In this post we will see science class 8th chapter 8 solutions.
You can check the Complete Science Solution here – NCERT Class 8th Science Solutions – Complete Solution List
Chapter 8 Solutions
1. Indicate whether the following statements are true (T) false (F).
(a) Unicellular organisms have one-celled body. (T / F)
(b) Muscles cell 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) Unicellular organisms have one-celled body. (T)
(b) Muscle cells are branched. (F)
(c) The basic 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?
Answer –
The function of a nerve cell is to transmit messages to the brain and also to take away message from the brain to the receptor organs. Thus, it controls the working of different parts of the body.
3. Write the short note on the following.
(a) Cytoplasm
Answer – It is fluid that fills the cell and occurs between the plasma membrane and nucleus. Cell organelles such as mitochondria. Ribosomes, golgi bodies, etc are suspended in the cytoplasm. The cytoplasm helps in the exchange of materials between cell organelles
(b) Nucleus of a cell
Answer – The nucleus is a spherical structure generally present at the centre of a cell. THe nucleus is composed of the following components.
(i) Nuclear membrane:
It is a double-layered membrane which is separates the contents of the nucleus from the cytoplasm. The nuclear membrane has nuclear pores that allow the transfer of specific substance in and out of the nucleus.
(ii) Nucleolus:
It is a small spherical body that is not bound by any membrane.
(iii) Chromosomes:
These are thread-like structures that carry genes. Genes contain information necessary for the transfer of characteristics from the parents to the offspring. Thus, chromosomes play an important role in the inheritance of characteristics.
4. Which part of the cell contains organelles?
Answer – Cytoplasm is the part of the cell that contains various organelles such as mitochondria, ribosomes, Golgi bodies, etc. Cytoplasm is a fluid that fills the cell and occurs between the plasma membrane and the nucleus.
5. Make sketches of animal and plant cells. State three differences between them.
Answer –
|
Animal cell |
Plant cell |
 |
 |
| They are generally small in size. | They are usually larger than animal cells. |
| Cell wall is absent. | Cell wall is present. |
| Vacuoles are small in size. | Vacuoles are larger in size. |
| No other animal cell possesses plastid sex protozoan Euglena. | Plastids are present. |
6. State the difference between eukaryotes and prokaryotes.
Answer –
|
Prokaryotes |
Eukaryotes |
| Most prokaryotes are unicellular. | Most eukaryotes are multicellular. |
| The nucleus is poorly defined due to the nucleus membrane. | The nucleus is well defined and is surrounded by a nuclear membrane. |
| Nucleolus is absent. | Nucleolus is present. |
| Cell organelles such as plastids, mitochondria, gogli bodies, etc are present. | Cell organelles such as plastids, mitochondria, golgi bodies, etc are absent. |
| Bacteria and blue- green algae prokaryotic cells. | Fungi, plant and animal cell are eukayotic cells. |
7. Where are chromosomes found in a cell ? State their function .
Answer – The nucleus contain threat-like structure called chromosomes. chromosomes play an important role in the inheritance of characters. They carry genes that help in the transfer of characters from the presents to the offspring.
8. ‘Cells are basic structural units of living organisms’. Explain.
Answer – Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions. Cells are the building blocks of life. This is the reason why cells are referred to as “the basic structural and functional units of life.” All cells vary in their shapes, sizes, and activities they perform. In fact, the shapes and size of the cell is related to the specific function it performs.
9. Explain why chloroplasts are found only in plant cells ?
Answer – Chloroplasts are found only in plant cells. They contains a green pigment called chlorophyll. This green pigment is important for photosynthesis in green plants. This chlorophyll
pigment traps solar energy and utilizes it to manufacture food for the plant.
10. Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Terms 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.
Answer –
Across
1. CHLOROPHYLL
3. ORGANELLE
6. PROTOPLASM
8. GENES
Down
1. CHLOROPLAST
2. ORGAN
4. MEMBRANE
5. VACUOLE
7. TISSUE
You can check the Complete Science Solution here – NCERT Class 8th Science Solutions – Complete Solution List
You can see other posts here.
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