Questions

Activity 1:

Trace a food chain of the vegetables, fruit, cheese, eggs or meat that you had for breakfast or will have for dinner.

Activity 2:

1. In the food chain shown in the text which of the three organisms is the

   1. herbivore
   2. carnivore
   3. producer
2. Draw in the decomposers in the above food chain. Ensure that the direction of the arrows is correct.
3. What organism(s) will feed on the leopard?
4. Construct a new food chain showing at least four organisms.
5. Producers use sunlight to manufacture their own food. Write a word equation to depict this process. [Hint: think of the requirements and outcomes of the process of photosynthesis]

Answers

Activity 1:

Any logical food chain will be acceptable:

• rice $\rightarrow$ man $\rightarrow$ bacteria
• seeds $\rightarrow$ chicken $\rightarrow$ man $\rightarrow$ bacteria
• grass $\rightarrow$ cow $\rightarrow$ cream from milk becomes cheese $\rightarrow$ man $\rightarrow$ fungi

Do not accept ANY part of the food chain if it does not start with a producer or part of a producer.

Activity 2:

1. 1. Impala
   2. Leopard
   3. Green Plant
2. $\rightarrow$ bacteria
3. Bacteria
4. • Flower bulbs $\rightarrow$ rabbit $\rightarrow$ eagle $\rightarrow$ bacteria
   • Leaves $\rightarrow$ locust $\rightarrow$ bird $\rightarrow$ cat $\rightarrow$ bacteria
   • Any other acceptable food chain.
5. Sunlight + water + carbon dioxide $\rightarrow$ sugars or starch + oxygen

Questions

1. Identify a food chain that has three trophic levels.
2. Identify a food chain that has four trophic levels.

3. Name two:

   1. producers
   2. primary consumers
   3. secondary consumers
   4. tertiary consumers
4. There are very few tertiary consumers compared to the primary consumers. Why?
5. What will happen if the hyena is removed from the food web?

Answers

1. • acacia / tree $\rightarrow$ giraffe $\rightarrow$ lion
   • any other suitable example
2. • algae $\rightarrow$ mosquito larvae $\rightarrow$ frog $\rightarrow$ crane
   • grass $\rightarrow$ zebra $\rightarrow$ hyena $\rightarrow$ vulture
   • any other suitable example

3. Learner-dependent answers. Some examples are provided below. Any two of:

   1. grass, trees, algae, aquatic plants
   2. insects, fish, snails, zebra, termites, elephant, giraffe
   3. rat, frog, fish, cheetah, hyena, lion
   4. snake, crane, duck, sparrow, vulture, decomposers, detritus feeders
4. The amount of energy available decreases as one moves up a food chain, so the number of organisms also decreases. An ecosystem cannot support equal numbers of tertiary consumers and primary consumers – there would be too many top predators. Predators would wipe out their food supply and then starve.
5. There are a few possibilities:
   • The number of herbivores would increase, as they are not being predated so heavily – they will only be eaten by cheetahs.
   • The place of the hyena will be filled by other predators or scavengers, such as lions and vultures. Predators and scavengers will increase in number, as they have more food available.
   • Regardless of whether one or both the above occur in an ecosystem, the result will be the same – a new balance will be achieved in the long term, even if the hyenas are removed.