NCERT Class VIII Science Solutions: Chapter 8-Cell Structure and Functions Part 1

Download PDF of This Page (Size: 569K)

Question 1:

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

  1. Unicellular organisms have one-celled body. (T/F).

  2. Muscle cells are branched. (T/F).

  3. The basic living unit of an organism is an organ. (T/F).

  4. Amoeba has irregular shape. (T/F).

Answer:

  1. Unicellular organisms have one-celled body. (True)

  2. Muscle cells are branched. (False)

  3. The basic living unit of an organism is an organ. (False)

  4. Amoeba has irregular shape. (True)

Question 2:

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

Answer:

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

As showing in image is a nerve cells

Nerve Cells

As showing in image is a nerve cells

Question 3:

Write short notes on the following:

  1. Cytoplasm.

  2. Nucleus of a cell.

Answer:

Cytoplasm.

The jelly-like substance between the nucleus and the cell membrane is called cytoplasm. Various cell organelles like ribosomes, mitochondria etc. are suspended inside cytoplasm. It helps exchange and storage of substances among cell organelles. Most of the metabolic activities occur inside cytoplasm.

As showing in image is a Cytoplasm

Cytoplasm

As showing in image is a Cytoplasm

  • Nucleus of a cell.

  • The central dense round body in the centre is called the nucleus. It is an important component of the living cell. It is generally spherical and located in the centre of the cell. It can be stained and 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. A smaller spherical body in the nucleus, is called the nucleolus. Nucleus also contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the offspring.

This diagram shows Cell Nucleus

Cell Nucleus Diagram

This diagram shows Cell Nucleus