Question
The Chinese pangolin (Manis pentadactyla) is a critically endangered species that has declined in numbers by 80% since 2000. It inhabits both forest and grassland, where it uses long, powerful claws to open ant and termite nests and ingests the insects using a long, sticky tongue.
(a) (i) State with a reason whether pangolins are autotrophic or heterotrophic.
(ii) Explain what information is needed to find the trophic level of pangolins.
(b) Outline evidence for evolution from the limbs of mammals such as pangolins.
(c) The cladogram shows relationships between all living species of pangolin. The numbers on the cladogram indicate time in millions of years since divergence from a common ancestor.
(i) State how many genera of pangolin are recognized.
(ii) Outline how times since divergence are estimated when cladograms are constructed.
Answer/Explanation
Answer:
(a)
(i) heterotrophic because it feeds on/eats food/other organisms /eats ants/termites/
doesn’t photosynthesise/does not produce its own food;
(ii) a. what (prey) it eats/feeds on/ stomach content;
b. the trophic level of what (prey) it eats/feeds on/the trophic level of
ants/termites;
c. trophic level is the position an organism occupies in the food chain/web;
(b)
a. pentadactyl;
b. homologous with limbs of other vertebrates;
c. due to common ancestry;
d. adaptation;
(c)
(i) three;
(ii) by counting the number of base/amino acid sequence differences;
Question
Discuss the health consequences and environmental consequences of the use of DDT.
▶️Answer/Explanation
Ans:
a. DDT is a pesticide/insecticide
b. reduction in disease vectors
OR
reduction in mosquitos carrying malaria
c. leading to a reduction in disease/malaria rates
Accept other diseases such as typhus carried by lice.
d. biomagnification in food chains
e. negative impact on health of top predators / example of top predator
f. thin eggs shells
OR
reduced reproductive success in birds of prey
Question
In 1911, twenty-five reindeer (Rangifer tarandus) were introduced onto Saint Paul Island in Alaska and the population was recorded for 40 years
a.i. State the type of growth of this population up to 1940 .
a.ii.Suggest one possible cause for the decrease of the number of animals after 1940.[1]
b. Explain biogeographic factors that increase the effectiveness of nature reserves.
▶️Answer/Explanation
Ans:
a.i. exponential «population growth»
a.iilack of food / disease / hunting / increase of predators
b. a. 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
Question
The interaction web shows top-down and bottom-up effects in a seagrass study system.
a. Identify which of the types of interaction shown in the key occur between crabs and seagrass.[2]
b. Describe how the sea otter indirectly affects seagrass.[2]
c. Explain how nutrients can have a positive or negative bottom-up effect on seagrass.[3]
▶️Answer/Explanation
Ans:
a. a. indirect
b. negative «effect»
c. top-down
b. a. sea otters have a positive «indirect» effect as sea otters feed on crabs that feed on isopods that feed on algae
b. less crabs means more isopods so less algae
c. less algae means more seagrass
\(O R\)
less competition between algae and seagrass
c. a. the positive «bottom up» effect is due to availability of nutrients
b. «nutrients» increase abundance/plant growth rates
c. the negative «bottom-up» effect as excess of nutrients causes a bloom in algae growth/eutrophication/competition
d. limited nutrients have negative effect on seagrass «growth»
e. “excess» algae cause seagrass to die/decompose/replenish nutrients
Do not accept answers referring to top down effects.
Question
The table shows the distribution of four coral reef species along a transect as a function of depth.
a. From the data, identify the depth along the transect where the greatest species richness is observed.[1]
b. Outline the relationship between Zooxanthellae and reef-building coral reef species.[2]
c. Suggest one way in which depth may act as a limiting factor for coral.[1]
▶️Answer/Explanation
Ans:
a. \(6.5 \mathrm{~m} \checkmark\)
Unit required
b. a. a symbiotic/mutualistic relationship \(\checkmark\)
b. Zooxanthellae obtain shelter/habitat/exposure to light \(\checkmark\)
c. coral obtains energy/food through photosynthesis of the Zooxanthellae \(\checkmark\)
c. low light levels/lower temperatures cannot support growth/metabolism \(\checkmark\)
Requires the explanation for the mark
Question
Outline one example of an active management strategy employed in the context of in situ conservation.
