Cell - Structure And Functions

Exercises 

1. Indicate whether the following statements are True (T) or False (F).

(a) Unicellular organisms have one-celled body. (T)

(b) Muscle cells are branched. (F)

(c) The basic living unit of an organism is an organ.  (F)

(d) Amoeba has irregular shape. (T)

2. Make a sketch of the human nerve cell. What function do nerve cells perform?

Ans:-

Function of nerve cell :

The nerve cell receives and transfers messages, thereby helping to control and coordinate the working of different parts of the body.

3. Write short notes on the following.

(a) Cytoplasm

Ans:-

It is one of the basic components of the cell which is enclosed within the cell membrane. It is the jelly-like substance present between the cell membrane and the nucleus. Various other components, or organelles, of cells are present in the cytoplasm. These are mitochondria, golgi
bodies, ribosomes, etc.

(b) Nucleus of a cell

Ans:-

It is an important component of the living cell. It is generally spherical and located in the centre of the cell. It can be seen easily with the help of a microscope. Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane.This membrane is also porous and allows the movement of materials between the cytoplasm and the inside of the nucleus.With a microscope of higher magnification, we can see a smaller spherical body in the nucleus called the nucleolus. In addition, nucleus contains thread-like structures called chromosomes which carries genes and help in inheritance. Thus, nucleus acts as control centre of the activities of the cell.

4. Which part of the cell contains organelles?

Ans:-

Cytoplasm contains organelles.

5. Make sketches of animal and plant cells. State three differences between them.

Ans:-

6. State the difference between eukaryotes and prokaryotes.

Ans:-

7. Where are chromosomes found in a cell? State their function.

Ans:-

Chromosomes are found in the nucleus of the cell. They are thread like structure whose function is to carry genes and help in inheritance or transfer of characters from the parents to the offspring.

8. ‘Cells are the basic structural units of living organisms’. Explain.

Ans:-

'Cells are the basic structural units of living organisms'. This statement is absolutely true because the group of similar cells performing same function forms a tissue which further combine to built an organ.That's why they are the building blocks of a body.

9. Explain why chloroplasts are found only in plant cells?

Ans:-

Chloroplasts are only present in plants because it is a type of plastids that contains green color pigment called chlorophyll which is an essential for plants to make their food during photosynthesis.

10. Complete the crossword with the help of clues given below.

Across

1. This is necessary for photosynthesis.

3. Term for component present in the cytoplasm.

6. The living substance in the cell.

8. Units of inheritance present on the chromosomes.

Down

1. Green plastids.

2. Formed by collection of tissues.

4. It separates the contents of the cell from the surrounding medium.

5. Empty structure in the cytoplasm.

7. A group of cells.

Ans:-

Across

1. Chlorophyll
3. Organelles
6. Protoplasm
8. Genes

Down
1. Chloroplasts
2. Organ
4. Membrane
5. Vacuole
7. Tissue