GATE XL topic:life-sciences PYQs & Answers — Page 42

Questions 411–420 of 1235. Imported answers require independent review unless marked reviewed.

An organism uses only the glycerophosphate shunt pathway to transport cytosolic NADH to mitochondria. For every two electrons transported, complex I, complex III, and complex IV of the electron transport chain in this organism transport 2.5, 1.5, and 2.0 protons (H⁺), respectively. The H⁺ to ATP ratio of F₀F₁-ATPase of this organism is 4.0. Terminal electron acceptor is oxygen.

The number of ATP molecules synthesized by oxidizing NADH from glycolysis is ________ (rounded off to two decimal places).

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If the extracellular concentration of sodium ion (Na⁺) is ten times more than its intracellular concentration, then the sodium equilibrium potential at 20 °C in mV is ______________ (rounded off to two decimal places). Assume that the membrane is permeable only to Na⁺ ions. [Use R = 1.987 cal deg⁻¹ mol⁻¹ and F = 23062 cal mol⁻¹ V⁻¹]

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Which one of the following statements on Casparian strips is correct?

Your answerChoose one option.

Casparian strips are specific to vascular plants found in epidermal cells.

Casparian strips are modifications mostly found in shoot tissue.

Casparian strips act as a cellular barrier to allow selective nutrient uptake and exclusion of pathogens.

Casparian strips are common in root endodermal cells of non-vascular plants.

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Rotenone is a chemical often used to kill insect pests on crop plants and fishes in lakes. Rotenone acts by inhibiting electron transport from the NADH dehydrogenase enzyme in Complex I to ubiquinone in the mitochondrial electron transport chain. Which one of the following explains why plants can tolerate rotenone application?

Your answerChoose one option.

The Complex I in plants is resistant to rotenone.

Plants inactivate rotenone by enzymatic degradation.

Plants have specific channels that efflux rotenone out of the cell.

Plants have additional NAD(P)H dehydrogenases that are resistant to rotenone.

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Although Pseudomonas syringae infection in plants is actively inhibited by the endogenous salicylic acid (SA) of host origin, a successful infection is still established because the bacterium secretes coronatine, an effector molecule. Which one of the following best describes the mode of action of coronatine?

Your answerChoose one option.

Coronatine inhibits SA biosynthesis.

Coronatine promotes the biosynthesis of jasmonic acid (JA), and JA signal in turn inhibits SA response.

Coronatine is a structural analogue of SA, which binds to the SA receptor and inhibits its function.

Coronatine is a structural analogue of jasmonic acid (JA), which activates JA signaling to inhibit SA response.

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The schematic depicts an unexpanded plant cell within a hypocotyl with the arrangement of cellulose microfibrils marked on its cell wall.

Which one of the following shapes would most likely result from the expansion of this cell if the pattern of the cellulose fibers does not change?

Your answerChoose one option.

Diagram for Life Sciences question 50 (figure 2)

Diagram for Life Sciences question 50 (figure 3)

Diagram for Life Sciences question 50 (figure 4)

Diagram for Life Sciences question 50 (figure 5)

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Which one or more of the following statements is/are NOT CORRECT with respect to pollen development in angiosperm?

Your answerSelect all correct options. You can choose more than one.

Tapetal cell wall in all angiosperms breaks down to release the cytoplasmic content.

Tapetal cell wall in all angiosperms remains intact.

Tapetal cell wall breaks down in some angiosperm species, whereas it remains intact in others.

Within an angiosperm species, the tapetal cell wall breaks down in some individuals and not in others.

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Regulation of phosphoenolpyruvate carboxylase (PEPCase) governs CO₂ fixation in both C4 and CAM (crassulacean acid metabolism) plants. Which one or more of the following statements with respect to PEPCase activity is/are CORRECT?

Your answerSelect all correct options. You can choose more than one.

PEPCase in C4 plants is inactivated by dephosphorylation during the day.

PEPCase in CAM plants is inactivated by dephosphorylation during the day.

PEPCase in C4 plants is inactivated by dephosphorylation at night.

PEPCase in CAM plants is inactivated by dephosphorylation at night.

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Which one or more processes listed below DOES NOT/DO NOT produce carbon dioxide during fermentation?

Your answerSelect all correct options. You can choose more than one.

Brewing wine using yeast.

Baking bread using yeast.

Making yogurt using lactobacillus.

Making cheese using fungus.

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The ovule of a diploid species with 2n = 8 undergoes double fertilization. If the pollen is contributed by an individual with meiotic nondisjunction, the chromosome number of the zygote will be __________.

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GATE XL topic:life-sciences PYQs

Question 45

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Question 49

Question 50

Question 51

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Question 53

Question 54