▶️Answer/Explanation
Ans:
a. name of strategy \(\checkmark\)
b. detail of the strategy \(\checkmark\)
example:
a. anti-poaching restrictions within a nature reserve
b. patrolling of the reserve to enforce restrictions
Accept only the first stated strategy if several are listed.
The outline must match the strategy.
Question
Torre Guaceto is a marine protected area which covers over 22 km2 of the Adriatic Sea in south-eastern Italy. The diagram shows a food chain within this area.
.
The data refers to the numbers of these three species inside the marine protected area, where fishing is limited, and outside the marine protected area, where fishing is allowed.
▶️Answer/Explanation
Ans:
a. State the trophic level of the sea urchin.[1]
b. Compare and contrast the community structure within and outside the marine protected area.[3]
c. With respect to this food chain, outline what is meant by a keystone species.[3]
Ans:
a. herbivore/primary consumer \(\checkmark\)
Do not accept second trophic level
b. compare:
a. all three species present in both
OR
richness is the same \(\checkmark\)
b. sea urchin numbers highest in both
OR
sea bream density less than sea urchin density in both \(\checkmark\) Allow converse answer
c. all species numbers are affected by fishing \(\checkmark\)
contrast:
d. sea urchin population is greater outside the marine protected area \(\sqrt{ }\)
e. reduction in sea bream/sea grass percent cover outside the marine protected area \(\checkmark\)
f. less species evenness outside the marine protected area \(\checkmark\)
c. a. keystone species have a disproportionate effect on the biological community \(\checkmark\)
b. removal of the sea bream «due to fishing» \(\checkmark\)
c. results in more sea urchins \(\checkmark\)
d. which significantly reduce the producers/seagrass \(\checkmark\)
Do not accept first trophic level for mpd
Question
The table shows the distribution of four coral reef species along a transect as a function of depth.
a. From the data, identify the depth along the transect where the greatest species richness is observed.[1]
b. Outline the relationship between Zooxanthellae and reef-building coral reef species.[2]
c. Suggest one way in which depth may act as a limiting factor for coral.[1]
▶️Answer/Explanation
Ans:
a. \(6.5 \mathrm{~m} \checkmark\)
Unit required
b. a. a symbiotic/mutualistic relationship \(\checkmark\)
b. Zooxanthellae obtain shelter/habitat/exposure to light \(\checkmark\)
c. coral obtains energy/food through photosynthesis of the Zooxanthellae \(\checkmark\)
c. low light levels/lower temperatures cannot support growth/metabolism \(\checkmark\) Requires the explanation for the mark
Question
Outline three ways in which a named environmental disturbance can impact an ecosystem.
▶️Answer/Explanation
Ans:
a. numbers of species \(\checkmark\)
b. types of species \(\checkmark\)
c. impacts on food chains/webs \(\checkmark\)
d. food production/availability \(\checkmark\)
e. habitat/ecosystem alteration \(\checkmark\)
f. biochemical processes «photosynthesis/respiration/decomposition» \(\checkmark\)
g. biogeochemical processes «erosion/nutrient cycles» \(\checkmark\)
h. first example of abiotic environmental factor \(\checkmark\)
i. second example of abiotic environmental factor \(\checkmark\)
Award [ 2 max] if the environmental disturbance is not named.
The environmental disturbance may be a factor such as fire, farming, construction, extreme weather, introduction of an alien species/other human intervention.
Explanations are not required.
Question
Explain what is meant by competitive exclusion, with respect to a named example of an invasive species.
▶️Answer/Explanation
Ans:
a. when two species with similar niches occupy the same habitat \(\checkmark\)
b. the competition increases
OR
reduction in resources \(\checkmark\)
c. the population of one species will die/be excluded \(\checkmark\)
d. an invasive species «often» lacks predators \(\checkmark\)
e. the endemic species is usually the one that cannot compete \(\checkmark\)
f. eg: grey squirrel/Japanese knot weed/cane toad \(\checkmark\)
[ 3 max] if the invasive species is not named.
Do not allow humans.
