B3 - The effects of the population

Question 1

What do humans pollute?

Answer 1

Humans pollute:
• Waterways with sewage, fertiliser and toxic chemicals
• Air with smoke and gases eg. sulphur dioxide
• Land with toxic chemicals eg. pesticides and herbicides

Question 2

Why does building houses for humans affect animals and plants?

Answer 2

Land has to be cleared, which destroys their habitats.

Question 3

Why must sewage be treated?

Answer 3

Sewage must be treated properly to remove guy parasites and toxic chemicals or these could get into the land.

Question 4

Why does landfill cause pollution?

Answer 4

Landfill causes pollution because toxins leak out into the surrounding soil and into underground water.

Question 5

Name three affects of land pollution.

Answer 5

• Toxic chemicals from landfills can leak out and destroy soil
• Chemical fertilisers can be washed into rivers
• Poisons sprayed onto crops can get into the soil and into the food chain

Question 6

Name three reasons for water pollution: a

Answer 6

• Herbicides, pesticides and chemical fertilisers all get washed into rivers and streams
• Fertilisers and untreated sewage can cause a high level of nitrates
• Toxic landfill chemicals can leak into waterways and pollute the water, killing organisms eg. fish

Question 7

How might farmers keep their land fertile?

Answer 7

Farmers may use chemical fertilisers to keep the soil fertile, which can be washed into rivers.

Question 8

What is the definition of parasite?

Answer 8

Organism which lived in it on other living organisms and gets some or all of its nourishment from its host organism.

Question 9

What’s the definition of fertile?

Answer 9

A fertile soil contains enough minerals (eg. nitrates) to supply the crop plants with all the nutrients needed for healthy growth.

Question 10

How are birds affected by acid rain?

Answer 10

Acid rain can cause damage to trees, a source of food and habitat for birds.

Question 11

How do humans cause air pollution?

Answer 11

Humans cause air pollution by:
• Burning fuels - sulphur dioxide + acidic gases

• Power stations and cars - Acidic gases

Question 12

Why does acid rain affect areas a long way from where the sulphur dioxide is released?

Answer 12

Sulphur dioxide is blown by winds before it dissolves in the rain.

Question 13

What is the definition of deforestation?

Answer 13

Deforestation means that many trees are cut downs

Question 14

Which process removes carbon dioxide from the air?

Answer 14

Photosynthesis

Question 15

Why has deforestation occurred?

Answer 15

So that:
• Crops can be grown to produce ethanol based biofuels

• There can be increased in cattle and rice fields for food

Question 16

What the affects of deforestation?

Answer 16

• Reduced rate at which carbon dioxide is removed from the air
• Reduced biodiversity due to loss of food and habitats
• Increased release of methane in the atmosphere

Question 17

What is the definition of biodiversity?

Answer 17

The variety of animals and plants in a particular area or the world.

Question 18

How is carbon dioxide sequestered?

Answer 18

Carbon dioxide is removed from the air by plants in photosynthesis and by dissolving in oceans, rivers and lakes.

Question 19

Why might sea levels rise in the future?

Answer 19

If the climate gets warmer the ice will melt.

Question 20

How is ethanol extracted from the fermenter?

Answer 20

By distillation

Question 21

Why is ethanol described as carbon neutral?

Answer 21

Ethanol is described as carbon neutral because only the carbon dioxide used for photosynthesis by the crops is returned to the atmosphere when the ethanol is burned.

Question 22

Which gas is the fuel in biogas?

Answer 22

Methane

Question 23

Why are farm animals sometimes kept in warm sheds?

Answer 23

More of their energy used to maintain their body temperature, can be converted into new growth.

Question 24

Why is it more efficient for us to eat plants than it is to eat animals?

Answer 24

The shorter the food chain, the less energy is wasted.

Question 25

Why can’t fishermen remove small, young fish?

Answer 25

Fishermen cannot remove small, young fish because the population could become extinct if the young fish don’t grow and reproduce.

Question 26

What type of food is produced by Fusarium?

Answer 26

Mycoprotein

Question 27

What are the features of industrial fermenters?

Answer 27

• Air supply - oxygen for respiration
• Stirrers/gas bubbles - keep microorganism spread out and evens out the temperature
• Water-cooled jacket - on outside to prevent overheating
• Sensors to monitor both pH and temperature

Question 28

Why must biogas be produced anaerobically?

Answer 28

In aerobic respiration, the bacteria would produce carbon dioxide, not methane.

Question 29

Why is it important to prevent species from becoming extinct?

Answer 29

There may be unknown benefits to the human population that species can provide.

Question 30

Explain how greenhouse gases may cause droughts and rising sea levels.

Answer 30

• Reduce heat that is radiated by the Earth into space
• So more heat is radiated back to Earth
• Causes global warming
• Melts polar ice caps, rising sea levels and climate change

Question 31

Give one way the efficiency of human food production can be increased.

Answer 31

• Reduce the stages in the food chain

* Less energy is lost between the stages

Question 32

Give two ways in which global warming might affect species on a worldwide scale.

Answer 32

• Loss of habitats
• Changes in distribution
• Changes migration pattern

Question 33

Name two gases produced by burning fossil fuels.

Answer 33

• Sulphur dioxide

* Nitrogen oxides

Question 34

Describe three different ways in which people have reduced the amount of land for wild animals and plants.

Answer 34

• Building of roads
• Cleared land for building houses
• Industrial farming