module 4.2.1: biodiversity

Question 1

what is biodiversity

Answer 1

a measure of the variation found in the living world

Question 2

what is a habitat

Answer 2

where an organism lives

Question 3

what is a species

Answer 3

a group of organisms that can freely interbreed to produce fertile offspring

Question 4

what is biodiversity a measure of

Answer 4

a measure of all the different plant, animal, fungus and other microorganism species worldwide, the genes they contain, and the ecosystems of which they form a part. biodiversity is about the structural and functional variety in the living world. we can consider it at a number of levels

Question 5

what is a habitat biodiversity

Answer 5

a habitat is the place where individuals in a species live. the range of habitats in which different species live is known as the habitat biodiversity

Question 6

what are some common habitats found in the UK

Answer 6

sand dunes, woodland, manicured lawns, ponds, dark corners between buildings or a small patch of trees are all different habitats. each habitat will be occupied by a range of organisms

Question 7

what is species biodiversity

Answer 7

a species consists of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics. as a result, individuals in a species can interbreed freely to produce fertile offspring

Question 8

what is genetic biodiversity

Answer 8

the variation between individuals belonging to the same species. this is the variation found within any species that ensures that we all do not look identical

Question 9

disadvantages of using samples to measure biodiversity

Answer 9

it would very difficult to count all organisms in a habitat. some microorganisms can be cultured on a nutrient medium in the laboratory to gain an estimate of numbers, but not all will grow like this

Question 10

what can you do instead of using samples to measure biodiversity and what does it mean

Answer 10

sample a habitat which means you select a small portion and study that carefully. then you can multiply up the numbers of individuals of each species found, in order to estimate the number in the whole habitat

Question 11

what is random sampling

Answer 11

sample sites inside the habitat are randomly selected. this can be achieved by using randomly generated numbers as coordinates for your samples, or possibly selecting coordinates from a map and using a portable global-positioning satellite system to find the exact position inside the habitat

Question 12

what is an advantage of random sampling

Answer 12

it ensures that the data are not biased by selective sampling

Question 13

what is a disadvantage of random samplign

Answer 13

it may not cover all areas of a habitat equally
also species with a low presence may be missed, leading to an underestimate of biodiversity

Question 14

what is opportunistic sampling

Answer 14

when the researcher makes sampling decisions based on prior knowledge or during the process of collecting data. the researcher may deliberately sample an area that he or she knows for (or can see) contains a particular species

Question 15

what are advantages of opportunistic sampling

Answer 15

easier and quicker than random sampling

Question 16

what are disadvantages of opportunistic sampling

Answer 16

may be biased
the presence of large or colourful species may entice the researcher to include that species. this may lead to an overestimation of its importance and therefore an inaccurate estimate of biodiversity

Question 17

what is stratified sampling

Answer 17

dividing a habitat into areas which appear different, and sampling each area separately. this ensures that all different areas of a habitat are sampled and species are not underrepresented due to the fact that random sampling may miss certain areas

Question 18

what is systematic sampling

Answer 18

This is when samples are taken at fixed intervals across the habitat. Line transects and belt transects are systematic techniques

Question 19

what is an advantage of systematic sampling

Answer 19

this method is particularly useful when the habitat shows a clear gradient in some environmental factor such as getting direr further from a pond

Question 20

what is a disadvantage of systematic sampling

Answer 20

only species on the line or within the belt can be recorded, so other species may be missed, leading to an underestimate of biodiversity

Question 21

what is the preparation of sampling plants in a habitat

Answer 21

• suitable clothing — this will depend upon the type of habitat and the expected weather conditions
• suitable footwear
• apparatus needed to carry out the sampling
• clipboard, pen and paper to record your observations
• appropriate keys to identify plants
• camera or smartphone to record specimens and grid location

Question 22

what can help you identify different species

Answer 22

features such as shape and size of leaf hairs and colour will all help to identify it. you may find that it helps to look at other plants nearby to see if they have more leaves or flowers that may help identification. some plants look different at different times of year. in spring only a few small leaves may be visible. it may be necessary to visit a site several times to get a full estimate of biodiversity

Question 23

what happens at the site when sampling plants in a habitat

Answer 23

it may be best to use a range of techniques

Question 24

why would it be helpful to use random sampling

Answer 24

it may be helpful to modify the sampling technique if the habitat is not homogeneous (even)

Question 25

why would opportunistic sampling help with

Answer 25

as you are making decisions during the sampling process

Question 26

what would stratified sampling help with

Answer 26

as you are treating parts of the habitat differently

Question 27

describe how sampling plants work

Answer 27

large plants such as trees in a wood or in a field can be identified and counted individually. however, many plants may be too small or too numerous. in this case it may be best to calculate a value of percentage ground cover occupied by each species

