Plant Physiology Biochemistry

(a) Label the Vacuole and Plasma Membrane.
In a turgid plant cell, there are two key structures that need to be labelled:
1. Vacuole
The vacuole is a large, membrane-bound organelle found at the center of a plant cell. It contains cell sap, which is a mixture of water, sugars, salts, and waste products. The vacuole plays several important roles in plant cells, including:
- Storage: It stores nutrients, waste products, and other substances the cell might need or want to expel.
- Turgor Pressure: The vacuole is critical in maintaining turgor pressure within the cell. This pressure is created by the water filling the vacuole, pushing against the cell wall, which helps keep the plant cell rigid and supports the overall structure of the plant.

2. Plasma Membrane
The plasma membrane, also known as the cell membrane, is the outermost layer of the cell. It surrounds the entire cell and separates the internal components from the external environment. The plasma membrane plays a crucial role in maintaining the cell's integrity and homeostasis. Its functions include:
- Selective Permeability: The plasma membrane controls the movement of substances into and out of the cell. It allows essential nutrients to enter the cell and waste products to be expelled. It also helps regulate the internal environment by controlling the concentration of ions and other molecules inside the cell.
- Protection and Structure: The plasma membrane provides structural support to the cell and protects it from harmful substances. It also plays a role in communication with other cells through receptors on its surface, which can respond to signals from the environment or neighboring cells. - The vacuole helps maintain the shape and size of the cell, making it an essential component for plant growth and rigidity. Without the vacuole, plant cells would lack the necessary turgor pressure, and the plant would wilt. - The plasma membrane is important for the cell’s interaction with its environment. By selectively allowing substances to pass through, it ensures that the cell can take in necessary materials, expel waste, and maintain a balanced internal environment.