CBSE – 9th Standard Science

Class 9 Question Bank Chapter 5 – The fundamental unit of life


Q1. What is a Cork?

Ans. Cork is a substance which comes from the bark of a tree.

Q2. What are Cells?

Ans. Robert Hooke called small compartments as cells. Cell is a Latin word for ‘a little room’.

Q3. What is Epidermis?

Ans. The Inner layer of the skin is called Epidermis.

Q4. Who discovered the nucleus in the cell?

Ans. It was Robert Brown who discovered the nucleus in the cell in 1831.

Q5. What is the term for the fluid substance in the cell. Who discovered it?

Ans. Purkinje in 1839 named the term ‘Protoplasm’ for the fluid substance of the cell.

Q6. What Shleiden and Schwaan stated about the cell theory?

Ans. They stated that all the plants and animals are composed of cells and that the cell is the basic unit of life.

Q7. What do you mean by unicellular Organisms?

Ans.A single cell may constitute a whole organism as in Amoeba,and bacteria. These organisms are called unicellular Organisms.

Q8. What are multi cellular organisms?

Ans. Many cells group together in a single body and performs different functions in it to form various body parts are called multicellular organisms.

Q9. What do you mean by cell organelles?

Ans. Division of labour within a single cell performs special function and has got certain specific components within it known as cell organelles.

Q10. What Plasma Membrane does?

Ans. The plasma membrane permits the entry and exit of some materials in and out of the cell.

Q11. What is osmosis?

Ans. The movement of water molecules through a selectively permeable membrane is called osmosis.

Q12. What is the process of diffusion?

Ans. Difference of concentration of any substance inside and outside a cell, whichmoves out of the cell, from a region of high concentration, to a region of lowconcentration outside the cell is the process of diffusion.

Q13. What do you mean by cell wall?

Ans. Plasma membrane, have another rigid outer covering called the cell wall.

Q14. What is Plasmolysis?

Ans. Shrinkage or contraction of the contents of the cell is known as Plasmolysis.

Q15. What do you mean by nuclear membrane?

Ans. The nucleus has a double layered covering called nuclear membrane.

Q16. What chromosomes composed of?

Ans. Chromosomes are composed of DNA and protein.

Q17. What is DNA?

Ans. DNA stands for Deoxyribo Nucleic Acid.

Q18. What are Prokaryotes?

Ans. Such organisms, whose cells lack a nuclear membrane, are called prokaryotes.

Q19. What are Eurokaryotes?

Ans. Organisms with cells having a nuclear membrane are called eukaryotes.

Q20. What is Cytoplasm?

Ans. The cytoplasm is the fluid content inside the plasma membrane. It also contains many specialised cell organelles.

Q21. What is Endoplasmic reticulum(ER)?

Ans. The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules bags.

Q22. What are the types of Endoplasmic Reticulm?

Ans. There are two types of ER– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

Q23. What ER does?

Ans. The ER also functions as a cytoplasmic framework providing a surface for some of the biochemical activities of the cell.

Q24. Why RER looks rough under a microscope?

Ans. RER looks rough under a microscope because it has particles called ribosomes attached to its surface.

Q25. What SER helps in?

Ans. The SER helps in the manufacture of fat molecules, or lipids, which are important for cell function.

Q26. Why SER is necessary?

Ans. SER plays a crucial role in detoxifying many poisons and


Q27. What is membrane biogenis?

Ans. Some of the manufactured proteins and lipids help in building the cellmembrane. This process is known as membrane biogenesis.

Q28. What is Golgi Apparatus?

Ans. The Golgi apparatus consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.

Q29. What is the function of Golgi Apparatus?

Ans. Its functions are the storage, modification and packaging of products inVesicles, complex sugars may be made from simple sugars.

Q30. What do you mean by Lysosomes?

Ans. Lysosomes are a kind of waste disposal system of the cell. It helps to keep the cell clean by digesting any foreign material as well as worn-out cell organelles.

Q31. What is Mitochondria?

Ans. Mitochondria are known as the powerhouses of the cell. The energy required for various chemical activities needed for life is released by mitochondria in the form of ATP.

Q32. What are Plastids?

Ans. Plastids are present only in plant cells. There are two types of plastids chromoplasts and leucoplasts.

Q33. What are Chloroplast?

Ans. Plastids containing the pigment chlorophyll are known as chloroplasts.

Q34. What is Stroma?

Ans. The internal organisation of the plastids consists of numerous membrane layers embedded in a material called the stroma.

Q35. What do you mean by vacuoles?

Ans. Vacuoles are storage sacs for solid or liquid contents. Vacuoles are small sized in animal cells while plant cells have very large vacuoles.