8.3 ADDITIONAL QUESTIONS:
1. What is a cell Name the longest cell in human body. Draw its diagram also.
Ans. All organisms are made of basic units known as cell. Nerve cell is the longest cell in human body.
2. Why are mitochondria known as the “power house of the cell”
Ans. Mitochondria is known as the power house of the cell because they perform the function of respiration and provide the cell with energy.
3. Are the cells of an elephant larger than cells of a rat.
Ans. No, the size of the cell has no relation with the size of the body of the animal or plant.
4. What are the “building blocks of life” Why are they so called
Ans. Cells are building blocks of life because all living things are made up of one or more cells.
5. What is the difference between tissue and organ
Ans. Group of cells of the same type make up the different tissues of the organisms, e.g., muscle tissue. Several different types of tissues together form an organ, e.g., a stomach.
6. Differentiate between an organ and a system.
Ans. Several different types of tissues that work together to perform one or more life activities is known as an organ.
An organ system is a group of organs that work together to carry on life activities.
7. What is pseudopodia.
Ans.The projections of various lengths that are protruding from the body of the amoeba are called pseudopodia
8.What features are possessed by both plant cells and animal cells
Ans. All plant and animal cells have three parts — cell membrane, cytoplasm and nucleus.
9. What is nuclear membrane
Ans. The nucleus is separated from the cytoplasm by a membrane called as nuclear membrane
10. Give the functions of cell wall.
Ans. It provides rigidity to the cell wall. It provides protection against plant viruses and pathogens.
11. What is nucleolus.
Ans. Nucleolus is a small, dense, spherical part within the nucleus.
12 Name any three elements which form major part of protoplasm.
Ans. Protoplasm is made up of compounds of carbon, hydrogen, nitrogen and oxygen.
13. Why are plant cells more rigid in shape than animal cells. Also name the largest and the smallest cells in the living world.
Ans. Plant cells are more rigid in shape than animal cells due to the presence of cell wall.
Largest – Ostrich’s egg. Smallest – PPLO (Pleuro Pneumonia Like Organisms).
14 Why do plant cells need a cell wall.
Ans. Plant cells need a cell wall for protection against variations in temperature, high wind speed, atmospheric moisture, etc.
15. If you boil a hen’s egg, what changes do you observe.
Ans. When a hen’s egg is boiled, a white material surrounds the yellow part. White material is albumin which solidifies on boiling. The yellow component is yolk.
16. What are the functions of the cell membrane.
Ans. It protects the cell. It provides shape to the cell. It allows materials to enter and leave the cell through the tiny holes.
17. What are vacuoles
Ans: Some blank looking structures found in the cytoplasm of the cell are called vacuoles
18. What is a cell. Who discovered the cell.
Ans. The basic structural unit of an organ is known as a cell. Robert Hooke, an English scientist in 1665 discovered the cell.
19. Draw a neat diagram of Amoeba
Ans.
