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AQA A level Biology > Plants And Biodiversity PPQs > Flashcards

Plants And Biodiversity PPQs Flashcards

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1
Q

During the light independent reaction of photosynthesis, carbon dioxide is converted into organic substances. Describe how. (6)

A

Carbon dioxide combines with Ribulose Biphosphate

Produces two GP (glycerate phosphate)

GP reduced to TP (triose phosphate)

Using reduced NADP

Using energy from ATP

Triose Phosphate converted to glucose

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2
Q

Suggest how the ecologists decided to take the samples of captured insects on a number of sites on an island (2)

A

Draw grid over map of area

Select coordinates using random generator

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3
Q

Give two assumptions made when using the mark release recapture method. (2)

A

No immigration or emigration
No losses to predation
Marking doesn’t affect survival
Birth rate and death rate equal

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4
Q

Suggests the advantage of using fluorescent powder in the mark release recapture experiment (2)

A

Fluorescent powder only glows brightly in UV light so doesn’t make insect more visible

So it doesn’t increase predation on insect

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5
Q

Equation for mark release recapture

A

Estimated population size = total number individuals in 1st sample x total number individuals in second sample / total number marked individuals recaptured

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6
Q

Suggest one way the method used by the ecologists may have caused an increase in their estimates of the size of insect population (2)

A

They removed large numbers of insects from the same AREA

Which affected the ratio of marked to unmarked

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7
Q

Calculate the number of insects on the island one day after release of the marked insects

A

WHAT IS THE ANSWER
HOW THE DUXK DID THEY GET
10 130

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8
Q

What does genetic diversity mean on a genetic level rather than population level?

A

Population - number of different alleles of genes in a population

Genetic diversity when comparing same genes between animals - number of different alleles of each gene

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9
Q

What is the difference between species richness and an index of diversity? (2)

A

Species richness only measures the number of different species, not the number of individuals

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10
Q

Suggest why there was variation in the height of traps in the trees if they were measuring species of butterfly in the leaves versus understorey. (1)

A

Trees vary in height

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11
Q

Explain what the results of the statistical test (p values) of the butterfly distribution shows.(3)

A

Greater than 5% probability of difference in distribution of Z. Itys being due to chance

For all other species the difference in distribution is unlikely to be due to chance

Because the p value is < 0.001 which is highly significant/ much less than 5%

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12
Q

Suggestion how this student would obtain data to give a more precise index of diversity of this habitat (2)

A

Take more samples and find the mean

Using random sampling with a random generator

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13
Q

Suggest one consideration the scientist had to take into account to make sure the message allowed them to identify accurately the species to which each bee belonged (1)

A

Method must allow close examination and use key (field guide) to identify species

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14
Q

Bee question

Suggest and explain two ways in which the scientist could’ve improved the messages for data collection in this investigation (2)

A

Collect bee samples at more times of the year - so more plots on the graph

Collect sample of bees from more sites - to improve accuracy

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15
Q

Do these days to show that there were any significant changes in the grass and communities on these islands?(3)

A

Because greater than 5% probability of getting that species diversity change on Islay by chance.

So change in diversity in Islay not significant

Less than 0.001 probability the increase in species richness on Islay and Colonsay is due to chance so difference is significant. Less than 0.001 probability decrease in Harris is due to chance so decrease is also significant.

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16
Q

Why was the index of diversity of insects higher in the hedge that in the barley field (3)

A

More plant species/ larger diversity of plants
More habitats/niches
More food resources

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17
Q

Explain the purpose of a control

A

Ensures results aren’t due to another factor

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18
Q

Describe how to determine the main percentage cover for beach grass on a sand dune (3)

XX

A

Random sampling with random generator

Use large sample of quadrats (20+)

Divide total % by number of quadrats

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19
Q

Succession marking points (4)

A

Pioneer species (named species)

Changes conditions

making them less hostile for (named species)

(Named species) represents climax community

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20
Q

Using evidence from figure 2 what can you conclude about the net primary productivity in the sand dunes that older than 1000 years (2)

