Class 8 - Science
Chapter 8 - Cell Structure and Functions
Top Block 1
Question :1. Indicate whether the following statement are true (T) or false(F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscles 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)
Answer :
(a) T
(b) F
(c) F
(d) T
Question :2. Make a sketch of the human nerve cell. What function do nerve cells perform?
Answer :
Nerve cell-
Question :3. Write short notes on the following.
(a) Cytoplasm
(b)Nucleus of a cell
Answer :
(a) Cytoplasm- It is the jelly-like substance found in between the nucleus and the cell membrane. It contains many cell organelles. Cytoplasm along with nucleus forms the protoplasm.
(b) Nucleus- It is a spherical structure located in the Centre of the cell. It is known as brain of the cell as it controls the activities of cells. It is separated from cytoplasm by a membrane called nuclear membrane.
Question :4. Which part of the cell contains organelles?
Answer :
Cytoplasm contains organelles of the cell.
Question :5. Make sketches of animal and plant cells. State three differences between them.
Answer :
Mddle block 1
Difference between plant and animal cell-
| Animal Cell | Plant Cell |
|---|---|
| 1. Cell wall is absent | 1. Cell wall is present |
| 2. Plastids are absent | 2. Plastids are present |
| 3. Nucleus is in the middle of cell | 3. Nucleus is towards periphery |
Question :6. State the difference between eukaryotes and prokaryotes.
Answer :
Eukaryotes have well-organized nucleus with nuclear membrane while prokaryotes do not have well organized nucleus.
Prokaryotic cell is generally smaller in size than eukaryotic cells.
Question :7. Where are chromosomes found in a cell? State their function.
Answer :
Chromosomes are found in the nucleus of the cell. They carry genes and help in inheritance of characters from the parents to the offspring
Question :8. ‘Cells are the basic structural units of living organisms’. Explain.
Answer :
All the living organisms are made of cells either unicellular or multicellular. The basic functions of life like respiration, assimilation and all major metabolic activities are carried inside the cell. So, cell is known as structural and functional units of living organism.
Question :9. Explain why chloroplasts are found only in plant cells?
Answer :
Chloroplast contains chlorophyll which synthesizes food in plants by the process of photosynthesis. No photosynthesis occurs in animals. So, they do not contain chloroplast.
