Topic 9 - Ecosystems And Material Cycles

Question 1

How is CO2 removed from the air in the carbon cycle?

Answer 1

Photosynthesis

Question 2

How is CO2 but back into the air in the carbon cycle?

Answer 2

Burning fossils fuels
Plant and animal respiration
Decay of dead organisms

Question 3

How does carbon get into animals in the carbon cycle?

Answer 3

Animals eating plants

Question 4

What is the carbon cycle?

Answer 4

Carbon being naturally recycled in an ecosystem

Question 5

How does water get put in the atmosphere in the water cycle?

Answer 5

Evaporation and transpiration

Question 6

How is water returned to the sea in the water cycle?

Answer 6

Precipitation

Question 7

Why is the water cycle needed?

Answer 7

It is a natural way of cleaning water of salt and microorganisms

Question 8

What do decomposers do in the nitrogen cycle?

Answer 8

Decompose proteins and urea into ammonia. The ammonia forms ammonia ions that plants can use.

Question 9

What do nitrifying bacteria do i the nitrogen cycle?

Answer 9

Turn ammonia into nitrites and then into nitrates

Question 10

What do nitrogen fixing bacteria do in the nitrogen cycle?

Answer 10

Turn nitrogen in the air into ammonia, which forms ammonia ions

Question 11

What do denitrifying bacteria do in the nitrogen cycle?

Answer 11

Turn nitrates into nitrogen gas

Question 12

What is the mutualistic relationship between legume plants and nitrogen fixing bacteria?

Answer 12

Nitrogen fixing bacteria live in the nodules on the roots of legume plants. The bacteria provide the plants with ammonia ions, the bacteria get sugar from the plant.

Question 13

Why does a lightning strike cause nitrogen fixation?

Answer 13

There is so much energy in a bolt of lightning that it is enough to Make nitrogen react with oxygen.

Question 14

What is an indicator species?

Answer 14

A species that is very sensitive to environment change. You can look to see if these species are present or not to see what condition the environment is in.

Question 15

How does an indicator species show water pollution?

Answer 15

Some species are very sensitive to water pollution. Stonefly larvae can only live in very clean water. While other prefer polluted conditions, such as bloodworms.

Question 16

What happens when too many nitrates get in a body of water?

Answer 16

If too many nitrates get into the water from fertilisers or sewage, the number of microorganisms will increase. These will use up all the oxygen in the water. Killing other organisms in the water.

Question 17

How are lichens an indicator species for air pollution?

Answer 17

Certain species of lichen can only grow in certain levels or air pollution.

Question 18

What is mutualism?

Answer 18

It is a relationship between two organisms, where both organisms benefit.

Question 19

State the four abiotic factors that affect ecosystems

Answer 19

Temperature
Amount of water
Light intensity
Level of pollution

Question 20

State the two biotic factors that affect ecosystems

Answer 20

Competition

Predatation

Question 21

How is energy lost between levels of a food chain?

Answer 21

Organisms moving and growing uses up the energy. Not all of the organism gets eaten, such as bones.

Question 22

State the equation for efficiency of energy transfer between levels of a food chain.

Answer 22

Efficiency = (energy transferred to next level / energy available at previous level) x 100

Question 23

What are the three factors that affect rate of decay?

Answer 23

Temperature
Water content
Oxygen availability

Question 24

Why does temperature affect rate of decay?

Answer 24

A high temperature speeds up the rate of enzyme controlled reactions. But if the temperature gets too high the enzymes will denature and so the reactions will stop.

Question 25

Why does water content and oxygen availability affect rate of decay?

Answer 25

The decomposers need oxygen and water to live. The more of it the more decomposers there can be.

Question 26

List 5 methods of preserving food

Answer 26

Storing foods in a fridge or freezer
Storing food in a sterilised airtight container.
Drying the food
Adding salt
Adding sugar

Question 27

State 3 human interactions that affect biodiversity in an ecosystem

Answer 27

Hunting
Farming
Introduction of non-indigenous species
Fertilisers leaking into bodies of water

Question 28

Why does fish farming affect biodiversity?

Answer 28

Food is added to the farms, which leaves waste that causes eutrophication. Fish farms act as breeding grounds for parasites, the parasites can get out and infect the wild populations. Predators will be attracted to the farms, and can be caught in the nets and die.

Question 29

What is eutrophication?

Answer 29

When an excess of nitrates gets into a body of water. This causes algae to rapidly grow blocking out the light. The plants in the water die and decompose. Microorganisms that feed on decomposing plants rapidly increase in number and use up all the oxygen. The lack of oxygen kills of the other organisms, such as fish.

Question 30

Why does the introduction of non-indigenous species reduce biodiversity?

Answer 30

The non-indigenous species may out compete the indigenous species for things like food and shelter. This causes the indigenous species to reduce in numbers and eventually die out.

Question 31

State 5 benefits of conserving biodiversity

Answer 31

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

Question 32

What is food security?

Answer 32

Everyone in the world having enough food that is safe to eat and has enough nutritional value.

Question 33

State the five biological factors that affect food security

Answer 33

Human population 
Consumption of meat
Environmental changes
Sustainability 
New pests and pathogens

Question 34

What is a population?

Answer 34

All the organisms of one species in a habitat

Question 35

What is a community?

Answer 35

All the organisms of different species living in a habitat.

Question 36

What is mutualism?

Answer 36

A relationship between two organisms where both organisms benefit.

Question 37

Why are bees and flowers an example of a mutualistic relationship?

Answer 37

When bees land on the flower to get nectar, pollen is transferred to their body. The bees then spread the pollen to other flowers, helping the flowers to reproduce.

Question 38

Why is a parasite living on a host not a mutualistic relationship?

Answer 38

The parasite takes what it needs, but the host doesn’t get anything out of it. So only the parasite benefits.

Question 39

What happens to the energy as you move along a food chain?

Answer 39

The energy transferred between each level is reduced.

Question 40

Why is energy lost between levels in a food chain?

Answer 40

The organism being eaten will have used some of the energy to move, grow and reproduce. As well as not all of the organism will be eaten.

Question 41

What is a produced in a food chain?

Answer 41

An organism that produces its own food instead of consuming other organisms, such as plants.

Question 42

The organism on the first level of a food chain is always a what?

Answer 42

Producer

Question 43

What is a consumer in a food chain?

Answer 43

An organism that consumes other organisms for food

Question 44

NOTE: you need to know how to do biomass pyramids

Answer 44

CGP Guide page 97