Question 1

Which of the following is a macronutrient required by plants in relatively large amounts and is directly involved in the process of photosynthesis?

Accepted Answer

Magnesium

Question 2

A plant shows yellowing of older leaves while the younger leaves remain green. Which nutrient is most likely deficient, and why does this pattern occur?

Accepted Answer

Nitrogen; because it is a mobile nutrient and moves to younger leaves

Question 3

Which process describes how plant roots obtain cations such as $$\mathrm{K^+}$$ and $$\mathrm{Ca$$^{2+}$$}$$ from soil particles?

Accepted Answer

Cation exchange, where $$\mathrm{H^+}$$ ions displace cations from soil particles

Question 4

Which of the following best explains why leaves curl under drought stress?

Accepted Answer

To conserve water by reducing surface area exposed to air

Question 5

Which mutualistic association increases a plant's ability to absorb water and minerals, and what is the main benefit for the fungus?

Accepted Answer

Mycorrhizae; the fungus receives sugars from the plant

Question 6

Which plant hormone is primarily responsible for promoting stem elongation and is used commercially to increase fruit size in seedless grapes?

Accepted Answer

Gibberellins

Question 7

A gardener uses a rooting powder containing indolebutyric acid (IBA) to propagate plants from cuttings. Which hormone is being utilized, and what is its primary effect?

Accepted Answer

Auxin; stimulates adventitious root formation

Question 8

Which hormone is responsible for promoting seed dormancy and drought tolerance in plants?

Accepted Answer

Abscisic acid (ABA)

Question 9

A farmer notices that after removing the terminal bud from a plant, the plant becomes bushier. Which hormones are most directly involved in this process?

Accepted Answer

Auxin, cytokinin, and strigolactone

Question 10

Which hormone is a gaseous compound that promotes fruit ripening and is responsible for the changes seen in the banana ripening sequence?

Accepted Answer

Ethylene

Question 11

Which of the following best describes the role of cytokinins in plant development?

Accepted Answer

Stimulate cell division and delay leaf senescence

Question 12

A plant is treated with a synthetic auxin herbicide (such as 2,4-D). What is the most likely outcome for broadleaf weeds?

Accepted Answer

They will die due to overdose of auxin disrupting normal growth

Question 13

Which of the following is a micronutrient required by plants in very small amounts and is essential for chlorophyll synthesis?

Accepted Answer

Iron

Question 14

Which type of mycorrhizae penetrates the cell wall but not the plasma membrane of root cells?

Accepted Answer

Arbuscular mycorrhizae

Question 15

Which hormone is primarily responsible for the triple response in seedlings (inhibition of stem elongation, promotion of lateral expansion, and horizontal growth)?

Accepted Answer

Ethylene

Question 16

A seed fails to germinate until it experiences heavy rain, light, or prolonged cold. Which hormone is most likely responsible for maintaining dormancy until these conditions are met?

Accepted Answer

Abscisic acid (ABA)

Question 17

Which of the following best explains why negatively charged ions such as $$\mathrm{NO_3$^-}$$ are more likely to be lost from soil than cations?

Accepted Answer

They do not bind to soil particles and are easily leached by water

Question 18

Which hormone is produced in high concentrations during senescence, leaf abscission, and fruit ripening, and is also synthesized in response to wounding?

Accepted Answer

Ethylene

Question 19

Which of the following best describes the interaction between auxin and cytokinin in the control of apical dominance?

Accepted Answer

Auxin inhibits axillary bud growth, cytokinin promotes it

Question 20

A plant is observed to have stunted growth, yellowing between the veins of older leaves, and poor fruit development. Which nutrient is most likely deficient?

Accepted Answer

Magnesium

Plant Nutrition and Hormones: Essential Elements, Soil Interactions, and Hormonal Regulation

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