4. Genetic Diversity

Question 1

Other factors affecting Genetic diversity

Answer 1

Genes come in different forms called alleles. Alleles code for different polypeptides that may result in organisms having different phenotypes for a particular gene eg: small and large beaks.

Genetic diversity = the number of different alleles of genes in a particular species or a population.

The LARGER the number of different alleles in a population the higher the genetic diversity and the more likely a species or population is to be able to adapt to a changing environment and evolve. Populations with low genetic diversity are more likely to be wiped out by single events like a disease

Question 2

Genetic diversity Key points:

Answer 2

Variation in DNA base codes (eg: due to mutations)of different genes leads to the production of new alleles and the expression of different polypeptides – these control an organisms characteristics.

Organisms of a species contain the same genes, so it is the inheritance of different combinations of alleles that result in variation.

Question 3

Migration increases genetic diversity

Answer 3

Introduction of a new individuals with different alleles result in more new combinations of alleles and increased variation (this is called GENE FLOW)

Question 4

The Founder effect reduces genetic diversity

Answer 4

A few individuals from a population colonise a new region. Theses few individuals carry with them a small fraction of the populations alleles. As the population increases they show less genetic diversity than the original population. (The total number of alleles in a population is called the gene pool)
The Founder effect reduces the gene pool.

Question 5

Genetic Bottlenecks reduce genetic diversity

Answer 5

Populations of species suffers a dramatic drop in numbers – maybe due to a chance event (volcano eruption) or interference by man (over hunting).
The few survivors possess a smaller variety of alleles (have a smaller gene pool) so show less genetic diversity.

Question 6

Selective breeding or Artificial selection reduce genetic diversity

Answer 6

Individuals with desirable characteristics are identified and used to parent the next generation, the process is repeated many times.
Offspring that do not have the desired characteristic may be killed and will not take part in the next cycle of breeding.
Alleles for unwanted characteristics are bred out of the population and genetic diversity decreases

Question 7

1. It is the proteins which make up an organism that make them different from each other…
2. RNA stores the code for the considerable number of proteins that make each organism different… T/F
3. A section of DNA codes for one or more amino acids…T/F
4. All members of the same species have the same genes… T/F
5. All organisms of the same species have the same alleles… T/F
6. A gene only has 2 possible alleles… T/F
7. The greater the number of different alleles that all members of a species possess, the lower the genetic diversity of the species… T/F
8. The greater the genetic diversity of a species the more likely that a species will adapt to some environmental change: the less susceptible all members will be to the same disease And the fewer genetic abnormalities will be seen… T/F
9. Genetic diversity is reduced when a species has fewer different alleles… T/F
10. Artificial selection (aka: selective breeding) involves identifying individuals with desired characteristics and using them to parent the next generation… T/F

1234 11. Selective breeding increases genetic diversity … T/F

12. Selective breeding produces high yielding breeds of plants and strains of domesticated animals…

T/F The founder effect is when large numbers of individuals from a population colonise a new region… T/F 13.

14. In the founder effect a few Individuals carry a small fraction of the original populations alleles, which may not be representative of the larger population… T/F
15. The new population may in time develop into a new species…T/F
16. A genetic bottleneck may result from a sudden dramatic increase in numbers, due to some chance event eg: volcanic eruption…T/F
17. The survivors of a genetic bottleneck share few different types of alleles, so have an Increased genetic diversity…T/F
18. Ethical Issues arising due to selective breeding Include: who funds the research: personal + moral bellefs of the scientists carrying out the research; which features Is it right to select for: how do we balance Increased yields with animal welfare; could we be breeding out alleles that may be useful in the future; is selective breeding Interfering with nature

Answer 7

1. T
2. F
3. F
4. T
5. F
6. F
7. F
8. T
9. T
10. T
11. F
12. F
13. F
14. T
15. T
16. F
17. F
18. T