A

NPP constant because GPP and R are constant

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21
Q

Give two differences in the variation in body length of male and female thorny lizards (2)

A

Female lizards tend to have longer body length

Female lizards have more variation in body length

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22
Q

Give one limitation of using a transect to collect this data (1)

A

Transect line may not go through representative area/may avoid certain areas

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23
Q

What information does the bar representing standard deviation give? (1)

A

Shows the spread of data

Around the mean (say what the mean is eg. Around the mean height of plants)

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24
Q

Describe what the results show about the variation of the height of plants in relation to altitude. (2)

A

Plants are shorter at higher altitudes

Higher the altitude the lower the standard deviation

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25
Q

Why does a small standard deviation occur?

A

Because an abiotic factors limited extreme values

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26
Q

What does a low standard deviation means in terms of reliability

A

Smaller range

Results more reliable

27
Q

Describe how you would collect a random sample of each population of dog whelk (3)

A 
Use random generator
Large sample (use 20+ quadrats)
Identify and COLLECT dog whelk species in the quadrat
28
Q

What did the standard deviations tell you about the two populations of dogwhelks?

A

(Population A has larger standard deviation) so greater spread around the mean

So greater variation in population A

29
Q

Suggest how the effect of wave action on the two populations of dog whelks could result in differences between

The mean L/A ratios

The standard deviations

(4)

A

B has a smaller L/A ratio than A so it has a relatively larger foot
So can grip better (because it lives in place where there is large wave action)

B has a smaller standard deviation than A because wave action limits extreme values
So greater age range on the shore (because extreme values can live so larger range of ages?)

30
Q

Niche

A

No two species of THE SAME GENUS can occupy the same niche

31
Q

Explain how the results shown in the graph relate to the distribution of these to see which on the seashore (3)

A

Spiralis retains more water

Because better adapted to drier conditions

(Spiralis is on the upper shore whereas serratus on the lower shore because same genus so) to avoid competition of light/abiotic factor

32
Q

The wolf numbers are given per unit area. Explain why.(2)

A

To allow for comparison

Because different sized areas covered

33
Q

When something is PER something think …

A

You are controlling the variable that comes after per

34
Q

Prey-predator relationships think about…

A

Energy transfers

35
Q

Suggest why pre-index gives a better idea of food available(2)

A

Takes into account if the wolf doesn’t eat all of the animal

Takes into account if (individual) prey have different proportions of edible/inedible parts

36
Q

What does the graph suggest about the factors that determine the wolf numbers in North America? Explain your answer (2)

A

As prey increases, wolf numbers increase

But large range so other factors must be involved

37
Q

Explain what a carbon dioxide uptake is a measure of net productivity (1)

A

NPP = GPP - R

Shows productivity minus respiration

38
Q

And explain how the shade plant is better adapted in the Sun plant to grow in at low light intensities (2)

A

Shade plant has lower rate of respiration

Because less carbon dioxide released at 0 light intensity

So it has greater productivity and more sugars available

39
Q

Describe how you would investigate the distribution of Marholm grass from one side of the dune to the other (3)

A

Lay a transact

Place quadrants at regular intervals along the line

Count plants in quadrats

40
Q

Use your knowledge of succession to explain how planting marram grass is useful in helping sand dune ecosystems recover from damage (2)

A

Stabilises sand

Marram improves soil making conditions less hostile

41
Q

The species that are present change during succession. Explain why (2)

A

Pioneer species change environment
So less hostile
(So new species that colonise) are better competitors )and outcompete the pioneer species)

42
Q

The pine trees have leaves all year. Explain how this results in a low species diversity of plants in the forest.(1)

A

Only plants that can PHOTOSYNTHESISE with less light remain

43
Q

What is an increase in the index of diversity suggest about the organisms (2)

A

Increases in number of different species

Increase in numbers (of individuals) of some species

44
Q

Describe the features of a succession that would bring about an increase in the index of diversity (3)

