Biology Test Plant Biology 3 — Questions and Answers
Question 1: What is the primary pigment responsible for capturing light energy during photosynthesis?
- Carotenoid
- Xanthophyll
- Chlorophyll a (Correct answer)
- Phycobilin
Correct answer: Chlorophyll a
Chlorophyll a is the main photosynthetic pigment that directly participates in the light reactions by absorbing red and blue light.
Question 2: During which phase of the cell cycle does DNA replication occur in plants?
- G1 phase
- S phase (Correct answer)
- G2 phase
- M phase
Correct answer: S phase
DNA replication occurs during the S (synthesis) phase of interphase, duplicating the entire genome before cell division.
Question 3: What type of root adaptation allows mangrove trees to exchange gases in waterlogged soils?
- Prop roots
- Pneumatophores (Correct answer)
- Haustoria
- Contractile roots
Correct answer: Pneumatophores
Pneumatophores are specialized vertical roots that extend above the waterline to allow gas exchange in oxygen-poor, flooded soils.
Question 4: Which layer of the leaf is responsible for most photosynthesis and has loosely packed cells to allow gas diffusion?
- Palisade mesophyll
- Spongy mesophyll (Correct answer)
- Upper epidermis
- Lower epidermis
Correct answer: Spongy mesophyll
Spongy mesophyll cells have large air spaces between them that facilitate CO2 and O2 diffusion to and from chloroplasts.
Question 5: What is the role of the Casparian strip in plant roots?
- Stores starch
- Prevents backflow of water into the soil
- Forces water through the symplast into the vascular tissue (Correct answer)
- Absorbs mineral ions by active transport
Correct answer: Forces water through the symplast into the vascular tissue
The Casparian strip is a waxy band in endodermal cell walls that blocks the apoplastic pathway, forcing water and solutes through the symplast into the stele.
Question 6: Which plant tissue type provides structural support and is composed of dead cells at maturity?
- Collenchyma
- Parenchyma
- Sclerenchyma (Correct answer)
- Meristematic tissue
Correct answer: Sclerenchyma
Sclerenchyma cells have thick, lignified secondary cell walls and are dead at functional maturity, providing rigid mechanical support.
Question 7: What is vernalization in plants?
- Leaf color change in autumn
- Requirement for cold temperature to trigger flowering (Correct answer)
- Growth response toward light
- Root elongation in spring
Correct answer: Requirement for cold temperature to trigger flowering
Vernalization is the process by which prolonged cold exposure enables or accelerates flowering in some plant species come spring.
Biology Test Plant Biology 3
What is the primary pigment responsible for capturing light energy during photosynthesis?