AQA Biology (UK A-Level) Paper 2 A2 Exam Questions
with answers ( 100 Questions)
1. What is meant by a gene?
Answer: A gene is a sequence of DNA that codes for a polypeptide or functional
RNA.
2. Define allele.
Answer: An allele is a different form of a gene found at the same locus on a
chromosome.
3. What is the difference between genotype and phenotype?
Answer: Genotype refers to the genetic makeup of an organism; phenotype is the
observable characteristics resulting from the genotype and environment.
4. What is meant by homozygous and heterozygous?
Answer: Homozygous means having identical alleles for a gene; heterozygous
means having different alleles.
5. What is codominance?
Answer: Codominance occurs when both alleles are expressed in the phenotype of
a heterozygote.
6. What is a monohybrid cross?
Answer: A cross examining the inheritance of a single gene.
7. Define dihybrid cross.
Answer: A genetic cross between individuals differing in two traits.
, 8. What is a test cross?
Answer: A cross between an organism of unknown genotype and a homozygous
recessive to determine the unknown genotype.
9. What is autosomal linkage?
Answer: When two or more genes are located on the same autosome and are
inherited together.
10. What is sex linkage?
Answer: Inheritance of a gene that is located on a sex chromosome, typically the
X chromosome.
11. What is epistasis?
Answer: The interaction between genes at different loci where one gene masks the
expression of another.
12. What is the chi-squared test used for in genetics?
Answer: To determine whether the observed results differ significantly from the
expected results.
13. What assumptions are made in the Hardy-Weinberg principle?
Answer: No mutation, random mating, no gene flow, large population size, and no
selection.
14. Write the Hardy-Weinberg equation.
Answer: p² + 2pq + q² = 1
with answers ( 100 Questions)
1. What is meant by a gene?
Answer: A gene is a sequence of DNA that codes for a polypeptide or functional
RNA.
2. Define allele.
Answer: An allele is a different form of a gene found at the same locus on a
chromosome.
3. What is the difference between genotype and phenotype?
Answer: Genotype refers to the genetic makeup of an organism; phenotype is the
observable characteristics resulting from the genotype and environment.
4. What is meant by homozygous and heterozygous?
Answer: Homozygous means having identical alleles for a gene; heterozygous
means having different alleles.
5. What is codominance?
Answer: Codominance occurs when both alleles are expressed in the phenotype of
a heterozygote.
6. What is a monohybrid cross?
Answer: A cross examining the inheritance of a single gene.
7. Define dihybrid cross.
Answer: A genetic cross between individuals differing in two traits.
, 8. What is a test cross?
Answer: A cross between an organism of unknown genotype and a homozygous
recessive to determine the unknown genotype.
9. What is autosomal linkage?
Answer: When two or more genes are located on the same autosome and are
inherited together.
10. What is sex linkage?
Answer: Inheritance of a gene that is located on a sex chromosome, typically the
X chromosome.
11. What is epistasis?
Answer: The interaction between genes at different loci where one gene masks the
expression of another.
12. What is the chi-squared test used for in genetics?
Answer: To determine whether the observed results differ significantly from the
expected results.
13. What assumptions are made in the Hardy-Weinberg principle?
Answer: No mutation, random mating, no gene flow, large population size, and no
selection.
14. Write the Hardy-Weinberg equation.
Answer: p² + 2pq + q² = 1
