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).
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Gametes only have 23 chromosomes; chromosomes are not in pairs.
This karyogram shows 46 chromosomes, indicating it is from a diploid somatic cell.
Step 2
State the gender shown by this karyogram.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Male (the presence of an X and a Y chromosome indicates male gender).
Step 3
Complete the Punnett square to show how gender is inherited.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
X
Y
X
XX
XY
Y
XY
YY
Step 4
State the probability that a child will be male.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The probability that a child will be male is 50% (2 out of 4 combinations in the Punnett square are XY).
Step 5
Name structure Z.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Middle piece or 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.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Sperm B has a larger middle section, which contains more mitochondria. This provides it with a higher energy supply, allowing it to swim faster and with greater stamina, improving its chances of reaching and fertilising the egg.
