Question

define vacuoles-
__________________ cells have a single large __________________ filled with liquid (water).
central vacuole ____________________ rigidity, why is this important?
what is the difference between contractile and central vacuole?
what are the functions of vesicles?

Explanation:

1. Define Vacuoles: Vacuoles are membrane - bound organelles. Plant cells have a single large vacuole filled with liquid (water).
2. Central Vacuole: The central vacuole provides rigidity to the plant cell. This is important because it helps the plant cell maintain its shape, supports the plant's structure (especially in non - woody plants), and also helps in functions like storing nutrients, waste products, and in maintaining turgor pressure which is essential for processes like photosynthesis as it keeps the chloroplasts close to the cell surface.
3. Difference between contractile and central vacuole:

• Central vacuole (found in plant cells): It is a large, permanent structure. Its main functions include storage (of water, nutrients, waste), maintaining turgor pressure for cell rigidity and plant structure, and sometimes breaking down macromolecules.
• Contractile vacuole (found in some protists like paramecia): It is a smaller, temporary structure (it expands and contracts). Its main function is osmoregulation, i.e., it pumps out excess water from the cell to prevent the cell from bursting in a hypotonic environment.

1. Functions of Vesicles:

• Transport: Vesicles transport materials (like proteins, lipids, and other molecules) within the cell, from one organelle to another, or to and from the cell membrane (e.g., in exocytosis and endocytosis).
• Storage: They can store various substances like neurotransmitters in synaptic vesicles, or enzymes in lysosomal - like vesicles.
• Digestion: Lysosomal vesicles (lysosomes) contain hydrolytic enzymes that can break down macromolecules, worn - out organelles, and foreign particles.
• Secretion: In cells that secrete substances (like glandular cells), vesicles carry the substances to the cell membrane for release outside the cell (exocytosis).

Answer:

s:

• Define Vacuoles - Plant cells have a single large vacuole filled with liquid (water).
• Central Vacuole provides rigidity. It is important for maintaining cell shape, plant structure, turgor pressure for photosynthesis, and storage.
• Central vacuole (plant cells): large, permanent, stores/maintains turgor. Contractile vacuole (protists): small, temporary, osmoregulation.
• Functions of Vesicles: Transport, storage, digestion, secretion.