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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

Name

Date

Score/ 16

1
Question 1
How many pairs of chromosomes are in a human body cell, and how many of them are sex chromosomes?
- A. 22 pairs, no sex chromosomes
- B. 46 pairs, 2 pairs of sex chromosomes
- C. 23 pairs, all sex chromosomes
- D. 23 pairs, 1 pair of sex chromosomes
Question 2
What is the probability (in %) that a couple's first two babies will both be XX?
Answer%
3
Question 3
Sex chromosomes: which statement is NOT true?
- A. Human body cells contain one pair of sex chromosomes.
- B. The chance of a baby being XY is about 50 % for each pregnancy.
- C. Every human egg cell carries an X chromosome.
- D. Human gametes contain two sex chromosomes.
4
Question 4
How many pairs of chromosomes are in a human body cell, and how many of them are sex chromosomes?
- A. 23 pairs, 1 pair of sex chromosomes
- B. 23 pairs, all sex chromosomes
- C. 46 pairs, 2 pairs of sex chromosomes
- D. 22 pairs, no sex chromosomes
Question 5
A couple already have three daughters. What is the probability (in %) that their next baby will be XY?
Answer%
6
Question 6
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. Every human egg cell carries an X chromosome.
7
Question 7
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. 22 pairs, no sex chromosomes
- C. 23 pairs, all sex chromosomes
- D. 23 pairs, 1 pair of sex chromosomes
Question 8
A couple already have three daughters. What is the probability (in %) that their next baby will be XY?
Answer%
9
Question 9
Sex chromosomes: which statement is NOT true?
- A. Human body cells contain one pair of sex chromosomes.
- B. Every human egg cell carries an X chromosome.
- C. The Y chromosome is smaller than the X chromosome.
- D. The egg cell decides whether a baby is XX or XY.
10
Question 10
Which gamete decides whether a baby is XX or XY?
- A. the sperm cell
- B. neither: it depends on diet
- C. both equally
- D. the egg cell
Question 11
What is the probability (in %) that a baby will be biologically male (XY)?
Answer%
12
Question 12
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. Every human egg cell carries an X chromosome.
13
Question 13
Which gamete decides whether a baby is XX or XY?
- A. the egg cell
- B. the sperm cell
- C. both equally
- D. neither: it depends on diet
Question 14
What is the probability (in %) that a baby will be biologically male (XY)?
Answer%
15
Question 15
Sex chromosomes: which statement is NOT true?
- A. Every human egg cell carries an X chromosome.
- B. The egg cell decides whether a baby is XX or XY.
- C. The Y chromosome is smaller than the X chromosome.
- D. Human body cells contain one pair of sex chromosomes.
16
Question 16
A family has four sons and no daughters. A student says the father "only makes Y sperm". Why is this wrong?
- A. Sons cannot have the same father
- B. Sperm never carry Y
- C. The mother decides the sex
- D. About half his sperm carry X; four boys in a row can happen by chance (1 in 16)

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