6.2 Monogenic Inheritance

Question 1

variation is the phenotypic differences between who?

Answer 1

organisms of the same species

Question 2

what 4 things can variation be the result of?

Answer 2

1. independent assortment of homologous chromosomes
2. crossing over in meiosis
3. random fertilisation of gametes
4. mutation

Question 3

monogenic inheritance explains what?

Answer 3

how genes are passed one generation to the next

Question 4

monogenic inheritance - the basic laws by which characteristics were inherited were established by who?

Answer 4

Mendel

scientist and monk in the 19th century

Question 5

(monohybrid inheritance) inheritance of a single characteristic is controlled by what?

Answer 5

a single gene

Question 6

(monohybrid inheritance) a single gene can have how many alleles?

Answer 6

multiple

Question 7

(monohybrid inheritance) what 3 things can alleles be?

Answer 7

dominant
recessive
co-dominant

Question 8

(monohybrid inheritance) what is a gene?

Answer 8

specific length of DNA occupying a position on a chromosome known as a locus

Question 9

(monohybrid inheritance) what is a chromosome?

Answer 9

linear sequence coding for many genes

Question 10

(monohybrid inheritance) what does it mean if genes are homozygous?

Answer 10

same alleles

Question 11

(monohybrid inheritance) what does it mean if genes are heterozygous?

Answer 11

different alleles

Question 12

(monohybrid inheritance) what do chromosomes exist in?

Answer 12

pairs
one chromosome originally from the mother
one chromosome originally from the father

Question 13

1. when performing a genetic cross you first need to state what?

Answer 13

phenotypes of both the parents

Question 14

2. when performing a genetic cross you need to then state what of the parents?

Answer 14

genotype

assign letters to represent alleles

Question 15

3.when performing a genetic cross, after you have stated the genotype what do you have to state of the parents?

Answer 15

gametes

Question 16

4. when performing a genetic cross you use what type of square? and what does it show?

Answer 16

punnet square

show random fusion of gametes

Question 17

5. when performing a genetic cross, after you have done the punnet square you state what?

Answer 17

proportion of each genotype produced amongst the offspring

Question 18

6. when performing a genetic cross, you then state the corresponding what?

Answer 18

phenotype for each genotype

Question 19

what did mendel carry out many of his experiments on?

Answer 19

pea plants

Question 20

when a homozygous green pea plant is crossed with a homozygous yellow pea plant which allele is dominant?

Answer 20

allele for green pea plant

Question 21

what are true breeding/pure breeding organisms?

Answer 21

organisms containing homologous alleles for a particular gene

Question 22

co-dominance occurs when 2 alleles occur for a gene, both of which are what?

Answer 22

dominant

Question 23

(co-dominance) what happens to the alleles in the phenotype?

Answer 23

both are expressed

Question 24

(co-dominance) give an example of an organism in which co-dominance is found:

Answer 24

colour of snapdragon flowers

Question 25

(co-dominance - snapdragons) the allele which codes for red flowers codes for production of what?

Answer 25

an enzyme catalysing production of the red pigment

Question 26

(co-dominance - snapdragons) the allele coding for white flowers codes for what?

Answer 26

altered version of the enzyme which doesn't catalyse production of the pigment so flowers are white

Question 27

(co-dominance - snapdragons) when do red flowers occur?

Answer 27

when the plant is homozygous for the allele coding for the red pigment

Question 28

(co-dominance - snapdragons) when do white flowers occur?

Answer 28

when the plant is homozygous for the allele coding for the white pigment

Question 29

(co-dominance - snapdragons) when do pink flowers occur?

Answer 29

when the plant is heterozygous - allele for red pigment produces enough for flowers to be pink

Question 30

(co-dominance - snapdragons) how are co-dominant alleles represented?

Answer 30

uppercase letter with a smaller lowercase letter to indicate colour

Question 31

(sex linkage) some characteristics are carried on which chromosomes?

Answer 31

sex chromosomes

Question 32

(sex linkage) why do are there a number of genes on the X chromosome men have only one copy of?

Answer 32

Y chromosome is smaller than the X

Question 33

(sex linkage) why may characteristics caused by recessive alleles on the X chromosome appear more frequently in men?

Answer 33

because it is missing on the Y in males - females may have dominant allele present on another X chromosome

Question 34

(Sex linkage) what is a sex linked genetic disorder?

Answer 34

Haemophilia

Question 35

(Sex linkage) what happens in haemophilia?

Answer 35

Blood clots slowly due to lack of protein blood clotting factor Small cuts could be fatal

Question 36

(Sex linkage) if a male inherits the recessive allele for haemophilia on their X chromosome will they inherit it?

Answer 36

Yes | Don't have the corresponding dominant allele on their Y chromosome

Question 37

(Sex linkage) do females who are heterozygous for haemophilia suffer?

Answer 37

No they are carriers

Question 38

(Multiple alleles) how many alleles does a gene have to be classed as a multiple allele?

Answer 38

3+

Question 39

(Multiple alleles) how many alleles can be present in an individual?

Answer 39

2

Question 40

(Multiple alleles) what is determined by a gene with multiple alleles?

Answer 40

Blood group

Question 41

(Multiple alleles) blood group - what does immunoglobulin gene code for?

Answer 41

Production of different antigens on surface of RBCs

Question 42

(Multiple alleles) blood group what does Ia result in?

Answer 42

Production of antigen A

Question 43

(Multiple alleles) blood group - what does Ib code for?

Answer 43

Production of antigen B

Question 44

(Multiple alleles) blood group - what does Io code for?

Answer 44

Neither antigen

Question 45

(Multiple alleles) blood group - which alleles are co dominant?

Answer 45

Ia and Ib

Question 46

(Multiple alleles) blood groups - which allele is recessive?

Answer 46

Io

Question 47

(Determining sex) which chromosome determines sex?

Answer 47

23rd

Question 48

(Determining sex) which chromosome carries the gene causing the embryo to develop as male?

Answer 48

The Y chromosome

Question 49

(Determining sex) how is the sex of the offspring determined?

Answer 49

By the sperm fertilising the egg containing an X or Y

Question 50

(Dihybrid inheritance) what is dihybrid inheritance used to show?

Answer 50

Inheritance of 2 characteristics caused by two genes

Question 51

(Dihybrid inheritance) give an example of dihybrid inheritance?

Answer 51

Phenotype of pea plants Yellow or green Round or wrinkled