1. Ecology Questions

2. SQ 11. Giraffes live in the grassland of Africa
SQ 11. Giraffes live in the grassland of Africa. They move freely among tall trees, dense forests and open plains.
Most cacti live in habitats subject to at least some drought. Many live in extremely dry environments, even being found in the Atacama Desert, one of the driest places on earth
(a) State two adaptations which can be observed from their physical appearance.
(a) Giraffe
-The long neck which enables them to eat leaves from tall trees.
-They have camouflaged skin.
Cactus
-It has thick fleshy stem to store water;
-It has needle-like leaves to reduce water loss.

3. (b) State and explain two ways how the frog adapts to its habitat.
Land Adaptations:  1.) Capability of breathing oxygen without the use of gills.  2.) Powerful limbs are able to allow the animal to escape quickly.  3.) Can feed on many land-dwelling animals.  Water Adaptions:  1.) Ability of breathing oxygen via skin pores.  Frogs have webbed feet, which help them to swim. Their long hind limbs, which help them to leap on land, also aid them in swimming.
 3.) Ambush predation. 
Frogs are carnivores. They eat insects, spiders, worms, snails, fish, and even small rodents like mice.
When a frog spots a tasty meal, it flicks out its long, sticky tongue. The tongue lassos the meal/creature and pulls it back into the frog's mouth.

4. (c) Describe how each of the following protects itself from predators.
(i) Chameleon
(ii) Centipede
(c) (i) Able to change colour to camouflage from predators
(ii) Produces poison that can deter predators
(d) Predator-prey

5. Plants giraffe cheetah
(d) Study a food chain below.
Plants giraffe cheetah
What is the relationship between a giraffe and a cheetah?
(c) (i) Able to change colour to camouflage from predators
(ii) Produces poison that can deter predators
(d) Predator-prey

6. SQ12. Study the following food webs in a habitat as shown.
Fig 15.1
Fig 15.2
(a) (i) Which organism is placed at the beginning of all the food chains?
(ii) Explain why this organism is placed at the beginning of all the food chains.

7. SQ12. Study the following food webs in a habitat as shown.
Fig 15.1
Fig 15.2
(b) (i) Write down a food chain which has four trophic levels from Fig 15.1.
(ii) Which two organisms are the primary consumers from Fig 15.1?

8. krill

9. SQ12. Study the following food webs in a habitat as shown.
Fig 15.1
Fig 15.2
(c) Write down a food chain which has the least amount of energy when it reaches Bird D from Fig 15.2.

10. SQ12. Study the following food webs in a habitat as shown.
Fig 15.1
Fig 15.2
(d) From one trophic level to the next, only 10% of the energy is transferred. Oysters and zooplankton both receive kJ from the algae. What would be the amount of energy being transferred at X, Y and Z respectively?

11. SQ12. Study the following food webs in a habitat as shown.
Fig 15.1
Fig 15.2
(e) What is the amount of energy lost as heat from algae to oysters?

12. 90000 kJ ?????

13. SQ13. A simple food chain is presented as shown.
How are sparrow and hawk classified in this food chain?
If only 10% of energy from food is passed on from one trophic level to the next, determine the amount of energy being transferred at the trophic level P and Q respectively.
What is the total energy transferred from the sun to plants initially?
(d) State two ways how the energy is lost at each trophic level.

14. Tree  Dragonfly  Archerfish  Eagle
(e) A food chain along a river bank is shown below.
Tree  Dragonfly  Archerfish  Eagle
(i) Name a secondary consumer from the food chain above.
(ii) What is a pyramid of numbers? Draw a pyramid of numbers for the food chain above.
(iii) Explain the importance of the 'tree' in this food chain.
(iv) 1. Which organism, archerfish or eagle, should a human consume in order to obtain the largest amount of energy?
2. Give an explanation for your answer

15. Archerfish

16. The pyramids of numbers shows the raw number of each species at each trophic level. The top example is a typical food chain with a large number of producers but diminishing numbers of consumers. However, if the producer was a tree, followed by insects, then the bottom bar would appear small as many organisms feed on one tree. In this instance the pyramid of biomass is more useful as the tree is much larger.

17. In the lower example, both the pyramid of numbers and biomass show a smaller producer bar; given what was discussed under the previous heading - this does not make sense. This is because the phytoplankton reproduce very quickly. However, when we represent this information in a pyramid of energy we get a true pyramid.

18. Plotting the energy will always give a true pyramid because it is impossible to create new energy so a trophic level will always be smaller than the one below it and as discussed above there is a great deal of energy loss at each level.

19. SQ14. In Pulau Ubin, farmers were troubled by the increasing population of rabbits. Rabbits ate their flower bulbs and grass meant for their sheep. The outbreak of sheep disease (farmers had to dispose of their sheep) brought an end to their rabbit problem.
(a)(i) Referring to the food web above, explain how the outbreak brought an end to their rabbit problem
(ii) Write down a food chain that is present in the above food web.
Carbon is an important element in the ecosystems.
(b) Explain why carbon is an important element to all the living things in the ecosystems.

20. (c) The following shows the carbon cycle.
Identity the process taking place in
(i) A (ii) B (iii) C:
and explain how the processes take part in carbon cycle.
(d) Explain why the carbon cycle is important in the ecosystems.

