CNS = brain + spinal cord. The peripheral nervous system (PNS) includes cranial and spinal nerves. The autonomic nervous system controls involuntary functions.
Consider the following statements about the plant root:
1. Root hairs increase absorption surface area.
2. The root cap protects the root tip.
3. The zone of elongation is responsible for root growth in length.
Which of the above is/are correct?
In plant physiology, the 'Root pressure' is a positive pressure that develops in the roots due to the active absorption of minerals and the subsequent osmotic entry of water. It is most evident during:
A.Winter when the ground is frozen
B.Mid-day when transpiration is high
C.Drought conditions
D.Early morning or night when transpiration is low and soil moisture is high
Explanation:
Root pressure is a positive hydrostatic pressure generated in the xylem of roots due to the active secretion of ions into the xylem, which lowers the water potential and causes water to enter osmotically from the soil. This pressure can push water up the stem. Root pressure is most evident and measurable during the early morning or at night, when the rate of transpiration from the leaves is very low (or zero) and the soil moisture is high, allowing for maximum water absorption. It is responsible for phenomena like guttation and the exudation of sap from cut stems.
Explanation:
Sericulture is the process of rearing silkworms (primarily Bombyx mori) for the production of silk. The silkworm feeds on mulberry leaves (Morus alba) and spins a continuous filament of silk protein (fibroin) to form a cocoon around itself during its pupal stage. The cocoons are then boiled to kill the pupa and unwind the silk filament for textile production.
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