Download Interdependence /53 1. Name the type of organism that is found at

Interdependence /53
1. Name the type of organism that is found at the start of most food chains.
mark)
Producer (1)
2. What does a pyramid of biomass show?
The amount of energy available at each level of the food chain (1)
(1
(1 mark)
3 State two ways in which energy can be lost between organisms in a food chain (trophic levels) e.g.
between a
rabbit and fox in a food chain.
marks)
Any 2 from heat, respiration, movement, excretion.
4. Suggest how a farmer rearing chickens could limit energy loss from the chickens.
marks)
Keep them in a small pen to limit movement. (1)
Keep them warm so no energy is lost keeping warm (1)
5. Tubeworms rely on bacteria to gain the correct amount of nutrition. The bacteria also rely on the
tubeworms to
survive. What is the name given to this type of relationship?
mark)
Mutualism / symbiosis (1)
(2
(2
(1
6. Describe 3 other mutalistic relationships
(3 marks)
Note in an exam say how each organism benefits from the relationship.
 Oxpeckers ( will eat pests and alert the animal to predators) and buffalo (provide oxpeckers with a
source of food) (1)
 Cleaner fish (eat dead skin and parasites) and larger fish (provide a source of food and help the
cleaner fish to avoid being eaten).
 Nitrogen fixing bacteria (provide plants with nitrates), and plants (provide bacteria with a constant
supply of nutrients (1).
7. Describe 4 parasitic relationships
(4
marks)
Note say how the parasite benefits and the host suffers.
 Fleas and animals. Fleas feed by sucking the blood of their hosts, host has bites (1)
 Head lice and human scalps. Headlice suck blood for food, host will then itch (1)
 Tapeworms and humans – attach to intestinal wall using hooks or suckers and will absorb
nutrients from the host. Host becomes malnourished (1)
 Mistletoe and trees – Mistletoe absorbs the nutrients from the host, the host e.g tree reduces in
growth due to lack of nutrients.
8. The human population is increasing. Why is this a potential problem
(3
marks)
 Raw materials/non renewable resources are running out (1)
 More waste is being produced (1)
 More pollutants such as phosphates from detergents, nitrates from fertilisers and sulphur dioxide
from power stations are being produced. (1)
9. What do we call the build-up of nutrients such as nitrates and phosphates in an aquatic (water)
environment?
Eutrophication. (1)
mark)
(1
10. Suggest how farming can lead to a build-up of nutrients such as nitrates and phosphates in a lake and
then
lead to the death of aquatic life.
(8
marks)
 Farmers spray excess fertiliser onto crops,
 These are washed into nearby lakes when it rains, we call this leeching.
 The nitrate / phosphate fertiliser makes algae grow out of control, covering the surface of the
lake
 Algae blocks the light from reaching plants in the water.
 Plants can no longer photosynthesis and die.
 Bacteria break down the dead plants.
 The bacteria remove oxygen from the water for respiration.
 The oxygen levels decrease in the water so fish etc cannot respire, fish die.
11. What are the problems associated with re-cycling?
marks)
 Recycling uses energy which is costly
 Some waste materials are time consuming to sort out.
 Equipment needed to recycle is expensive
 Quality of recycled material isn’t good
 Some materials can only be recycled a certain number of times
(5
12 What indicator species would you use to test for air pollution in the environment, say what you would
look for
(2 marks)
blackspot fungus shows clean air as it is killed by sulphur dioxide (1)
lichen, air is clean if there is lots of lichen (1)
13. Explain how the quality of a river can be monitored by studying the organisms present in the water, hint,
there
are 2.
(4 marks)
 If you find stonefly larva or freshwater shrimp (1) this indicates low levels of pollution and plenty of
oxygen (1)
 If you sludgeworm or bloodworms (1) this indicates low oxygen levels and the water could be
polluted –
possibly eutrophication is occurring (1)
14. Name the processes that put carbon back into the atmosphere.
mark)
Respiration, combustion,
15. Name the processes that take carbon from the atmosphere?
Photosynthesis, dissolving into oceans
(1
(1 mark)
16 Explain how carbon is cycled in nature.
(6
marks)
 Plants take carbon dioxide in during photosynthesis,
 Plants release carbon dioxide into the atmosphere during respiration (as do animals and bacteria).
 Plants use the carbon dioxide to make glucose which is then eaten by animals.
 Animals release waste or die which are them broken down by decomposers which respire and put
CO2 back into the atmosphere.
 Some plants and animals, over millions of years become fossil fuels which are the burned.
 Combustion releases the CO 2 back into the atmosphere.
17 . Explain how composting increases carbon dioxide concentration in the air.
(2 marks)
Bacteria break down waste material (1), releasing CO2 into the atmosphere through respiration (1)
18 Explain why nitrates are important for plants.
Nitrates are used by plants to make proteins and used for growth
(1 mark)
19 . Name one type of bacteria that takes nitrates out of the soil
Denitrifying bacteria.
(1 mark)
20. Name each type of bacteria involved in the nitrogen cycle and explain their role in the cycling of
nitrogen.
(4 marks)
 Nitrogen fixing bacteria: - Converts nitrogen straight into nitrates / ammonia for the plant to use (1)
 Decomposer bacteria - Break down dead animals and plants and also waste into ammonia (1)
 Nitrifying bacteria - Convert the ammonia in the soil into nitrites then nitrates for plants to take into
their roots (1)
 Denitrifying bacteria: Convert nitrates in waterlogged soil into nitrogen gas and put it back into the
atmosphere (1)