Cell Structure and Functions - Exemplar Solutions 4

CBSE Class 08 Sceince
NCERT Exemplar Solutions
Cell - Structure and Functions

38. Cells consist of many organelles, yet we do not call any of these organelles as structural and functional unit of living organisms. Explain.
Ans. Although cell organelles have specific structure and perform specific functions but they cannot be called as structural and functional units of living organisms because they perform their functions only when they are within a living cell. They cannot function outside the living cell as an independent unit.

39. Why do plant cells have an additional layer surrounding the cell? What is this layer known as?
Ans. As plants, cannot move from one place to another, they need protection against variations in temperature, wind speed, atmospheric moisture etc. Therefore, for protection plant cells have additional protective layers. This layer is called the cell wall. Plant cells have an additional layer surrounding the cell wall.

40. The size of the cells of an organism has no relation with the size of its body. Do you agree? Give reason for your answer.
  • I agree because cells in the body of an elephant is not necessarily bigger than those in a rat, it is not true that bigger organisms have bigger sized cells in their body.
  • The size of cells of an organism is related to the functions it perform. For example, the nerve cells in both elephant and rat is long and branched. They perform the same function, that of transferring messages.