BiologyQ101–129 of 177 questions
Page 3 of 3 · English
101
BiologyMediumMCQAIPMT · 1992
What is the number of chromatids in a chromosome during metaphase?
A
Two in both mitosis and meiosis.
B
Two in mitosis and one in meiosis.
C
Two in mitosis and four in meiosis.
D
One in mitosis and two in meiosis.
Solution
(A) During the $S$-phase of interphase,$DNA$ replication occurs,resulting in each chromosome consisting of two sister chromatids joined at the centromere.
In mitosis,the chromosomes align at the metaphase plate,and each chromosome still consists of two chromatids.
In meiosis $I$,homologous chromosomes pair up and align at the metaphase plate; each chromosome still consists of two chromatids.
Therefore,in both mitosis and meiosis (specifically metaphase $I$),each chromosome consists of two chromatids.
In mitosis,the chromosomes align at the metaphase plate,and each chromosome still consists of two chromatids.
In meiosis $I$,homologous chromosomes pair up and align at the metaphase plate; each chromosome still consists of two chromatids.
Therefore,in both mitosis and meiosis (specifically metaphase $I$),each chromosome consists of two chromatids.
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102
BiologyEasyMCQAIPMT · 1992
Guttation is primarily caused by which of the following?
A
Root pressure
B
Osmosis
C
Transpiration
D
Imbibition
Solution
(A) Guttation is the exudation of water droplets from the margins of leaves through specialized structures called hydathodes.
It occurs primarily due to high root pressure when the rate of transpiration is low,typically at night or early morning.
When the soil moisture level is high and the absorption of water by roots is active,the accumulated water creates a positive hydrostatic pressure in the xylem,known as root pressure,which forces the water out through the hydathodes.
It occurs primarily due to high root pressure when the rate of transpiration is low,typically at night or early morning.
When the soil moisture level is high and the absorption of water by roots is active,the accumulated water creates a positive hydrostatic pressure in the xylem,known as root pressure,which forces the water out through the hydathodes.
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103
BiologyMediumMCQAIPMT · 1992
The ringing (girdling) experiment cannot be performed on sugarcane because:
A
Its phloem is located internal to the xylem.
B
Its stem surface is covered with a waxy layer.
C
Its vascular bundles are not arranged in a ring.
D
Its stem is very thin.
Solution
(C) The ringing or girdling experiment involves removing a ring of bark (phloem) from the stem to demonstrate that phloem is responsible for the translocation of food.
In dicot stems,vascular bundles are arranged in a ring,allowing for the easy removal of the phloem layer without damaging the xylem.
However,in monocots like sugarcane,the vascular bundles are scattered throughout the ground tissue rather than being arranged in a ring.
Therefore,it is impossible to remove a ring of phloem without also damaging the xylem and other tissues,making the experiment ineffective.
In dicot stems,vascular bundles are arranged in a ring,allowing for the easy removal of the phloem layer without damaging the xylem.
However,in monocots like sugarcane,the vascular bundles are scattered throughout the ground tissue rather than being arranged in a ring.
Therefore,it is impossible to remove a ring of phloem without also damaging the xylem and other tissues,making the experiment ineffective.
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104
BiologyMediumMCQAIPMT · 1992
When sugar in guard cells is converted into starch,the stomatal pore $..........$
A
closes completely
B
opens partially
C
opens completely
D
remains unchanged
Solution
(A) According to the starch-sugar interconversion theory,the opening and closing of stomata depend on the osmotic pressure of guard cells.
When sugar is converted into starch,the osmotic pressure of the guard cells decreases.
This leads to the movement of water out of the guard cells (exosmosis),causing them to become flaccid.
As a result,the stomatal pore closes completely.
When sugar is converted into starch,the osmotic pressure of the guard cells decreases.
This leads to the movement of water out of the guard cells (exosmosis),causing them to become flaccid.
As a result,the stomatal pore closes completely.
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105
BiologyMediumMCQAIPMT · 1992
The conversion of starch into organic acids is essential for:
A
Stomatal closure
B
Stomatal opening
C
Stomatal initiation
D
Stomatal growth
Solution
(B) According to the starch-sugar interconversion theory (proposed by Steward),the opening and closing of stomata are regulated by the concentration of sugar and starch in the guard cells.
During the day,the $pH$ of the guard cells increases due to photosynthesis (consumption of $CO_2$).
This high $pH$ triggers the enzyme phosphorylase to convert starch into glucose$-1-$phosphate (an organic acid/sugar derivative).
