Ecology

Question 1

What is the equation for working out the index of diversity ?

Answer 1

N(N-1) /
sum of n(n-1)

N=total number of organisms of all species
n=total number of organisms of each species

Question 2

What farming techniques can affect biodiversity ?

Answer 2

The use of pesticides
Use of inorganic fertilisers
Removal of hedgerows
Monoculture
Absence of crop rotation
Overgrazing of land by sheep
Escape of slurry 
Filling in ponds and draining marshlands

Question 3

What is index of diversity?

Answer 3

A method of describing the relationship between the number of species and the number of individuals of a community

Question 4

What is a species?

Answer 4

A group of organisms with similar characteristics that are able to reproduce and form fertile offspring

Question 5

What is a community ?

Answer 5

All the populations of different species living and interacting in a particular place at the same time

Question 6

What is a niche?

Answer 6

A niche describes how an organism fits into their environment. A niche refers to what it does and where it lives. It includes all the biotic and abiotic factors to which an organism is adapted to in order to survive, reproduce and maintain a viable population.

Question 7

What are abiotic factors?

Answer 7

Non-living factors

Question 8

What are biotic factors?

Answer 8

Living factors

Question 9

What is a habitat?

Answer 9

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

Question 10

What is species richness?

Answer 10

The number of different species

Question 11

What is a population ?

Answer 11

A group of individuals of the same species that occupy a habitat at the same time and are able to interbreed

Question 12

What is species diversity?

Answer 12

The number of species with the number of organisms of each species as well

Question 13

What is succession ?

Answer 13

A gradual change in a community over time.

Question 14

Describe primary succession.

Answer 14

In natural and suitable conditions land will gradually become colonised by pioneer species, and then by secondary and tertiary colonisers as a climax community. At each stage species (biotic) change the environment (abiotic) and make it less hostile and improve soil (humus) so that it becomes suitable for other species. More and different niches are created, which leads to more organisms and a more complex food web.

Question 15

Describe random quadrant sampling

Answer 15

• Lay out two long tape measures at right angles
• Obtain a series of coordinates using random numbers
• Place the quadrat at the intersection of each pair of coordinates and record the frequency / percentage cover / species etc in it.
• Repeat multiple times to collect a mean average.

Question 16

When do we use random quadrat sampling?

Answer 16

We use random sampling when we want to compare two areas.

Question 17

When do we use a transect ?

Answer 17

• A transect is useful when you are looking for a change in organisms over a certain distance.
• It is used when there is some sort of transition in conditions over a distance

Question 18

Describe using a transect.

Answer 18

Place the transect along an area. Place the quadrat at regular intervals and record the species in it. At each interval flip over the quadrat and take multiple readings at the same point to collect a mean.

Question 19

What is required for the Mark, Release, Recapture method ?

Answer 19

• You mustn’t impede the animals chances of survival by making the animal
• The marking mustn’t be easily washed off or removed
• You need to give time for animals to disperse.

Question 20

What is the equation to calculate an estimate or a total population size (MRR)?

Answer 20

N=(MC)/R
Where
N=estimate of total population size
M=Number of animals captured and marked first
C=Total number of animals captured again
R=Number of animals that were marked and recaptured.

Question 21

What are some sources of error from Mark, Release and Recapture ?

Answer 21

• the proportion of marked to unmarked animals is the same in the second sample as in the population as a whole
• The population changes in the time period (births and deaths)
• The population has a definite boundary

Question 22

Describe secondary succession

Answer 22

A succession that is (potentially) at its climax community is disrupted. Succession starts again, but the soil is already created, so it does not start from the bare rock serall stage

Question 23

Describe the conservation of habitats by controlling succession.

Answer 23

By maintaining the earlier stages of succession a greater variety of habitats are conserved and therefore a greater range of species.