Master GCSE Biology

MS1:

- Allele: Alternative form of a gene (1)

- Dominant allele: Expresses its phenotype in both homozygous and heterozygous genotypes (1)

- Recessive allele: Only expresses its phenotype in homozygous genotypes (1)

MS2:

- Random segregation of chromosomes during meiosis (1)

- Independent assortment of alleles from each parent (1)

Application of Knowledge

MS3:

- Bacteria with resistance genes survive antibiotic treatment (1)

- Resistant bacteria reproduce more (1)

- Resistant genes become more common in future generations (1)

MS4:

- Inserting normal genes into cells to correct mutations (1)

- Introducing therapeutic proteins through genetic modification (1)

- Preventing genetic disorders by screening embryos (1)

Extended Response

MS5:

Advantages:

- Produces organisms with desired traits (1)

- Can improve yield or resistance (1)

Disadvantages:

- Slow process (1)

- Can reduce genetic diversity (1)

MS6:

- Produces haploid gametes with increased genetic variation (1)

- Different combinations of alleles during fertilization (1)

- Provides the raw material for natural selection (1)

MS7:

Process:

- Each strand of DNA acts as a template (1)

- New complementary strands are synthesized (1)

- Ends up with two double-stranded DNA molecules (1)

Importance:

- Ensures accurate transmission of genetic information (1)

MS8:

Genotype: Genetic makeup (1)

Phenotype: Observable characteristics (1)

Example:

Genotype: Tt (heterozygous for tall)

Phenotype: Tall (dominant allele masks the recessive allele)

MS9:

- Mutation rate (1)

- Generation time (1)

- Population size (1)

- Strength of selection (1)

MS10:

- Groups organisms based on shared characteristics (1)

- Provides a hierarchical system of classification (1)

- Shows evolutionary relationships between species (1)