This increases the osmotic pressure of the guard cells,causing water to enter from adjacent cells via endosmosis.
The resulting turgor pressure causes the stomata to open.
Conversely,at night,the $pH$ decreases,and glucose$-1-$phosphate is converted back into starch,leading to stomatal closure.
During the day,the $pH$ of the guard cells increases due to photosynthesis (consumption of $CO_2$).
This high $pH$ triggers the enzyme phosphorylase to convert starch into glucose$-1-$phosphate (an organic acid/sugar derivative).
This increases the osmotic pressure of the guard cells,causing water to enter from adjacent cells via endosmosis.
The resulting turgor pressure causes the stomata to open.
Conversely,at night,the $pH$ decreases,and glucose$-1-$phosphate is converted back into starch,leading to stomatal closure.
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106
BiologyMediumMCQAIPMT · 1992
The movement of water between cells is determined by which of the following?
A
$T.P.$
B
$W.P.$
C
$D.P.D.$
D
Plasmolysis
Solution
(B) The movement of water between cells occurs along a gradient of water potential ($W.P.$ or $\Psi_w$).
Water always moves from a region of higher water potential to a region of lower water potential.
While $D.P.D.$ (Diffusion Pressure Deficit) was historically used to describe this movement,modern plant physiology uses water potential $(\Psi_w)$ as the standard thermodynamic parameter to predict the direction of water movement between cells.
Water always moves from a region of higher water potential to a region of lower water potential.
While $D.P.D.$ (Diffusion Pressure Deficit) was historically used to describe this movement,modern plant physiology uses water potential $(\Psi_w)$ as the standard thermodynamic parameter to predict the direction of water movement between cells.
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107
BiologyMediumMCQAIPMT · 1992
What is the primary $CO_2$ acceptor in $C_4$ plants?
A
Phosphoenolpyruvate $(PEP)$
B
Ribulose $1,5$-bisphosphate $(RuBP)$
C
Oxaloacetic acid $(OAA)$
D
Phosphoglyceric acid $(PGA)$
Solution
(A) In $C_4$ plants,the primary $CO_2$ acceptor is a $3$-carbon molecule called Phosphoenolpyruvate $(PEP)$.
This reaction is catalyzed by the enzyme $PEP$ carboxylase $(PEPCase)$ in the mesophyll cells.
The $CO_2$ combines with $PEP$ to form a $4$-carbon compound,Oxaloacetic acid $(OAA)$,which is the first stable product of the $C_4$ cycle.
This reaction is catalyzed by the enzyme $PEP$ carboxylase $(PEPCase)$ in the mesophyll cells.
The $CO_2$ combines with $PEP$ to form a $4$-carbon compound,Oxaloacetic acid $(OAA)$,which is the first stable product of the $C_4$ cycle.
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108
BiologyMediumMCQAIPMT · 1992
Chlorophyll $a$ is present in which of the following?
A
All autotrophic photosynthetic organisms
B
All higher plants
C
All oxygen-evolving photosynthetic organisms
D
All plants (except fungi)
Solution
(C) Chlorophyll $a$ is the primary photosynthetic pigment found in all oxygen-evolving photosynthetic organisms.
It acts as the reaction center in both Photosystem $I$ and Photosystem $II$.
While other pigments like chlorophyll $b$,carotenoids,and xanthophylls are accessory pigments,chlorophyll $a$ is essential for the conversion of light energy into chemical energy during the light-dependent reactions of photosynthesis.
It acts as the reaction center in both Photosystem $I$ and Photosystem $II$.
While other pigments like chlorophyll $b$,carotenoids,and xanthophylls are accessory pigments,chlorophyll $a$ is essential for the conversion of light energy into chemical energy during the light-dependent reactions of photosynthesis.
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109
BiologyMediumMCQAIPMT · 1992
Which enzyme catalyzes $CO_2$ fixation in $C_4$ plants?
A
$RuBP$ carboxylase
B
$PEP$ carboxylase
C
Carbonic anhydrase
D
Carboxydismutase
Solution
(B) In $C_4$ plants,the primary $CO_2$ fixation occurs in the mesophyll cells.
The enzyme responsible for this initial fixation is $PEP$ carboxylase (Phosphoenolpyruvate carboxylase).
This enzyme catalyzes the reaction between $CO_2$ and $PEP$ (a $3$-carbon compound) to form oxaloacetic acid $(OAA)$,which is a $4$-carbon compound.
