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Describe how a sample of chloroplasts could be isolated from leaves - AQA - A-Level Biology - Question 5 - 2021 - Paper 1
Question 5
Describe how a sample of chloroplasts could be isolated from leaves. Scientists grew two groups of plants: - control plants with all the inorganic ions needed - ir... show full transcript
Worked Solution & Example Answer:Describe how a sample of chloroplasts could be isolated from leaves - AQA - A-Level Biology - Question 5 - 2021 - Paper 1
Step 1
Describe how a sample of chloroplasts could be isolated from leaves
Answer
To isolate chloroplasts from leaves, follow these steps:
- Break Open Cells: Crush or blend the leaf tissue in cold, buffered solution to break open the cells and release chloroplasts.
- Filter the Mixture: Use a filter to remove larger cellular debris, allowing the chloroplasts to remain in the solution.
- Centrifuge the Solution: Spin the filtered solution at a low speed to separate cellular debris from the chloroplasts.
- Collect Chloroplasts: Centrifuge at a higher speed to pellet the chloroplasts, allowing for their collection from the resulting mixture.
Step 2
Step 3
Step 4
Use the information in Table 4 to calculate the ratio of protein to chlorophyll in iron-deficient plants
Answer
According to Table 4, the mass of protein in the iron-deficient plants is 10% of the control group, while the mass of chlorophyll is 40% of the control group. Therefore, the ratio of protein to chlorophyll in iron-deficient plants can be calculated as follows:
Ratio = Protein / Chlorophyll = 10 / 40 = 1:4.
Step 5
Use Figure 6 to suggest why iron-deficient plants have a reduced growth rate
Answer
The electron microscope image in Figure 6 likely shows that chloroplasts in iron-deficient plants are fewer in number or have reduced size compared to those in control plants. This decrease would result in lower photosynthetic efficiency, thereby contributing to a reduced growth rate in iron-deficient plants.