4.2.1 biodiversity

Question 1

what is biodiversity?

Answer 1

the variety of living organisms present in an area

Question 2

what is habitat biodiversity?

Answer 2

the number of different habitats found within an area

Question 3

what are the two components of species biodiversity?

Answer 3

• species evenness

- species richness

Question 4

what is species richness?

Answer 4

the number of different species living in a particular area

Question 5

what is species evenness?

Answer 5

a comparison of the numbers of individuals of each species living in a community

Question 6

what is genetic biodiversity?

Answer 6

the variety of genes that make up a species

Question 7

what is sampling?

Answer 7

taking measurements of a limited number of individual organisms present in a particular area

Question 8

what is the purpose sampling?

Answer 8

• estimate the number of organisms in an area (the abundance of a species)
• measure a particular characteristic of an organism

Question 9

what is random sampling?

Answer 9

each individual in the population has an equal likelihood of selection

Question 10

what is non-random sampling?

Answer 10

where the sample is not chosen at random

Question 11

what are some methods of non-random sampling?

Answer 11

• opportunistic sampling
• stratified sampling
• systematic sampling

Question 12

what is opportunistic sampling?

Answer 12

sampling using the organisms that are conveniently available
the weakest form of sampling - may not be representative of the population

Question 13

what is stratified sampling?

Answer 13

sampling where populations are divided into sub-groups based on a particular characteristic
a random sample is then taken from each of these strata proportional to its size

Question 14

what is systematic sampling?

Answer 14

different areas of a habitat are identified and sampled separately
often carried out using a line or belt transect

Question 15

how to carry out a random sample?

Answer 15

• mark a grid out of the area using two tape measures laid out at right angles
• use random numbers to determine the x coordinate and y coordinate on the grid
• use a quadrat to take a sample at each of the coordinate pairs generated

Question 16

why is a sample not entirely representative?

Answer 16

• sampling bias - the selection process may be biased - deliberate or by accident
• chance - the organisms selected may not be representative of the whole population, effect minimised by large sample size

Question 17

how can animals be sampled?

Answer 17

• pooter - catch small insects
• sweep nets - catch insects in areas of long grass
• pitfall traps - catch small crawling invertebrates , hole dug in ground which insects fall into
• tree beating - take samples of invertebrates that live in tree or bush, white cloth stretched under the tree, tree shaken or beaten to dislodge the invertebrates
• kick sampling - river bank and bed kicked to disturb the substrate, net held downstream to capture any organisms released into the flowing water

Question 18

how can plants be sampled?

Answer 18

• point quadrat - consists of a frame containing a horizontal bar, pins pushed through bar to reach ground, species of plant that touches the pin is recorded
• frame quadrat - square frame divided into a grid, type and number of species in each section is recorded

Question 19

how can frame quadrats be used?

Answer 19

• density - count number in 1m x 1m quadrat
• frequency - count number of small squares that a species is present in
• percentage cover - estimate of the percentage a species covers

Question 20

how can animal population size be estimated?

Answer 20

capture-mark-release-recapture
compare number of marked individuals with the number of unmarked individuals in the second sample
the greater number of marked individuals recaptured, the smaller the population

Question 21

Simpson’s Index of Diversity

Answer 21

D = 1 - Σ(n/N)²
n = total number of organisms of a particular species
N = total number of organisms of all species

Question 22

what is the importance of genetic biodiversity?

Answer 22

more able to adapt to changes in the environment

Question 23

factors that cause genetic biodiversity to increase

Answer 23

• mutations in the DNA of the organism

- gene flow - interbreeding between different populations

Question 24

factors that cause genetic biodiversity to decrease

Answer 24

• selective breeding - only a few individuals within a population are selected for breeding for advantageous characteristics
• captive breeding programmes
• artificial cloning
• natural selection - alleles for less advantageous characteristics are lost from a population over time
• genetic bottleneck - only a few individuals in a population survive an event or change, reducing the gene pool
• founder effect - small number of individuals create a new colony, geographically isolated from the original. gene pool is small
• genetic drift - due to randomness of reproduction, the frequency of occurrence of an allele will vary