Kindly help with the following questions!
1. What is cell theory?
2. What are the three main components of a cell?
3. State the differences between a plant cell and an animal cell.
4. Why do plants have big vacuoles?
5. What is the structure of a Nucleus?
6. State the function of the nucleus.
7. What is osmosis and diffusion?
8. What is Plasmolysis?
9. Write the function of the cell wall.
10. Where does plasmolysis occur?
11. What's the structure of the plasma membrane?
12. Why is the plasma membrane called a semi-permeable membrane?
13. What is the role of the crystal?
14. State the main function of the plasma membrane.
15. State the two organelles that contain their own genetic material.
16. Why are lysosomes known as "suicide-bags"?
17. State the structure of the mitochondria.
18. What's the function of the cytoplasm?
19. What are plastids?
20. What is cell division? How many types of cell-divisions exist in plants and animal cells? Explain.
21. What is mitosis?
22. If a cell is dead, what will be the condition of the plasma membrane?
Answers
1. Cell Theory:
- a. Cell is the basic unit of life.
- b. All cells arise from pre - existing cells.
- c. All organisms are composed of cells.
2. 3 main components of a cell: Cell membrane, nucleus and cytoplasm.
3. Difference between plant cells and animal cells:
Plant cell:
- A plant cell is usually larger in size.
- Plastids are present.
- Nucleus lies on one side.
- Centrioles are absent.
Animal cell:
- An animal cell is usually smaller when compared to a plant cell.
- Plastids are absent.
- Nucleus lies in the center.
- Centrioles are rare.
4. Plant cells have large vacuoles to store food and water.
5. Nucleus is a membrane-bound structure that contains the cell’s hereditary information and controls the cell’s growth and reproduction.
6. It is the control center and controls all functional activities of the cell. It helps in cell division. It determines cell development and maturity.
7. Osmosis: Spontaneous movement of water molecules from a region of its higher concentration to a region of its lower concentration through a semi - permeable membrane. Example: Absorption of water by roots.
Diffusion: The spontaneous movement of molecules from a region of higher concentration to a region of lower concentration. Example: Exchange of gases.
8. Contraction of the protoplast of a plant cell as a result of loss of water from the cell is known as plasmolysis.
9. Function of the cell wall: To give the cell strength and structure, and to filter molecules that pαss in and out of the cell.
10. Plasmolysis occurs in the plant cell when there is excess loss of water through leaves to the surroundings.
11. The plasma membrane is flexible and made up of many different types of molecules.
12. It is called semi - permeable membrane because it allows only certain materials to pαss in and out. It prevents the entry of certain materials.
13. The needle - like crystals in certain cells help in the regulation of calcium and defense against grazing animals.
14. Function of plasma membrane: To protect the cell from its surroundings. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.
15. Mitochondria and Chloroplast.
16. Lysosomes are called 'Suicide Bags' because they help in keeping the cell clean. If the part of a cell gets damaged, then one of the lysosomes bursts, releasing their own digestive enzymes.
17. Mitochondria is made up of two membranes. The outer membrane covers the organelle and in it contains a skin-like feature. The inner membrane folds over many times and creates layered structures called cristae.
18. Cytoplasm provides mechanical support to the internal structures. It also stores many chemicals.
19. Plastid is a double - membrane organelle found in plants, a large ovoid or disc-shaped structure. It contains three parts: Chloroplast (carries out photosynthesis), Chromoplast (provides colour to fruits and flowers), Leucoplast (stores starch, oil etc.).
20. Cell division is the process by which a parent cell divides into two or more daughter cells. There are two types of cell division: mitosis and meiosis. There are several types of cell division, depending upon what type of organism is dividing. Organisms have evolved over time to have different and more complex forms of cell division.
21. Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus has.
22. If a cell dies, the components of the cell will leak out and it results in the rupturing of the plasma membrane and the process of diffusion and osmosis will be disturbed.
Answer:
In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. ... All living organisms are composed of one or more cells.