B7 - Further Biology (Learning from Ecosystems)

Question 1

Define an ecosystem.

Answer 1

An ecosystem is the community and habitat in which organisms live.

Question 2

A perfect, stable ecosystem is called a _________ loop system.

Answer 2

A perfect, stable ecosystem is called a closed loop system.

N.B: No system is “perfect”. This is the closest we can get to perfection.

Question 3

An unstable ecosystem is called a ________ loop ecosystem.

Answer 3

An unstable ecosystem is called a open loop ecosystem.

Question 4

Why is no ecosystem perfect?

Answer 4

• Due to migration.
• Due to nutrients being migrated through rivers.

Question 5

What are the 3 stages of a linear ecosystem?

Answer 5

Take –> Make –> Dump.

During making, energy is released and raw materials are used.

During disposal, energy may be used.

Disposed products are not re-used.

Question 6

What are the stages of a closed-loop ecosystem?

Answer 6

Raw materials –> Waste.

Raw materials

(N.B: Simplified - in between stages missed out as not important).

This creates a loop.

There is no waste whatsoever - not even during production stages (This is very unlikely in the real world).

Question 7

How are closed loop ecosystems “perfect”?

Answer 7

Because there are no overall gains or losses (What goes in = What goes out).

Question 8

Give examples of natural resources.

Answer 8

Any of the following:

• Fish stocks.
• Timber.
• Clean air.
• Fertile soil.
• Fresh water.
• Any other suitable answer.

Question 9

Gives examples of how humans can negatively affect ecosystems.

Answer 9

Any of the following:

• Household waste.
• Industrial waste.
• Agricultural waste.
• Chemical waste (From fossil fuels).
• Any suitable answer.

Question 10

Define sustainable.

Answer 10

Taking the resources you need whilst keeping enough resources for future generations to use.

Question 11

Give examples of natural waste.

Answer 11

Any of the following:

• DOM (Dead organic matter):
• Twigs.
• Petals.
• Leaves.
• Fruit.
• Feathers.
• Faeces.
• Any suitable answer.

Question 12

What feeds on dead organic matter (DOM)?

Answer 12

Detritivores (e.g: Worms, beetles and maggots)

and

Decomposers (Microscopic level, e.g: Fungi, bacteria).

Question 13

Give an example of a closed-loop ecosystem.

Answer 13

• Nitrogen cycle.
• Carbon cycle.
• Any other suitable cycle.

Question 14

Define biodiversity.

Answer 14

Biodiversity is the variety of plant and animal life in the world, in a particular habitat or within a species.

Question 15

What is threatening biodiversity?

Answer 15

• Availability vs demand.
• Endangering species (Sometimes as a result of culture) such as elephants, tigers and shark fins.

Question 16

What is the value of having biodiversity?

Answer 16

• Economic.
• Tourism.
• Emblamatic appeal.

Question 17

What are the effects of reducing biodiversity?

Answer 17

• Ethics - Is it ethical?
• Endangered animals.
• Affects food chain.

Question 18

What are the solutions to help increase/maintain biodiversity?

Answer 18

• Bans.
• Reserves.
• Park rangers.
• Enforced.

Question 19

Is an ecosystem an open or closed loop system? Why?

Answer 19

An ecosystem is a type of closed loop system since most of the waste materials are not lost, but are used as food or reactants.

Question 20

Give an example of an ecosystem where the output is balanced by gains (Closed-loop).

Answer 20

e.g: Rainforest which loses water through rivers, transpiration and photosynthesis, but gains it through rain.

Or, any other suitable example.

Question 21

Give examples of some reproductive structures that are produced in large quantities.

Answer 21

Cells

• Pollen.
• Sperm.
• Eggs (In amphibians).

Structures

• Flowers.
• Fruits.

Question 22

Why do some wildlife produce eggs in large quantities?

Answer 22

To ensure the best chance of successful reproduction, often due to many offspring failing to live to adulthood.

Note that the excess is not wasted, as it acts as inputs to other processes, such as the food chain.

Question 23

Suggest why apple trees make so many flowers.

Answer 23

Because more flowers attract more pollinators, and more flowers make the apple trees stand out from the competition, which pollinators may otherwise go to.

Question 24

What is desertification?

Answer 24

When fertile land becomes desert, and can no longer support the same plant growth it had in the past.

It is irreversible.

Question 25

What factors increase the chance of desertification?

