NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions
Question :- 1. Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape. (T/F)
- (a) True
- (b) True
- (c) False
- (d) True
Question :- 2. Make a sketch of the human nerve cell. What function do nerve cells perform?.
Answer:- Function of Nerve Cells:- The nerve cell’s function is to receive and transmit messages, as well as to help control and coordinate the functions of various parts of the body.
Question :- 3. Write short notes on the following:
Answer:- The cytoplasm is a fluid that contains all of the cell’s organelles, including mitochondria, ribosomes, and Golgi bodies. it can be found b etween the nucleus and the cell membrane. It helps in the material exchange between cell organelles. It’s mostly transparent and colourless, and it’s made up of 80% water.
(b) Nucleus of a cell
Answer:- The nucleus is found in the centre of the cell. It is a double-membrane bound cell organelle. It contains the genetic material called DNA. A membrane called the nuclear membrane separates it from the cytoplasm.
Question :- 4. Which part of the cell contains organelles?
Question :- 5. Make sketches of animal and plant cells. State three differences between them.
Plant cell are large in size
They are smaller than plant cells
The cell wall is present in Plant cell
The cell wall is absent
Vacuoles are large in Plant cell
Vacuoles are small as compared to Plant cell
Plastids could be seen in Plant cell
Except for Euglena, Plastids could not be seen in animal cells.
Question :- 6. State the difference between eukaryotes and prokaryotes.
Most of prokaryotes are unicellular.
Most of eukaryotes are multicellular.
The nucleus is poorly defined as there is no nuclear membrane.
The nucleus is well defined as there is a nuclear membrane present in it.
All the cell organelles are not present.
All the cell organelles are present.
Nucleolus is absent in prokaryotes.
Nucleolus is present in eukaryotes.
Eg: Blue-green algae, Bacteria.
Eg: Plant, Animal cells and Fungi.
Question :- 7. Where are chromosomes found in a cell? State their function.
Answer:- Chromosomes are found in the nucleus. The functions of chromosomes is to carry genes on them and to transfer character from one generation to the next.
Question :- 8. ‘Cells are the basic structural units of living organisms’. Explain.
Answer:- Different cells combine and form tissues then these tissues combine to form organs. Similarly, all these organs combine to form a body. Thus they are known as the basic structural unit of every living organism.
Question :- 9. Explain why chloroplasts are found only in plant cells?
Answer:- Chloroplasts are plastids required for photosynthesis, and thus they are only present in plant cells.
Question :- 10. Complete the crossword with the help of clues given below:
- This is necessary for photosynthesis.
- Term for component present in the cytoplasm.
- The living substance in the cell.
- Units of inheritance present on the chromosomes.
- Green plastids.
- Formed by collection of tissues.
- It separates the contents of the cell from the surrounding medium.
- Empty structure in the cytoplasm.
- A group of cells.