Chapter Exam

Unit 4: Plant Physiology — Online MCQ Test

Q: Name the plant growth regulator which upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop.

Answer: A. Gibberellin — Gibberellins are used to increase the length of stems in sugarcane, thereby increasing the yield as sugar is stored in the stem.

Q: In light reaction, plastoquinone facilitates the transfer of electrons from :

Answer: D. PS-II to Cyt b6f complex — In the Z-scheme of photosynthesis, electrons travel from PS-II to plastoquinone (PQ), which then transfers them to the Cytochrome b6f complex.

Q: Which of the following is not an inhibitory substance governing seed dormancy?

Answer: D. Gibberellic acid — Abscisic acid, phenolic acid, and para-ascorbic acid are inhibitors. Gibberellic acid promotes seed germination and breaks dormancy.

Q: Match the following concerning essential elements and their functions in plants: (a) Iron (i) Photolysis of water (b) Zinc (ii) Pollen germination (c) Boron (iii) Required for chlorophyll biosynthesis (d) Manganese (iv) IAA biosynthesis

Answer: B. (2) (iii) (iv) (ii) (i) — Iron is involved in chlorophyll biosynthesis. Zinc is essential for IAA (auxin) synthesis. Boron is crucial for pollen germination and tube growth. Manganese is involved in the photolysis of water.

Q: Which of the following is not an inhibitory substance governing seed dormancy?

Answer: D. Gibberellic acid — Gibberellic acid (GA) is a growth promoter that promotes seed germination and breaks dormancy, unlike the others which are inhibitors.

Q: The process responsible for facilitating loss of water in liquid form from the tip of grass blades at night and in early morning is:

Answer: A. Root pressure — Guttation (the loss of water as droplets) is caused by high root pressure when transpiration is low.

Q: The complex II of mitochondrial electron transport chain is also known as

Answer: B. Succinate dehydrogenase — Complex II of the ETC is succinate dehydrogenase, which links the TCA cycle to the electron transport chain.

Q: Attractants and rewards are required for

Answer: A. Entomophily — Entomophily is pollination by insects. To attract them, plants provide rewards such as nectar and pollen grains.

Q: Which part of the tobacco plant is infected by Meloidogyne incognita?

Answer: D. Root — Meloidogyne incognita is a nematode that infects the roots of tobacco plants.

Q: Stomatal movement is not affected by

Answer: B. O₂ concentration — Stomatal movement is affected by light (blue light triggers opening), CO₂ concentration (high CO₂ causes closure), and temperature (extreme temperatures affect stomatal movement). However, O₂ concentration does not directly affect stomatal movement — it is not a recognised factor in the regulation of guard cell turgor.

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Practice Unit 4: Plant Physiology with a free chapter-wise online MCQ test for NEET NEET (All) BIOLOGY. This chapter covers: Photosynthesis: Photosynthesis as a means of Autotrophic nutrition; Site of photosynthesis take place; pigments involved in Photosynthesis (Elementary idea); Photochemical and bios.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Unit 4: Plant Physiology — Important Questions & Answers (FAQ)

Frequently asked questions from NEET NEET (All) BIOLOGY — Unit 4: Plant Physiology, with answers and explanations. These are sample questions; the exam has its own separate question set.

Name the plant growth regulator which upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop.

A. Gibberellin ✓
B. Ethylene
C. Abscisic acid
D. Cytokinin

Answer: A. Gibberellin
Gibberellins are used to increase the length of stems in sugarcane, thereby increasing the yield as sugar is stored in the stem.

In light reaction, plastoquinone facilitates the transfer of electrons from :

A. Cyt b6f complex to PS-I
B. PS-I to NADP+
C. PS-I to ATP synthase
D. PS-II to Cyt b6f complex ✓

Answer: D. PS-II to Cyt b6f complex
In the Z-scheme of photosynthesis, electrons travel from PS-II to plastoquinone (PQ), which then transfers them to the Cytochrome b6f complex.

Which of the following is not an inhibitory substance governing seed dormancy?

A. Abscisic acid
B. Phenolic acid
C. Para-ascorbic acid
D. Gibberellic acid ✓

Answer: D. Gibberellic acid
Abscisic acid, phenolic acid, and para-ascorbic acid are inhibitors. Gibberellic acid promotes seed germination and breaks dormancy.

Match the following concerning essential elements and their functions in plants: (a) Iron (i) Photolysis of water (b) Zinc (ii) Pollen germination (c) Boron (iii) Required for chlorophyll biosynthesis (d) Manganese (iv) IAA biosynthesis

A. (1) (iv) (iii) (ii) (i)
B. (2) (iii) (iv) (ii) (i) ✓
C. (3) (iv) (i) (ii) (iii)
D. (4) (ii) (i) (iv) (iii)

Answer: B. (2) (iii) (iv) (ii) (i)
Iron is involved in chlorophyll biosynthesis. Zinc is essential for IAA (auxin) synthesis. Boron is crucial for pollen germination and tube growth. Manganese is involved in the photolysis of water.

Which of the following is not an inhibitory substance governing seed dormancy?

A. Abscisic acid
B. Phenolic acid
C. Para-ascorbic acid
D. Gibberellic acid ✓

Answer: D. Gibberellic acid
Gibberellic acid (GA) is a growth promoter that promotes seed germination and breaks dormancy, unlike the others which are inhibitors.

The process responsible for facilitating loss of water in liquid form from the tip of grass blades at night and in early morning is:

A. Root pressure ✓
B. Imbibition
C. Plasmolysis
D. Transpiration

Answer: A. Root pressure
Guttation (the loss of water as droplets) is caused by high root pressure when transpiration is low.

The complex II of mitochondrial electron transport chain is also known as

A. Cytochrome bc1
B. Succinate dehydrogenase ✓
C. Cytochrome c oxidase
D. NADH dehydrogenase

Answer: B. Succinate dehydrogenase
Complex II of the ETC is succinate dehydrogenase, which links the TCA cycle to the electron transport chain.

Attractants and rewards are required for

A. Entomophily ✓
B. Hydrophily
C. Cleistogamy
D. Anemophily

Answer: A. Entomophily
Entomophily is pollination by insects. To attract them, plants provide rewards such as nectar and pollen grains.

Which part of the tobacco plant is infected by Meloidogyne incognita?

A. Flower
B. Leaf
C. Stem
D. Root ✓

Answer: D. Root
Meloidogyne incognita is a nematode that infects the roots of tobacco plants.

Stomatal movement is not affected by

A. Light
B. O₂ concentration ✓
C. Temperature
D. CO₂ concentration

Answer: B. O₂ concentration
Stomatal movement is affected by light (blue light triggers opening), CO₂ concentration (high CO₂ causes closure), and temperature (extreme temperatures affect stomatal movement). However, O₂ concentration does not directly affect stomatal movement — it is not a recognised factor in the regulation of guard cell turgor.

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