4. variation and inheritance

Question 1

gene

Answer 1

a region of DNA on a chromosome that codes for a characteristic

Question 2

allele

Answer 2

different forms of the same gene

Question 3

homozygous / true breeding

Answer 3

an individual with two copies of the same allele present

Question 4

heterozygous

Answer 4

an individual with two different alleles present

Question 5

phenotype

Answer 5

the physical characteristics of an organism

Question 6

dominant

Answer 6

an allele that always shows its affects as a phenotype and masks the presence of the other form

Question 7

recessive

Answer 7

an allele that is masked by the dominant allele (i.e. it will only show its effect/show in the phenotype if both alleles are present)

Question 8

genotype

Answer 8

the set of genes (alleles) possessed by an individual

Question 9

P

Answer 9

parent generation

Question 10

F1

Answer 10

first (filial) generation

Question 11

F2

Answer 11

second (filial) generation

Question 12

phenotypic ratio

Answer 12

the ratio of the appearance of the offspring produced in a genetics cross

Question 13

genotypic ratio

Answer 13

the ratio of genotypes of the offspring produced in a genetics cross

Question 14

discrete variation

Answer 14

• cant ‘measure’ it
• puts individuals into groups
• present in bar graph
• controlled by one gene

either you have it or you dont

Question 15

continuous variation

Answer 15

• can measure it
• has a range of values from small to large
• present as a histogram
• controlled by more than one gene