Question 28

describe the process of using random quadrats

Answer 28

a quadrat is a square frame used to define the size of a sample area. a quadrat may be any size, but it often measures 50 cm or 1 m on each side. for random sampling, you can generate random numbers and then use these numbers as coordinates to place the quadrats within the habitat. a tape measure will help with placing the quadrat accurately. alternatively, counting even paces will help to locate the correct coordinates. inside the quadrat you will need to identify the plants found and then calculate the percentage cover as a measure of their abundance
* it may be possible to estimate the percentage cover of each species. some quadrats have a grid of string that divides the quadrat into a number of smaller squares (usually 100). this grid can help to make your estimates more accurate
* you can measure percentage cover using a point frame. this is a frame holding a number of long needles or pointers. you lower the frame into the quadrat and record any plant touching the needles. if the frame has 10 needles, and is used 10 times in each quadrat, you will have 100 readings. so each plant recorded as touching the needle will have 1% cover. as one needle may touch several plants, it is possible to find you have 300-400% cover in some habitats. don’t forget to record bare ground. it is easy to bias your readings by using the point frame non-randomly within the quadrat. therefore, it may be best to use the point frame at regular intervals across the quadrat

Question 29

describe the process of using a transect

Answer 29

• a transect is a line taken across the habitat
• you stretch a long string or tape measure across the habitat and take samples along the line
• in a large habitat, you might use a line transect. in this case you would record the plants touching the line at set intervals along it. you may also decide to use a quadrat at set intervals along the line. this is called an interrupted belt transect
  this will provide quantitative data at intervals across the habitat
• alternatively, you may use a continuous belt transect. in this case you place a quadrat beside the line, and move it along the line so you can study a band or belt in detail. you should study each quadrat as described above
• this will provide quantitative data in a band or belt across the habitat

Question 30

describe the process of sampling animal by observation

Answer 30

many animals are not easy to spot and are more difficult to count. larger animals can detect the presence of humans before we see them, and will hide away. small animals will also hide, and often move too quickly to count accurately. therefore, obtaining quantitative data on animals is difficult. you can note the presence of many larger animals by careful observation — looking for signs that they have left behind. for example, many animals leave footprints or easily identified droppings; owls deposit pellets of undigested food; rabbits have obvious burrows; and deer damage the bark of trees in a particular way. ecologists often rely on these signs to estimate population sizes. recent advances allow scientists to use DNA sequencing to distinguish droppings from different individuals. this provides a more accurate way to calculate the population size

Question 31

describe the process of using a stout net

Answer 31

you sweep the net through the vegetation in wide arcs. any small animals, such as insects, will be caught in the net. then you can empty the contents on to a white sheet to identify them. you need to be careful, as many of the animals may crawl or fly away as soon as you release them from the net. you can use a device called a pooter to collect the animals before they fly away. this type of sampling is suitable for low vegetation that is not too woody. you can use a similar technique to take samples in water

Question 32

describe the process of spreading a white sheet out under a branch, and knock the branch with the stick

Answer 32

the vibrations dislodge any small animals, which then drop on to the sheet. again, you will need to be quick to identify and count the animals before they crawl or fly away

Question 33

describe the process of doing a pitfall trap

Answer 33

a trap set in the soil to catch small animals. it consists of a small container buried in the soil so that its rim is just below the surface. any animals moving through the plants or leaf litter on the soil surface will fall into the container. the trap should contain a little water or scrunched paper to stop the animals crawling out again. in rainy weather, the trap should be sheltered from the rain so that it does not fill up

Question 34

describe the process of using a tullgren funnel

Answer 34

a device for collecting small animals from leaf litter. you place the leaf litter in a funnel. a light above the litter drives the animals downwards as the litter dries out and warms up. they fall through the mesh screen to be collected in a jar underneath the funnel

Question 35

describe the process of using a light trap

Answer 35

can be used to collect flying insects at night. it consists of an ultraviolet light that attracts the insects. under the light is a collecting vessel containing alcohol. moths and other insects attracted to the light eventually fall into the alcohol

Question 36

use trapping small animals

Answer 36

small animals can be trapped and population estimates calculated. the technique that you use will depend on the habitat and the type of animals you are hoping to catch. beware though, you may need a licence to trap some animals, and care should also be taken not to harm the animals in any way. small mammals can be trapped using a Longworth trap. this is a humane trap that does not harm the animal. these traps must be monitored regularly to release any trapped animals

Question 37

describe the process of mark release recapture

Answer 37

• first you need to capture a sample of animals
• mark each individual in some way that causes it no harm. the number captured will be C1
• release the marked animals and leave the traps for another period of time
• the number captured on this second occasion will be C2. the number of already marked animals captured on the second occasion is C3
• you can then calculate the total population using the formula: total population = (C1 x C2)/C3

Question 38

what is an allele/ gene variant

Answer 38

a version of a gene

Question 39

what is a locus

Answer 39

the position of that gene on a chromosome

Question 40

what is a polymorphic gene locus

Answer 40

a locus that has more than two alleles

Question 41

what is Simpson’s index of biodiversity

Answer 41

a measure of the diversity of a habitat