$RuBP$ carboxylase (Rubisco) is involved in the Calvin cycle within the bundle sheath cells,but the initial fixation in $C_4$ plants is mediated by $PEP$ carboxylase.
The enzyme responsible for this initial fixation is $PEP$ carboxylase (Phosphoenolpyruvate carboxylase).
This enzyme catalyzes the reaction between $CO_2$ and $PEP$ (a $3$-carbon compound) to form oxaloacetic acid $(OAA)$,which is a $4$-carbon compound.
$RuBP$ carboxylase (Rubisco) is involved in the Calvin cycle within the bundle sheath cells,but the initial fixation in $C_4$ plants is mediated by $PEP$ carboxylase.
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110
BiologyEasyMCQAIPMT · 1992
Which of the following is a $C_4$ plant?
A
Papaya
B
Pea
C
Potato
D
Maize
Solution
(D) $C_4$ plants are those that utilize the $C_4$ dicarboxylic acid pathway for carbon fixation.
Examples of $C_4$ plants include maize (corn),sugarcane,sorghum,and crabgrass.
Papaya,pea,and potato are examples of $C_3$ plants,which use the Calvin cycle ($C_3$ pathway) as the primary method for carbon fixation.
Therefore,maize is the correct answer.
Examples of $C_4$ plants include maize (corn),sugarcane,sorghum,and crabgrass.
Papaya,pea,and potato are examples of $C_3$ plants,which use the Calvin cycle ($C_3$ pathway) as the primary method for carbon fixation.
Therefore,maize is the correct answer.
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111
BiologyEasyMCQAIPMT · 1992
Where is Photosystem-$II$ located?
A
Stroma
B
Cytochrome
C
Grana
D
Mitochondrial surface
Solution
(C) Photosystem-$II$ $(PS-II)$ is a protein complex involved in the light-dependent reactions of photosynthesis.
It is located in the thylakoid membranes of the chloroplasts.
The thylakoid membranes are stacked to form structures known as grana.
Therefore,Photosystem-$II$ is found in the grana of the chloroplasts.
It is located in the thylakoid membranes of the chloroplasts.
The thylakoid membranes are stacked to form structures known as grana.
Therefore,Photosystem-$II$ is found in the grana of the chloroplasts.
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112
BiologyMediumMCQAIPMT · 1992
In what form are carbohydrates generally translocated as nutrients in plants?
A
Glucose
B
Maltose
C
Starch
D
Sucrose
Solution
(D) In plants,carbohydrates are synthesized in the leaves during photosynthesis,primarily in the form of glucose.
However,glucose is highly reactive and cannot be transported efficiently through the phloem.
Therefore,it is converted into sucrose,which is a non-reducing sugar.
Sucrose is chemically stable and soluble,making it the primary form of sugar translocated from the source (leaves) to the sink (roots,fruits,seeds,etc.) through the phloem tissue.
However,glucose is highly reactive and cannot be transported efficiently through the phloem.
Therefore,it is converted into sucrose,which is a non-reducing sugar.
Sucrose is chemically stable and soluble,making it the primary form of sugar translocated from the source (leaves) to the sink (roots,fruits,seeds,etc.) through the phloem tissue.
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113
BiologyMediumMCQAIPMT · 1992
In photosynthesis and respiration,$ATP$ synthesis occurs through oxidation processes. From where is the energy obtained for this process?
A
Cytochromes
B
Ferredoxin
C
Electrons
D
Carbon dioxide
Solution
(C) In both photosynthesis (photophosphorylation) and respiration (oxidative phosphorylation),$ATP$ synthesis is driven by the movement of electrons through an electron transport chain $(ETC)$.
As electrons move from a higher energy state to a lower energy state through various carriers (like cytochromes or ferredoxin),they release energy.
This released energy is used to pump protons $(H^+)$ across a membrane,creating a proton gradient.
The dissipation of this proton gradient through $ATP$ synthase provides the energy required to phosphorylate $ADP$ into $ATP$.
Therefore,the energy for $ATP$ synthesis is derived from the movement of electrons.
As electrons move from a higher energy state to a lower energy state through various carriers (like cytochromes or ferredoxin),they release energy.
This released energy is used to pump protons $(H^+)$ across a membrane,creating a proton gradient.
The dissipation of this proton gradient through $ATP$ synthase provides the energy required to phosphorylate $ADP$ into $ATP$.
Therefore,the energy for $ATP$ synthesis is derived from the movement of electrons.
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114
BiologyMediumMCQAIPMT · 1992
Which final cytochrome in the respiratory chain donates electrons to oxygen?
