UNIT 5 QA

Question 1

gross primary productivity (GPP).

Answer 1

(rate at which) energy {incorporated intobiomass by { plants

Question 2

Using the information in the table, describe and explain the effects of temperature and precipitation on GPP.

Answer 2

1. GPP {depends / eq} on photosynthesis ; 2. higher the temperature the higher the GPP / eq ; 3. enzymes in (photosynthesis / chemical reaction ) {can work faster / more kinetic energy / eq } ; 4. higher the {precipitation / eq} the higher the GPP / eq ; 5. idea that water is needed for the light-dependent reaction ;

Question 3

Answer 3

1. (trophic level 2) 2300 - 1500 / 800 (kJ) ;
2. (trophic level 3) 760 - 690 / 70 (kJ) ;
3. ((70 ÷ 800) x 100) = 8.8 / 8.75 (%)

Question 4

) Using the information in the table, explain the effects of temperatures above 40 °C on the activity of RUBISCO.

Answer 4

1. idea that enzyme activity decreases ;
2. credit calculated reduction e.g. 0.6, 2.7 , 3.3 ;
3. idea that an increase in temperature results in increase in kinetic energy ;
4. causing changes in bonds (in the enzyme) / eq ;
5. idea that enzyme is denaturing (above 40 ºC) ;
6. idea that carbon fixation is reduced ;

Question 5

Name the two substrates that would have been used in this experiment.

Answer 5

{RuBP / ribulose bisphosphate} AND {carbon dioxide / CO2} ;

Question 6

Answer 6

Question 7

Using the information in the graph, describe the changes in the pollen count in the layers of peat from a depth of 12.5 m to a depth of 13.5 m.

Answer 7

1. idea that cellulose is a {polymer / polysaccharide} of β glucose ;
2. reference to 1-4 glycosidic {bonds / eq} ;
3. idea that every other glucose is inverted ;
4. idea of cellulose molecules arranged {parallel /as microfibrils} ;
5. joined by hydrogen bonds / eq ;

Question 8

b) Suggest why there is no data for some of the depths

Answer 8

1. idea of {lack of / very slow} decomposition ;
2. due to lack of {microorganisms / bacteria / fungi / named decomposer} (involved in decomposition) / eq ;
3. as a result there are fewer enzymes / eq ;
4. low pH {reduces enzyme activity / kills microorganisms /eq} ;

Question 9

Suggest why temperature changes affect sea level.

Answer 9

in double fertilisationone (haploid) male {gamete fuses with (haploid) {egg cell /

to produce a {diploid zygote one (haploid) male nucleus} fuses with { polar nuclei to produce a {triploid / 3n} endosperm (nucleus) ;

Question 10

It is claimed that the volcanic eruption of Toba caused a change in world climate. (i) Using the information in both graphs, describe the evidence that supports this claim

Answer 10

1. decrease in pollen count (in peat) after eruption / eq ;
2. decrease in sea level after eruption

Question 11

(ii) Using the information in both graphs, suggest why this claim may not be true. (3)

Answer 11

data only comes from one peat bog ;

dea of {fluctuations (in the data)

Question 12

(i) Using the information in the graph, describe the changes in abundance of spruce, ash and elm trees over the last 14 000 years. (

Answer 12

1. idea that spruce present 14 000 years ago but disappeared about 10 000 years ago ; 2. idea that ash was very high around 12 000 years ago and then remained (in low numbers) until about 2 000 years ago ;
2. idea that elm was very high around 11 000 years ago and then remained (in low numbers) until about 2 000 years ago

Question 13

(ii) Ash and elm trees grow in wet, poorly-drained soils. Grass grows in drier conditions. Using the information in the graph, describe the changes in climate at this lake over the last 14 000 years.

Answer 13

1. idea that conditions were (fairly) dry 14 000 years ago ;
2. idea that conditions got wetter ;
3. and then got gradually drier about 5000 years ago ;

Question 14

(iii) Explain how the information in the graph indicates that other types of plant were present around this lake.

