Diversity, Classification and Variation

Question 1

What are chromosome mutations?

Answer 1

When meiosis goes wrong, and the clerks produce variations in the numbers of whole chromosomes, or parts of chromosomes.

Question 2

What is non-disjunction?

Answer 2

A chromosome mutation - a failure of chromosomes to separate properly, eg leading to Down’s Syndrome.

Question 3

What are gene mutations?

Answer 3

Any change in the DNA base sequence of chromosomes.

Question 4

Define mutation.

Answer 4

Any cane to the quantity / or base sequence of DNA in an organism

Question 5

What are the two types of mutation?

Answer 5

Substitution and deletion.

Question 6

Outline substitution.

Answer 6

One base is replaced by another nucleotide base.

(Eg GTG to GTC).

Question 7

What can the effects of substitution be?

Answer 7

• the polypeptide chain will differ in a single amino acid. If it was important in forming bonds that determine the tertiary structure of the final protein, then the replacement AA may not form the same bonds. Protein may then be a diff shape and not function properly. Eg enzymes.
• the new triplet of bases could code for the same AA as before due to degenerative nature of genetic code.

Question 8

Outline deletion.

Answer 8

One nucleotide is removed from the normal DNA sequence.

Question 9

Outline the effects of deletion(

Answer 9

• all triplets in a sequence are now read differently because each has been shifted to the left by one base.

Question 10

Polyploidy is a chromosome mutation. Outline what it is.

Answer 10

Change in whole sets of chromosomes, so organisms have >3 sets of chromosomes rather than the usual 2.

Question 11

Outline the second type of chromosome mutation.

Answer 11

Change in the number of individual chromosomes.

Sometimes individuals pairs of homologous chromosomes fail to separate during meiosis - called non-disjunction.

Question 12

What are alleles?

Answer 12

Different versions of a single gene.

Question 13

Define genetic diversity.

Answer 13

The number of different alleles of genes in a species.

Question 14

How is genetic diversity increased in a population?

Answer 14

• mutations in the DNA; forming new alleles.

- different alleles being introduced into a population (gene flow)

Question 15

What s gene flow and what does it do?

Answer 15

Gene flow is when individuals form another population migrate into them and reproduce.

Question 16

Genetic bottlenecks __________ genetic diversity.

Answer 16

Reduce

Question 17

Outline genetic bottlenecks.

Answer 17

1. An event causes a big reduction in a population (eg volcanic eruption kills).
2. This reduced the number of different alleles in the gene pool, so reduced genetic diversity.
3. The survivors reproduce and a larger population is greater from fewer individuals.

Question 18

Outline the Founder Effect (type of genetic bottleneck).

Answer 18

1. A few organisms from a population start a new colony, and there are only a small number of different alleles in the initial gene pool.
2. The freq of each allele in the new colony might be v different to the freq in the original population (eg rare allele becomes common). May lead to higher incidence of genetic disease.
3. Can occur as a result of migration leading to geographical separation, or new colony separated from original population eg for religion.
   3.

Question 19

How does natural selection occur?

Answer 19

1. Random mutation can result in new alleles of a gene.
2. Many mutations are harmful, but, if the new allele of a gene is beneficial, there’s an increased reproductive success - so they’re more likely to survive, reproduce and pass on their genes.
3. The advantageous allele is inherited by members of the next generation.
4. As a result, over many generations, the new allele increases in freq in the population.

Question 20

In what 3 ways can natural selection lead to populations becoming better adapted?

Answer 20

• behavioural adaptations
• anatomical adaptations
• physiological adaptations

Question 21

Give an example of a physiological adaptation from natural selection.

Answer 21

These include processes inside an organism’s body that increase its chance of survival.

Eg brown bears hibernating over winter, so lowers their metabolism. This conserved energy, so they don’t need to look for food in the winter when it’s scarce.

Question 22

Give an example of an anatomical adaptation due to natural selection.

Answer 22

These are structural features that will increase its chance of survival.

Eg whales have a thick layer of blubber to help keep them warm.

Question 23

Give an example of an behavioural adaptation due to natural selection.

Answer 23

Ways an organism acts to increase its change of survival and reproduction.

Eg possums play dead if they’re being threatened by a predator.

Question 24

What is directional selection?

Answer 24

Where individuals with alleles for characteristics (a phenotype) of extreme types are more likely to survive and reproduce.

Question 25

Give an example of directional selection.

Answer 25

Antibiotic resistance.

Question 26

Outline antibiotic resistance as directional selection.

Answer 26

1. Some individuals in a population have alleles which give them resistance to an antibiotic. 2. The population is exposed to the antibiotic, killing bacteria without the resistant allele. 3. The resistant bacteria survive and reproduce without competition, passing on their advantageous allele. 4. After time, most organisms in the population have the antiobitoc resistance allele.

Question 27

What is stabilising selection?

Answer 27

If environmental conditions remain stable, the individuals with phenotypes closest to the mean are favoured. Therefore more likely to pass their alleles onto the next generation.

