4.2 - Biodiversity Flashcards Preview

Biology - Paper 3 > 4.2 - Biodiversity > Flashcards

Flashcards in 4.2 - Biodiversity Deck (60)
Loading flashcards...
1

What is biodiversity?

A measure of variation found in the living world.

2

What is a habitat?

Where an organism lives.

3

What is a species?

A group of organisms that can breed together to produce fertile offspring. They share similar physical characteristics, anatomy, biochemistry and genetics.

4

What is species diversity?

The number of species and abundance of each species that live in a particular location.

5

What is species richness?

The number of different species found in a habitat.

6

What is species evenness?

The degree to which each species is represented. If each species is found in similar numbers biodiversity is even. If each species is found in differing numbers it is uneven.

7

What does abundance mean?

The number of individuals of a species.

8

What is genetic biodiversity?

The variation within individuals of the same species. Genetic variation accounts for the differences within species - why we don’t all look the same. Genetic variation creates breeds within species e.g. spaniels and labradors.

9

Describe sampling methods and the advantages and disadvantages of each.
Note: for representative data the number of samples taken should be equivalent to 1% of the total area. E.g. 100m2 area, 1m2 quadrat = 10 samples taken.

Random: select habitat at random using randomly generated coordinates. Removes bias from data collected but may not be representative - rare/infrequent species may be missed, so biodiversity may be underestimated.
Non-random opportunistic: habitat chosen deliberately. Quicker - no random coordinates needed but can lead to bias, so biodiversity may be underestimated or overestimated.
Non-random stratified: habitat divided into areas and sampled separately. Sampling within areas may be random. Ensures all habitats of interest are sampled but areas of differing sizes may be under/over sampled.
Non-random systematic: samples taken at fixed intervals across habitats, sampling for change over distance, e.g. from shore to dunes. Shows change in biodiversity with change in conditions but only species along belt transect recorded.

10

State the way in which plant numbers may be counted.

By individual numbers of each species
Percentage cover.
Abundance using the ACFOR scale - Abundant, Common, Frequent, Occasional, Rare.

11

Describe the method for random sampling of a habitat.

Grid area and randomly select area to be sampled.
Set up grid using tape measures at right angles.
Generate random coordinates using a random number generator.
Place left hand corner of quadrat at coordinate.
Record the number of individuals of each species in the quadrat, use 50% rule.
Repeat multiple times so that 1% of area is covered.
Percentage cover can be used for frame quadrats when frequency is hard to measure.

12

Describe the errors that might arise when using random sampling to estimate biodiversity.

Misidentification of plant species - use a key to reduce error.
50% in rule is subjective - may lead to under/over estimation.
% cover count is subjective - may lead to under/over estimation.
Can be difficult placing quadrat in rough terrain - could use point frame quadrat.
Placing of quadrat at coordinate may be inaccurate - grid area within sample area or use GPS.

13

Describe the method for sampling using a belt transect.

Decide on area to be sampled using research/prior knowledge - this depends on factor being investigated, e.g. shade to light in a woodland.
Place tape to span area of interest.
Line transect - count plants touching tape.
Belt transect - use left hand rule to place quadrat on tape. Continuous belt transect - move quadrat along tape. Interrupted belt transect - place quadrat at determined intervals along tape e.g. every 1m.

14

Describe the errors that might arise when using transects to estimate biodiversity.

Only plants along line counted.
May be biased.
Misidentification of plant species - use a key to reduce error.
50% in rule is subjective - may lead to under/over estimation.
% cover count is subjective - may lead to under/over estimation.
Can be difficult placing quadrat in rough terrain - could use point frame quadrat.

15

Describe the methods for catching invertebrates and the advantages/disadvantages.

Sweep net - move net with figure of eight motion, tip net contents onto white sheet for identification. +: catch small invertebrates hidden in long plants; catch flying insects. -: disturbance causes invertebrates to fly/flee misidentification.
Pooter - place tube over invertebrate, suck through second tube, drawing invertebrate into chamber. +: individual collection of organism. -: limited to size of tube.
Tree knocking - place white sheet under tree and knock firmly, invertebrates fall onto sheet. +: can collect samples from areas that are not suitable for net. -: invertebrates by fly/jump off/hold on; care with damage to trees.
Pitfall trap - dig hole in ground and place collecting cup in hole; may contain water to prevent insects crawling out; cover to prevent flooding. +: traps can be set and left to collect data over time. -: chance if organism falls in; organisms may prey on one another; organism may drown in water.
Tullgren funnel - place soil sample in funnel, switch on lamp, invertebrates move away from heat and light and fall into collecting cup; may contain ethanol to kill samples. +: can collect difficult to find invertebbrates. -: inhumane killing samples.

16

What is the mark, capture, release method?

A known number of individuals are captured, marked and released, C1.
Appropriate method of marking is used so that it doesn’t harm the organism.
A second random known number of individuals are captured, C2.
The number of marked individuals recaptured, C3, is recorded and then they are released.
Population size can then be calculated from this data using the formula: Total population = (C1x C2)/ C3.

17

What are the conditions needed for mark-release-recapture investigations to give reliable results?

Marking not removed.
No immigration/emigration.
Sufficient time for marked individuals to mix with the population.
No births/deaths.
Sampling method is the same for each collection.

18

How can you ensure reliable survey results?

Random samples – no bias involved.
Larger sample size.
Larger sample area.
Smaller quadrat when sampling plants.
Same technique in each habitat.
Random number generator generating coordinates for quadrat placement.
Control/note abiotic variables.

19

What is an allele?

Different version of a gene.

20

What does locus mean?

The position along a chromosome at which a gene is located.

21

What is a polymorphic gene locus?

A locus that has more than two alleles.

22

Which two factors determine biodiversity?

Species richness and species evenness.

23

What is Simpson’s index of diversity and what does it measure?

D= 1 - [ ∑(n/N)2 where n = number of individuals of a species and N is the total number of the population (all the n’s added together).
The diversity of a habitat.
Takes account of species richness and evenness.
A high index value (closer to 1) is more diverse than a low index value.
The richer and more even a habitat, the more stable it is.

24

Why is a rich and even habitat is more stable?

More habitats for organisms to live in.
More food sources.
More breeding sites.
More inter and intraspecific interactions.

25

What is the importance of genetic diversity?

Increase in naturally occurring mutations may confer selection pressure.
Protects individuals from disease/death, e.g. Ash dieback - all trees genetically identical so no natural immunity to fungus.

26

How do you calculate genetic diversity?

Count number of loci of interest - this is number of individuals in population x2 (because each individual has two alleles for each gene).
Count number of heterozygotes in population (heterozygotes have two different alleles at a locus and so are more genetically diverse than homozygotes who have the same allele).
Genetic diversity = Number of heterozygous loci/total number of loci in population.
The closer the value to 100%, the greater the genetic diversity.

27

How do you calculate polymorphic genetic diversity?

Count population and multiply by number of loci of interest.
Count number of individual heterozygous for each allele.
Calculate mean of heterozygous population.
Divide by total allele population.

28

What is climate change?

Significant and long lasting changes in weather patterns - do not refer to global warming!

29

What is a monoculture?

A crop consisting of one strain of a species, e.g. palm oil trees.

30

In which way do humans use the environment?

Agriculture - farming to produce more food.
Destruction and fragmentation of habitats - farming, housing, road networks, logging.
Overuse of Earth’s resources - water, minerals, fossil fuels.
Pollution.
Overpopulation.