Answer 14

idea that the {abundance / types} of plant is reflected by the percentage of pollen grains present ;

2. idea that pollen from all species are low ;

Question 15

Answer 15

B methane and carbon dioxide ;

Question 16

(b) Explain how dendrochronology may also be used to provide evidence for climate change.

Answer 16

1. dendrochronology is the study of tree rings / eq ;
2. idea that each year a (new) tree ring is formed ;
3. idea that the size of the ring reflects the growth of the tree (that year) ;
4. idea that {size of ring / growth} is affected by {climate / named factor} ;
5. idea that photosynthesis is affected by {climate / named factor} ;
6. idea that the number of rings can be used to work out the timescale;

Question 17

(ii) Describe how an increase in greenhouse gases could cause the loss of sea ice.

Answer 17

1. idea that {UV / shorter wavelengths of / eq} light can pass through the greenhouse gases ;
2. {heat (energy) / IR / longer wavelengths of light / eq} cannot pass back out (through greenhouse gases) / eq ;
3. increasing the temperature of the earth’s {atmosphere / surface} / eq ;
4. idea that higher temperatures melt more of the ice ;
5. idea that less ice will {refreeze / form / eq} ;

Question 18

Suggest why the loss of sea ice could result in a decrease in the number of polar bears.

Answer 18

. idea of less {habitat / hunting ground / eq} ;

2. idea that there will be less (seals) to feed on ;
3. idea that the bears are not building up sufficient food reserves ;
4. idea that the polar bears have to swim further {for food / to reach their dens};
5. idea that there are fewer dens ;

Question 19

Distinguish between the terms environment and habitat.

Answer 19

1. idea that an environment includes the biotic and abiotic factors (of a habitat) ;
2. idea that a habitat is an area where organisms {live / interact / eq} ;

Question 20

Explain why microorganisms are added to the soil in the biosphere.

Answer 20

1. for decomposition / eq (of plants / animals / excrement);
2. to improve the {quality / mineral content / depth / structure / eq } of the soil ;
3. idea of releasing carbon dioxide (back into atmosphere) ;
4. idea that carbon dioxide is used in photosynthesis

; 5. to recycle the {nitrogen / elements} ;

6. (microbes) provide food for other (soil) organisms

Question 21

Explain the meaning of the term species richness.

Answer 21

/ abundance} of (different) species ; 2. in an {area

Question 22

Suggest why a decrease in species richness would decrease the use of light energy in the biosphere.

Answer 22

fewer {types of plant / (plant) species} ;

absorbing different {amounts / wavelengths} of light ;

3. different species have different structures (related to absorbing light) eq ;

Question 23

) Explain why the uptake of carbon dioxide and plant productivity both decrease as species richness decreased.

Answer 23

1. idea that if there is less light (energy) being used there will be less photosynthesis ;
2. idea that if light-dependent reaction is reduced there will be less {ATP / reduced NADP / eq} ;
3. idea that {carbon fixation / Calvin cycle / light-independent reaction } will be less ;
4. idea that as a result less GALP will be made ;
5. so less {hexose / glucose} made ;
6. so less {biomass

Question 24

Describe the structure of a cellulose molecule.

Answer 24

cellulose is {polymer / polysaccharide} of β glucose ;

2. reference to 1-4 glycosidic {bonds / eq} ;
3. idea that every other glucose is {inverted / rotated by 180°C} ;

Question 25

habitat species number finding

Answer 25

1. idea that {each / all} of the 5 habitats have to be sampled ;
2. idea that an area is marked off in each habitat ;
3. idea of placing the quadrat at random ;
4. credit method of generating random sites ;
5. idea of counting which { quadrat / quadrat sections} contain pellets (and which don’t) ; 6. idea that several quadrats used in each area to calculate a mean ;
6. credit description of how percentage is calculated ;

Question 26

State two conclusions that can be made from the results of this investigation.

