Download Unit 3 Key Area 3.4

Exercise 10.
Unit 3 Key Area 3.4 – Energy In Ecosystems.
Under natural conditions an ecosystem really contains many interconnecting food chains. This more complex relationship is called a FOOD
WEB.
Using the food web above, answer the following questions.
1. If all the snails died out, what would you expect to happen to the
duck population and why?
(1 marks)
2. If all the snails died out, what would you expect to happen to the
mosquito larvae population and why? ( 1 marks)
3. If the dragonfly larvae population died out what would you expect
to happen to the minnow population and why? (1 marks)
4. Using the following information construct a food web in your
jotters. (2 marks)
In a rainforest there are many producers including trees and flowering
plants. Insects and bats feed on the flowering plants, whereas monkeys
and parrots mainly feed on the fruits growing on the trees. Many
predators are also found in the rainforest. Snakes will hunt bats, parrots
and monkeys and frogs will hunt for insects. A jaguar is the top predator
found in a rainforest. They will hunt for monkeys, snakes, parrots and
frogs.
5. Using the following information construct a food web in the space
below.
(2 marks)
1
In the Antarctic seas killer whales are commonly found hunting for seals,
penguins, squid and large fish species such as cod. Baleen whales are also
found in such seas but they feed on krill. Krill consume phytoplankton, the
main producer in the seas. Phytoplankton is also eaten by small fish,
shrimp and squid. Seals, cod and penguins will in turn consume small fish,
shrimp and squid.
Total 7 marks.
Exercise 11.
Using the following food web to answer the following questions.
1. Give two examples of producers. (2 marks)
2. Give an example of a primary consumer and a secondary consumer.
(2 marks)
3. State a food chain with 5 stages in it.
Total 5 marks.
2
(1 marks)
Exercise 12.
The diagram below shows part of the nitrogen cycle.
Nitrogen gas in the
atmosphere
F
G
A
Proteins in
plants
E
Proteins in
animals
B
Nitrates in
the soil
D
Nitrites in the
soil
C
B
Ammonium compounds
in the soil
Use the diagram above to answer the following questions.
1 (a) What is represented by arrow A. (1 mark)
(b) What letter(s) represent death and decomposition. (1 mark)
(c) What letter(s) represent the action of nitrifying bacteria. (1 mark)
(d) What letter(s) represent the action of denitrifying bacteria. (1
mark)
(e) What letter(s) represent the action of nitrogen fixing bacteria. (1
mark)
2. Why is nutrient cycling important in ecosystems? (1 mark)
3. Give an example of an organism responsible for process B. (1 mark)
4. Give a possible source of nitrates that is artificial. ( 1 mark)
Total 8 marks.
3
Exam Style Questions.
Q1
4
Q2
5
Q3
6
7