Suggested answers


• Loss of habitat: Animals die or move away to another place and others move in; animals and plants may become extinct.


• Loss of species: Affects plants or animals that depend on the list species; other species are introduced as the competition has been eradicated.


• Change of weather or climate: Animals cannot tolerate the change and move to another area, or those that survive have adaptations for survival.


Assessment guidelines


• This activity is intended for informal assessment. • Use the memorandum supplied above to assess learners informally during a class discussion.


Activity 2


Evaluate the impact on a food web when one of the organisms is removed


Learner’s Book page 36 Guidelines to implement this activity


• This is an individual activity. • Read the two case studies through with the learners and ask them to answer the questions in the activity.


Suggested answers 1.1 The Serengeti wildebeest food chain 


1.2 The California sea otter food chain  2.1 Grass → Wildebeest → Predators 


2.2 The learners recognised that when the keystone species was removed, the entire ecosystem was disrupted. 


Assessment guidelines


• This activity is intended for informal assessment. • Use the suggested answers supplied above to assess learners informally. Allocate learners a mark out of 8 and give them feedback on their performance to prepare them for formal assessment.


41


(1) (1) (2)


Humans → California sea otter → Kelp eating sea urchins → Kelp  (2) (2) Total: 8 marks


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