6 - Human Impact on the Environment (C1)

Question 1

What is the problem of land use change caused by?

Answer 1

Natural ecosystems, such as rain forests, have been used for urban development, raising livestock and farming, including growing biofuel crops

Question 2

What are 3 examples of endangered species?

Answer 2

• Black rhino - Orangutan - Bengal tiger

Question 3

What is biodiversity?

Answer 3

The variety of life on the plant (species number and evenness)

Question 4

How does pollution of inorganic chemicals cause extinction?

Answer 4

• Industrial chemicals such as PCBs and pesticides are not biodegradable so accumulate through the food chain - Most of these pollutants are fat soluble and accumulate in body tissues

Question 5

Why is manure and compost often added to soils?

Answer 5

To add nitrate to the soil

Question 6

What is coppicing?

Answer 6

A technique whereby trees are cut down close to the ground and then left for several years to re-grow shoots

Question 7

What is monoculture?

Answer 7

The simultaneous growth of a large number of crop plants of similar age and type within a defined area

Question 8

What are some reasons for deforestation?

Answer 8

• Land needed for agriculture - Land needed for road and housing development - For resources e.g. timber

Question 9

What is selective cutting?

Answer 9

Cutting only some trees, leaving the others in place

Question 10

What steps can be taken to improve the efficiency of forestry?

Answer 10

• Planting trees optimum distance apart - Controlling pests and diseases
• Cutting a similar number of trees each year for long periods of time, allowing the forest ecosystem to be maintained

Question 11

What are advantages and disadvantages of coppicing?

Answer 11

+ Promotes regrowth and a sustainable supply of timber for future generations - Time consuming and labour intensive

Question 12

What are advantages and disadvantages of selective cutting?

Answer 12

+ Helps maintain nutrients in forest soil + Minimises amount of soil washed into nearby waterways - Expensive - Time consuming - Some species won’t regrow as fast

Question 13

What is long rotation time?

Answer 13

When many years are left between harvesting adjacent areas of forest

Question 14

What are advantages and disadvantages of long rotation time?

Answer 14

+ Increases sustainability + Allows a variety of habitats to develop - Time consuming

Question 15

What is replanting trees?

Answer 15

When all trees in the area are cut down at the same time

Question 16

What are advantages and disadvantages of replanting trees?

Answer 16

+ Supplies resources for future generation - Care must be taken to ensure trees are being planted specific distances from other trees

Question 17

What is regeneration?

Answer 17

The process by which new tree seedlings become established after forest trees have been harvested or died

Question 18

What are advantages and disadvantages of regenerating trees?

Answer 18

+ Cheap, native plants that grow this way are likely to be well adapted to the area - Little control over spacing - May require some preharvesting operations to ensure regeneration

Question 19

What do fishing exclusion zones do?

Answer 19

Prohibit fishing in certain areas and certain times of the year, allowing fish to reproduce

Question 20

What do fishing quotas do?

Answer 20

Ensure only a certain mass of fish can be brought to land

Question 21

What does increasing the fishing mesh size do?

Answer 21

Ensures young fish that are not yet sexually active are not caught

Question 22

What are some methods of combatting over fishing?

Answer 22

• Exclusion zones - Removing subsidies - Quotas - Reducing vessels and fishing time - Controlling mesh size - Eating non-traditional fish

Question 23

Why are diseases common on fish farms and why do treatments lead to environmental problems?

Answer 23

• Fish are crowded together so diseases spread easily - Many treatments are toxic to other organisms - Antibiotics used may lead to antibiotic resistant bacteria developing

Question 24

What are benefits of fish farming?

Answer 24

• Food security for expanding population - Employment - Makes fish more affordable

Question 25

Why does fish farming cause eutrophication?

Answer 25

High levels of protein in food of predatory fish, therefore large amounts of nitrogenous waste

Question 26

What are the 9 planetary boundary global processes?

Answer 26

- Climate change - Biodiversity - Land use change - Nitrate and phosphate - Ozone - Acidification - Freshwater - Aerosol - Inorganic pollution

Question 27

What is meant by the term planetary boundary?

Answer 27

A **threshold value** for a **global process** that is affected by **human activity**. Crossing these boundaries could lead to abrupt or **irreversible environmental changes**

Question 28

What is the ozone problem?

Answer 28

- Conc of ozone in the stratosphere has decreased, creating a hole in the ozone layer - Due to use of CFCs as aerosols

Question 29

What are consequences of the hole in the ozone layer?

Answer 29

- More UV light penetrates atmosphere - UV light generates mutations in DNA and causes damage to living organisms

Question 30

What is an endangered species?

Answer 30

A **species** of plant or animal that is **low in number** and at serious **risk of extinction**

Question 31

Why is secondary succession often quicker than primary succession?

Answer 31

- There is already an **existing seed bank** of suitable plants in the soil - Root systems undisturbed in the soil, stumps and other plant **parts from previously existing plants** can **rapidly regenerate** - The **fertility and structure of the soil** has already been substantially modified by previous organisms to make it more **suitable for growth and colonisation**

Question 32

How does non-contiguous populations cause animals to become endangered or extinct?