Answer 26

t hares eat fivedifferent plant species ; most feeding is done on young heather / old heather and mat grass is fed on the least}

Question 27

(iii) Suggest the limitations of using the percentage of quadrats containing pellets as an indication of the food preferences of mountain hares. (3)

Answer 27

1. idea that there may be other plants that they eat (that weren’t sampled) ;
2. idea that the abundance of food affected the number of pellets ;
3. idea that pellets may have been from other species ;
4. idea that quantity of pellets was not measured (so may not represent the number of hares in an area) ;
5. idea that hares move from feeding site before producing pellets ;
6. idea of seasonal variation ;
7. idea that the pellets get moved {away from/ into / eq} where they were sampled ;
8. idea that pellets get {decomposed / eaten / eq} ;

Question 28

Suggest how a subspecies of giant panda evolved in the Qinling Mountains.

Answer 28

1. idea that these pandas are NOT reproductively isolated ;
2. idea that the two populations are geographically isolated ;
3. idea that {conditions / environments} (in the two areas) were different ;

. reference to mutation in the {DNA / gene} causing a change in {phenotype / trait / eq } ;

Question 29

) Suggest why the giant panda has become endangered.

Answer 29

1. habitat destroyed / eq ;
2. idea of (habitat destruction has resulted in) {lack of food / places to breed / eq} ;
3. idea that populations of panda have become {fragmented / isolated / separated / eq}; 4. idea that genetic diversity has become low ;

Question 30

Using the information in the graph, describe the overall changes in the population sizes of elk and grey wolves between 1995 and 2010. Give explanations for these overall changes.

Answer 30

1. elk decrease and wolves increase / eq ;
2. idea that elk decrease as they are { being killed / eaten / predated } by the wolves at a faster rate than they are reproducing ;
3. idea that the number of wolves increase as they are reproducing faster than they are dying ;

Question 32

Suggest two reasons for the decrease in the population of grey wolves between 2011 and 2012

Answer 32

. birth rate less than death rate / eq ;

2. idea that the elk population is too low provide enough food for the wolves ;
3. disease ;
4. idea that the wolves are being { shot / hunted } ;
5. movement of wolves out of the Park ;

Question 33

Explain why, since 1995, the areas of forest in Yellowstone National Park have increased.

Answer 33

1. idea that there is less grazing (as there are fewer elk) ;
2. idea that (secondary) succession can now take place ;
3. resulting in a climax community

Question 34

Suggest how the populations of other animals in Yellowstone National Park might be affected by the reintroduction of the grey wolves. Give explanations for your answer.

Answer 34

. idea that other animals (prey of wolves) might decrease in number ;

2. as they are also being {killed / eaten / predated} by the wolves / eq ;
3. idea that other {carnivores / predators of elk / eq } might decrease in number ;
4. as there are {fewer elk to eat / more competition for the elk} ;

Question 35

Answer 35

succession

Question 36

Answer 36

forensic entomology

Question 37

Answer 37

to produce reliable data

Question 38

state other than food source two variables that can be controlled

Answer 38

1. { age / time of laying / batch } of eggs ;
2. { species / type } (of butterfly / caterpillar / egg) ;

Question 40

Describe how the growth rates of the caterpillars could be determined in this investigation.

Answer 40

1. measure { length / mass / eq } of caterpillar ;
2. idea of measuring several caterpillars to calculate the mean (change in growth measurement) ;
3. idea of taking measurements over a period of time ;
4. growth rate = change in { length / mass } divided by time / eq ;

Question 41

(iv) Suggest why the food source of the caterpillars could affect their growth rate.

Answer 41

1. idea that different types of {food / cabbages} could have different composition of nutrients / eq } ;
2. idea different {carbohydrate / lipid / eq} content will provide different yields of energy 3. idea that {respiration / metabolism / production of ATP} is affected (by energy content / carbohydrate / lipid) ;

Question 42

Answer 42

1. (energy used ) = 100 + 67 / 167 (J)
2. (energy available) = 200 - 167 / 33 (J)
3. = 16.5 (%)