A
$Cyt \, b$
B
$Cyt \, c$
C
$Cyt \, a$
D
$Cyt \, a_3$
Solution
(D) In the electron transport system $(ETS)$ of aerobic respiration,the final complex is Complex $IV$,also known as cytochrome $c$ oxidase.
This complex contains cytochromes $a$ and $a_3$,along with two copper centers.
The cytochrome $a_3$ is the terminal component that transfers electrons directly to the final electron acceptor,which is oxygen $(O_2)$,to form water $(H_2O)$.
This complex contains cytochromes $a$ and $a_3$,along with two copper centers.
The cytochrome $a_3$ is the terminal component that transfers electrons directly to the final electron acceptor,which is oxygen $(O_2)$,to form water $(H_2O)$.
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115
BiologyMediumMCQAIPMT · 1992
When one molecule of glucose is completely oxidized,it is converted into:
A
$36$ $ADP$ molecules and $36$ $ATP$ molecules
B
$30$ $ADP$ molecules and $30$ $ATP$ molecules
C
$38$ $ADP$ molecules and $38$ $ATP$ molecules
D
$32$ $ADP$ molecules and $32$ $ATP$ molecules
Solution
(C) During aerobic respiration,one molecule of glucose $(C_6H_{12}O_6)$ undergoes complete oxidation to produce $CO_2$,$H_2O$,and energy in the form of $ATP$.
According to the theoretical yield calculation,the complete oxidation of one glucose molecule results in the net gain of $38$ $ATP$ molecules in prokaryotes (or in some eukaryotic cells via the malate-aspartate shuttle).
This process involves the conversion of $38$ $ADP$ molecules and $38$ inorganic phosphate $(Pi)$ molecules into $38$ $ATP$ molecules.
Therefore,the correct option is $C$.
According to the theoretical yield calculation,the complete oxidation of one glucose molecule results in the net gain of $38$ $ATP$ molecules in prokaryotes (or in some eukaryotic cells via the malate-aspartate shuttle).
This process involves the conversion of $38$ $ADP$ molecules and $38$ inorganic phosphate $(Pi)$ molecules into $38$ $ATP$ molecules.
Therefore,the correct option is $C$.
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116
BiologyEasyMCQAIPMT · 1992
Which instrument is used to measure the rate of respiration and the respiratory quotient $(RQ)$?
A
Auxanometer
B
Potometer
C
Respirometer
D
Manometer
Solution
(C) $Respirometer$ is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide.
It is specifically used to calculate the respiratory quotient $(RQ)$,which is the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$Auxanometer$ is used to measure the growth of plants.
$Potometer$ is used to measure the rate of transpiration.
$Manometer$ is a general instrument used to measure pressure.
It is specifically used to calculate the respiratory quotient $(RQ)$,which is the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$Auxanometer$ is used to measure the growth of plants.
$Potometer$ is used to measure the rate of transpiration.
$Manometer$ is a general instrument used to measure pressure.
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117
BiologyMediumMCQAIPMT · 1992
What is produced by oxidative phosphorylation?
A
$ATP$ in photosynthesis
B
$ATP$ in respiration
C
$NADPH$ in photosynthesis
D
$NADPH$ in respiration
Solution
(B) Oxidative phosphorylation is the process in which $ATP$ is formed as a result of the transfer of electrons from $NADH$ or $FADH_2$ to $O_2$ by a series of electron carriers.
This process occurs in the inner mitochondrial membrane during cellular respiration.
In contrast,photophosphorylation is the process of $ATP$ synthesis in the chloroplast during photosynthesis.
Therefore,oxidative phosphorylation is specifically associated with the production of $ATP$ during respiration.
This process occurs in the inner mitochondrial membrane during cellular respiration.
In contrast,photophosphorylation is the process of $ATP$ synthesis in the chloroplast during photosynthesis.
Therefore,oxidative phosphorylation is specifically associated with the production of $ATP$ during respiration.
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118
BiologyMediumMCQAIPMT · 1992
What happens when the temperature increases above $35^{\circ}C$?
A
The rate of photosynthesis decreases more than the rate of respiration.
B
The rate of respiration decreases more than the rate of photosynthesis.
C
There is no definite pattern.
D
Both rates become parallel to each other.