Question
The graph shows how the world rock phosphate production and world population changed between 1900 and 2005.
a. Describe the relationship between rock phosphate production and world population.[2]
b. Phosphate can be lost from agricultural land in several different ways. State one of these.[1]
c. Describe how the changes in world rock phosphate production after 1985 may have affected world food supplies.[2]
▶️Answer/Explanation
Ans:
a. a. as population increases so does phosphate production/positive correlation \(\checkmark\)
b. since 1985 phosphate production has not risen while population has continued to increase \(\checkmark\)
b. leaching/soil erosion, run-off/removed by the harvesting of agricultural crops \(\checkmark\)
c. a. phosphorus is important as a fertilizer \(\checkmark\)
b. a drop in phosphate could lead to less agricultural output \(\sqrt{ }\)
c. «this could mean» less food available for increasing population \(\checkmark\)
Question
In Wales, UK, the grey squirrel (Sciurus carolinensis) is an alien species and the red squirrel (Sciurus vulgaris) is endemic. The maps show the distribution of red and grey squirrels in 1945 and 2010.
a.i. Outline the changes of distribution of the grey squirrel from 1945 to 2010 .[2]
a.ii.Suggest two possible reasons for the change in distribution.\([2]\)
1.
2.
b. The niches of the red and grey squirrels overlap. Explain the concept of competitive exclusion with respect to the changes in squirrel distribution shown in the maps.[3]
▶️Answer/Explanation
Ans:
a.i.a. overall the grey squirrel distribution has increased «and the red squirrel decreased» \(\checkmark\)
b. in 2010 the grey squirrel was found in areas where it was previously not found \(\checkmark\)
c. grey squirrel has dominated/red squirrel virtually eliminated \(\checkmark\)
OWTTE
a.ii.a. no predators \(\checkmark\)
b. ample food supply/habitats \(\checkmark\)
c. few competitors \(\checkmark\)
d. resistant to disease \(\checkmark\)
e. high reproductive rate \(\checkmark\)
f. no physical barrier to prevent spread of grey squirrels on mainland \(\checkmark\)
b. a. competitive exclusion states two species that occupy a similar niche in the same location cannot coexist \(\checkmark\)
b. one of the two competitors will always have an advantage over the other \(\checkmark\)
c. leads to extinction/displacement/evolution of the second competitor \(\checkmark\)
d. grey squirrels have replaced/occupied niches formerly occupied by red squirrels
OR
habitats favour the grey squirrel in competition for the niche \(\checkmark\)
e. the niche of one competitor/both competitors becomes narrower \(\checkmark\)
Question
The Vancouver Island marmot (Marmota vancouverensis) is a small rodent that is only found on Vancouver Island and is listed as critically endangered. Captive breeding and release programs for this species began in 1997 to attempt to restore population numbers on the island. The graph shows the causes of death of the marmots born in the wild and of those marmots released after being born and reared in captivity.
a.i. Distinguish between levels of predation in marmots born in the wild and those born in captivity.
a.ii.Suggest reasons for the differences in predation.[2]
b. Distinguish between ex situ and in situ conservation of endangered species.[1]
▶️Answer/Explanation
Ans:
a.i. predation was greater in those born in captivity \(\checkmark\)
a.ii.a. the marmots have experience with/recognize predators \(\checkmark\)
b. parents shield them from predators
OR
parents teach them about predators \(\checkmark\)
c. those born in the wild are favoured in natural selection \(\checkmark\)
b. ex situ is in artificial environment, in situ is in natural environment \(\checkmark\)
Accept examples as long as it is clear one is natural and one artificial
Question
The illustration shows a Gersmehl diagram of the taiga biome.
a. Outline what is represented by the arrows in the Gersmehl diagram.[1]
b. Explain how the amount of litter in a tropical rainforest would differ from the taiga’s and how this would be represented in a Gersmehl diagram.[3]
▶️Answer/Explanation
Ans:
a. nutrient flow \(\sqrt{ }\)
b. a. the circle would be «relatively» smaller
OR
litter layer is less \(\checkmark\)
b. warmer weather favours the decomposition of litter/results in thicker arrow between litter and soil \(\checkmark\)
c. more rainfall favours the decomposition of litter/results in thicker arrow between litter and soil \(\checkmark\)
d. greater number of saprophytes/decomposers in rain forest \(\checkmark\)
e. nutrients would be stored in biomass/biomass circle would be larger \(\checkmark\)
Question
The diagram shows the copper concentration \(\left(\mu \mathrm{g} \mathrm{g}^{-1}\right)\) in the seaweed Porphyra umbilicalis collected along the shoreline in Arklow, Ireland.
Explain how the copper found in these seaweeds could affect the birds living in Arklow town.
