20 Human influences on ecosystems

Question 1

Subsistence farming

Answer 1

Type of farming where the produce is used the feed the farmer and family rather than to sell at market for profit.

Question 2

Agricultural machinery

Answer 2

Agricultural machinery has developed from simple hand tools, and machines powered by animals, to large and complex powered machines.Wide-ranging uses of machinery include preparation of fields for planting and maintaining crops and harvesting.

Question 3

Fertiliser

Answer 3

A substance that contains important mineral ions needed for plant growth. It is added to soil by farmers and gardeners.

Question 4

Chemical fertilisers

Answer 4

A fertiliser is a substance that contains important nutrients for plant growth, such as magnesium and nitrates. It is used when these nutrients are missing from the soil, or are only present at very low concentrations. Fertilisers may be artificial (manufactured) or natural. The use of chemical fertilisers increases the yield of crops.

Question 5

Insecticides

Answer 5

Insect pest species can cause huge damage to crops by reducing the yield and increasing costs for farmers and consumers. Insecticides are substances that kill insects and, in doing so, protect the crop plants from damage.

Question 6

Herbicides

Answer 6

Plants compete with each other for resources such as light, soil nutrients and water. Weeds can grow rapidly among crop plants, using up the resources the crop plants need. Herbicides are substances that kill plants by disrupting their growth in some way. The most useful herbicides can kill weed species without harming the crop plants.

Question 7

Selective breeding

Answer 7

Selective breeding involves humans selecting individual animals or plants with desirable features, crossing them to produce the next generation, then selecting offspring that show the desirable features. This process is carried out over many generations to improve domesticated animals and crop plants

Question 8

The main methods that have been used to improve the amount and quality of food

Answer 8

Selective breeding
Herbicides
Insecticides
Chemical fertilisers
Agricultural machinery

Question 9

Monoculture

Answer 9

Growing a single crop across a large area

Question 10

Intensive farming

Answer 10

Intensive Farming refers to an agricultural system, wherein there is high level use of labor and capital, in comparison to the land area

Question 11

Advantages of intensive farming

Answer 11

Intensive farming is advantageous to farmers, as growing one type of crop or raising one type of animal improves efficiency, improves yield and reduces production costs.
Simplicity
Higher yields
Reduced costs
Larger land and machinery

Question 12

Disadvantages of intensive farming

Answer 12

Land clearance
Reduced biodiversity
Soil damage
Water pollution
Air pollution

Question 13

Extensive farming

Answer 13

Extensive Farming is a farming system, in which large farms are being cultivated, with moderately lower inputs, i.e. capital and labor. It is followed in densely populated region.

Question 14

Biodiversity

Answer 14

A measure of how many different species of organisms live in an ecosystem.

Question 15

Habitat destruction

Answer 15

Using more land for food crops, livestock Production and housing
The extraction of natural resources
Freshwater and marine pollution.

Question 16

Increased use of land

Answer 16

The size of the human population is increasing, with more land needed for housing and food production. According to the World Wide Fund for Nature (WWF), farming on land and in water are the greatest threats to species and ecosystems.

Question 17

Extraction of natural resources

Answer 17

Raw materials, such as minerals and oil, are needed for many industrial purposes. The extraction of crude oil and natural gas destroys habitats because:
Pollution is created by fuels when they are burned
The search for oil or gas damages natural habitats
Drilling and mining operations need wells, roads, pipelines and other facilities.

Question 18

Water pollution

Answer 18

Water pollution occurs when particles, chemicals or even unnatural sounds enter a freshwater or marine ecosystem:

Oil spills (Figure 4)
Untreated sewage
Careless disposal of rubbish
Mining waste
Nitrates entering rivers from fertiliser use
Herbicides and pesticides
Heavy metal runoff (this can carry toxic metals such as mercury that pose a danger to water life and human health).

Question 19

Deforestation and what it leads to

Answer 19

Deforestation is the cutting down of trees in forests. Deforestation is an example of habitat destruction. It can lead to:

reduced biodiversity
flooding
loss of soil
extinction of species
an increase in carbon dioxide in the atmosphere.

Question 20

Environmental effects of deforestation

Answer 20

Reduced biodiversity
Flooding
Loss of soil
Species extinction
Increased carbon dioxide

Question 21

Pollution

Answer 21

Release of any substance that has an undesired, unexpected, harmful or toxic effect on the environment.

