9th Class Biology 3rd Quarter Book Paper

Q1. Multiple choice questions (Attempt all · 12 × 1 = 12)

1.  What happens when the pH changes for an enzyme?

   1. It increases the enzyme's activity

   2.  It alters the ionization of amino acids at the active site, slowing or blocking enzyme activity

   3. It strengthens the enzyme's bond with the substrate

   4. It increases the enzyme's temperature

2. Sucrose enters the sieve tubes of phloem by ......:

   1.  Passive transport 

   2. Osmosis 

   3. Diffusion 

   4. Active transport

3. Which of the following processes if used by plants to make oxygen during the process of photosynthesis?

   1. Intake of water

   2. Intake of CO₂

   3. Photolysis of water

   4. Calvin cycle

4. What are enzymes?

   1.  Chemical catalysts that are consumed during reactions

   2.  Biological catalysts that accelerate chemical reactions without being consumed

   3. Substances that slow down chemical reactions

   4. Non-protein molecules that catalyze reactions

5. The transpiration is regulated by:

   1. Mesophyll

   2. Guard cells

   3. Xylem

   4. Phloem

6. Light reactions of photosynthesis occur in;

   1. Plasma membrane of cell

   2. Cytoplasm of cell

   3. Stroma of chloroplasts

   4. Thylakoids of chloroplasts

7. Ionization of amino acids at the active site is affected by?

   1. Change in temperature

   2. Change in substrate concentration

   3. Change in pH

   4. Change in temperature and substrate concentration

8. Pressure flow machanism is about:

   1. Translocation of food

   2. Transport of water

   3. Opening of stomata

   4. Tranpiration

9. Which molecule donates electrons in the light-dependent reactions of photosynthesis?

   1. NADPH

   2. Water

   3. Oxygen

   4. Carbon dioxide

10. What is metabolism?

    1. The breakdown of glucose into energy

    2.  The sum of all chemical reactions that occur within an organism to sustain life

    3.  The conversion of carbon dioxide into glucose

    4. The process of forming proteins from amino acids

11. From which process plants get their food:

    1. Respiration

    2. Photosynthesis

    3. Oxidation

    4. Gaseous Exchange

12. The main pigment of plants is:

    1. Carotenoids

    2. Chlorophyll-b

    3. Chlorophyll-a

    4. All of these