▶️Answer/Explanation
Ans:
a. seaweed close to the estuary/town has a higher concentration of copper \(\checkmark\)
b. birds feed on fish/seaweed that have accumulated copper \(\checkmark\)
c. copper accumulates in tissues of organisms/bioaccumulation \(\checkmark\)
d. copper accumulates at a rate faster than that at which it is lost by excretion \(\checkmark\)
e. copper concentration increases as trophic level increases \(\checkmark\)
f. biomagnification occurs \(\checkmark\)
Question
A survey was made of the intertidal zone at Butter Lump Bay, Great Cumbrae, Scotland. The three species of barnacle found were Elminius modestus (EM), Chthamalus montagui (CM) and Semibalanus balanoides (SB). The kite diagram shows the vertical distribution of these three species from the low tide mark at 0 m to 2.25 m above low tide.
a. Outline how the data could have been obtained.[2]
b. Describe the distribution of C. montagui and S. balanoides barnacles in Butter Lump Bay.[2]
c. E. modestus is an invasive barnacle while the others are native species. Analyse the data to show how it supports this statement.[2]
d. State one abiotic factor that could have determined the distribution of barnacles.[1]
e. Barnacles are sensitive to pollution. Outline how it might be possible to use these organisms as indicator species.[2]
▶️Answer/Explanation
Ans:
a. a. transect across area to be studied \(\checkmark\)
b. count/record barnacles “per species» in quadrats at regular intervals \(\checkmark\)
b. a. both species present throughout the range \(\checkmark\)
b. C. montagui has small number of individuals «throughout»
OR
C.montagui occupies «mostly» upper shore/intertidal zone
C. S. balanoides «mostly» occupies low tide area \(\checkmark\)
OR
S.balanoides has large number of individuals «throughout» \(\checkmark\)
OWTTE referring to maximum numbers at specific heights.
c. a. native species/C. montagui and S. balanoides have niches that don’t overlap much / are distinct
OR
range of \(E\). modestus overlaps with both native species \(\checkmark\)
b. niches of native species «which don’t overlap much» shows competition between native species
OR
E.modestus invades habitats of C. montaguilS. balanoides resulting in competition with «both» native species \(\checkmark\)
c. EM has a wide niche/higher tolerance/covers entire «intertidal» range making it easier to invade the habitat \(\checkmark\)
d. a. exposure/tides/waves \(\checkmark\)
b. temperature \(\checkmark\)
c. surfaces «of attachment» \(\checkmark\)
d. resource availability/nutrients \(\checkmark\)
e. \(\mathrm{pH} \checkmark\)
f. light \(\sqrt{ }\)
g. salinity \(\checkmark\)
Do not accept biotic factors eg: “competition or predation”
e. a. indicator species need particular environmental conditions
OR
indicator species tolerate only certain environmental conditions \(\checkmark\)
b. increase/decrease in population size «over time» shows effect of environmental conditions \(\checkmark\)
c. used to calculate biotic index/index of cleanliness \(\checkmark\)
d. index of \(10 /\) high index number indicates totally unpolluted
OR
index of 2 or \(1 /\) low index number indicates severe pollution \(\checkmark\)
Question
The photograph shows small, isolated Eucalyptus forest fragments in New South Wales, Australia, as part of a long-term experiment on habitat fragmentation.
a. State two abiotic factors that are increased in the fragmented forest with respect to the centre of the core forest.[2]
1.
2.
b. Explain the likely effects on biodiversity if a forest becomes fragmented.[2]
▶️Answer/Explanation
Ans:
a. a. light «penetration» \(\checkmark\)
b. temperature \(\checkmark\)
c. wind \(\checkmark\)
d. fires \(\checkmark\)
Allow any two but mark only the first two if more are given in a list.
b. a. reduction in diversity in fragmented forest as a whole \(\checkmark\)
b. greater diversity towards the edge \(\checkmark\)
c. new species appear/immigration of new/alien/invasive species \(\checkmark\)
d. local species decrease/emigrate
OR
unable to move between fragments \(\checkmark\)
e. faster species turnover than core forest \(\checkmark\)
Question
Explain how food conversion ratios in livestock affect the amount of food for human consumption.
