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Q1. List any four cell organelles found in animal cell and write their function.

Solution

(i) Mitochondria produce energy from food during respiration. That is why mitochondria are called power house of the cell. Both animal and plant cells contain mitochondria. (ii) Endoplasmic reticulum helps in the transport of substances within the cell. (iii) Ribosomes help in protein synthesis. Ribosomes are found both in the plant and animal cells. (iv) Golgi bodies synthesize, store and secrete many substances. 

Q2. Write two functions of plasma membrane of animal cells.

Solution

(i) The plasma membrane forms the outer boundary of the cell and keeps the cell contents within it.(ii) It is porous and allows the movement of substances or materials both inward and outward.

Q3. Differentiate between plant and animal cells.

Solution

  Plant cell Animal cell 1 Plant cells have an outer, rigid cell wall. Animal cells lack cell wall. 2 Plastids are present in plant cell. Plastids are absent in animal cell. 3 Large, central and permanent vacuole is present. Animal cells have small and many vacuoles which may be temporary. 4 Plant cell is generally larger than animal cell. Animal cell is smaller in size.

Q4. What is the importance of cell wall in plant cell?

Solution

The cell wall surrounding the cell membrane protects plant cells against variations in temperature, high wind speed, atmospheric moisture, etc.

Q5. Briefly describe the structure of nucleus .

Solution

The nucleus consists of the following four parts: (i) Nuclear membrane: It surrounds the nucleus. It controls and allows the passage of certain materials in and out of the nucleus.  (ii) Nucleoplasm: A dense fluid in the nucleus is called nucleoplasm. (iii) Nucleolus: It is a spherical body present inside the nucleus. It contains ribonucleic acid (RNA). (iv) Chromosomes: Chromosomes are thread-like structures composed of deoxyribonucleic acid (DNA). These contain basic hereditary units called genes.

Q6. What is the difference between unicellular and multicellular organisms?

Solution

Unicellular organisms are made up of a single cell whereas multicellular organisms made of more than one cell.

Q7. What would happen if plant cells did not have large vacuoles?

Solution

If a cell did not have a vacuole, then it would be unable to carry out its usual functions and would eventually die. In plants, the vacuole plays an important role in water storage and the maintenance of structure.

Q8. Mention two important functions of nucleus.

Solution

i. It controls all the life processes taking place inside the cell. ii. It helps in the transmission of hereditary characteristics from one generation to another.

Q9. Name the following: a. Cell organelle responsible for protein synthesis b.Temporary finger-like projections formed in Amoeba which helps in its movement

Solution

a. Ribosome is responsible for protein synthesis. b. Amoeba moves from place to place by forming temporary finger-like projections called pseudopodia.

Q10. Write a short note on cytoplasm.

Solution

Cytoplasm is a thick jelly-like fluid inside the cell membrane. Nearly 80% of the cytoplasm is water. It occupies the space between the cell membrane and the nucleus. All the life functions take place in the cytoplasm. There are many small cytoplasmic bodies in cytoplasm. These are called cell Organelles. All organelles in cytoplasm play an active role in the functioning of the cell.

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