Organisms and environment

Question 1

Removal of carbon dioxide

Answer 1

1. Photosynthesis
   - Green plants absorb CO2 from atmosphere and use it produce glucose during photosynthesis
2. Feeding
   - Animals obtain carbon by feeding on plants and other animals

Question 2

Release of carbon dioxide

Answer 2

1. Respiration
   - Living organisms respire and oxidize glucose into carbon dioxide
2. Decomposition
   - Decomposers break down dead organisms to release CO2 into environment
3. Combustion
   - Fossil fuels are burnt to release CO2 from the carbon stored in them

Question 3

Importance of carbon cycle

Answer 3

1. Ensure continuous supply of CO2 for plants to carry out photosynthesis
2. Enable energy to flow through ecosystem as carbon compounds carry trapped solar energy from organism to organism in food chains in the form of chemical energy

Question 4

Carbon sinks

Answer 4

Carbon sinks are areas that absorb more carbon dioxide than they release
Examples:
- Oceans (photosynthesis, CO2 dissolve in water)
- Forests (photosynthesis)

Question 5

Importance of carbon sinks

Answer 5

1. Remove carbon dioxide from atmosphere
2. Reduce rate of global warming

Question 6

Eutrophication

Answer 6

The process where water receives excess nutrients like phosphates and nitrates, which causes excessive growth of algae and water plants

Question 7

Process of eutrophication

Answer 7

1. Untreated sewage / Excess fertilizer is washed into a water body
2. Nitrates and phosphates are nutrients that increase growth of algae and floating water plants in water body, covering water surface.
3. This causes submerged plants to die due to lack of sunlight
4. Aerobic bacteria decompose organisms and multiply rapidly, using up oxygen in water
5. This lack of oxygen causes other organism to die

Question 8

Bioaccumulation

Answer 8

Chemicals that are not excreted accumulate in bodies of organisms that consume them

Question 9

Bioamplification

Answer 9

Chemicals passes along the food chain and increasing in concentration in the bodies of organisms along the trophic levels

Question 10

Effect of plastic waste on ecosystem

Answer 10

1. Burning plastic waste enhances global warming
2. Marine animals mistake plastic for food and die
3. Microplastics are ingested, leading to bioaccumulation and biomagnification

Question 11

Reasons for conservation

Answer 11

1. Marine life is a major source of human food
2. Rainforests are a source of raw materials for industries
3. Studies on wildlife give an insight on humans

Question 12

Ways to reduce effects of enhanced greenhouse effect

Answer 12

1. Reduce the use of fossil fuels, opt for renewable sources of energy like solar and wind
2. Reduce consumption of energy. Use more energy efficient devices like LED light bulbs
3. Reduce daily consumption of electricity

Question 13

Forest management

Answer 13

1. Reforestation where new seedlings are planted to replace chopped down trees
2. Control forest fires
3. Education program should be conducted to make people aware of the importance of forests and the reason for its conservation

Question 14

Conservation of fishing grounds

Answer 14

1. Banning the use of drift nets, trawlers and dredges
2. Limiting the number of ships allowed in fishing grounds at any one time

Question 15

Conservation of coral reefs

Answer 15

1. Do not use sunscreen when diving
2. Do not touch the coral reefs
3. Do not buy live corals