induce parthenocarpy in many plants.
When auxins are applied to unfertilized ovaries,they stimulate the ovary to develop into a fruit,bypassing the need for fertilization.
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12
BiologyEasyMCQAIIMS · 1990
The pigment phytochrome is involved in:
A
Phototropism
B
Photorespiration
C
Photoperiodism
D
Geotropism
Solution
(C) Phytochrome is a light-sensitive pigment found in plants that acts as a photoreceptor. It plays a crucial role in photoperiodism,which is the physiological response of plants to the relative lengths of light and dark periods. The stimulus of light is perceived by the phytochrome present in the leaves,which then triggers flowering and other developmental processes.
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13
BiologyEasyMCQAIIMS · 1990
Triple antigen or $DPT$ is meant for
A
$A$ vaccine against malaria,typhoid and cancer
B
Mixture of viruses that causes common cold,polio and hepatitis
C
$A$ vaccine against polio,rabies and hepatitis
D
$A$ vaccine against tetanus,whooping cough and diphtheria
Solution
(D) $DPT$ stands for Diphtheria,Pertussis (whooping cough),and Tetanus vaccine.
It is a combination vaccine used to protect against these three infectious diseases.
Diphtheria is caused by the bacterium $Corynebacterium$ $diphtheriae$.
Pertussis (whooping cough) is caused by the bacterium $Bordetella$ $pertussis$.
Tetanus is caused by the bacterium $Clostridium$ $tetani$.
It is a combination vaccine used to protect against these three infectious diseases.
Diphtheria is caused by the bacterium $Corynebacterium$ $diphtheriae$.
Pertussis (whooping cough) is caused by the bacterium $Bordetella$ $pertussis$.
Tetanus is caused by the bacterium $Clostridium$ $tetani$.
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14
BiologyEasyMCQAIIMS · 1990
$A$ crassinucellate ovule shows:
A
Absence of nucellus
B
Well developed nucellus
C
Partially developed nucellus
D
Reduced nucellus
Solution
(B) In a crassinucellate ovule,the megaspore mother cell is cut off from the epidermis by the primary parietal cell.
This results in a massive or well-developed nucellus.
In contrast,a tenuinucellate ovule has a very small or poorly developed nucellus.
This results in a massive or well-developed nucellus.
In contrast,a tenuinucellate ovule has a very small or poorly developed nucellus.
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15
BiologyMediumMCQAIIMS · 1990
Ovulation in mammals is caused by
A
$FSH$ and $TSH$
B
$FSH$ and $LH$
C
$FSH$ and $LTH$
D
$LTH$ and $LH$
Solution
(B) The Graafian follicle develops under the influence of $FSH$ (Follicle Stimulating Hormone) secreted by the anterior pituitary.
Its follicular cells secrete estrogen.
The rising level of estrogen decreases the production of $FSH$ and stimulates the secretion of $LH$ (Luteinizing Hormone).
$A$ surge in $LH$ levels,often referred to as the $LH$ surge,causes the mature Graafian follicle to rupture and release the ovum,a process known as ovulation.
Its follicular cells secrete estrogen.
The rising level of estrogen decreases the production of $FSH$ and stimulates the secretion of $LH$ (Luteinizing Hormone).
$A$ surge in $LH$ levels,often referred to as the $LH$ surge,causes the mature Graafian follicle to rupture and release the ovum,a process known as ovulation.
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16
BiologyEasyMCQAIIMS · 1990
The largest newsprint manufacturing industry in India is situated at:
A
Mysore
B
Lucknow
C
Nepanagar
D
Delhi
Solution
(C) The National Newsprint and Paper Mills Limited,commonly known as Nepanagar,is located in the Burhanpur district of Madhya Pradesh,India.
It was the first newsprint mill in India,established in $1947$.
It is famous for being the largest producer of newsprint in the country.
It was the first newsprint mill in India,established in $1947$.
It is famous for being the largest producer of newsprint in the country.
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17
BiologyEasyMCQAIIMS · 1990
Clove oil is obtained from
A
Wood of Santalum
B
Leaves of Syzygium aromaticum
C
Flower buds of Syzygium aromaticum
D
Rhizome of Vatevaria
Solution
(C) Clove $(Syzygium\, aromaticum)$ belongs to the family $Myrtaceae$.
Clove oil is extracted from the dried flower buds of the plant.
It is widely used in perfumes,flavoring agents,and medicines due to its antiseptic and analgesic properties.
Clove oil is extracted from the dried flower buds of the plant.
It is widely used in perfumes,flavoring agents,and medicines due to its antiseptic and analgesic properties.
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