Question
The climograph shows data collected at Bangalore, 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. [1]
a.iii. Using the climograph, outline the pattern of rainfall. [1]
b. Natural forests in the area around Bangalore 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]
The image shows a Gersmehl diagram of tropical rainforest.
c. Explain what this diagram indicates about nutrients in this type of ecosystem. [3]
▶️Answer/Explanation
Markscheme
«30 − 26 =» 4 «°C» ✔
Accept answers between 3 to 5 «°C».
maximum temperature occurs just when rainfall begins/at the onset of the rainy season/monsoon
OR
negative relationship «as maximum temperature drops, rainfall increases» ✔
rainfall concentrated between April to December/peaks in June-August «followed by months with little/no rainfall» ✔
a. dry season/Jan/Feb ✔
b. «drop leaves» to prevent water loss/transpiration «since no rainfall for almost four months» ✔
a. statement correctly explaining the quantity of nutrients in identified circle/circles ✔
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 ✔
eg high transfer rate of nutrients from soil to biomass.
c. statement correctly explaining low nutrient flow/transfer of any thin arrow ✔
eg low transfer rate of nutrients from litter to the outside/another ecosystem.
d. any statement correctly comparing nutrient storage/flow rates ✔
eg higher nutrient transfer between soil and biomass than between biomass and litter .
e. a Gersmehl diagram models «interrelationships between» nutrient stores and flows in an ecosystem ✔
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
Markscheme
a. higher FCR implies less sustainability ✔ Do not accept efficiency instead of sustainability.
b. salmon based diet is more sustainable/chicken is less ✔
c. salmon diet would have lower energy losses/chicken diet higher energy losses ✔
d. salmon diet will produce less waste/chicken more✔
Advantages:
a. food webs summarize all possible food chains «in the community» ✔ OWTTE
b. realistic representation ✔
Limitations:
c. some communities/ecosystems are too complex to represent ✔
d. only shows qualitative information/not quantitative data
OR
saprotrophs/abiotic factors not taken into account ✔
Needs one advantage and one limitation to obtain [2].
Do not accept mentions of trophic levels.
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 ✔
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 ✔
Do not accept protecting keystone species prevents disappearance of other species since it repeats the question.
a. the role of an organism in its environment
OR
functional position of an organism in its environment ✔
b. includes «spatial» habitat AND feeding activities AND interactions with other species in the community ✔ All required.
c. no two species can occupy the same niche ✔
d. a niche can be fundamental or realized ✔ OWTTE