Biology Section A and C weird stuff

What is the function of the tap and the rersevoir in a potometer?

To reset the potometer

to replenish water in the tube

Why are phosphates important for crops?

phosphorus is important as a fertilizer

a drop in phosphate could lead to less agricultural output

less food available for increasing population

What do the arrows in Gersmehl diagram show?

nutrient flow

Why are there differences in predation between animals reared in captivity and then released into the wild and animals born and raised in the wild?

wild animals are better able to recognise predators

wild animals have parents which protect them from predators.

what is the fundamental difference between ex situ and in situ conservation?

ex situ is in an artificial environment

in situ is in a natural environment

What are the limitations to the capture-mark-recapture method?

g. assumes sample size is large enough to be significant ✔

h. assumes there is no emigration/immigration/death of snails ✔

i. assumes the marking of the snail does not affect their survival ✔

j. assumes no misidentification of species ✔

k. assumes marked snails do not lose their marks ✔

Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue:

a. weigh all pieces to ensure same amount of plant material/allow comparisons ✔

b. control surface area by having same shape/ size ✔

c. carry out experiment at same temperature e.g. using a water bath or constant

room temperature ✔

d. all samples in solution for same length of time ✔

What apparatus measures tidal volume?

spirometer

How do you calculate the total volume of air inhaled using a graph showing tidal volume and ventilation rate?

tidal volume x ventilation rate

What are the limitations of using a potometer to measure transpiration rate?

1. not all of the water taken up by the plant is used for transpiration ✔

2. some water taken up might be used for photosynthesis/ cell turgidity ✔

3. (bubble) potometer measures rate of water uptake not transpiration directly

Give an example of mutualism:

oxpecker bird and rhinoceros

the oxpecker bird eats the parasites on the rhinoceros so gains food.

the rhinoceros has fewer parasites/ pest control.

Outline the events of primary succession:

a. (bare ground) colonized by microorganisms/pioneer species ✔

b. thin soil forms from rock fragments / decomposing organisms ✔

c. soil retains water from melting permafrost/ice ✔

d. grasses/small plants/herbaceous plants/moss grow ✔

e. (larger plants) create habitat for animals ✔

f. weather/climate may limit plant size/biodiversity

OR

climax community form

Outline the similarities and differences between food chains and food webs:

Similarities:

a. in both food webs and chains organisms are arranged by trophic levels/feeding

positions ✔

b. both represent the transfer of food/energy in an ecosystem ✔

c. both include producers and consumers ✔

Differences:

d. one species could occupy different trophic levels in a food web but not in a food

chain / converse ✔

e. food chain represents one possible feeding option for each organism but food

web represents more possible feeding relationships/trophic levels ✔

Global consequences of alien invasive species:

inter-specific competition/alien species may out-compete native species ✔

b. lack of predators may allow alien species to thrive / reproduce more rapidly ✔

c. alien species may utilize areas/ resources that native species cannot ✔

d. predation by invasive species can cause loss of biodiversity ✔

e. can lead to species extinction ✔

f. alien species may introduce new diseases ✔

g. global shipping/air travel allows rapid transfer of alien species to new

ecosystems ✔

Using one example, outline biological control of an invasive alien species.

• rabbits introduced into Australia ✔

• b. controlled by release of myxoma virus / myxomatosis (from South America) ✔

what are the consequences of plastic pollution?

organisms may get tangled in plastic debris ✔

b. animals accidentally eat plastic mistaking it for food/feed plastic pieces to

offspring ✔

c. (floating) plastic debris can block sunlight preventing photosynthesis ✔

Explain biogeographic factors that increase the effectiveness of nature reserves.

large area can support greater range of habitats / longer food chains / higher

population numbers ✔

b. low edge effect with circular reserves

OR

reduced edge effect minimises area that is disturbed/competition ✔

c. intact / unbroken areas represent less disturbance on habitats ✔

d. fragmented areas linked by corridors ✔

e. (proximity of fragmented areas) allows for animal movement / genetic

exchange ✔

Explain how human activities could affect the phosphorus cycle.

phosphorus in rock (reserves) enters slowly into the biosphere by weathering ✔

b. mining of phosphorus (-bearing) rocks accelerates the natural cycle/faster than

natural erosion ✔

c. (mined) phosphorus is made into fertilizers/animal feeds/other products

OR

artificial fertilizers contain phosphate ✔

d. (phosphorous products) transported to agricultural areas (all over the world) ✔

e. with use of fertilizers phosphorus makes its way into the soil ✔

f. run-off/drainage from farms causes phosphorus to move into aquatic

ecosystems ✔

g. use of detergents adds phosphorus to water ✔

h. release of sewage adds phosphorus to water ✔

i. excess phosphorus can lead to over growth of algae and plants in water ✔

j. decomposition of dead plant material (by bacteria) use up all the oxygen in the

water/increase BOD

OR

decomposition of dead plant material causes eutrophication ✔

k. «eutrophication» can kill fish and other plants / is negative for ecosystems ✔

l. phosphorus removed (from ecosystem) by the harvesting of agricultural crops ✔