Important questions based on NCERT syllabus for Chapter 8 - Cell - Structure and Functions:
Question-1: Cells are the basic structural units of living organisms’. Mention three points in favour.
Solution: 1. Cells are the smallest units from which a living organism is made.
2. A cell contains all the necessary structures which are required to carry out various biological processes.
3. A group of cells makes a tissue which further makes organs and finally an organism.
Thus, cells are called the basic structural unit of living organisms.
Question-2: Write a note on: (a) Cytoplasm (b) Cell Membrane
Solution: (a) Cytoplasm 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, ribosome, etc.
(b) The cytoplasm and nucleus are enclosed within the cell membrane, also called the plasma membrane. The membrane separates cells from one another and also the cell from the surrounding medium. The plasma membrane is porous and allows the movement of substances or materials both inward and outward.
Question-3: Write a note on plastids and nucleus of a cell.
Solution: 1. Plastids are a major organelle found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell. They often contain pigments used in photosynthesis and the types of pigments present can change or determine the cell's colour. They are of different colours. Some of them contain green pigment called chlorophyll. Green coloured plastids are called chloroplasts.
- Nucleus acts as control centre of the activities of the cell. The entire content of a living cell is known as protoplasm. It includes the cytoplasm and the nucleus. Protoplasm is called the living substance of the cell. Nucleus contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the offspring. Genes have all the information to carry out all the processes of the cell.