CBSE Class 9 Science Cell: The Building Block of Life (Class 9 NCERT New) Quiz 8

1. Why is the cell membrane considered "fluid"?

A It is composed entirely of liquid water. B Molecules within it can move sideways, flip, and rotate. C It lacks any definite boundary. D It dissolves easily when heated.

2. Which molecules are embedded in the lipid bilayer and act like gatekeepers to help substances pass?

A Carbohydrates B Proteins C Nucleic acids D Starches

3. Why is the fluid-mosaic model given the descriptor word "mosaic"?

A It changes color under light. B Molecules are arranged like tiles in a mosaic pattern. C It contains crystalline stone deposits. D It is highly rigid and glassy.

4. Which gas moves across the membrane of alveoli into the blood down its concentration gradient?

A Nitrogen B Carbon dioxide C Oxygen D Hydrogen

5. If mung bean seeds are kept in a highly concentrated salt solution after being soaked in water, they will:

A Swell further B Lose water and shrink C Germinate instantly D Turn into single cells

6. Which group of organisms lacks a cell wall completely?

A Plants B Fungi C Bacteria D Animals

7. What is the primary function of the cell wall in plant cells?

A To synthesize proteins B To provide rigidity and withstand environmental stresses C To control the entry of genetic codes D To generate energy molecules

8. What is the primary carbohydrate chemical component that makes up the plant cell wall?

A Glycogen B Starch C Cellulose D Chitin

9. What role does cellulose play when consumed in the human diet?

A Provides instant caloric energy B Acts as roughage, aiding in digestion C Forms the base of blood plasma proteins D Synthesizes enzymes inside liver cells

10. What is the permeability nature of a typical plant cell wall?

A Selectively permeable B Impermeable to all fluids C Completely permeable to water and some dissolved minerals D Only permeable to gases