9th Standard NCERT Chapter 5 And Solution of Chapter 5

Cell Biology Questions and Answers

1. Make a comparison and write down ways in which plant cells are different from animal cells.

Plant cells have a cell wall, chloroplasts, and a large vacuole. Animal cells do not have a cell wall and chloroplasts and have small vacuoles. Plant cells can make their own food, but animal cells cannot. Plant cells are mostly rectangular, while animal cells are mostly round.

2. How is a prokaryotic cell different from a eukaryotic cell?

Prokaryotic cells do not have a true nucleus, while eukaryotic cells have a proper nucleus with a membrane. Prokaryotic cells are smaller and simpler, while eukaryotic cells are larger and complex. Bacteria are prokaryotic, while plants and animals have eukaryotic cells with membrane-bound organelles.

3. What would happen if the plasma membrane ruptures or breaks down?

If the plasma membrane breaks, the cell’s contents will leak out, and harmful substances can enter. The cell will lose control over material movement, and it cannot survive. The plasma membrane protects the cell and helps in maintaining its internal environment, so the cell will die.

4. What would happen to the life of a cell if there was no Golgi apparatus?

Without the Golgi apparatus, the cell cannot package and transport proteins and other materials. The formation of lysosomes will not occur, and the cell will not remove waste properly. It will disturb important processes, and the cell will not function properly and may die.

5. Which organelle is known as the powerhouse of the cell? Why?

Mitochondria are called the powerhouse of the cell because they produce energy by breaking down food. They release energy in the form of ATP, which is used for different activities in the cell. Without mitochondria, cells will not get energy for their functions.

6. Where do the lipids and proteins constituting the cell membrane get synthesized?

Lipids are made in the smooth endoplasmic reticulum, and proteins are made in the rough endoplasmic reticulum, which has ribosomes. Later, these lipids and proteins go to the Golgi apparatus for processing and then form the cell membrane to help protect the cell.

7. How does an Amoeba obtain its food?

An Amoeba uses pseudopodia to surround and capture food particles from water. It forms a food vacuole around the food, where enzymes digest it. The nutrients are absorbed into the cell, and the waste is removed from the body after digestion in the vacuole.

8. What is osmosis?

Osmosis is the movement of water from an area of high water concentration to low water concentration through a semi-permeable membrane. It helps in maintaining water balance inside the cell. Plants use osmosis to absorb water from the soil into their roots for survival.

9. Carry out the following osmosis experiment:

(i) Explain why water gathers in the hollowed portion of B and C.

Water gathers in B and C because sugar and salt create a high concentration inside the potato cups, and water moves from the surrounding water (high concentration) into the cups (low concentration) through osmosis, filling the hollow portions with water.

(ii) Why is potato A necessary for this experiment?

Potato A is necessary as a control to compare results. It shows that without sugar or salt, water does not enter the potato cup, proving that osmosis happens only when there is a concentration difference inside and outside the potato cup.

(iii) Explain why water does not gather in the hollowed-out portions of A and D.

Water does not gather in A because there is no sugar or salt to create a concentration difference. In D, the boiled potato’s cells are dead and their membranes are damaged, so osmosis cannot happen, and water does not gather in the hollow.

10. Which type of cell division is required for growth and repair of body and which type is involved in formation of gametes?

Mitosis is required for growth and repair of the body as it produces identical cells for replacing old and damaged cells. Meiosis is involved in the formation of gametes (sperm and egg) because it reduces the chromosome number to half, helping in sexual reproduction.