Answer 25

Any of the following:

• Removal of vegetation cover.
• Overgrazing.
• Uncontrolled fuel wood collection.
• Unsustainable farming practise and loss of soil fertility.
• Excessive tree felling.
• Drought.

Question 26

List the ways plants protect soil from erosion.

Answer 26

Any of the following:

• The contribution of nutrients to the soil.
• Awareness that soil is held in place by roots.
• The prevention of soil erosion and prevention of land slides.
• The maintenance of a stable temperature due to insulation by trees. Also, this influences absorption of water and nutrients.
• The movement of water into the atmosphere to create clouds and rain through transpiration, instead of surface runoff/ground saturation.

Question 27

Name ways that humans depend on natural ecosystems.

Answer 27

Any of the following:

• For respiration (Aerobic), we need oxygen.
• Wood for fires.
• Medicines from plants.
• Food from animals.
• Any other suitable answer.

Question 28

What is bioaccumulation?

Answer 28

Bioaccumulation is when toxins build up in a food chain. The animals at the top of the food chain are affected most severely.

Question 29

What is eutrophication?

Answer 29

Eutrophication is when fertilisers are added to farmland in large quantities, which can contamiante nearby rivers and lakes, consequently resulting in the death of organisms.

Question 30

What is bioamplification (AKA biomagnification)?

Answer 30

Bioamplification refers to an increase in the concentration of a substance as you move up in the food chain. This often occurs because the pollutant is persistent, and is transferred up the food chain faster than it is broken down or excreted.

It is seen in bioaccumulation.

Question 31

Explain how bioaccumulation works.

Answer 31

1. Small quantities of toxic substances - often from human activity - are taken up by plants (e.g: DDT).
2. The plants are eaten by primary consumers.
3. The primary consumers are eaten by secondary consumers, who are then eaten by higher level consumers.
4. At each stage (Trophic level) of the food chain, harmless substances are excreted but the toxins remain in the tissues of the organism, so the concentration of toxin becomes highest in animals at the top of the food chain.

Question 32

Explain how eutrophication works.

Answer 32

1. Excessive use of nitrate fertiliser is flushed from the land into rivers or lakes by rainwater.
2. Plants flourish - the fertilisers result in accelerated aquatic plant growth of algae, duckweed and other plants.
3. Algae blooms - A layer of algae on top of the water, preventing sunlight reaching other plants. Consequently, these plants die.
4. Decomposition further depletes oxygen levels - Dead plants are broken down by bacteria decomposers, using up even more oxygen in the water.
5. Death of the ecosystem - Oxygen levels reach a point where no life is possible. Fish and other organisms die.

Question 33

DDT was banned in the UK in 1984, but is still detectable in animals living in areas where it was used. How can you explain this?

Answer 33

Because DDT never actually leaves the environment, and when it is excreted by waste from a consumer, it will only be picked up by another primary consumer.

Question 34

Give three examples of waste materials that are not recycled.

Answer 34

• Batteries.
• Glassware.
• Plastic bags.
• Any other suitable answer.

Question 35

What is the environmental impact of unsustainable timber harvesting? How can it be made sustainable?

Answer 35

It results in deforestation, killing animal habitats and also reducing photosynthesis.

It can be made sustainable by replanting a sapling for each tree destroyed.

Question 36

What is the environmental impact of unsustainable fishing?

Answer 36

It affects the food chain as consumers of fish would find it difficult to capture their prey and may consequently die, having a knock-on effect down the entire food chain. Also, it endangers the fish if there is a low population - as they may find it difficult to find a mate.

Question 37

How does replacing vegetation with agriculutral crops lead to a loss of biodiversity?

Answer 37

Because there is a low number of the vegetation which has been replaced, decreasing biodiversity.

Question 38

How does replacing vegetation with agriculutral crops lead to silting of rivers?

Answer 38

Because overgrazing can lead to soil erosion, and this soil can be washed into rivers as silt.

Question 39

How does replacing vegetation with agricultural crops lead to desertification?

Answer 39

Because overgrazing can lead to soil erosion, and the loss of nutrients/moisture in the soil which can cause soil degradation, desertifying the land which is no longer arable.

Question 40

What is slash-and-burn agriculture?

Answer 40

Slash-and-burn is an agricultural technique that involves the cutting and burning of plants in forests or woodlands to create fields.

If you want to learn how it works, info taken from Geography flashcards:

Shifting cultivation is a traditional, sustainable method of agriculture that has been practised for centuries.

