Science Group
Explore subjects and practice MCQs
10
Chapters
1,000
Total MCQs
Unit-8 Plant Physiology
Answer: Higher temperature increases evaporation from leaf surfaces and therefore raises the transpiration rate.
Answer: Light triggers the opening of stomata, which in turn increases transpiration.
Answer: Transpiration pull, a negative pressure, is the main force drawing water up the xylem.
Answer: The more concentrated cell sap has a lower water potential, so water moves into the root hair by osmosis.
Answer: Water uptake by osmosis is passive and does not require metabolic energy.
Answer: Sucrose is the principal sugar translocated through the phloem of most plants.
Answer: Phloem transport is bidirectional, moving food from sources to sinks in any direction needed.
Answer: Photosynthesis uses carbon dioxide and releases oxygen during daylight.
Answer: Respiration is a continuous process that takes place in every living cell of the plant.
Answer: Respiration continues at night, so plants release carbon dioxide even when stomata are mostly closed.
Answer: Transpiration cools the leaves and helps in the transport of water and minerals.
Answer: When water loss is greater than absorption, cells lose turgor and the plant wilts.
Answer: Adhesion is the attraction of water molecules to the xylem walls, helping water rise.
Answer: Cohesion is the attraction between water molecules that keeps the xylem water column unbroken.
Answer: The cuticle is a waxy coating that limits cuticular transpiration.
Answer: Active uptake of minerals draws water into the xylem, building up positive root pressure.
Answer: Guttation takes place through hydathodes, not through the stomata.
Answer: Hydathodes are special pores at the margins of leaves that release water droplets during guttation.
Answer: Guttation water is not pure; it contains dissolved minerals that came up with the xylem sap.
Answer: Oxygen is produced when water molecules are split during the light reactions of photosynthesis.