Category: Biology Second Paper

1. The skin of green leaves and young green stems has pores. The root has no stomata.
2. Anthers are present on the lower surface of the opposite sided leaves (dicots, apple), on the upper and lower sides of the equilateral (barley, bhutra) leaves and on all sides of the equilateral (onion) leaves.
3. In flower bud, bracts, bracts and clusters or petals have leaf pores.
4. The young green fruit pods and fruits have leaf pores.
5. Stomata occur in some bryophytes and pteridophytes.
6. A floating plant (shapla) has water pores on the upper part of its leaves. However, submerged aquatic plants have no stomata.
7. The leaf pore is located inside the skin of the plant. It is called sunken. Plants such as pine, cactus, sedum, casuarina etc. have hidden leaf pores.

The stomata open, sometimes partially or fully open, sometimes closed, depending on the environment and time of day and night. This biological rhythm of the stomata is called stomatal clock. The stomata of the plant are fully open from 10-11 am and 2-3 pm. Other times are partially open.

A pore or pore surrounded by two crescent-shaped guard cells located in the leaves and young green stems of plants is called a leaf spore. The lower skin of the opposite sided leaf and the two skins of the same sided leaf have stomata. The aerial parts of plants such as leaves, shoots, petals, fruits etc. have stomata. Leaves may have 1,000-60,000 pores per square centimeter. When open, the stomata are 10-40 cm long and 3-12 cm wide.

Root stress is the stress that occurs in the xylem vessels as a result of the metabolic activity of the root. Absorption of water by the rhizomes results in chlorosis of the outer layer of the plant cells. The stress exerted by the cells of the root cortex when fully inflated is called root stress.

The pressure exerted by the cell wall on the protoplasm due to buoyancy or turgidity is called wall pressure.

The pressure exerted by the protoplasm on the cell wall due to turgidity is called turgor pressure.

When water enters the cell in the process of osmosis, the volume of the cell increases and the cell swells. This condition is called gas inflation or turgidity. Diffusion pressure deficit (DPD) occurs due to gas inflation.

When water escapes from the cell, the protoplasm shrinks, this is called plasmolysis. When water enters the plyomylated cells, the protoplasm expands, this is called deplasmolysis.

Osmotic pressure is the ability of two solutions of different concentrations at the same atmospheric pressure and temperature to move the solute from the lower concentration region to the higher concentration region when separated by a semipermeable membrane.

When two solutions of different concentrations are separated by a semipermeable membrane at the same atmospheric pressure and temperature, the movement of solute from the lower concentration region to the higher concentration region is called osmosis. Osmosis is of two types. Endogenous and exogenous. The movement of solutes from outside the cell into the cell is called endocytosis and the movement of solutes from inside the cell to the outside of the cell is called efflux. Substances that cause water to enter cells are called osmotic agents.