6 (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell - Edexcel - GCSE Biology - Question 6 - 2019 - Paper 1
Question 6
6 (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell. Figure 8 shows a human karyogram.
(i) State two reasons why this karyogram ... show full transcript
Worked Solution & Example Answer:6 (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell - Edexcel - GCSE Biology - Question 6 - 2019 - Paper 1
Step 1
State two reasons why this karyogram cannot be from a gamete (sex cell).
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Answer
Gametes contain only 23 chromosomes, while a karyogram from a somatic cell shows 46 chromosomes.
The presence of homologous pairs of chromosomes in a karyogram indicates it is from a diploid cell.
Step 2
State the gender shown by this karyogram.
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Answer
The gender shown by this karyogram is female, indicated by the presence of two X chromosomes.
Step 3
Complete the Punnett square to show how gender is inherited.
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The completed Punnett square is:
| X | Y |
===================
X | XX | XY |
-------------------
X | XX | XY |
This shows that 50% of the offspring are expected to be female (XX) and 50% male (XY).
Step 4
State the probability that a child will be male.
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The probability that a child will be male is 50%.
Step 5
Name structure Z.
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Structure Z is the acrosome.
Step 6
Explain why sperm B will be more likely to fertilise an egg than sperm A if they were both released at the same time.
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Sperm B is more likely to fertilise an egg because its larger middle section is associated with more mitochondria, providing greater energy reserves for motility. This allows sperm B to swim faster and more efficiently towards the egg, increasing the chances of successful fertilisation.
