Ecosystems and Material Cycles

Question 1

Define Population

Answer 1

All the organisms of one species in a habitat

Question 2

Define Ecosystem

Answer 2

A community of organisms along with all the abiotic conditions

Question 3

What is interdependency?

Answer 3

Organisms relying on each other for food and shelter.

Question 4

What is mutualism?

Answer 4

A relation ship where both organisms benefit.

Question 5

Name an example of a mutualistic relationship.

Answer 5

Bees and plants

Question 6

What is Parasitism?

Answer 6

A relationship where the host doesn’t benefit.

Question 7

Name an example of a parasitism relationship

Answer 7

Dogs and fleas

Question 8

What does abiotic mean?

Answer 8

Non-living factors in a ecosystem

Question 9

What does biotic mean?

Answer 9

Living factors in a ecosystem

Question 10

Name 3 abiotic factors

Answer 10

Temperature, Amount of water, Light intensity and Level of pollutants.

Question 11

Name 2 biotic factors

Answer 11

Competition, Predation

Question 12

What do you use a quadrant for?

Answer 12

To study the distribution of small organisms

Question 13

What is a quadrant?

Answer 13

A square frame enclosing a known area

Question 14

Give 2 reasons why energy is lost through the food chain.

Answer 14

Respiration, Heat, Excretion and not all of the biomass is eaten.

Question 15

What is biomass ?

Answer 15

the total quantity or weight of organisms in a given area or volume.

Question 16

The bird has 5000KJ of energy and the Worm has 45000KJ. Calculate the efficiency.

Answer 16

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Question 17

Describe how Eutrophication occurs.

Answer 17

1) Fertilisers enter the water adding excess nitrates.
2) The excess nitrates cause algae to grow fast and block out the light.
3) Plants can’t photosynthesise due to lack of light and die and decompose.
4) With more food available, microorganisms that feed on decomposing plants use up oxygen in water.
5) Fish that need oxygen die.

Question 18

What grows in fish farms that cause reduction in biodiversity?

Answer 18

Parasites that feed on fish food

Question 19

What is Reforestation?

Answer 19

Planting trees in previously forested areas.

Question 20

Give 3 reasons for maintaining biodiversity.

Answer 20

Protecting the human food supply
Ensuring minimal damage to food chains
Providing future medicines
Cultural aspects
Ecotourism
Providing new jobs

Question 21

What is food security?

Answer 21

Having enough safe food to eat.

Question 22

Name 2 ways food security can be affected?

Answer 22

Increasing consumption of meat and fish and increasing animal farming
Environmental changes caused by human activity
Sustainability
New pests and pathogens

Question 23

Give 2 ways carbon can be put back into the atmosphere.

Answer 23

Plant respiration, Animal respiration, CO2 released by decay and Burning

Question 24

What is the only way carbon can enter the carbon cycle?

Answer 24

Being used by plants in Photosynthesis.

Question 25

What is precipitation?

Answer 25

Water falling from the sky. (Rain, snow, sleet, hail)

Question 26

Name 2 ways to produce potable water.

Answer 26

Reverse Osmosis and Desalination

Question 27

How does Reverse Osmosis work?

Answer 27

Salt water is treated to remove solids
It is then passed at very high pressure through a partially permeable membrane.
The pressure causes water to move from high salt concentration to low salt concentration.

Question 28

Name 3 ways nitrogen can enter the Nitrogen cycle.

Answer 28

Lightening, Nitrogen fixing bacteria in the soil and Nitrogen fixing bacteria in plant roots.

Question 29

How can farmers increase the amount of nitrates in their soil?

Answer 29

Crop rotation- Growing different crops in a yearly cycle including a nitrogen fixing crop like peas or beans which put nitrates back into the soil.

Fertilisers- Spreading animal manure or compost on fields recycles the nutrients left and returns them to the soil by decomposition.

Question 30

What are the 4 different types of bacteria in the nitrogen cycle and what do they do?

Answer 30

Decomposers- Decompose proteins and urea and turn them into ammonia, which forms ammonium ions in solution that plants can use.

Nitrifying bacteria- turns ammonia in decaying matter into nitrites and then nitrates.

Nitrogen-fixing bacteria- turns atmospheric nitrogen into ammonia.

Denitrifying bacteria- Turn nitrates back into Nitrogen gas. Often found in waterlogged soils and is of no benefit to organisms.

Question 31

Name 2 organisms which indicate clean water.

Answer 31

Stonefly larvae and freshwater shrimps.

Question 32

Name 2 organisms which indicate dirty water.

Answer 32

Bloodworms and Sludge worms.

Question 33

Name 2 organisms which indicate clean air.

Answer 33

Bushy lichen and Blackspot fungus.

Question 34

Name an organism which indicates dirty air.

Answer 34

Crusty Lichen

Question 35

How could you get a more accurate reading of air and water pollution than using indicator species?

Answer 35

Dissolved oxygen meters and chemical tests to show how the level of water pollution changes.

Electronic meters and laboratory tests can be used to measure the amount of sulphur dioxide in the air.

Question 36

What 3 main things does the rate of decay depend on?

Answer 36

Temperature- the higher the temp the faster the rate of decay until it becomes to hot that the enzymes denature

Water content- The higher the water content the higher the rate of decay because the bacteria need water to survive.

Oxygen availability- The higher the amount of oxygen present, the faster the rate of decay because many bacteria need oxygen for aerobic respiration.

Question 37

Give 3 ways of preserving food.

Answer 37

Storing foods in a fridge or freezer lowers the temperature of the food, slowing down the rate of decay.

Storing foods in airtight containers stops microorganisms getting in .

Drying foods removes the water that microorganisms need to survive.

Adding salt or sugar also removes water by osmosis.

Question 38

321 arbitrary units of mould grew on a piece of cheese in April. Calculate the average rate at which the cheese decomposed giving your answer in units of mould per day.

Answer 38

10.7 units of mould per day