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Unit-8 Plant Physiology
Answer: Lenticels are pores present on woody stems and some roots for gaseous exchange.
Answer: Stomatal transpiration accounts for about 90% of the total water lost by a plant.
Answer: Roots absorb most of the water a plant needs through their root hairs.
Answer: Active transport uses metabolic energy to move ions against the concentration gradient.
Answer: If soil water is more concentrated, minerals diffuse into the root cells.
Answer: Osmosis and diffusion are passive, while active transport needs energy.
Answer: The hypertonic salt solution draws water out of the cells by osmosis, causing plasmolysis.
Answer: Evaporation of water from leaf cells creates tension that pulls the water column upward.
Answer: Water passes from root hairs through the cortex into the xylem and then to the leaves.
Answer: Food transport is the function of the phloem, not the xylem.
Answer: Oxygen is released as a by-product of photosynthesis.
Answer: All living plant cells respire continuously to release energy.
Answer: Phloem translocates organic food from the leaves to other parts of the plant.
Answer: Sucrose is the main form in which sugar is transported in the phloem of most plants.
Answer: Xylem conducts water and minerals in only one direction, upward from the roots.
Answer: In the early morning, transpiration is low and root pressure is high, so guttation occurs.
Answer: Transpiration is greatly reduced at night but does not stop completely.
Answer: Oxygen is given out as a by-product of photosynthesis.
Answer: Nitrogen is mobile, so it moves to young parts, and the older leaves show deficiency symptoms first.
Answer: High humidity with high root pressure and low transpiration forces water out through the hydathodes.