Answer 32

- If groups of members of species are **isolated**, they can't **interbreed** and each group functions as a separate population - There may be too **little genetic diversity** to ensure a healthy population, leading to **extinction**

Question 33

Why can a loss of hedgerows cause animals to become endangered or extinct?

Answer 33

- Hedgerows provide a **habitat** for insects, birds and reptiles, and provide **food** - Vary **light intensity** and **water availability** for plants - Act as **wildlife corridors**, enabling animals to move from one area to another, helping to **maintain biodiversity**

Question 34

What are some examples of overhunting by humans?

Answer 34

- Trophy hunting - Traditional medical practices - For food - Overfishing

Question 35

Why can oil spilt into water kill animals?

Answer 35

- Oil floats and prevents oxygenation of surface water - Animals that break through the surface are covered by a film of oil. Animals such as birds are chilled to death as their feathers clump and can't provide insulation

Question 36

What are some reasons why species are endangered or extinct?

Answer 36

- Human activities are causing habitats to change faster than natural selection allows species to adapt - Non-contiguous populations - Loss of habitat: **deforestation**, **drainage** of wetlands, **hedgerow loss**, also farmers often sow crops in autumn rather than spring so **plants are an unsuitable height** for birds to **build nests** - Overhunting by humans - Competition from introduced species - Pollution

Question 37

What is conservation?

Answer 37

The **protection** and management of **natural habitats** and their ecological communities, to **enhance biodiversity** while allowing for suitable human activity

Question 38

How can species be conserved?

Answer 38

- Nature reserves - Sperm banks - Education - Legislations - Ecotourism

Question 39

How do sperm banks work?

Answer 39

**Store genes** of economically important animals and of **threatened species**

Question 40

What is ecotourism?

Answer 40

Responsible travel to **natural areas** that **conserves the environment** and improves the well-being of local people

Question 41

What are reasons for species conservation?

Answer 41

- Ethical reasons - Agriculture - If the environment changes, some alleles will provide an advantage to individuals, preventing the extinction of the species - Potential medical uses

Question 42

What is soil erosion?

Answer 42

The removal of topsoil, which contains valuable nutrients

Question 43

Other than CO2 production, what are consequences of deforestation?

Answer 43

- **Soil erosion** - Deforestation of uplands causes **lowland flooding** - **Destruction of habitats**, reducing biodiversity - **Less rainfall**, as water only returns to the atmosphere by **evaporation** from the soil, not by transpiration, and evaporation is slow

Question 44

Why is raising fish rather than pork, poultry and beef better?

Answer 44

- Fish convert their food into protein more efficiently - A greater proportion of fishes' bodies are edible - Fish farming has a lower carbon footprint

Question 45

What are problems that fish farming causes?

Answer 45

- Diseased fish: pesticides used to control fish parasites harm invertebrates - Pollution and eutrophication - Escaped fish outcompete wild fish for food, habitat and mates - Resource use: farmed salmon eat 3 times their bodyweight of other fish

Question 46

What are the 4 planetary boundaries that have been crossed?

Answer 46

- Climate change - Biodiversity - Land use change - Nitrate and phosphate (biochemical flows)

Question 47

What is a biofuel?

Answer 47

A fuel made by a biological process, such as anaerobic digestion

Question 48

What are some concerns related to biofuel production?

Answer 48

- 'Food vs fuel': **land used to grow food** is now used for **crop production for biofuels**, so less food is produced - Carbon emissions: **European bioethanol production** and **use reduce greenhouse gas** production - **Deforestation** occurs to grow biofuel crops - **Reduction in water availability**, as biofuel crops require a large volume of irrigation water - **Combustion of biodiesel** produces more **nitrous oxide**, a **greenhouse gas**, than fossil fuel

Question 49

What is the difference between the composition of biodiesel and petrodiesel?

Answer 49

- Biodiesel contains **less carbon** and **more hydrogen and oxygen** than petrodiesel - Biodiesel releases **less carbon particles** and **less carbon monoxide**, but **more nitrous oxide**

Question 50

What planetary boundary has been avoided, which are avoidable and which are unknown?

Answer 50

**Avoided:** Ozone boundary **Avoidable:** Ocean acidification, fresh water **Unknown:** Aerosol use, inorganic pollution

Question 51

What are some reasons for the reduction in freshwater availability?

Answer 51

- **Changing landscapes**: deforestation, draining wetlands and soil erosion influence the flow of fresh water - **Agriculture** consumes more fresh water than any other human activity - **Water pollution** e.g. eutrophication - **Climate change**: rising sea levels that contaminate freshwater - **Increase in population** due to increasing life expectancy

Question 52

What are some methods to increase freshwater availability?

Answer 52

- Water conservation - Wastewater reclamation - Desalination: where minerals are removed from salt water producing fresh water

Question 53

What are some environmental problems caused by desalination? (removing minerals from salt water)

Answer 53

- Brine (concentrated sodium chloride solution) is discharged, but is diluted before returning to ocean - Brine is denser than seawater so sinks and damages seabed ecosystem - Burning of fossil fuels to generate heat to run the desalination system

Question 54

What are atmospheric aerosols?

Answer 54

The **microscopic particles** put into the atmosphere by **combustion of fuels**, specifically diesel motor vehicles, and by creating **dust from digging and quarrying**