1.7 Genetics, populations, evolution and ecosystems (A-level only)

Question 1

Define Genotype

Answer 1

the genetic constitution of an organism( the allele is has for a gene)

Question 2

Define Phenotype

Answer 2

the expression of the genes and their interaction with the environment

Question 3

Define Homozygous

Answer 3

A pair of homologous chromosomes carrying the same alleles for a single gene

Question 4

Define Heterozygous

Answer 4

A pair of homologous chromosomes carrying two different alleles for a single gene

Question 5

Define recessive allele

Answer 5

An allele is only expressed if no dominant allele is present

Question 6

Define Dominant allele

Answer 6

An allele that will always be expressed in a phenotype

Question 7

Define Codominant

Answer 7

Both alleles are equally dominant and expressed in the phenotype

Question 8

Define multiple alleles

Answer 8

more than two alleles for a single gene

Question 9

Define Sex-linkage

Answer 9

a gene whose locus is on the X chromosome

Question 10

Define Autosomal linkage

Answer 10

Genes that are located on the same chromosome (not the sex chromosomes)

Question 11

Define epistasis

Answer 11

When one gene modifies or masks the expression of a different gene at a different locus

Question 12

Define monohybrid

Answer 12

genetic inheritance cross of a characteristics determined by one gene

Question 13

Define Dihybrid

Answer 13

Genetic inheritance cross for a characteristic determined by two genes