▶️Answer/Explanation
Ans:
a. «food conversion ratio is» mass of animal food required to produce a certain product «in livestock» \(\checkmark\)
b. product may be consumable meat / milk / eggs \(\checkmark\)
C. some dietary choices are more sustainable than others
OR
maximum production of human food for little animal feed is desired \(\checkmark\)
d. some animals are more efficient at converting feed into useful product than others. \(\checkmark\)
e. amount of biomass lost affects this ratio \(\checkmark\)
f. some animal feeds will be better for producing useable products than others \(\checkmark\)
Accept examples for any of these marking points.
Question
The climograph shows data collected at Mangalore, India. The natural vegetation of the surrounding area is forest and the climate is tropical.
a.i. Using the climograph, calculate the range of temperature.[1]
a.ii.Using the climograph, identify the relationship between maximum temperature and rainfall.
a.iiiUsing the climograph, outline the pattern of rainfall.
b. Natural forests in the area around Mangalore contain hardwood trees such as teak, Tectona grandis, which are deciduous, shedding their leaves
once a year. Suggest, with a reason, when this might happen.[2]
c. The image shows a Gersmehl diagram of tropical rainforest.[3]
Explain what this diagram indicates about nutrients in this type of ecosystem.
▶️Answer/Explanation
Ans:
a.i. \(« 30-26=» 4 \ll{ }^{\circ} \mathrm{C} » \checkmark\)
Accept answers between 3 to \(5:{ }^{\circ} \mathrm{C} »\).
a.iimaximum temperature occurs just when rainfall begins/at the onset of the rainy season/monsoon
OR
negative relationship «as maximum temperature drops, rainfall increases» \(\checkmark\)
OWTTE
a.iiirainfall concentrated between April to December/peaks in June-August «followed by months with little/no rainfall» \(\checkmark\)
OWTTE
b. a. dry season/Jan/Feb \(\checkmark\)
b. «drop leaves» to prevent water loss/transpiration «since no rainfall for almost four months» \(\checkmark\)
c. a. statement correctly explaining the quantity of nutrients in identified circle/circles \(\checkmark\)
eg most nutrients are stored in biomass/equal quantities of nutrients stored in soil and litter.
b. statement correctly explaining high nutrient flow/transfer of any thick/large arrow \(\checkmark\) eg high transfer rate of nutrients from soil to biomass.
c. statement correctly explaining low nutrient flow/transfer of any thin arrow \(\checkmark\) eg low transfer rate of nutrients from litter to the outside/another ecosystem.
d. any statement correctly comparing nutrient storage/flow rates \(\checkmark\) eg higher nutrient transfer between soil and biomass than between biomass and litter OWTTE.
e. a Gersmehl diagram models «interrelationships between» nutrient stores and flows in an ecosystem \(\checkmark\)
Question
Outline a named example of the captive breeding and reintroduction of an endangered animal species.
▶️Answer/Explanation
Ans:
a. name of organism \(\sqrt{ }\)
b. why endangered \(\sqrt{ }\)
c. where bred \(\sqrt{ }\)
d. how programme carried out \(\checkmark\)
e. success rate \(\checkmark\)
To award [3] name of organism, either scientific or correct common name, must be given.
eg Giant panda
eg loss of habitat/hunted for fur
eg in zoos/ex situ/in situ/China
eg bred/raised in captivity
eg relative success re: introducing to wild/some reproduction in zoos
Question
The blackberry (Rubus fruticosus) is a plant that grows in deciduous woodlands in many parts of the world. A 30 m transect was laid out in a woodland to investigate the relationship between light intensity and blackberry growth. The percentage cover of blackberries and the light intensity were measured at 26 positions along this transect.
a. Outline how these results indicate that blackberry distribution is limited by light intensity.[2]
b. Distinguish between the transfer of matter and energy in closed ecosystems.[1]
c. A pyramid of energy represents the amount of energy taken in by each trophic level per unit time and per unit area. Discuss the advantages and
disadvantages of the use of pyramids of energy as models of energy flow in an ecosystem.[4]
▶️Answer/Explanation
Ans:
a. a. as light level changes so does the percentage cover “of blackberry” \(\checkmark\)
b. distribution is higher at intermediate/moderate light intensities \(\checkmark\) Accept appropriate numerical values
c. little growth at low light intensities
OR
little growth at high light intensities \(\checkmark\) Accept appropriate numerical values
d. distribution is bell shaped \(\checkmark\)
b. only energy can be lost/gained/exchanged/transferred “with the exterior»
\(O R\)
only matter is constant/recycled \(\sqrt{ }\)
c. Advantages:
a. can show the energy loss/transfer between trophic levels \(\checkmark\)
b. permits a «quantitative) comparison between ecosystems \(\checkmark\)
c. shows change over time \(\sqrt{ }\)
Disadvantages:
d. are difficult to produce accurately \(\checkmark\)
e. require destructive methods to obtain the data \(\checkmark\)
f. do not show all the interactions/food chains/feeding relationships «between different members of the community» \(\checkmark\)
g. cannot represent organisms that feed at different trophic levels \(\checkmark\)
Award [3 max] if only one side of the argument is given.
