4.6.1- Biodiversity

Question 1

Compare species diveristy with species richness [2 Marks]

Answer 1

Both species richness and species diversity measure the number of different species in a community

Species diveristy takes into account the abundance of species, (appulation sizes) Awheraes species richness doenst

Question 2

Fertilizers are most commonly used today by most farmers as they help to increase crop yield and profit. If it rains shortly after fertilizers are applied to a filed then some of the fertilizers can enter neraby water sources as runoff. A conservationist invesigated the effect that runoff fertilizer from a nearby farm had on the distribution of organismd living in the stream. At the point where fertilizer had enrted the stream , she found a high density of specifc organism but a low index diversity

Suggest how fertilizer contaminating the strema could explain their finding [2 Marks]

Answer 2

1. Presence of fertilizer causes death/ toxicity /oxygen depletion
2. Only a few species survive as a result / prevents many species from reproducing

OR

1. Fertilizer acts as a food source for some plant species
2. Only those species increase in number

Question 3

Predict how index diversity will change as the conservationist moves further away from the farm to take her sample. Justify your answer [2 Marks]

Answer 3

1. Will increase

2. As fertilizer will be more diluted further from the farm

Question 4

Explain the importance of taking a large number of samples at random sites [2 Marks]

Answer 4

Taking a large number of samples

1. Produces a more reliable mean/ make sure that the samples are representative or reduces the effect of extreme values / anomailes

Random sampling
2. removes bias

Question 5

Explain one ecological advantage and state one disadvantage of this practice over the felling of mature trees for timber [3 Marks]

Answer 5

Advantage

1. Increases biodiversity by allowing light to reach ground so allowing a wider range of plant species to grow
2. Which creates a range of different food sources/habitats for insects ( which can i turn feed birds or small animals)

OR

1. Quick regrowth becuase trees keep mature root systems
2. Tree life prolonged

Disadvantage

1. Animals can graze on newly coppiced stumps , preventing growth
2. Not all trees suitable for coppicing

Question 6

Suggest why this measure of species richness might have limited usefulness in analyzing ecological relationships in these two areas [3 Marks]

Answer 6

1. 6= A
   3=B

This might have limited unsefulness in analysing ecological relationships becasue

2. There is no measure of the eveness of species/ the relative number of individuals of each species/ one individual or many still equals one species
3. Researches are unlikey to be able to find/calulate all different types of invetebrae / likely to be many hundreds or thousands of inbetebrae species present

Question 7

Explain how use of the index diveristy of biodiversity adds clarity into the analysis of bd in two contrasting areas like those described in part c , over species richness [1 Mark]

Answer 7

Takes into account the number of individuals in each population

Question 8

Explain why it is more useful to calculate an index diveristy than to record species richness [2 Marks]

Answer 8

-It measures the abundance of each species because there may be many of 1 species or very few of one species.
[1. (Index of diversity also) measures abundance /
number / population (size) of each species;
2. (So useful because) may be many of some
species
OR
(So useful because) may be few of other
species;]

Question 9

suggest how scientists measured the rate of water flow [1 Mark]

Answer 9

1. *Movement of (floating) object over known

distance and over given time*

Question 10

It was important that the sampling procedure was standardised when collecting the Slate Drake mayflies from the two sites.
Give one way in which the sampling procedure could be standardised.

Answer 10

Same size of area (sampled)
OR
Same size net/mesh
OR
Same sampling time
OR
Samples taken at same time of day/on same day;

Question 11

Suggest and explain a reason for the difference in number of slate drake mayfly at the sites [2]

Answer 11

• Site 2 more food variety

- so more likely yo survive and reproduce