Inheritance And Variation

Question 1

What does heterozygous mean?

Answer 1

Different alleles

Question 2

What does homozygous mean?

Answer 2

Same alleles

Question 3

What are alleles?

Answer 3

Different forms of the same gene

Question 4

What are genes?

Answer 4

DNA which codes for polypeptides, characteristics

Question 5

What is the genotype?

Answer 5

Combination of alleles

Question 6

What allele is expressed?

Answer 6

Dominant

Question 7

What is discontinuous variation?

Answer 7

Controlled by a few genes eg. Blood group

Question 8

What is continuous variation?

Answer 8

Controlled by a group of genes eg. Height

Question 9

What type of allele is cystic fibrosis?

Answer 9

Recessive

Question 10

What type of allele is polydactyly?

Answer 10

Dominant

Question 11

What is the position of genes called?

Answer 11

Loci which are in the same place on both maternal and paternal chromosomes

Question 12

What does autosomal mean?

Answer 12

Recessive gene not found on a sex chromosome and so is found on 1 to 22 chromosome

Question 13

What are sex linkage genes?

Answer 13

Genes carried on sex chromosomes

Question 14

What is the ratio when 2 heterozygous parents breed?

Answer 14

9:3:3:1

Question 15

What is the ratio when a heterozygous a recessive parents breed?

Answer 15

1:1:1:1

Question 16

Define epistasis

Answer 16

Interacting of genes on different loci which prevents one gene being expressed

Question 17

What does hypostatic mean?

Answer 17

The gene wich is effected by epistasis

Question 18

When does repressive epistasis occur?

Answer 18

When 2 recessive alleles are inherited

Question 19

When happens when dominant epistasis occur?

Answer 19

Dominant allele prevents other genes being expressed

Question 20

Define allele frequency

Answer 20

Frequency of alleles of a single gene

Question 21

Define gene pool

Answer 21

Total of all genes in a population

Question 22

What is the equation for allele frequency?

Answer 22

P squared + 2×p×q + Q squared

Question 23

Name a density dependant factor

Answer 23

Competition

Question 24

Name some density independent factors

Answer 24

Climate change

Question 25

When should you square root in allele frequency equation?

Answer 25

If asked for pp Pq etc

Question 26

Name some factors which can effect evolution

Answer 26

Sexual or natural selection
Gene flow
Genetic drifts

Question 27

What shaped graph is produced by normal distribution?

Answer 27

Bell shape curve

Question 28

What are the 3 types of Speciation?

Answer 28

Stabilising
Directional
Disruptive

Question 29

Define stabilising Speciation

Answer 29

Norm or average

Question 30

Define directional stabilisation

Answer 30

Change in the environment makes common phenotype less advantageous

Question 31

Define disruptive stabilisation

Answer 31

Extremes are selected and norm is selected against. Eg. Darwin finches

Question 32

Define Speciation

Answer 32

Formation of new species through evolution

Question 33

What can isolation of species cause?

Answer 33

No gene flow
No interbreeding
Mutations due to selection pressures
Changes in phenotype and allele frequency

Question 34

Define allopatric Speciation

Answer 34

Original species separated by physical barrier creating new species

Question 35

Define sympatric Speciation

Answer 35

New species formed by isolation mechanisms

Question 36

What are prezygotic barriers?

Answer 36

Preventing mating

Question 37

What are postzygotic barriers?

Answer 37

Cause zygote to not develop