Question

1. Describe the process of photosynthesis.
2. Differentiate between autotrophs and heterotrophs, giving two examples of each.
3. How are nutrients put back in the soil?
4. Distinguish between total parasites and partial parasites in plants, giving one example of
each.
5. What are the methods by which nutrients in the soil can be replenished?
6. Write an activity to show that carbon dioxide is necessary for photosynthesis.
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Answer 1

1. Photosynthesis is the process by which plants, some bacteria and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed.

2. answer is in picture

3. Nutrients get into the soil many different ways: from decomposed animal waste and dead plants, the atmosphere, weathering of rocks and bacteria conversions. When soils are used to grow foods, the soils need to be kept healthy, as a lot of nutrients are taken up by plants and not replaced.

4. Answer is in image

5. Nutrients in the soil are replenished by adding fertilisers and manures. Fertilisers and manures contain plants nutrients and minerals like nitrogen, phosphorus and potassium. ... The bacterium called Rhizobium can take atmospheric nitrogen and convert it into a soluble form.

6. Materials needed: potted plants, bell jars, Petri dish, potassium hydroxide, water, alcohol, iodine, beakers

Method:

1. Take two potted plants and cover them with bell jars.

2. Place a petri dish containing potassium hydroxide in one of the jars. (potassium hydroxide absorbs carbon dioxide.)

3. Place the plants in sunlight for a day.

4. Pluck a leaf from each of them and test the leaves for starch.

The plants in the jar with potassium hydroxide does not get any carbon dioxide. When you perform the iodine test on a leaf from this plant, it will test negative for starch. This proves that photosynthesis did not occur in the absence of carbon dioxide. The leaf in the other plant will test positive for starch.