Question 22

Water pollution causes

Answer 22

Untreated sewage: may carry harmful pathogens that cause disease; uses up oxygen when it rots; hormones affect reproduction of some organisms

Fertilisers: algal blooms and eutrophication

Question 23

Plastic pollution is caused by

Answer 23

Discarded rubbish
Rubbish can take a long time to decompose. The decomposition of rubbish can contribute to the low oxygen levels in water. This is a result of the decomposers reproducing rapidly and using up the oxygen. Some types of rubbish, such as plastics, take a very long time to decompose. Bacteria cannot digest these substances, so they are called non-biodegradable plastics.
Non-biodegradable plastic is a hazard for marine life. Birds, fish, turtles and other animals may mistake a piece of plastic for food.

Question 24

Air pollution is caused by

Answer 24

The air can be polluted by increased emissions of greenhouse gases, such as carbon dioxide and methane.
Carbon dioxide: volcanoes and during respiration in living organisms.
Human activity: burning fossil fuels, producing electricity
Deforestation: can also reduce the amount of carbon dioxide removed from the atmosphere during photosynthesis.
Building housing and growing livestock.

Question 25

Green house effect

Answer 25

The absorption of reflected radiation by greenhouse gases in the atmosphere that reduces the transfer of energy into space, so increasing the average temperature of the Earth.

Question 26

Sustainable resource

Answer 26

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

Question 27

NON- renewable resources

Answer 27

Something that is being used up faster than it is being formed.

Question 28

What land structures do we need to maintain

Answer 28

Forests are extremely important for biodiversity
The edges of rivers, to promote the retention of water
Mountain slopes, to reduce erosion
Areas with rare species and habitats .

Question 29

How to maintain forests

Answer 29

Setting quotas for logging, which may mean banning logging entirely in some areas
Using education programmes to help local people to understand why the forest is important
Creating protected areas.
Replanting trees

Question 30

Over fishing

Answer 30

Catching too many fish, causing the population size to decrease.

Question 31

How to stop over fishing

Answer 31

Education: Fishers must understand why it is important to maintain fish stocks. Education plays a vital role in this.
Closed seasons: The breeding season of a fish can be closed to fishing
Protected areas: This aims to provide safe havens for fish populations to recover from prior over fishing. Protected areas also protect aquatic biodiversity, which is essential to all ecosystems.
Quotas: Limiting the size and amount of fish caught is important
Controlling net types and mesh size: Regulating the size of the mesh used in the fishing net is an important way to conserve fish
Monitoring: To manage fish stocks sustainably, it is important to understand the biology of a fish species. This includes the age at which it reproduces, where it reproduces and the size of its population.

Question 32

Threats to wildlife

Answer 32

Destruction of habitat
Pollution
Climate change
Hunting
Introduced species
Overharvesting

Question 33

Climate change

Answer 33

Changes in long-term weather patterns associated with global warming and the greenhouse effect.

Question 34

Why is Population size and variation damaging to wildlife

Answer 34

As the size of a population decreases, genetic variation within the population is also reduced. This means that there are fewer different alleles expressing different phenotypes, so the population is less able to adapt to changes in the environment.

Question 35

What do Conservation programmes do

Answer 35

Monitoring and protecting species and habitats
Education
Seed banks
Captive breeding programmes.

Question 36

How do scientists do Monitoring and protecting of endangered wildlife

Answer 36

Monitor migration routes
Note changes in behaviour
Observe feeding and mating activities
Record changes to habitats.

Question 37

How can you help endangered Wildlife

Answer 37

Education
Seed banks
Captive breeding
Reproduction in captivity: Artificial insemination or In vitro fertilisation

Question 38

Reasons for conservation

Answer 38

Reduces extinction of species
Increases biodiversity
Protects ecosystems
Maintains important ecosystem functions.

Question 39

eutrophication

Answer 39

When fertilisers and untreated sewage enter water systems, there is an increase in nitrate concentration in the water.

These nitrates increase the growth of algae in the water, leading to algal blooms. Algal blooms on the surface of the water block sunlight.

Other aquatic plants cannot carry out photosynthesis.

These plants die and are decomposed by decomposers that carry out aerobic respiration.

The decomposers use up oxygen in the water. Eventually, fish and other organisms that require dissolved oxygen in water will die.