Chapter 17 - Inherited Change

Question 1

What is the genotype of an organism?

Answer 1

All the alleles possessed by an organism

Question 2

What is the phenotype of an organism?

Answer 2

Observable characteristics

Question 3

What two factors contribute to the phenotype?

Answer 3

Genetics and environment

Question 4

What is a gene?

Answer 4

Length of DNA, codes for polypeptide

Question 5

What is the locus?

Answer 5

Position of gene on DNA strand

Question 6

What is an allele?

Answer 6

Different forms of genes

Question 7

What are codominant alleles?

Answer 7

Both contribute to phenotype

Question 8

What are multiple alleles?

Answer 8

More than two alleles

Question 9

What is pure breeding?

Answer 9

Organisms have two of the same alleles for a gene

Question 10

What is a ratio?

Answer 10

A proportion

Question 11

Why are the predicted results rarely the same as the observed results?

Answer 11

Only a prediction
Chance
Small sample

Question 12

What is dihybrid inheritance?

Answer 12

Looking at how two genes on different chromosomes are inherited

Question 13

How do you work out a dihybrid cross?

Answer 13

Do the same as a normal cross but include both genes

Question 14

Which genotypes result in blood group A?

Answer 14

IA, IA or IA, IO

Question 15

Which genotypes result in blood group B?

Answer 15

IB, IB or IB, IO

Question 16

Which genotypes result in blood group AB?

Answer 16

IA, IB

Question 17

Which genotypes result in blood group O?

Answer 17

IO, IO

Question 18

What is autosomal linkage?

Answer 18

Two or more genes are carried on the same autosome

Question 19

What impact does autosomal linkage have on a genetic cross?

Answer 19

Rather than having AB, ab, Ab, aB, you only have AB and ab because the two are linked

Question 20

What is epistasis?

Answer 20

One allele affects or masks the expression of another

Question 21

Explain epistasis in mice

Answer 21

Gene A (black bands) is affected by the expression of B (production of melanin)
bb means no melanin and an albino mouse
B means melanin is produced
If A is also present, there is a black-banded mouse
If a is also present, there is a black mouse

Question 22

What does the Chi-squared test do?

Answer 22

Test the null hypothesis

Question 23

What is the null hypothesis?

Answer 23

There will be no statistically significant difference between our expected and observed values

Question 24

What requirements does the Chi-squared test have?

Answer 24

Large sample size
Discrete categories
Raw counts, not percentages

Question 25

Formula for Chi-squared

Answer 25

https://www.statisticshowto.datasciencecentral.com/wp-content/uploads/2013/09/chi-square-formula.jpg

Question 26

What are the degrees of freedom?

Answer 26

One less than the number of categories

Question 27

If the probability that the data is due to chance is bigger than 5%, what do we do?

Answer 27

Accept the null hypothesis - the deviation is insignificant

Question 28

If the probability that the data is due to chance is less than 5%, what do we do?

Answer 28

Reject the null hypothesis - the deviation is significant

Question 29

Why will characteristics that are controlled by recessive alleles on the non-homologous section of the X chromosome appear more frequently in males?

Answer 29

There is no homologous section on the Y chromosome that may contain the dominant allele

Question 30

Example of X linked disease?

Answer 30

Haemophilia

Question 31

Where must males get their Y chromosome from?

Answer 31

Their father

Question 32

What is the law of independent assortment?

Answer 32

Each member of a pair of alleles may combine randomly with either of another pair

Question 33

How can results of genetic crosses be made to be closer to predicted ones?

Answer 33

By using a very large, representative sample

Question 34

Why are actual results of genetic crosses rarely the same as predicted?

Answer 34

Due to statistical error

Question 35

What is the law of segregation?

Answer 35

In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete.

Question 36

Which sex chromosomes do females have?

Answer 36

XX

Question 37

Which sex chromosomes do males have?

Answer 37

XY

Question 38

How many different types of gamete do males produce?

Answer 38

2, one X and one Y

Question 39

What are sex-linked genes?

Answer 39

Any gene carried on wither the X or Y chromosome

Question 40

Why can some genes be more prevalent in males than females?

Answer 40

The X chromosome is much longer than the Y, so more most of the X chromosome, there is no homologous equivalent and those recessive characteristics on the X chromosome will be more frequent in males