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6 (a) Figure 9 shows a sperm cell - Edexcel - GCSE Biology Combined Science - Question 6 - 2021 - Paper 1
Question 6
6 (a) Figure 9 shows a sperm cell. Describe how structure A and structure B enable fertilisation. (2) (b) Figure 10 shows a human egg cell, magnified ×700. Calcu... show full transcript
Worked Solution & Example Answer:6 (a) Figure 9 shows a sperm cell - Edexcel - GCSE Biology Combined Science - Question 6 - 2021 - Paper 1
Step 1
Describe how structure A and structure B enable fertilisation.
Answer
Structure A of the sperm cell, known as the acrosome, contains enzymes that help penetrate the outer layers of the egg during fertilisation. This allows the sperm to reach the egg's membrane and facilitate fusion.
Structure B, which is the tail (flagellum), provides motility to the sperm, allowing it to swim effectively towards the egg. The combined functions of these structures enable successful fertilisation.
Step 2
Calculate the actual width of the region indicated by the line on Figure 10.
Answer
To calculate the actual width of the region indicated in Figure 10, we need to know the magnification factor and the size indicated in the image. Given that the egg cell is magnified ×700, if we assume the width of the line indicated in the image measures, for example, 2.5 cm, we can use the formula:
ext{Actual Size} = rac{ ext{Measured Size}}{ ext{Magnification}}
Converting 2.5 cm to mm gives us 25 mm. Thus,
ext{Actual Size} = rac{25 ext{ mm}}{700} = 0.03571 ext{ mm}
In standard form, this is approximately .
Step 3
Evaluate the results of this investigation.
Answer
Upon evaluating the data from Figure 11, we see that the mass of the eggs before immersion was constant at 77 grams across all solutions. After 24 hours in the different solutions, the weights varied:
- In tap water, the eggs' mass remained unchanged at 77 grams.
- In 5% salt solution, the eggs also maintained a mass of 77 grams, indicating they did not gain or lose water.
- However, in the 10% salt solution, the mass decreased to 75 grams.
This indicates that in the presence of a hypertonic solution (10% salt), water moved out of the eggs, causing them to lose mass. The results demonstrate that osmotic pressure affects the weight of eggs when immersed in solutions of varying salt concentrations.