Solution
(A) Photosynthesis is an enzymatic process,and enzymes are sensitive to temperature. As the temperature rises above $35^{\circ}C$,the enzymes involved in photosynthesis (such as RuBisCO) begin to denature,leading to a sharp decline in the rate of photosynthesis. Conversely,respiration is less sensitive to high temperatures compared to photosynthesis. Therefore,at temperatures above $35^{\circ}C$,the rate of photosynthesis decreases significantly faster than the rate of respiration.
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119
BiologyMediumMCQAIPMT · 1992
The link between glycolysis,the Krebs cycle,and the $\beta$-oxidation of fatty acids/carbohydrate and fat metabolism is ...........
A
Oxaloacetic acid
B
Succinic acid
C
Citric acid
D
Acetyl $CoA$
Solution
(D) Glycolysis converts glucose into pyruvate,which is then converted into Acetyl $CoA$ by the link reaction.
$
$Fatty acids undergo $\beta$-oxidation to produce Acetyl $CoA$.
$
$Acetyl $CoA$ acts as the common substrate that enters the Krebs cycle ($TCA$ cycle) for further oxidation.
$
$Therefore,Acetyl $CoA$ serves as the metabolic bridge or link between carbohydrate metabolism (glycolysis) and fat metabolism ($\beta$-oxidation) and the Krebs cycle.
$
$Fatty acids undergo $\beta$-oxidation to produce Acetyl $CoA$.
$
$Acetyl $CoA$ acts as the common substrate that enters the Krebs cycle ($TCA$ cycle) for further oxidation.
$
$Therefore,Acetyl $CoA$ serves as the metabolic bridge or link between carbohydrate metabolism (glycolysis) and fat metabolism ($\beta$-oxidation) and the Krebs cycle.
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120
BiologyMediumMCQAIPMT · 1992
What are the end products of aerobic respiration?
A
Sugar and $O_2$
B
Water and energy
C
$CO_2$, water, and energy
D
$CO_2$ and energy
Solution
(C) Aerobic respiration is the process of breaking down glucose in the presence of oxygen to produce energy.
The overall chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}$.
As shown in the equation, the end products are carbon dioxide $(CO_2)$, water $(H_2O)$, and energy (in the form of $ATP$).
The overall chemical equation for aerobic respiration is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}$.
As shown in the equation, the end products are carbon dioxide $(CO_2)$, water $(H_2O)$, and energy (in the form of $ATP$).
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121
BiologyMediumMCQAIPMT · 1992
Which hormone is responsible for apical dominance?
A
$IAA$
B
$GA$
C
$ABA$
D
Florigen
Solution
(A) Apical dominance is the phenomenon where the main central stem of the plant grows more dominantly than the side (lateral) stems.
This process is primarily controlled by the hormone $Auxin$,specifically $Indole-3-Acetic Acid$ $(IAA)$.
$IAA$ is synthesized in the apical meristem and transported downwards,where it inhibits the growth of lateral buds.
Therefore,the correct option is $A$.
This process is primarily controlled by the hormone $Auxin$,specifically $Indole-3-Acetic Acid$ $(IAA)$.
$IAA$ is synthesized in the apical meristem and transported downwards,where it inhibits the growth of lateral buds.
Therefore,the correct option is $A$.
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122
BiologyMediumMCQAIPMT · 1992
Which of the following can be used to control dwarfism in plants?
A
Cytokinin
B
Gibberellic acid
C
Auxin
D
Antigibberellin
Solution
(B) Gibberellins are a group of plant growth regulators that promote stem elongation.
In genetically dwarf plants, the application of $Gibberellic \text{ } acid$ $(GA_3)$ induces internode elongation, thereby overcoming the dwarf phenotype and allowing the plant to grow to a normal height.
Therefore, $Gibberellic \text{ } acid$ is used to control or reverse dwarfism in plants.
In genetically dwarf plants, the application of $Gibberellic \text{ } acid$ $(GA_3)$ induces internode elongation, thereby overcoming the dwarf phenotype and allowing the plant to grow to a normal height.
Therefore, $Gibberellic \text{ } acid$ is used to control or reverse dwarfism in plants.
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123
BiologyMediumMCQAIPMT · 1992
The over-ripening of bananas can be delayed by:
A
Keeping them at room temperature
B
Refrigeration
C
Dipping in a solution of Abscisic Acid
D
Storing in a freezer
Solution
(B) The ripening of fruits like bananas is a metabolic process that is temperature-dependent.
Refrigeration slows down the enzymatic activities and the production of ethylene,which is the primary hormone responsible for fruit ripening.
By lowering the temperature,the rate of respiration and the ripening process are significantly reduced,thereby delaying the over-ripening of bananas.
