Unit 20 : Human Influences on Ecosystems

Question 1

5 Ways that Humans have increased food production

Answer 1

1. agricultural machinery to use larger areas of land and improve efficiency
2. chemical fertilisers help crops grow better
3. insecticides: a type of pesticide that kills insects
4. herbicides: a type of pesticide that kills weeds
5. selective breeding to improve production by crop plants and livestock

Question 2

Define Large-Scale Monoculture

Answer 2

the continuous production of one type of genetically identical crop

Question 3

4 Negative Impacts of Large-Scale Monoculture

Answer 3

1. if a natural disaster occurs, the whole crop could be wiped out.
2. if pests & diseases attack crops, they could harm them easily
3. using large fields and pesticides reduces the variety of species. This hinders biodiversity.
4. when insecticides are used persistently, the pests may eventually become resistant to them, reducing their effectiveness

Question 4

3 Negative Impacts of Intensive Livestock Production

Answer 4

1. welfare issues for the livestock
2. diseases can spread easily among them
3. waste can pollute land and waterways nearby

Question 5

Define Biodiversity

Answer 5

the number of different species that live in an area

Question 6

3 Reasons for Habitat Destruction

Answer 6

1. increased area for food crop growth, livestock production, and housing
2. extraction of natural resources
3. freshwater and marine pollution

Question 7

2 Effects of Habitat Destruction

Answer 7

1. by altering food webs and food chains, humans can harm habitats
2. deforestation

Question 8

4 Effects of Deforestation

Answer 8

1. reduced biodiversity/destroys habitats/extinction
2. loss of CO2 fixation, thus increase in CO2, thus global warming
3. soil erosion: tree roots cannot retain soil and go into rivers, making the water dirty & causing blockages, and the soil becomes less fertile
4. flooding: 75% of water is usually absorbed by foliage, root systems or evaporates. after deforestation, water accumulates in valleys.

Question 9

2 Pesticides that cause Pollution and how

Answer 9

1. insecticides (kill insects): meant to kill insects which eat crops, but can kill other useful insects such as bees, which are pollinators, or by bioaccumulation
2. herbicides (kill weeds): can be harmful to animals which eat the plants

Question 10

3 Effects of Non-Biodegradable Plastics

Answer 10

1. choke birds, fish and other animals
2. fill up the animals’ stomachs so that they can’t eat food
3. collect in rivers and get in the way of fish

Question 11

5 Effects of Global Warming

Answer 11

1. increase in the average temperature of the Earth
2. methane from the burping of cows
3. it started at the same time as humans began burning fossil fuels
4. scientists believe fossil fuels are causing this – not proven yet
5. it increased carbon dioxide and methane concentrations in the atmosphere, causing an enhanced greenhouse effect that leads to climate change

Question 12

Define Eutrophication

Answer 12

a process in which nutrients build up in a water body, resulting in an increased growth of micro organisms that may decrease the oxygen in water.

Question 13

Describe the process of Eutrophication

Answer 13

1. fertilisers are put in soil by farmers.
2. fertilisers with nitrates/detergents with phosphates leach into rivers and lakes after rain
3. water plants grow more than usual
4. they block sunlight and kill plants underneath
5. they die and sink to the bottom
6. bacteria/fungi decompose remains using the O2 and decreasing the O2 concentration
7. fish and other creatures die from oxygen starvation

Question 14

Define Sustainable Resources

Answer 14

one which is produced as rapidly as it is removed from the environment so that it does not run out

Question 15

How can Forests be Conserved and Managed Sustainably

Answer 15

forests can be conserved using education, protected areas, quotas and replanting.

Question 16

How can Fish Stocks be Conserved and Managed Sustainably

Answer 16

fish stocks can be conserved using education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring

Question 17

How is Water used and describe it’s supply

Answer 17

water is used to grow food, keep it clean, provide power, control fires, and drink. We get water constantly through rainfall, but we use the planet’s freshwater faster than it can be replenished

Question 18

Describe Fossil Fuel’s supply

Answer 18

fossil fuels must be conserved as they will soon run out; therefore, they should be replaced with green energy

Question 19

How can Water be Recycled

Answer 19

water from sewage can be returned to the environment for human use by sanitation and sewage treatment

Question 20

How can Paper be Recycled

Answer 20

sent to special centres where it is pulped to make raw materials for industry

Question 21

How can plastic be recycled

Answer 21

fossil fuels, bottles → fleece clothing

Question 22

Why is Metal Recycled

Answer 22

mining takes a lot of energy, so recycling saves energy

Question 23

5 Reasons why Species and Habitats need to be conserved

Answer 23

1. organisms have value in themselves (ethical value)
2. value to medicine (new molecules from exotic plants = new drugs)
3. genetic resources are helpful to humans as well and are lost when species disappear (DNA for genetic engineering)
4. each species has its role in its ecosystem; if it is removed, then the whole ecosystem could collapse
5. the use of artificial insemination (AI) and in vitro fertilisation (IVF) in captive breeding programmes

Question 24

How do Endangered Species become Endangered

Answer 24

climate change, habitat destruction, hunting, pollution and introduced species

Question 25

How can Endangered Species be Conserved

Answer 25

they can be conserved by monitoring and protecting species and habitats, education, captive breeding programmes, and seed banks

Question 26

4 Reasons for Conservation Programmes

Answer 26

1. reducing extinction
2. protecting vulnerable environments
3. maintaining ecosystem functions by nutrient cycling and resource provision, e.g. food, drugs, fuel and genes
4. increase biodiversity