Key terms

Question 1

Meaning of homozygote

Answer 1

an individual with two identical alleles for a characteristic eg BB or bb

Question 2

meaning of heterozygote

Answer 2

an individual with different alleles for a characteristic e.g. Bb

Question 3

meaning of genotype

Answer 3

describes the alleles present or genetic makeup of an individual regarding a particular characteristic eg BB or bb

Question 4

meaning of phenotype

Answer 4

describes the physical appearance of an individual regarding a particular characteristic e.g. black or brown fur in mice. this is the expressed gene

Question 5

meaning of allele

Answer 5

a different version of a gene, can be dominant or recessive

Question 6

definition, genotypes and phenotypes for dominant alleles

Answer 6

Definition: An allele that expresses its trait even if only one copy is present.

Genotypes: Can be homozygous dominant (BB) or heterozygous (Bb).

Phenotype: The dominant trait is always visible if the allele is present (e.g., brown eyes, polydactyly).

Question 7

definition, genotypes and phenotypes for recessive alleles

Answer 7

Definition: An allele whose trait is only expressed when two copies are present.

Genotype: Must be homozygous recessive (bb) for the trait to appear.

Phenotype: The recessive trait is masked in the presence of a dominant allele but shows up in individuals with two recessive alleles (e.g., blue eyes, cystic fibrosis).