Refrigeration slows down the enzymatic activities and the production of ethylene,which is the primary hormone responsible for fruit ripening.
By lowering the temperature,the rate of respiration and the ripening process are significantly reduced,thereby delaying the over-ripening of bananas.
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124
BiologyEasyMCQAIPMT · 1992
The phenomenon where flowering is dependent on exposure to low temperatures is known as:
A
Cryotherapy
B
Cryogenics
C
Cryoscopy
D
Vernalization
Solution
(D) Vernalization is the process by which flowering is induced or promoted by exposure to low temperatures for a specific period. This ensures that plants flower only during the favorable season. It is a physiological response to cold treatment,commonly observed in winter varieties of wheat,barley,and rye.
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125
BiologyMediumMCQAIPMT · 1992
In short-day plants,flowering is induced by:
A
$A$ photoperiod shorter than $12$ hours
B
$A$ photoperiod shorter than a critical length and a long uninterrupted night
C
$A$ long night
D
$A$ short photoperiod and an interrupted long night
Solution
(B) Short-day plants $(SDP)$ require a photoperiod shorter than a critical duration to flower.
Additionally,they require a long,continuous,and uninterrupted dark period (night) to trigger the flowering response.
If the dark period is interrupted by even a brief flash of light,the flowering process is inhibited.
Therefore,the correct condition is a photoperiod shorter than the critical length and a long uninterrupted night.
Additionally,they require a long,continuous,and uninterrupted dark period (night) to trigger the flowering response.
If the dark period is interrupted by even a brief flash of light,the flowering process is inhibited.
Therefore,the correct condition is a photoperiod shorter than the critical length and a long uninterrupted night.
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126
BiologyMediumMCQAIPMT · 1992
Which of the following can be used to artificially ripen banana fruits?
A
Auxin
B
Coumarin
C
Ethylene
D
Cytokinin
Solution
(C) Ethylene is a gaseous plant hormone that plays a crucial role in the ripening of fruits.
It promotes the breakdown of chlorophyll,the synthesis of carotenoids and anthocyanins,and the conversion of starch into sugars,which makes the fruit soft and sweet.
In commercial agriculture,ethylene is widely used to artificially ripen climacteric fruits like bananas,mangoes,and tomatoes to ensure uniform ripening before they reach the market.
It promotes the breakdown of chlorophyll,the synthesis of carotenoids and anthocyanins,and the conversion of starch into sugars,which makes the fruit soft and sweet.
In commercial agriculture,ethylene is widely used to artificially ripen climacteric fruits like bananas,mangoes,and tomatoes to ensure uniform ripening before they reach the market.
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127
BiologyMediumMCQAIPMT · 1992
What is the primary function of cytokinin?
A
It promotes senescence.
B
It promotes water transport.
C
It helps in delaying senescence by preventing chlorophyll degradation.
D
It inhibits cell division in mature tissues.
Solution
(C) Cytokinin is a plant hormone that stimulates cell division.
One of its significant functions is to delay senescence through the 'Richmond-Lang effect'.
It prevents the degradation of chlorophyll and maintains protein synthesis,which allows leaves to remain green for a longer period.
One of its significant functions is to delay senescence through the 'Richmond-Lang effect'.
It prevents the degradation of chlorophyll and maintains protein synthesis,which allows leaves to remain green for a longer period.
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128
BiologyEasyMCQAIPMT · 1992
Brunner's glands are found in the . . . . . . .
A
Submucosa of the duodenum
B
Submucosa of the stomach
C
Submucosa of the oesophagus
D
Mucosa of the ileum
Solution
(A) Brunner's glands (also known as duodenal glands) are characteristic features of the duodenum.
These glands are located in the submucosal layer of the duodenum.
Their primary function is to secrete an alkaline fluid that protects the duodenal mucosa from the acidic chyme coming from the stomach and provides an optimal pH for the action of pancreatic enzymes.
These glands are located in the submucosal layer of the duodenum.
Their primary function is to secrete an alkaline fluid that protects the duodenal mucosa from the acidic chyme coming from the stomach and provides an optimal pH for the action of pancreatic enzymes.
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129
BiologyEasyMCQAIPMT · 1992
The soil particles determine their ...........
A
Texture
B
Field capacity
C
Water holding capacity
D
Type of vegetation
Solution
(A) The nature and properties of soil in any location are determined by the size of the soil particles. The size of the soil particles determines the soil texture,which in turn influences the percolation and water-holding capacity of the soil. Therefore,the correct answer is $A$.
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