exam questions

Question 1

explain the advantage of species occupying different niches

Answer 1

less competition for food/ resource

Question 2

explain how the presence of fish in a lake could cause an increase in the number of water beetle species

Answer 2

fish feed on predator consumer on water beetle

Question 3

explain how microorganisms contributed to the increase in temperature during processing of organic waste

Answer 3

respiration releases heat

Question 4

explain the advantage of showing the data using standard deviations rather than ranges

Answer 4

SD is spread of data around mean, SD reduces anomalies

Question 5

suggest two advantages of rating the containers during the process

Answer 5

distributes heat/ prevents ‘hot’ spots, distributes microorganisms, more enzyme-substrate complex increases rate of decomposition

Question 6

use figures to evidence a form of succession has occurred

Answer 6

microorganisms change the abiotic conditions, less hostile conditions, decline in cocci and increase in rods, gram positive outcompete

Question 7

the scientists used percentage cover rather than frequency to record the abundance of algae present

Answer 7

too many to count, individual organisms not identifiable

Question 8

why the diversity of consumers will be greater at site B

Answer 8

greater variety of food, more variety of habits and niches

Question 9

suggest appropriate units for gross productivity

Answer 9

unit of energy/ mass, per area, per year

Question 10

explain the decrease in gross productivity as woodland matures

Answer 10

less light more shade
reduced photosynthesis

Question 11

use your knowledge of succession to explain the increase in biomass during the first 20 years

Answer 11

PINONEER SPECIES
change in abiotic conditions
increase in the number of diverse species

Question 12

use the information in the graph and your own knowledge of net productivity to explain why biomass shows little increase after 100 years

Answer 12

net productivity=gross productivity minus respiratory loss decreases in gross productivity

Question 13

suggest one reason for conserving woodlands

Answer 13

protecting habits, protecting endangered species, reduces global warming, source of medicines

Question 14

what is meant by uniformly distributed?

Answer 14

same number in each region equally spread

Question 15

how do the assumptions made in proportional sampling differ from those made in mark release recapture

Answer 15

mark release recapture does not assume that organisms are uniformly distributed and the size of total area is not required

Question 16

give one assumption about the animals caught that is made by both mark release recapture and proportional sampling

Answer 16

animals are from/ all part of the same population

Question 17

explain what is meant by succession

Answer 17

change in community over time, ether due to environmental change due to species present

Question 18

what is meant by a climax community

Answer 18

final community

Question 19

explain why the number of other plant species decreases between 4 and 12 years after burning

Answer 19

interspecific competition for light, nutrients and water

Question 20

the communities a to d are composed of different species. Explain how the change in species composition occurs in a succession

Answer 20

species present change the habitat, other species able to colonise new species are better competitors

Question 21

Explain what makes this the most stable community

Answer 21

more species present

Question 22

explain why it would be more appropriate to use a transect rather than random quadrants when investigating this succession

Answer 22

series of changes over a distance

Question 23

explain how this movement is important in maintaining genetic variability in lemming populations which have large fluctuations in size

Answer 23

smaller populations have fewer different alleles. migrants bring new alleles

Question 24

Explain how two species of lemming evolved from the original species

Answer 24

geographical isolation of population
variation present in population
different environmental conditions
change in genetic constitution of populations

Question 25

Give one limitation of using a line transect to collect these data

Answer 25

transect line may not go through representative areas

Question 26

suggest how plants should be chosen at each sampling site to avoid bias and to be representative

Answer 26

random number generator
large sample

Question 27

what information does the bar representing standard deviation give about the plants in a sample?

Answer 27

spread of values around the mean height of the plant