A

Initial environment hostel/few organisms adapted

Adapted organisms change environment

More habitats/more niches

Allowing other organisms to become established

45
Q

Explain how a change in species composition occurs in a succession (2)

A

Pioneer species change habitat/environment
Another species can colonise
These new species are better competitors (outcompete the old species)

46
Q

What makes a climax community the most stable? (2)

A

More species present

More complex food webs

Change in one species will have little effect on others

As alternative food sources

47
Q

Suggest how sunken stomata give an advantage to xerophytes (3)

A

Pocket of saturated air trapped near stomatal pore

Reduces water potential gradient

Reduce TRANSPIRATION

48
Q

Why is it more appropriate to use a transect rather than quadrats in this investigation (1)

A

Sereines of changes over a distance

Ensures sampling of each community

49
Q

Explain how succession resulted in the formation of the climax community (4)

A

Pioneer species colonise land

Changing the environment (give example)

Enables change in species (that can grow - basically different species able to colonise)

Conditions change father to favour (growth of) trees

50
Q

Explain why the buggy is described as a climax community (1)

A

No further succession

Stable community

51
Q

Suggest for trees are unable to survive in waterlogged soils which lack oxygen (2)

A

Roots cannot aerobically respire

So active transport of minerals stops

52
Q

The water and soil in Sphagnum bogs are usually acidic. Suggest why Sphagnum is not fully decomposed after it dies. (3)

A

Action of decomposers is inhibited
Because acid conditions inhibit/denature enzymes
Because the H+ ions affect the active site of the enzymes

53
Q

Explain why the soil nitric concentration is as shown in the graph (2)

A

Increasing dead organisms

Nitrifying bacteria convert ammonia to nitrates

54
Q

The pioneer plant had seeds that germinate better when the temperature fluctuates.

Explain the advantage of this to these pioneer plants.

XXXX

A

Bare Soil temperatures fluctuate

More bare soil in early succession

55
Q

Explain the advantage to plant the colonises after 50 years, of having a high rate of photosynthesis at low light intensities (1)

A

Plant will survive in shade if overshadowed by taller plants

56
Q

Conservation of grassland habitats involves management of succession. Use the data on the graph to explain why. (2)

A

Small annual plants

will be outcompeted by woody plants

So woody plants must be removed/grazed

57
Q

Describe how the numbers of aerobic bacteria after six months change with depth. (2)

A

Decrease then remain constant

From 200cm

58
Q

Explain the difference in the numbers of aerobic bacteria at a depth of 300 cm between one and six months. (2)

A

Oxygen decreases because soil becomes more compact it

Decrease in oxygen leads to fewer aerobic bacteria surviving

59
Q

Explain how the changes in bacterial numbers which take place at 150 cm illustrate the process of succession. (3)

XXX

A

Oxygen decreases by aerobic bacteria

So anaerobic bacteria replace (outcompete) aerobic bacteria

As aerobic bacteria are no longer able to survive in these (low oxygen) conditions

Remove competition ???

60
Q

From what depths in the soil store would you expect the soil samples to have been taken? Use info from table one to explain your answer (2)

???? Wahtttt

A

Near the surface

Table shows decrease with time at greater depths

61
Q

How do you expect dehydrogenase activity to vary with depth after six months? Use information from table 1 to explain your answer.

A

Dehydrogenase activity decreases
Because fewer aerobic bacteria as depth increases
So (less aerobic respiration because) oxygen concentration decreases

62
Q

What does Erebus tell you about the difference between the main dehydrogenase activity at six months and three years? Explain your answer in terms of probability and chance. (3)

A

Results are significant
Because error bars do not overlap
Greater than 95% probability results are NOT DUE to chance (or less that 5% probability results are DUE to chance)

63
Q

Explain how you would use table to to predict likely number of aerobic bacteria and 1 g of the soil sample. (3)

A

Plot a graph
Draw a line of best fit
Read off appropriate value (aka extrapolate)

AQA A level Biology (36 decks)

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