IGCSE Biology - Edexcel - Carbon and Water Cycles, Global Warming

Question 1

Describe the consequences of an increase in carbon dioxide for the world’s ecosystems (6 mark exam question)

Answer 1

• Increased greenhouse gases
• Greenhouse effect - trapping infrared heat
• Leads to global warming and an increase in temperature
• Leads to melting ice caps; rising sea levels; flooding
• Leads to drought; climate change and extreme weather (e.g. storms)
• Leads to loss of habitat
• Leads to acidification and desertification
• Leads to extinctions; food chain disruption and less biodiversity
• Can lead to migration; change in distribution; spread of disease / spread of pests

Question 2

Respiration

Answer 2

Adds carbon dioxide to the air.
Chemical change that takes place inside living cells, Uses glucose and oxygen to produce the energy organisms need to live.

Question 3

Photosynthesis

Answer 3

Removes carbon dioxide from the air.
A chemical process used by plants and algae to make glucose and oxygen from carbon dioxide and water, using light energy.
Oxygen is produced as a by-product.

Question 4

Decomposition

Answer 4

Break down of anime and plants (dead or waste) materials by bacteria or fungi.

Question 5

Combustion

Answer 5

Adds carbon dioxide to the air. The process of burning to produce heat.

Question 6

Acidification

Answer 6

Decrease in the pH of the Earth’s oceans, caused by the uptake of carbon dioxide from the atmosphere

Question 7

Desertification

Answer 7

When fertile land becomes desert, usually as a result of drought or deforestation

Question 8

Migration

Answer 8

Seasonal movement of animals from one region to another

Question 9

Global warming

Answer 9

The Earth becomes hotter as a result of increased greenhouse gases.
Can lead to climate change.

Question 10

Drought

Answer 10

climate change - a long period of none or low rainfall, leading to a shortage of water

Question 11

Greenhouse effect

Answer 11

1. The Sun’s rays enter the Earth’s atmosphere
2. Heat is reflected back from the Earth’s surface
3. This heat is absorbed by greenhouse gases and as a result becomes trapped in the Earth’s atmosphere
4. The Earth becomes hotter as a result and can lead to global warming and climate change.

Question 12

Greenhouse gases

Answer 12

Carbon dioxide, water vapour, methane and nitrous oxide are all greenhouse gases

Question 13

How can we reduce the amount of carbon dioxide being released into the atmosphere? (Exam question)

Answer 13

1. Reduce the use of fossil fuels (coal / oil / natural gas)
2. Use nuclear energy
3. Use renewable energy sources - such as: wind; sun; hydroelectricity; waves; today; geothermal.
4. Plant more trees / reduce deforestation / grow more plants
5. Use public transport / cycle / trains / fewer cars / electric cars;

Question 14

Biodiversity

Answer 14

The variety of plant and animal life in the world or in a particular habitat

Question 15

Deforestation

Answer 15

Removal of trees / forests.

Means that less carbon dioxide is absorbed from the atmosphere.

Question 16

How does deforestation affect the carbon cycle? (Exam question)

Answer 16

(less) photosynthesis;
2. more carbon dioxide in air / less carbon dioxide absorbed;
3. less consumption of plants / eq;
4. less decomposition / decay;
5. burning of trees produces carbon dioxide;

Question 17

Surface Runoff

Answer 17

Water, from rain, snowmelt, or other sources, that flows over the land surface

Question 18

Condensation

Answer 18

The process in which a gas (water vapour) turns into a liquid (water) by cooling.

Question 19

Precipitation

Answer 19

As water droplets in clouds get bigger and heavier, they begin to fall as rain, snow and sleet

Question 20

Evaporation

Answer 20

The process in which a liquid (water) turns into a gas (water vapour) by heating.

Question 21

Transpiration

Answer 21

The evaporation of water vapour
From the leaves of a plant
Through the stomata

Question 22

Explain the possible consequences of deforestation for the water cycle. (Exam question)

Answer 22

less transpiration /
less water loss from plants / eq;
2. less cloud formation / condensation;
3. less precipitation / rain /
less water falls on the ground / eq;

Question 23

Fossil fuels

Answer 23

Non renewable fuels made from the remains of living organisms
Heat and pressure produces fossil fuels over millions of years
Coal, Oil and Natural gas (methane)