Inheritance A2

Question 1

define gene

Answer 1

a section of DNA that codes for a polypeptide

Question 2

define allele

Answer 2

a version of a gene

Question 3

define genotype

Answer 3

the genetic makeup of an organism

Question 4

define phenotype

Answer 4

a person’s appearance due to the environment and genotype

Question 5

define homozygous

Answer 5

when the alleles of a particular gene are identical

Question 6

define heterozygous

Answer 6

when alleles of a particular gene are different

Question 7

define dominant allele

Answer 7

an allele always shown in the phenotype

Question 8

define recessive alleles

Answer 8

only shown in a phenotype if there are no dominant alleles

Question 9

how many copies of a chromosome do haploid cells have

Answer 9

1

Question 10

how many copies of each chromosome do diploids have

Answer 10

2

Question 11

how many copies of each chromosome do polyploids have

Answer 11

many

Question 12

define codominance

Answer 12

when both alleles are expressed in the phenotype

Question 13

how to script codominance

Answer 13

with different superscripted letters e.g. C^w C^b

Question 14

define multiple alleles

Answer 14

a gene with more than 2 possible alleles

Question 15

define sex linked genes

Answer 15

a gene found on X or Y chromosomes

Question 16

what sex chromosomes do males have

Answer 16

XY

Question 17

what sex chromosomes do females have

Answer 17

XX

Question 18

why are males more likely to be affected by an X linked condition

Answer 18

only have one X chromosome so only need one allele to be fully affected
no second X chromosome to mask condition

Question 19

define dihybrid

Answer 19

two genes
different chromosomes
independent characteristics
one does not control the other

Question 20

ratio for F2 generation

Answer 20

9:3:3:1

Question 21

how to script dihybrid inheritance

Answer 21

four letters e.g. AaBB

Question 22

define autosomal linkage

Answer 22

two genes on the same chromosome

Question 23

what are the three possible genotypes in autosomal linkage

Answer 23

AABB, aabb, AaBb

Question 24

process of autosomal linkage

Answer 24

GN and gn linked
gametes either GN or gn
only if crossing over occurs will there be Gn or gN gametes
so there will be fewer offspring with these alleles

Question 25

why might the predicted ratios not occur in reality

Answer 25

only probabilities
small sample size
fusion of gametes is random

Question 26

why use drosophila in experiments

Answer 26

short life cycle
small space needed
lays lot of eggs
not endangered

Question 27

what are the two hardy-weinberg equations

Answer 27

p^2 + 2pq + q^2 = 1

p + q = 1

Question 28

assumptions when doing a hardy weinberg

Answer 28

random mating
no mutations
large populations
population genetically isolated
no migration

Question 29

evidence that proves it’s a recessive gene

Answer 29

2 parents don’t have condition but their child does

Question 30

evidence that proves it’s a dominant gene

Answer 30

2 parents have condition but their child doesn’t

Question 31

what does it mean for a parent to be a carrier

Answer 31

heterozygous with the condition on the recessive gene

Question 32

evidence that proves it’s sex linked

Answer 32

dad always passes their X chromosome to daughter, if it is dominant the daughter will have it too