#biology #diffusion #diffusioninplants #plants #igcse #textbook

Pg:- 50,51,52

Ch:- 3

In plants, diffusion is essential for transporting gases, water, and other small molecules.

1. Gas Exchange in Leaves

• Oxygen and Carbon Dioxide: During photosynthesis, plant cells in the leaves produce oxygen as a byproduct, creating a high concentration inside the cells. Oxygen then diffuses out of the cell through tiny openings in the leaf called stomata. Meanwhile, carbon dioxide, which is needed for photosynthesis, diffuses into the cells from the surrounding air.

• Respiration: At night, plants also need oxygen for cellular respiration. Oxygen diffuses into the cells, and carbon dioxide diffuses out as a waste product.

2. Water Movement

• Water moves in and out of plant cells through osmosis, a special type of diffusion where water molecules move across a selectively permeable membrane. For instance:

  • If the soil around the roots has a higher water concentration than the cells in the roots, water will diffuse into the plant cells by osmosis.

  • This movement of water is crucial for keeping plant cells turgid (firm), which helps plants maintain their structure.

3. Nutrient Absorption in Roots

• Some minerals and nutrients from the soil can enter the root cells by diffusion. However, this only works when the concentration of nutrients outside the cell is higher than inside the cell.

Diffusion is essential because it:

• Delivers essential gases and nutrients: It helps plants get carbon dioxide for photosynthesis, oxygen for respiration, and water and nutrients from the soil.

• Removes waste products: It allows oxygen and other waste products of photosynthesis and respiration to leave the plant cells.

• Maintains cellular balance: By allowing the movement of substances in and out, diffusion helps maintain the internal balance of water, nutrients, and gases.

While diffusion is efficient over short distances, it’s slow over larger distances. To overcome this, plants rely on specialized tissues (like xylem and phloem) for transporting water, minerals, and food over long distances within the plant.