Module 4 Section 2 - Biodiversity

Question 1

What are the three levels at which we can consider biodiversity? Describe them briefly.

Answer 1

• Species - types and abundance of different species
• Habitats - physical factors of living in a certain environment
• Genetics - variations in alleles

Question 2

species richness

Answer 2

The number of different organisms in an area.

Question 3

species evenness

Answer 3

The relative abundance of each species in an area.

Question 4

habitat diversity

Answer 4

The number of different habitats in an area.

Question 5

How do you calculate the species evenness?

Answer 5

The range in the number of each species there are in the area

Question 6

taxonomic variety

Answer 6

Essentially the variety of taxonomic groups i.e. classified organisms in an area

I think, don’t quote me

Question 7

Simpson’s Index of Diversity - what do n and N represent?

Answer 7

n = number of organisms in one specific species
N = total number of all organisms

Question 8

Simpson’s Index of Diversity is always between ____ and ____.

Answer 8

0 and 1

Question 9

The higher the Simpson’s Index of Diversity is to 1, the ____ diverse the habitat and the ____ able it is to cope with sudden changes.

Answer 9

more, more

Question 10

A habitat with a Simpson’s diversity index of 0.2 is/isn’t dominated by one or a few species.

Answer 10

is

Question 11

How has increasing population sizes affected food sources?

Answer 11

Current sources of food are being exploited faster than they can be replenished e.g. fish stocks

Question 12

How has increasing population sizes affected waste & pollution? Give an example.

Answer 12

More waste and pollution is released (e.g. oxides of nitrogen from car exhausts) causing acid rain and lowering the pH of soil & water, killing trees and aquatic life

Question 13

Apart from using more land for farming, how has agriculture increased to feed the growing population? Give two examples.

Answer 13

Land currently used for food is being exploited more intensely.
* Overgrazing by cattle can lead to soil erosion
* Farmers rely on monocultures more. This leads to an increased use of fertilisers (monocultures in particular make soil depletion occur faster)

Question 14

Why is using lots of fertiliser bad for biodiversity?

Answer 14

Nutrient run-off can cause algal blooms in water, blocking sunlight from reaching the bottom of the bodies of water - aquatic plants die as they can no longer photosynthesise, closely followed by aquatic animals that can no longer respire

Question 15

aesthetic reason to maintain biodiversity

Answer 15

Tourists may travel to see landscapes with high biodiversity for leisure and personal joy as biodiverse areas are attractive to look at

Question 16

Why might you want to do non-random sampling? (2)

Answer 16

When you want to get samples from each of the different areas in a habitat, or to sample all the different species.

Question 17

Three types of non-random sampling techniques

Answer 17

• Systematic sampling
• Opportunistic sampling
• Stratified sampling

Question 18

When might you do systematic sampling?

Answer 18

Along a transect

Question 19

How could you investigate crawling insects? (2)

Answer 19

Set up pitfall traps or use a pooter (essentially an insect vacuum)

Question 20

Why can insects not escape a pitfall trap?

Answer 20

The contained has straight sides so insects can’t escape

Question 21

What is important about the straws in a pooter?

Answer 21

There are two straws, but one of them is covered so you don’t accidentally suck the insect up

Question 22

How could you investigate small animals? Explain how this works.

Answer 22

Use a Tullgren funnel (this is a funnel with a mesh, which is covered by soil/leaf litter) and a light is shone on top of it.
The light dries out the soil/leaf litter, drawing out any organisms inside - these then fall into the beaker below.

Question 23

How could you investigate aquatic life?

Answer 23

Use kick sampling - kick/agitate the sediment in a river for a set amount of time and then use a net to collect any disturbed organisms downstream

Question 24

How could you investigate organisms living in tall grass?

Answer 24

Use a sweep net - sweep once through the grass and empty the contents into a collection tray

Question 25

point frame/point quadrat

Answer 25

A standing frame with vertical metal spokes - count an organism that touches these spokes.

Question 26

What sort of marker must be used when getting a mark-release-recapture sample?

Answer 26

A non-toxic marker so it doesn’t increase the chance of capture by predators

Question 27

Why must you wait some time to get a valid mark-release-recapture sample?

Answer 27

Time must elapse in order for the organisms to redistribute within the habitat

Question 28

What two things must you assume when using a mark-release-recapture sample to estimate the population of an organism?

Answer 28

• have to assume no organisms have entered/left the environment
• have to assume enough time has been waited for the captured infividuals to redistribute within the habitat

Question 29

When you get an estimation of 63.7 organisms in an area using mark-release-recapture, what would you give your answer as?

Answer 29

Truncate it to get 63 - although 64 may or may not be accepted

Question 30

A question asks you to find the number of individuals to be sampled in each strata.
What do you if the total of the calculated sizes of the samples don’t add up to the specified sample size (i.e. there is an off by one error)?

Answer 30

Starting from the smallest value, find the value which is the highest proportion of the way to the next number and increment it by one.

I think, anyway

Question 31

bias

Answer 31

A sample that isn’t a representation of the whole population

Question 32

random sampling

Answer 32

Aa technique where every individual has the same probability of being selected

Question 33

Give an example of a non-random sampling technique.

Answer 33

Using transects

Question 34

Throwing a quadrat in a field is random sampling. T/F and why?

Answer 34

False - you are not randomising the direction or power of the throws.

Question 35

How can you reduce bias? (2)

Answer 35

• Use random sampling
• Do repeats

Question 36

How can you make samples that are more valid? (2)

Answer 36

Repeat at different times of the day and year/season

Question 37

How do you carry out stratified sampling?

Answer 37

• Split the population into mutually exclusive subgroups
• Sample each of these subgroups in the same proportion as their relative size within the population

Question 38

polymorphic gene

Answer 38

A gene that has multiple different potential alleles.

Question 39

polymorphic gene locus

Answer 39

A particular point on a chromosome where multiple different alleles can be found.

Question 40

What sort of genes are typically not polymorphic?

Answer 40

The ones that are required to synthesise certain proteins necessary to life e.g. lots of digestive enzymes, haemoglobin (if you discount sickle cell anemia)

Question 41

A scientist finds that 17 out of 24 genes are polymorphic in a species of bumblebee. Another scientist finds that only 10 out of 18 genes of a different bumblebee species are polymorphic. Evaluate the conclusion that the first species is more genetically diverse. [typically 3 marks]

Answer 41

For:
* There does seem to be more polymorphic genes in the first species of bumblebee.

Against:
* No statistical test and analysis done so can’t verify that the results are significant (and so not due to chance).
* Small sample size (only one bee of each species was sampled) -> can’t draw a conclusion.
* We cannot verfiy that the same genes were sampled.

Question 42

A human is heterozygous for eye colour. What does this mean in terms of the gene?

Answer 42

The gene is polymorphic (there are at least two different alleles).