21. SQ15. The following picture A shows a typical tropical rainforest.
The tropical rainforest is hot and receives a lot of rains throughout the year, an average of 250 cm per year. The thick rainforest reduces the risk of flooding, soil erosion and nutrients being washed out of the soil due to heavy rainfalls. Plants grow tremendously and use up any organic nutrients in the soil. There is not much sunlight on the ground because the light is not able to penetrate through the thick rainforest.
(a)(i) In picture A, which abiotic factor affects the height of the trees in the rainforest?
(ii) Why is this abiotic factor important to the trees?

22. (b)(i) This element is not found in carbohydrates but must be present in the organic nutrients in order for the plants to grow new cells. What could this element be?
(ii) State one way how this element is returned to air.
(c) A few years later, the view of the rainforest is shown in picture B.
(i) The destruction of the rainforest is caused by human activities. Name the possible activities.
(ii) Describe the undesirable effects after the rainforest is destroyed.

23. SQ16. (a) Both the organisms exhibit a special type of relationship called commensalism. Explain what is commensalism using the organisms below as an example in your explanation

24. (b) In the temperate rainforest, epiphytes such as staghorn ferns and mosses grow on the trunk of trees to receive sunlight for photosynthesis.
(i) What abiotic factors in the physical environment tropical rainforest that make it the most thriving environment for life?
(ii) Complete the following by placing a cross (X) to choose the correct relationship between the staghorn ferns and the trees.
Staghorn ferns are spectacular plants, but easy to own and enjoy;  they require almost no work, no soil and not much watering
All you have to do is provide a warm bright airy location and your Staghorn fern will perform, growing larger rapidly with almost no care

25. (iii) Explain your choice of answer in (ii). Parasitism Commensalism
(ii) Complete the following by placing a cross (X) to choose the correct relationship between the staghorn ferns and the trees.
(iii) Explain your choice of answer
in (ii).
Parasitism
Commensalism
Mutualism
Staghorn ferns are spectacular plants, but easy to own and enjoy;  they require almost no work, no soil and not much watering
All you have to do is provide a warm bright airy location and your Staghorn fern will perform, growing larger rapidly with almost no care

26. (a) Fig. 2.1 shows part of the carbon cycle.
State the letter that represents photosynthesis in Fig [1]
State the three letters that represent respiration in Fig [1]
(a) (i) A; [1]
(ii) B, E, F; [1]
(iii) starch/cellulose/sugar/any other correct ; [1] A
B, E, F

27. (a) Fig. 2.1 shows part of the carbon cycle.
(a) (i) A; [1]
(ii) B, E, F; [1]
(iii) starch/cellulose/sugar/any other correct ; [1]
(iii) Name one carbon-containing compound in plants. [1]
starch/cellulose/sugar

28. (b)(i) Earthworms play an important part in the carbon cycle
(b)(i) Earthworms play an important part in the carbon cycle. They eat leaves, and egest material containing plant nutrients into the soil.
Explain the meaning of the term egest. [2]

29. State the approximate percentage of carbon dioxide in the air. [1]
(b)(i) Earthworms play an important part in the carbon cycle. They eat leaves, and egest material containing plant nutrients into the soil.
Explain the meaning of the term egest. [2]
0.04%; (allow 0.03%)
(iv) 0.04%; (allow 0.03%) [1]
(b) (i)remove undigested substances ;
from the, alimentary canal/digestive system/anus or as faeces ; [2]
(ii) consumer and herbivore ; [1]
remove undigested substances ;
from the, alimentary canal/digestive system/anus or as faeces ; [2]

30. (ii) Underline the two words that describe the position of an earthworm in a food chain. [1]
carnivore consumer
herbivore producer
consumer and herbivore ; [1]
(iv) 0.04%; (allow 0.03%) [1]
(b) (i)remove undigested substances ;
from the, alimentary canal/digestive system/anus or as faeces ; [2]
(ii) consumer and herbivore ; [1]

31. Suggest why it is important to conserve earthworms.
(iii) Fishermen catch large numbers of earthworms to use as bait. There are concerns that too many earthworms are being collected.
Suggest why it is important to conserve earthworms.
(iii) to prevent extinction (of earthworms) ;
reference effect on, food chains/ecosystem ;
because they improve the soil by aeration(the process of exposing to air (so as to purify); "the aeration of the soil) ;
because they improve the soil by releasing plant nutrients ;
Earthworm transports minerals and nutrients from deeper soil layers to the surface, bury seeds, incorporate organic matter into the soil, and create burrows, which allow air and water to penetrate the soil more easily.
Earthworm is a consumer of dead organic matter, a source of food for other animals, a host to parasites, and bait for an angler.
Earthworm loosens the soil by burrowing and “plows” the soil when it deposits materials on the surface.

32. (c) Earthworms play an important part in the carbon cycle
(c) Earthworms play an important part in the carbon cycle. They are decomposers. Describe the role of decomposers in the carbon cycle.
(c) feed on dead (plant or animal) material/waste products (from plants or
animals) ;
use carbon-containing substances/sugar ;
for respiration ;
return carbon dioxide to the air ;