Module 7 - Inheritance

Question 1

What is a genotype?

Answer 1

The genetic constitution of an organism - the alleles an organism has

Question 2

What is a phenotype?

Answer 2

The expression of the genetic constitution and its interaction with the environment - an organism’s characteristics

Question 3

How many chromosomes will a diploid and haploid organism have?

Answer 3

Diploid - 2
Haploid - 1

Question 4

What are the two ways possible genotypes and phenotypes of an offspring can be determined?

Answer 4

Genetic diagram and punnett square.

Question 5

What type of genetic cross do we use when we are only crossing one type of characteristic?

Answer 5

Monohybrid

Question 6

What is a codominant allele?

Answer 6

A codominant allele is when both alleles are dominant and therefore both are expressed

Question 7

If in a monohybrid cross the question asks how many boys/girls will be affected, what do you do?

Answer 7

Multiply the probability by 50% because there is a 50/50 chance of having a boy or girl.

Question 8

What is it called when there are more than 2 alleles for a gene?

Answer 8

Multiple alleles

Question 9

What is a dihybrid cross?

Answer 9

This is when we are crossing 2 characteristics

Question 10

Why are sex chromosomes only carried on the X chromosomes in men and not on the Y chromosome?

Answer 10

The Y chromosome is smaller and so they carry fewer genes

Question 11

Why are males more likely of expressing a recessive phenotype?

Answer 11

Sex linked genes are on the X chromosome and men only have one x chromosome. This means they will express it even if it is recessive

Question 12

What is an autosome?

Answer 12

Any chromosome that isn’t a sex chromosome

Question 13

When are genes said to be linked?

Answer 13

When different genes are located on the same autosome, they are linked. They will stay together during independent segregation.

Question 14

What makes genes more closely linked?

Answer 14

When they are closer linked on a chromosome

Question 15

What will split an autosomal linkage?

Answer 15

Crossing over

Question 16

What is epistasis?

Answer 16

When an allele of one gene masks the expression of the alleles of other genes

Question 17

What are the two types of epistasis?

Answer 17

Dominant epistatic allele and recessive epistatic allele

Question 18

What is the phenotypic ratio for a dominant epistatic allele?

Answer 18

9:3:4

Question 19

What is the phenotypic ratio for a recessive epistatic allele?

Answer 19

12:3:1

Question 20

What is the chi-squared test?

Answer 20

A statistical test that is used to see if the results of an experiment support the theory

Question 21

What is the expected result and the observed result?

Answer 21

The expected result is the predicted result and the actual result is the observed result.

Question 22

What is the null hypothesis?

Answer 22

The Null hypothesis is always that there is no significant difference between the observed results and expected results

Question 23

When a chi-squared test is carried out and results are not significantly different, what do we say?

Answer 23

Fail to reject the null hypothesis

Question 24

What is the formula for chi-squared?

Answer 24

The sum of ((O-E)/E)

Question 25

How do we calculate the expected number of offspring for each phenotype?

Answer 25

(Total number of offspring/total of the ratio) X ratio

Question 26

How do we calculate if there is any significant difference between the observed result and the expected result?

Answer 26

We compare the x^2 to the critical value

Question 27

What is the critical value?

Answer 27

This the 5% level of probability that the difference between the expected and observed results is due to chance

Question 28

What does it mean if the x^2 is higher or equal to the critical value?

Answer 28

There is a significant difference between the expected value and the observed value. The null hypothesis can be rejected.

Question 29

What does it mean if the x62 is smaller than the critical value?

Answer 29

There is no significant difference between the expected value and the observed value. The null hypothesis has failed to be rejected. The theory is supported.