4. (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell - Edexcel - GCSE Biology Combined Science - Question 4 - 2019 - Paper 1
Question 4
4. (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell. Figure 4 shows a human karyogram.
(i) State two reasons why this karyogram... show full transcript
Worked Solution & Example Answer:4. (a) A karyogram is a picture of the chromosomes found in the nucleus of a single cell - Edexcel - GCSE Biology Combined Science - Question 4 - 2019 - Paper 1
Step 1
State two reasons why this karyogram cannot be from a gamete (sex cell).
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Answer
Gametes only have 23 chromosomes, while the karyogram shows 46 chromosomes.
Gametes are haploid, meaning they are not in pairs, which is evidenced by the presence of homologous pairs in the karyogram.
Step 2
State the gender shown by this karyogram.
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Answer
The gender shown by this karyogram is male.
Step 3
Complete the Punnett square to show how gender is inherited.
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Answer
X
Y
X
XX
XY
Y
XY
YY
Step 4
State the probability that a child will be male.
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Answer
The probability that a child will be male is 50% or 1 in 2.
Step 5
Name structure Z.
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Answer
Structure Z is the midpiece of the sperm.
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 has a larger middle section, which contains more mitochondria. This allows it to generate more energy, improving its motility and increasing the likelihood of reaching and fertilising the egg faster than sperm A.