Question
Blue fin tuna (Thunnus orientalis) are top carnivores in the marine ecosystem. Some radioisotopes of elements are produced by nuclear reactors. Following a nuclear accident at Fukushima in Japan in March 2011, the levels of certain radioisotopes were measured in the bodies of blue fin tuna caught off California in August 2011, the other side of the Pacific Ocean from Japan. The becquerel (Bq) is a measure of radioactivity.
a. Explain how the levels of the Caesium (Cs) radioisotopes could have accumulated in the tissues of these fish.[3]
b. Describe the use of indicator species in monitoring environmental change.[3]
▶️Answer/Explanation
Ans:
a. a. radioisotopes entered the sea/found in the water «in Japan» \(\checkmark\)
b. taken up by producers/phytoplankton/enter gills of fish \(\checkmark\)
c. producers eaten by consumers/fish \(\checkmark\)
d. «radioisotopes» are passed on up the food chain
\(O R\)
contaminated fish are eaten by tuna /other fish \(\checkmark\)
e. radioisotopes are not easily excreted \(\checkmark\)
f. at each level there is bioaccumulation/biomagnification \(\checkmark\)
b. a. presence/absence indicate environmental conditions \(\checkmark\)
b. changes in the environment affect these species \(\checkmark\) Number or type of species
c. «relative» numbers of individuals/indicator species can be used to calculate a biotic index \(\checkmark\)
d. changes monitored over time \(\checkmark\) Example of time frame
e. changes can lead to measures to protect the environment \(\checkmark\)
f. example of an indicator species \(A N D\) what it indicates «e.g. Tubifex for sediment pollution» \(\checkmark\) Award marks for a species, not a group
Award mp for species not group.
Question
a. State the impact of environmental disturbance on biodiversity.[1]
b.i. State an example of an alien species.[1]
b.ii.Outline the impact of alien species on endemic species in ecosystems.[2]
▶️Answer/Explanation
Ans:
a. changes/increases/decreases richness/biodiversity/evenness/the numbers of species \(\checkmark\)
b.i. name of species and where it is invasive e.g. introduction of cane toads in Australia \(\checkmark\)
Accept common name of species but not general groups e.g. toads.
b.ii.a. (interspecific) competition with endemic/native species \(\checkmark\) May be outlined using a specific example
b. may cause the extinction/reduction of endemic/native species
OR
reduces biodiversity
OR
becomes invasive \(\checkmark\)
c. does not have endemic / natural predators so may increase in numbers \(\checkmark\)
d. upsets the balance between predators and prey
OR
disrupts food chains \(\checkmark\)
Question
a. Explain why some biologists think protecting keystone species would help preserve biological diversity in an ecosystem.[1]
b. Compare and contrast fundamental and realized niche of a species.[2]
▶️Answer/Explanation
Ans:
a. a large effect on the ecosystem/community structure/environment«relative to abundance»
OR
influence the balance of other populations in the ecosystem
\(O R\)
other species in the habitat would also disappear
\(O R\)
many other species dependent on them for survival \(\sqrt{ }\)
b. a. both describe the habitat/role/relationship occupied by a species \(\checkmark\)
b. the fundamental niche is the potential role of a species in its ecosystem and realized niche is the actual role
\(O R\)
the fundamental niche depends on the adaptations of a species whereas the realized niche is limited by competition/predation
\(O R\)
realized niche is susually) smaller than fundamental niche \(\checkmark\)
Question
a. Feed conversion ratio (FCR) is the mass of animal feed in kilograms required for farmed animals to produce one kilogram of edible mass. For
example, the FCR for salmon is 1.2 and for chicken is 2.2 . Deduce the implication of these ratios for sustainability.[2]
b. Models are used as representations of the real world. Evaluate the use of food webs to represent ecological communities.[2]
c. Explain why some biologists think protecting keystone species would help preserve biological diversity in an ecosystem.[1]
d. Outline what is meant by the niche concept.[2]
▶️Answer/Explanation
Ans:
a. a. higher FCR implies less sustainability \(\checkmark\) Do not accept efficiency instead of sustainability.