Question 28

Give an example of stabilising selection.

Answer 28

Human birth weight.

Question 29

Outline human birth weight as stabilising selection.

Answer 29

1. V small babies are less likely to survive bc they find it hard to maintain body temp. 2. Giving birth to large babies is hard, so are less likely to survive too. 3. Therefore conditions are most favourable for medium sized babes, so weight of human babies tends to shift towards middle of range.

Question 30

What are the two types of classification?

Answer 30

Artificial classification and phylogenic classification.

Question 31

What's artificial classification?

Answer 31

Dividing organisms according to differences that are useful at the time, eg colour, size etc.

Question 32

What is phylogenic classification?

Answer 32

Classification based upon the evolutionary relationships between organisms and their ancestors. Arranged groups in hierarchy with no overlap.

Question 33

Define classification.

Answer 33

The grouping of organisms

Question 34

Define taxonomy.

Answer 34

The practice of biological classification.

Question 35

Name the 8 taxa.

Answer 35

``` Domain Kingdom Phylum Class Order Family Genus Species ```

Question 36

Des genus have uppercase or lowercase letter?

Answer 36

First part p is genus with capital letter.

Question 37

Does species have upper or lower case letter?

Answer 37

Second part of name and lower case letter.

Question 38

What is courtship behaviour?

Answer 38

Behaviour carried ur by organisms to attract a mate of the right species. It is species specific. Eg releasing chemicals of a series of displays.

Question 39

What is the purpose of courtship behaviour?

Answer 39

- recognise members of own species (prevent it between diff species) - identify a mate that's capable of breeding (sexually mature, receptive to mating) - form a pair bond - synchronise mating (so it takes place when maximum probability of egg and sperm meeting) - become able to breed (physiological state)

Question 40

How is courtship behaviour used in classification?

Answer 40

Because courtship behaviour is species specific, the more closely related the species are, the more similar their courtship behaviour is.

Question 41

What are the 3 ways of clarifying evolutionary relationships?

Answer 41

- genome sequencing - comparing AA sequence - immunological sequencing

Question 42

Outline genome sequencing as a way of clarifying evolutionary relationships.

Answer 42

The DNA base sequence of one organism can be compared with that of another. Closely related species will have a higher % of similarity in DNA base order.

Question 43

Outline comparison of AA sequence as a method of clarifying evolutionary relationships.

Answer 43

The more similar the AA sequence, the more closely p related the species are. This is bc proteins are made from AAs. And the sequence of AAs in a protein is coded for by the base sequence of DNA related organisms have similar DNA sequences, so similar AA sequences in their proteins.

Question 44

Outline immunological comparisons as a method of clarifying evolutionary relationships

Answer 44

Similar proteins will bond to the same antibodies.

Question 45

How has the way in which genetic diversity is assessed changed over time?

Answer 45

- early estimates of genetic diversity were made by looking at the frequency of observable characteristics eg number of people with blue eyes. - now, new technologies (eg comparing DNA base sequences) give more accurate estimates of genetic diversity within a population.

Question 46

Why was observable characteristics used as a measure of genetic diversity?

Answer 46

Because different alleles determine different characteristics, so a wide variety of each characteristic in a population indicates a high number of different alleles - so high genetic diversity.

Question 47

Define biodiversity.

Answer 47

The variety of living organisms in an area.

Question 48

Define habitat.

Answer 48

The place where an organism normally lives, and is characterised by the physical conditions and types of organisms present.

Question 49

Define community.

Answer 49

All the living organisms present in an ecosystem at a given time.

Question 50

Define ecosystem.

Answer 50

All living and non-living components of a particular area.

Question 51

Biodiversity can be at different levels, which are...

Answer 51

Local biodiversity and global biodiversity.

Question 52

Define species richness.

Answer 52

The number of different species in a community.

Question 53

How do you calculate the index of diversity?

Answer 53

Total number of organisms of all species (" - 1) Divided by Sum of Total number of organisms of one species (" - 1)

Question 54

Give three ways in which agriculture can reduce biodiversity.

Answer 54

- monoculture (a single type of plant reduces biodiversity directly, and supports fewer organisms which further reduces biodiversity). - hedgerow removal (done to increase area of farmland by turning lots of small fields into more larger ones. This reduces biodiversity because reduces number of trees and sometimes the number of diff tree species. Also destroys habitats, so some species lose shelter and food source - so die or migrate elsewhere - woodland clearance (same as above) - pesticides (these chemicals kill organisms (pests) that feed on crops, thus reducing biodiversity. Also animals that feed on said pests will lose a food source, so their numbers could decrease too).

Question 55

Give examples of conservation schemes to prevent the reduction of biodiversity.

Answer 55

- giving legal protection to endangered species. - creating protected areas eg SSSIs and AONB which restrict further development, including agricultural development. - the environmental stewardship scheme, which encourages farmers to conserve biodiversity eg by replanting hedgerows.