How Humans Can Affect the Environment

Question 1

What do humans pollute?

Answer 1

• Waterways with sewage, fertiliser, and toxic chemicals
• Air with smoke and gases such as sulfur dioxide, which contributes to acid rain
• Land with toxic chemicals such as pesticides and herbicides. These can be washed into the water

Question 2

What is the difference between a pesticide and a herbicide?

Answer 2

A pesticide kills animals (pests)

A herbicide kills plants (herbs…)

Question 3

How do humans reduce the amount of land available for plants and animals?

Answer 3

By building, quarrying, farming, and dumping waste

Question 4

What is produced when goods are made?

Answer 4

Industrial waste

Question 5

How is the land polluted by humans?

Answer 5

• Sewage contains gut parasites and toxic chemicals. It must be treated properly to remove these
• Household and industrial waste placed in landfill can leak toxic chemicals. Some industrial waste, such as radioactive waste, is very hazardous
• Farming methods can pollute the land
• Herbicides and pesticides are poisons and can enter the food chain or be washed into rivers
• Chemical fertilisers can be washed into rivers

Question 6

How is water polluted by humans?

Answer 6

• Herbicides, pesticides, and chemical fertilisers are washed into rivers + streams
• Fertilisers and untreated sewage can cause a high level of nitrates in the water
• Toxic chemicals from landfill also leak into the waterways and pollute the water, killing organisms such as fish

Question 7

What produces sulfur dioxide and other acidic gases?

Answer 7

Burning fuels

Cars and power stations release them

Question 8

How is acid rain produced?

Answer 8

Sulfur dioxide dissolves in the water in the air, forming acidic solutions

The solutions then fall as acid rain

This can happen a very long way from where the gases were produced

Question 9

How can acid rain affect organisms?

Answer 9

• Trees can be damaged if the leaves are soaked in acid rain for long periods
• When trees are damaged, food and habitats for other organisms are lost
• Acid rain can also change the soil pH, damaging roots and releasing toxic minerals such as aliminium ions
• Enzymes are also very sensitive to pH

Question 10

What has deforestation caused?

Answer 10

• Increased the rate of CO₂ in the atmosphere due to the burning of trees or decay of wood by microorgamisms
• Reduced the rate at which CO₂ is removed from the atmosphere by photosynthesis
• Reduced biodiversity due to loss of food + habitats

Question 11

Why has deforestation occured?

Answer 11

• So that crops can be grown to produce ethanol-based biofuels
• So there can be increases in cattle + rice fields for food

Question 12

What has led to an increase in the levels of methane in the atmosphere?

Answer 12

Cattle + rice growing

Question 13

What does the destruction of peat bogs lead to?

Answer 13

• Releases CO₂ into the atmosphere
• The peat is used in compost
• The compost is then decayed by microorganisms
• The decay is what leads to the release of CO₂

Question 14

How is carbon dioxide sequestered?

Answer 14

It is removed from the air by plants in photosynthesis and by dissolving in oceans, rivers, and lakes

Question 15

What might an increase in the Earth’s temperature by only a few degrees celcius lead to?

Answer 15

• Changes to the Earth’s climate
• Rise in sea levels due to the melting of the ice caps and glaciers
• Reduce biodiversity
• Cause changes in migration patterns
• Result in changes in the distribution of species

Question 16

How is ethanol produced from starch for use as a biofuel?

Answer 16

• Microorganisms respire anaerobically to produce it
• Sugars from crops are used as the energy source
• Glucose is produced from maize starch using carbohydrase
• The ethanol is then extracted via distillation to be used as a fuel

Digestion -> Fermentation -> Distillation

Question 17

How is biogas produced?

Answer 17

By anaerobic fermentation by bacteria using waste carbohydrate

Question 18

Which gas is the fuel in biogas?

Answer 18

Methane

Question 19

How do biogas generators work?

Answer 19

• Provide the ideal conditions for bacteria to reproduce and germent the carbohydrates
• Maintained at a suitable temperature in an oxygen-free environment
• Some are designed to mix the contents
• They are either burried in the ground for insulation or have insulating jackets

Question 20

Where do large-scale, commercial generators use waste from?

Answer 20

Sugar factories or sewage works

Question 21

What makes biogas better quality?

Answer 21

More methane = better quality

Question 22

Aside from methane, what else do biogas generators produce?

Answer 22

Slurry, which can be used as a fertiliser

Question 23

Why is it more efficient for us to eat plants and not animals?

Answer 23

The food chain is shorter, so less energy will be wasted

Question 24

How can we produce meat more efficiently?

Answer 24

• Preventing the animal from moving so it doesn’t waste energy on movement
• This is seen as cruel by many so is contraversial
• Keeping the animal in warm sheds so it doesn’t use as much energy from food to maintain its body temperature

Question 25

What is sustainable food production?

Answer 25

Methods of producing food which can be sustained/carried out over time without destroying the fertility of the land or ocean

Question 26

How are fish stocks in the oceans preserved?

Answer 26

• They are monitored
• Fishermen have quotas
• Fishermen have to use certian sized nets to avoid catching small, young fish

Question 27

What is Fusarium used to produce?

Answer 27

Mycoprotein - a protein-rich food suitable for vegetarians

Question 28

How is Fusarium grown?

Answer 28

Aerobically on cheap sugar syrup made from waste starch in a fermenter

Question 29

What features do industrial fermenters have?

Answer 29

• Air supply providing oxygen for respiration
• Stirrers or gas bubbled used to keep the microorganism spread out and to provide and even temperature
• A water-cooled jacket around the outside, as the respiring microorganisms release energy which heats the contents (to maintain correct temp.)
• Sensors to monitor both pH and temperature

Question 30

What human activities can affect the global environment?

Answer 30

• Deforestation - can increase levels of CO₂
• Rice growing + cattle farming lead to increase in levels of methane
• Building dams to store water in reservoirs causes loss of habitat, drying out of rivers, and reduction of fertile land