genetics year 13

Question 1

what is phenotype

Answer 1

the expression of the genetic constitution and its interaction with the environment

Question 2

what is genotype

Answer 2

the genetic constitution of an organism refering to the alleles that an organism has

Question 3

what is the F1 generation

Answer 3

the first generation of the cross over between pure breeds

Question 4

what is the F2 generation

Answer 4

the second generation of the cross over between the F1 parents

Question 5

what is the law of segregation

Answer 5

phenotype is determined by alleles that occur in pairs and only one allele in the pair can be present in a single gamete

Question 6

what is codominance

Answer 6

when both alleles are equally dominant so both are expressed in the phentype

Question 7

what are sex linked chromosomes

Answer 7

any gene carried on the X or Y chromosome

Question 8

why are recessive chromosomes on the X chromosomes more prevelent in males

Answer 8

males have no homologous dominant portion on the Y chromosome it would only be on the X chromosome but they are XY

Question 9

what is dihybrid inheritance

Answer 9

how 2 characteristics determined by 2 different genes on different chromosomes are passed down and inherited

Question 10

what does the crossing over of gametes from two heterozygous parents produce in crossing over

Answer 10

9:3:3:1

Question 11

what is the inheritance ratio if you cross a heterozygous with homozygous recessive

Answer 11

1:1:1:1

Question 12

what is epistasis

Answer 12

the interaction between different genes where the gene at one locus masks or suppresses the expression of another gene at a second locus

Question 13

what happens in dominant epistasis

Answer 13

one dominant allele at the first gene locus masks the expression of an allele at the second gene locus

Question 14

what happens in recessive epistasis

Answer 14

the two recessive alleles at one gene locus will mask the expression of alleles at the second gene locus

Question 15

what is the resulting ratio for the recessive epistasis

Answer 15

9:4:3

Question 16

what is autosomal linkage

Answer 16

when any two genes that occur on the same chromosome are said to be linked when it isn’t the X or Y chromosome

Question 17

what is special about the crossover in autosomal linkage

Answer 17

almost all of the time there is no crossing over of the linked genes and they stay together to be passed on to the offspring

Question 18

what is special about independent assortment in autosomal linkage

Answer 18

genes tend to be very close together and therefore most of the time there is no independent assortment as the chances of them being separated is very small

Question 19

what are the conditions for the Hardy Weinberg equation

Answer 19

large population
no emigration
no natural selection
no mutations
random mating is essential

Question 20

if the deviation probability is equal to or higher than 0.05 what does this mean

Answer 20

non-significant so the null hypothesis would be accepted

Question 21

if the deviation probability is less than 0.05 what does this mean

Answer 21

significant and disregard the null hypothesis