Revision Quiz 6: Chapter 7 - Nutrition in Plants

Marks scored: 26/50 (C6)
Wow, and I almost failed =p

1. Photosynthesis is the process by which green plants trap light energy using chlorophyll and convert it to chemical energy for the production of glucose from water and carbon dioxide. Oxygen is released as a by-product.

2. Leaf is an organ specialised for photosynthesis. Its broad and thin lamina provides and large surface area for maximum absorption of light. The thin lamina allows carbon dioxide to enter/diffuse into the cells quickly. The palisade cells contains numerous chloroplast and are packed closely together at the upper surface of the leaf. This enables them to absorb light energy efficiently. The spongy mesophyll cells are loosely packed so that large intercellular spaces are present for rapid diffusion of gaseous exchange. The numerous stomata at the lower epidermis allows rapid gaseous exchange between the leaf and the air. The extensive vain system of xylem and phloem help to provide rapid transport of water to, and manufactured food from the leaf.

Note: Another possible antagonistic action is here. If palisade cells are closely packed, then spongy mesophyll cells must be loosely packed!




3. State the word equation for photosynthesis.

                        sunlight
carbon dioxide + water -----------> oxygen + glucose
                       chlorophyll

4. State the effects of varying light intensity on photosynthesis.
- Light energy is trapped by chlorophyll to split water molecules during photosynthesis.
- Increasing light energy will speed up photolysis, hence increasing photosythesis.

5. State the effects of varying wavelights on photosynthesis.
- Red and blue wavelights highly absorbed.
- Green and yellow reflected.
- More light absorbed will increase rate of photosynthesis.

6. State the effects of varying carbon dioxide on photosynthesis.
- Increased CO2, increases rate of glucose produced, resulting in increase in rate of photosynthesis.

7. State the effects of varying temperature on photosynthesis.
- Temp affects rate of enzyme-catalysed reaction in photosynthesis.
- Low temp: enzymes inactive
- High temp: enzymes denature and no photosynthesis takes place.

8. Explain why other forms of life are completely dependant on photosynthesis.
- Can't use light energy directly.
- So depend on photosynthesis for light energy to convert to chem energy for food.
- Photosynthesis produces O2 ---> essential for survival

9. Describe the lack of nitrate ions on plant growth.
- Nitrate ions provide nitrogen for amino acids.
- Sans(French: without) amino acids, plants cannot produce protoplasm or new cells.
- Hence, lack of nitrate ions inhibits plant growth.

10. Describe the lack of magnesium ions on plant growth.
- Magnesium important component in chlorophyll.
- Kein(German: no, neuter negative indefinite article) Magnesium
---> cannot produce chlorophyll
-----> no photosynthesis can be carried on
- leaves turn yellow