b. salmon based diet is more sustainable/chicken is less \(\checkmark\)
c. salmon diet would have lower energy losses/chicken diet higher energy losses \(\checkmark\)
d. salmon diet will produce less waste/chicken more \(\checkmark\)
b. Advantages:
a. food webs summarize all possible food chains «in the community» \(\checkmark\) OWTTE
b. realistic representation \(\checkmark\)
Limitations:
c. some communities/ecosystems are too complex to represent \(\sqrt{ }\)
d. only shows qualitative information/not quantitative data
OR
saprotrophs/abiotic factors not taken into account \(\checkmark\)
Needs one advantage and one limitation to obtain [2].
Do not accept mentions of trophic levels.
c. a. «research demonstrates that keystone species» have a «disproportionately» large effect on their environment relative to abundance
OR
«keystone species» maintain a balance in the «stable» numbers of each species within a community
OR
«keystone species» have a large impact in preserving and stabilizing the biodiversity by preventing overpopulation/monopoly/out competition \(\checkmark\)
b. a keystone species’ disappearance would start a domino effect/other species in the habitat would also disappear
OR
their loss leads to an imbalance in the food web
OR
their loss leads to a decrease in biodiversity \(\checkmark\)
Do not accept protecting keystone species prevents disappearance of other species since it repeats the question.
d. a. the role of an organism in its environment
OR
functional position of an organism in its environment \(\checkmark\)
b. includes «spatial» habitat AND feeding activities AND interactions with other species in the community \(\checkmark\) All required.
c. no two species can occupy the same niche \(\checkmark\)
d. a niche can be fundamental or realized \(\checkmark\) OWTTE
Question
The table below summarizes the number and percentage of marine species worldwide with at least one documented record of becoming entangled and at least one record of ingesting marine debris, such as plastics and fishing nets.
a. Compare and contrast the information provided for baleen whales and sea turtles.
b. Outline how plastic ingestion may lead to biomagnification in these marine species.[1]
c. Describe the use of indicator species in monitoring environmental change.[3]
▶️Answer/Explanation
Ans:
a. a. both show cases of entanglement/ingestion \(\checkmark\)
b. sea turtles similar number of species affected by entanglement/ ingestion while baleen whales more species affected by entanglement than ingestion
OR
higher percentage of sea turtles species affected by entanglement/ ingestion than baleen whales \(O R\)
higher number of species of «baleen» whales than species of sea turtles \(\checkmark\)
Do not accept answers quoting numerical values only.
b. a. plastic broken down into microplastics to be able to enter the food chain \(\checkmark\)
b. plastic/microplastics become more concentrated at each trophic level \(\checkmark\)
Accept descriptions of biomagnification involving any of the species in the table.
c. a. presence/absence indicate environmental conditions \(\checkmark\) Accept named environmental condition/pollution.
b. changes in the environment affect these species \(\checkmark\) Number of species or type of species.
c. «relative» numbers of individuals/indicator species can be used to calculate a biotic index \(\checkmark\)
d. changes monitored over time \(\checkmark\) Accept example of time frame.
e. changes can lead to measures to protect the environment \(\checkmark\)
f. example of an indicator species \(A N D\) what it indicates «e.g. Tubifex for sediment pollution» \(\checkmark\) Award marks for a species, not a group.