It works by:

1. Clearing a small area of land and burning vegetation, providing a source of nutrients from the ash.
2. For a few years, the soil remains sufficiently fertile for the tribe to grow crops.
3. When the soil’s fertility is exhausted, the tribe moves on and clears another small area of forest.
4. The original area is regenerated, as it receives nutrients and seeds from surrounding vegetation.
5. As no lasting damage occurs, this method of agriculture is sustainable.
6. It is sometimes called ‘slash and burn’ agriculture.

Question 41

State three problems with the slash-and-burn approach to developing the rainforest.

Answer 41

• It pollutes the environment with CO₂ and CO.
• It kills animal habitats.
• It could continue further than expected and is very difficult to control, resulting in a large forest fire.

Question 42

What is a quota?

Answer 42

A limited or fixed number of things.

Question 43

Name some strategies of sustainable forest management.

Answer 43

• Agro-forestry - Growing trees and crops at the same time, allowing farmers to take advantage of shelter from the canopy of trees, preventing soil erosion, and the crops benefit from the nutrients of dead organic matter.
• Selective logging - Trees only felled when they reach a particular height.
• Education - Ensuring those involved understand the consequences of their actions.
• Afforestation - Planting trees after they are felled.
• Forest reserves - Areas protected from exploitation.
• Monitoring - Use of satellite technology and photography to check that any activites taking place are legal and follow sustainability guidelines.

Question 44

Explain how fishing can be made sustainable.

Answer 44

By using a quota so that only a specific number of fish can be caught. This would give the fish time to reproduce, and increase their population again.

Question 45

Compare the feelings of:

a) A fish conservation officer
b) A local fisherman from North Shields

for how they might feel about fishing quotas for the North Sea cod stocks.

Answer 45

The fish conservation officer would want fishing quotas to be low, and heavily enforced, to ensure fish have the best opportunity to reproduce and increase their population.

The local fisherman from North Shields would not want fishing quotas enforced, or would want them to be very high, so that they can catch more fish and make more profit.

Question 46

Give examples of ecosystem services.

Answer 46

• Pollination - Food.
• Pure water - Can be disrupted by human influence.
• Flood control.
• Fossil fuels.

Question 47

Name the 3 techniques farmers use in conventional farming (Non-organic).

Answer 47

N.B: The following can also exist organically.

• Fertilisers.
• Pesticides.
• Herbicides.

Note that the use of pesticides and herbicides reduces biodiversity.

Question 48

What are the problems of Over-fishing?

Answer 48

• Can lead to a loss in biodiversity.
• Can lead to an accumulation of organisms that would have been eaten by fish, which may have harmful effects on resources available.

Question 49

What defines whether natural resources are sustainable?

Answer 49

Whether or not the materials are replaced at the same rate they’re used.

Question 50

Is crude oil sustainable? Explain your reasons.

Answer 50

No, it is not. Because:

• Crude oil takes millions of years to form from the decay of dead organisms.
• The energy released from burning oil was fossil sunlight energy, as it orginated from the Sun when the organisms were alive.

Question 51

What is the input energy for all systems on Earth?

Answer 51

Sunlight energy (Estimated to last another five billion years).

Question 52

[6 MARKER]

The Tabin Reserve in Borneo covers 100,000 hectares of rainforest. Rare animals such as Borneo elephants and orang-utans live in the reserve.

Large areas of Borneo are now used to grow palm oil. Palm oil is used as biofuel in European vehicles.

Discuss the advantages and disadvantages of replacing fossil fuel with biofuel from palm oil.

Answer 52

LVL 1 Responses

• Less CO₂ produced when using biofuels.
• Less CO₂ means limiting effect of global warming.
• Uses up crop space and land.

LVL 2 Responses

• Biofuels are renewable.
• Biofuels are sustainable.
• The 100,000 hectares of rainforest could be lost.
• (Therefore) loss of biodiversity/wildlife/habitats.

LVL 3 Responses

• The palm oil is already being produced in large amounts, therefore it should be readily available.
• Use of biofuels would decrease the demand for fossil fuels, advantages of this (e.g: Decreasing fuel prices, less pollution).
• Uses up crop space and land which could be used for other crops, such as agricultural crops, which could be debated as being more important.
• Biofuels require growth, which takes time. This may have an impact on supply and demand.
• (Whereas) fossil fuels can be extracted immediately.
• Although biofuels produce less CO₂, they are still not carbon neutral, and therefore are not a perfect solution.

N.B: Not a real mark scheme.