NCERT Class 8 Science Chapter 8 Solution
Brief Information: This post contains the solution for Chapter 8 Cell Structure and Functions of Class 8 of the CBSE and also Gujarat Board (GSEB) books by GCERT (based on new NCERT).
Q1. Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have a one-celled body. – T (True)
(b) Muscle cells are branched. – T (True)
(c) The basic living unit of an organism is an organ. – F(False)
(d) Amoeba has an irregular shape. – F(False)
Q.2 Make a sketch of the human nerve cell. What function do nerve cells perform?
Ans. Long branched cells found in the brain and spinal cord are called nerve cells or neurons. The function of nerve cells is to receives and transfers messages. They help to control and coordinate the working of different parts of the body.
Q.3. Write short notes on the following.
(a) Cytoplasm
Ans. The jelly-like substance present between the cell membrane and the nucleus is called Cytoplasm. Other component or organelle of the cells such as mitochondria, golgi bodies, ribosomes, etc. are present in the cytoplasm.
(b) Nucleus of a cell
Ans. Nucleus is a spherical component of the cell located in centre of the cell. It can be seen through 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. The smaller spherical bodies in nucleus is called nucleolus. Nucleus also contains thread-like structures called chromosomes. They carry genes and help in inheritance or transfer of characters from the parents to the offspring.
Q.4. Which part of the cell contains organelles?
Ans. The Cytoplasm of cell contains organelle.
Q.5. Make sketches of animal and plant cells. State three differences between them.
Plant Cell | Animal Cell |
Cell wall is outer most part of a plant cell. | Do not contain cell wall. |
Have plastids like chloroplast which helps in process of photosynthesis. | Do not have plastids. |
Vacuoles are large. | Vacuoles are small. |
Do not contain organelle like lysosomes. | Contains Lysosomes. |
Q.6. State the difference between eukaryotes and prokaryotes.
Eukaryotes | Prokaryotes |
The cell in which nuclear material is bound by nuclear membrane are called Eukaryotic cell. Such organism are called Eukaryotes. | The cell in which nuclear material are without nuclear membrane are called Prokaryotic cell. Such organism are called Prokaryotes. |
Example – all organisms other than bacteria and blue green algae. | Examples are bacteria and blue green algae. |
Q.7. Where are chromosomes found in a cell? State their function.
Ans. Chromosomes are present in the nucleus of the cell. The functions of chromosomes – carry genes and transfer the character from parents to the next generation.
Q.8. ‘Cells are the basic structural units of living organisms.’ Explain.
Ans. A building is made of bricks similarly living organisms are made of cell. A organism is made up of organs, organs are made up of tissues and tissues are made of cells. The cells carry out various function which are vital for survival of an organism.
Q.9. Explain why chloroplast are found only in plant cells?
Ans. Plants are autotrophs. They make their own food with the help of photosynthesis process. Chloroplasts are the plastids found in plant leaves which enables them to carry out photosynthesis. That’s the reason why chloroplasts are found only in plant cells.
Q.10. Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Term 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.
Ans.
Across
1. This is necessary for photosynthesis. – Chlorophyll
3. Term for component present in the cytoplasm. – Organelle
6. The living substance in the cell. – Protoplasm
8. Units of inheritance present on the chromosomes. – Genes
Down
1. Green plastids. – Chloroplasts
2. Formed by collection of tissues. – Organs
4. It separates the contents of the cell from the surrounding medium. – Membrane
5. Empty structure in the cytoplasm. – Vacuole
7. A group of cells. – Tissue