Question
a. Explain why some biologists think protecting keystone species would help preserve biological diversity in an ecosystem.[1]
b. Compare and contrast fundamental and realized niche of a species.[2]
▶️Answer/Explanation
Ans:
a. a large effect on the ecosystem/community structure/environment«relative to abundance»
OR
influence the balance of other populations in the ecosystem
OR
other species in the habitat would also disappear
OR
many other species dependent on them for survival \(\sqrt{ }\)
b. a. both describe the habitat/role/relationship occupied by a species \(\checkmark\)
b. the fundamental niche is the potential role of a species in its ecosystem and realized niche is the actual role
OR
the fundamental niche depends on the adaptations of a species whereas the realized niche is limited by competition/predation
OR
realized niche is «usually) smaller than fundamental niche \(\checkmark\)
Question
a. Feed conversion ratio (FCR) is the mass of animal feed in kilograms required for farmed animals to produce one kilogram of edible mass. For
example, the FCR for salmon is 1.2 and for chicken is 2.2. Deduce the implication of these ratios for sustainability.[2]
b. Models are used as representations of the real world. Evaluate the use of food webs to represent ecological communities.[2]
c. Explain why some biologists think protecting keystone species would help preserve biological diversity in an ecosystem.[1]
d. Outline what is meant by the niche concept.[2]
▶️Answer/Explanation
Ans:
a. a. higher FCR implies less sustainability \(\checkmark\) Do not accept efficiency instead of sustainability.
b. salmon based diet is more sustainable/chicken is less \(\checkmark\)
c. salmon diet would have lower energy losses/chicken diet higher energy losses \(\checkmark\)
d. salmon diet will produce less waste/chicken more \(\checkmark\)
b. Advantages:
a. food webs summarize all possible food chains «in the community» \(\checkmark\) OWTTE
b. realistic representation \(\checkmark\)
Limitations:
c. some communities/ecosystems are too complex to represent \(\sqrt{ }\)
d. only shows qualitative information/not quantitative data
OR
saprotrophs/abiotic factors not taken into account \(\sqrt{ }\)
Needs one advantage and one limitation to obtain [2].
Do not accept mentions of trophic levels.
c. a. «research demonstrates that keystone species» have a «disproportionately» large effect on their environment relative to abundance
OR
«keystone species» maintain a balance in the «stable» numbers of each species within a community
OR
«keystone species» have a large impact in preserving and stabilizing the biodiversity by preventing overpopulation/monopoly/out competition \(\checkmark\)
b. a keystone species’ disappearance would start a domino effect/other species in the habitat would also disappear OR
their loss leads to an imbalance in the food web
OR
their loss leads to a decrease in biodiversity \(\checkmark\)
Do not accept protecting keystone species prevents disappearance of other species since it repeats the question.
d. a. the role of an organism in its environment
OR
functional position of an organism in its environment \(\checkmark\)
b. includes «spatial» habitat AND feeding activities AND interactions with other species in the community \(\checkmark\) All required.
c. no two species can occupy the same niche \(\checkmark\)
d. a niche can be fundamental or realized \(\checkmark\) OWTTE
Question
a. State the impact of environmental disturbance on biodiversity.[1]
b.i. State an example of an alien species.[1]
b.ii.Outline the impact of alien species on endemic species in ecosystems.[2]
▶️Answer/Explanation
Ans:
a. changes/increases/decreases richness/biodiversity/evenness/the numbers of species \(\checkmark\)
b.i.name of species and where it is invasive e.g. introduction of cane toads in Australia \(\checkmark\)
Accept common name of species but not general groups e.g. toads.
b.ii.a. (interspecific) competition with endemic/native species \(\checkmark\) May be outlined using a specific example
b. may cause the extinction/reduction of endemic/native species
OR
reduces biodiversity
OR
becomes invasive \(\checkmark\)
c. does not have endemic / natural predators so may increase in numbers \(\checkmark\)
d. upsets the balance between predators and prey
OR
disrupts food chains \(\checkmark\)
Question
a. State the impact of environmental disturbance on biodiversity.[1]
b.i. State an example of an alien species.[1]
b.ii.Outline the impact of alien species on endemic species in ecosystems.[2]
▶️Answer/Explanation
Ans:
a. changes/increases/decreases richness/biodiversity/evenness/the numbers of species \(\checkmark\)
b.i. name of species and where it is invasive e.g. introduction of cane toads in Australia \(\checkmark\)
Accept common name of species but not general groups e.g. toads.
b.ii.a. 〈interspecific) competition with endemic/native species \(\checkmark\) May be outlined using a specific example
b. may cause the extinction/reduction of endemic/native species
OR
reduces biodiversity
OR
becomes invasive \(\checkmark\)
c. does not have endemic / natural predators so may increase in numbers \(\checkmark\)
d. upsets the balance between predators and prey
OR
disrupts food chains \(\checkmark\)