Sex chromosomes and the chance of a boy or a girl
9th grade (Year 10 in England) · 16 questions · Common Core: NGSS.HS-LS3-2 · England: GCSE Combined Science: Inheritance, variation and evolution
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Date
Score/ 16
Question 1
Sex chromosomes: which statement is NOT true?
- A. After two XX babies, the next baby is more likely to be XY.
- B. The Y chromosome is smaller than the X chromosome.
- C. Human body cells contain one pair of sex chromosomes.
- D. The chance of a baby being XY is about 50 % for each pregnancy.
Question 2
What is the probability (in %) that a couple's first two babies will both be XX?
Answer%
Question 3
A family has four sons and no daughters. A student says the father "only makes Y sperm". Why is this wrong?
- A. Sperm never carry Y
- B. About half his sperm carry X; four boys in a row can happen by chance (1 in 16)
- C. Sons cannot have the same father
- D. The mother decides the sex
Question 4
Sex chromosomes: which statement is NOT true?
- A. The Y chromosome is smaller than the X chromosome.
- B. The chance of a baby being XY is about 50 % for each pregnancy.
- C. Human gametes contain two sex chromosomes.
- D. Every human egg cell carries an X chromosome.
Question 5
What is the probability (in %) that a baby will be biologically male (XY)?
Answer%
Question 6
How many pairs of chromosomes are in a human body cell, and how many of them are sex chromosomes?
- A. 46 pairs, 2 pairs of sex chromosomes
- B. 23 pairs, all sex chromosomes
- C. 22 pairs, no sex chromosomes
- D. 23 pairs, 1 pair of sex chromosomes
Question 7
Sex chromosomes: which statement is NOT true?
- A. The chance of a baby being XY is about 50 % for each pregnancy.
- B. Human body cells contain one pair of sex chromosomes.
- C. The Y chromosome is smaller than the X chromosome.
- D. Human gametes contain two sex chromosomes.
Question 8
What is the probability (in %) that a couple's first two babies will both be XX?
Answer%
Question 9
A gene on the X chromosome causes red–green colour blindness. Why is it more common in XY people?
- A. XY people have two X chromosomes
- B. It is caught from other people
- C. They have only one X, so one recessive allele is enough to show the condition
- D. The Y chromosome causes colour blindness
Question 10
Sex chromosomes: which statement is NOT true?
- A. Human gametes contain two sex chromosomes.
- B. Every human egg cell carries an X chromosome.
- C. The Y chromosome is smaller than the X chromosome.
- D. Human body cells contain one pair of sex chromosomes.
Question 11
What is the probability (in %) that a baby will be biologically male (XY)?
Answer%
Question 12
A gene on the X chromosome causes red–green colour blindness. Why is it more common in XY people?
- A. They have only one X, so one recessive allele is enough to show the condition
- B. XY people have two X chromosomes
- C. It is caught from other people
- D. The Y chromosome causes colour blindness
Question 13
Sex chromosomes: which statement is NOT true?
- A. Human gametes contain two sex chromosomes.
- B. The chance of a baby being XY is about 50 % for each pregnancy.
- C. The Y chromosome is smaller than the X chromosome.
- D. Human body cells contain one pair of sex chromosomes.
Question 14
What is the probability (in %) that a couple's first two babies will both be XX?
Answer%
Question 15
How many pairs of chromosomes are in a human body cell, and how many of them are sex chromosomes?
- A. 46 pairs, 2 pairs of sex chromosomes
- B. 23 pairs, all sex chromosomes
- C. 23 pairs, 1 pair of sex chromosomes
- D. 22 pairs, no sex chromosomes
Question 16
Sex chromosomes: which statement is NOT true?
- A. The chance of a baby being XY is about 50 % for each pregnancy.
- B. Human body cells contain one pair of sex chromosomes.
- C. Every human egg cell carries an X chromosome.
- D. The egg cell decides whether a baby is XX or XY.
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