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Inheritance
Class 12 · Biology · 8 questions
Name: ____________________ Date: ____________
A cross between a heterozygous and a homozygous recessive individual (Aa x aa) gives the phenotypic ratio:
- A 1 : 1
- B 3 : 1
- C 9 : 3 : 3 : 1
- D All the same
A dihybrid cross of two heterozygotes gives a phenotypic ratio of:
- A 3 : 1
- B 9 : 3 : 3 : 1
- C 1 : 2 : 1
- D 1 : 1
Haemophilia is carried on the:
- A Mitochondria only
- B X chromosome
- C Chromosome 21
- D Y chromosome
The sex of a human child is determined by the:
- A Environment
- B Egg
- C Mother's age
- D Sperm
Down syndrome is caused by an extra copy of chromosome:
- A 18
- B X
- C 13
- D 21
A test cross is used to find out if an individual is:
- A Old or young
- B Homozygous or heterozygous
- C Tall or short
- D Male or female
In incomplete dominance the heterozygote shows:
- A An intermediate phenotype
- B The recessive phenotype
- C No phenotype
- D The dominant phenotype
Colour blindness is more common in males because the gene is on the:
- A Y chromosome
- B Autosome
- C X chromosome
- D Mitochondria
Answer key
1. A, 2. B, 3. B, 4. D, 5. D, 6. B, 7. A, 8. C
Half show the dominant trait and half the recessive.
This is Mendel's dihybrid ratio.
It is an X linked recessive condition.
A sperm carries either X or Y.
It is trisomy 21.
The individual is crossed with a homozygous recessive.
For example, red and white flowers giving pink.
Males have only one X.