Chapter 9: Genetic diversity

Question 1

What are gametes?

Answer 1

Gamete are the sex cells in organisms. Sperm cells in males and egg cells in females

Question 2

What happens at fertilisation?

Answer 2

Gametes (eggs and sperm) join together at fertilisation to form a zygote. A haploid sperm fuses with a haploid egg to make a cell with the normal diploid number of chromosomes

Question 3

What is the diploid number (2n) of chromosomes i humans?

Answer 3

The diploid number of chromosomes in humans is 46

Question 4

Why do gametes have a haploid number of chromosomes?

Answer 4

The number of chromosomes would double to when the gametes fuse and the zygote would have too

Question 5

Gametes have a haploid (n) number of chromosomes. What does haploid mean?
Hint: H-aploid H-alf

Answer 5

It means that the gametes only have one copy of each chromosome

Question 6

Meiosis is a type of cell division that takes place where?

Answer 6

Meiosis is a type of cell division that takes place in the reproductive organs

Question 7

Why is variation between the members of a population is important?

Answer 7

Variation between the members of a population is essential to enable the population to withstand the pressures of natural selection to evolve

Question 8

What are the 3 ways in which meiosis produces variation?

Answer 8

random segregatiom/assortment of homologous chromosomes
random segregatiom/assortment of chromatids
crossing over or chiasmata

Question 9

When gametes fuse in fertilisation, new combinations of _____ are formed

Answer 9

alleles

Question 10

What is a mutation?

Answer 10

A mutation is a change in the sequence of bases in a nucleotide chain

Question 11

What is deletion in gene mutation?

Answer 11

One or more bases are removed during replication

Question 12

What is insertion in gene mutation?

Answer 12

One or more bases are added to the sequence

Question 13

What is substitution in gene mutation?

Answer 13

One or more bases are replaced

Question 14

What is inversion in gene mutation?

Answer 14

Two or more bases are reversed in sequence

Question 15

What is translocation in gene mutation?

Answer 15

One or more bases are transferred from the end of one gene onto the end of another gene

Question 16

What are mutagens?

Answer 16

Mutagens are environmental factors that increase the frequency of mutations

Question 17

How do mutagens increase the frequency

Answer 17

High energy mutagens can damage the genetic meterial directly by breaking it up or
They can alter the reactivity of other chemicals in the body (e.g. water) which the damade the DNA

Question 18

How does independent segregation lead to genetic

Answer 18

During meiosis I, homologous pairs are separated. Whcih chromosmes of a pair
The four dughter cells prduced by meiosis have different combination fo maternal and paternal chromosomes

Question 19

How does independent segregation lead to genetic variation?

Answer 19

During meiosis I, the homologous pairs of chromosmes line up together and are separated. The way they line up is completely random so that
The four dughter cells prduced by meiosis have different combination fo maternal and paternal chromosomes

Question 20

What is genetic diversity?

Answer 20

Genetic diversity is described as the total number of different alleles in a species or a population

Question 21

Give 2 ways in which genetic diversity within a population can be increased

Answer 21

mutations
in DNA forms new alleles
gene flow
when different alleles are introduced into a population such as when individuals from another population migrate into them and reproduce

Question 22

Explain how genetic bottlenecks reduce genetic diversity?

Answer 22

A genetic bottleneck causes a great reduction in a population and thus a reduction in the number of different alleles in the gene pool because for example lots of organisms die before reproducing. The survivors reproduce and a larger population is created from a few individuals and thus a few different alleles

Question 23

What is a genetic bottleneck?

Answer 23

A genetic bottleneck is an event that reduces the genetic diversity of a population by reducing the number of individuals in the population

Question 24

gene pool

Answer 24

o

Question 25

founder effect

Answer 25

The founder effect is a type of genetic bottleneck
a few organisms start a new colony
there are only a small number of different alleles in the initial gene pool
alleles present in the initial gene pool are more likely to get passed on

Question 26

Why is greater genetic diversity better than lower genetic diversity?

Answer 26

Greater genetic diversity means there is a larger number of different alleles and thus characteristics. Likelihood that

Question 27

Give an example of a behavioural adaptation.

Answer 27

behaviour

possums play dead to escape attach from a predator

Question 28

Give an example of a physiological adaptation.

Answer 28

internal processes

hibernation - brown bears lower their metabolic rate to conserve energy during winter months when food is scarce

Question 29

Give an example of an anatomical adaptation.

Answer 29

structural features

whales have a thick layer of blubber to act as insulation in cold seas

Question 30

Natural selection increases advantageous alleles in a population…

Answer 30

random mutations 
new allele
harmful
dies out quickly
beneficial
increases their chances of survival
certain environment
more likely to survive
reproduce 
pass on genes + advantageous allele
larger portion of next generation inherits advantageous allele
next generation also more likely to survive
so frequency increases from gen to gen
over many many gens
evolution
more common