Page 193 - Big Ideas Year 10 sciPAD 2025

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SCIPAD - BIG IDEAS - BOOK 2
THE BASIS OF HEREDITY
End of Chapter Review Questions
1. How many chromosomes are found in a human: (a) skin cell: 
(b) sperm cell: 
(c) fertilised egg: 
2. Describe the shape of a DNA molecule. 

3. Define the term ‘allele’: 

4. True of false.
(a) Sexual reproduction causes variation. True/False
(b) DNA is made up of chromosomes. True/False
(c) Females have one less chromosome than males. True/False
(d) If a couple have three daughters, the chance of them having
a son is 25%. True/False
(e) Dominant alleles are always shown with a capital letter. True/False
(f) Humans have 43 chromosomes in each cell. True/False
(g) Some animals can make clones of themselves by reproducing
asexually. True/False
(h) A person with two ‘X’ chromosomes would be born a male. True/False
(i) Vestigial organs can give us clues about the ancestors of modern
animals. True/False
(j) Usually younger fossils are found underneath older fossils. True/False
(k) Mutations can turn turtles into ninjas. True/False
5. In rats, black fur colour is controlled by the allele ‘B’ and white fur colour by the allele ‘b’.
(a) Use the Punnett square below to show how two black rats could have a white
offspring.
Black male
Black female
(b) As a percentage, what is the chance that the parents will have a white offspring?

(c) If two white rats mated, what is the chance (as a percentage) that they will have
a black offspring? 
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