Organisms & Their Environment

Question 1

Define producer

Answer 1

The organism at the 1st trophic level. They contain chlorophyll to convert carbon dioxide and water into glucose and oxygen, in the presence of light.

• The glucose they produce provides energy to organisms further up the food chain

Question 2

Define consumer

Answer 2

Organisms that obtain energy from feeding on other organisms as they cannot photosynthesise

Question 3

Define decomposer

Answer 3

Organisms that obtain energy by breaking down other dead organisms, faeces and excretory products.

• they released CO2 into the atmosphere
• and allow nutrients to return back to the soil

Question 4

Explain what Non-Cyclical flow of energy means?

Answer 4

Defin:
It means energy in the food chain does not return to its source (the Sun).

Exp:
- Only 10% of energy is TRANSFERRED from 1 trophic level to the next.
- 90% of energy is lost to the environment as heat from respiration, uneaten body parts & faeces

• This energy is not returned to the ecosystem

Question 5

Disadvantages of Using pyramids of numbers

Answer 5

1. Does not consider the size & mass of each organism
   1B. Does not state the energy required by each organism
2. Does not consider of the organism is an adult or juvenile
3. May not be representative of the feeding relationship between organisms

Question 6

1 Advantage & 1 Disadvantage of Using pyramids of biomass

Answer 6

Advantage
1. Considers the size and mass of the organisms

Disadvantage
1. Destructive to the ecosystem as organisms have to be killed to obtain dry mass for the pyramid

Question 7

3 Needs for Carbon Cycle?

Answer 7

1. Ensures continuous supply of CO2
   - Allows plants to photosynthesise and produce glucose and oxygen
   - CO2 is used for photosynthesis by plants to produce oxygen for organisms to respire
2. Regulates CO2 in atmosphere
   - CO2 released by organisms during aerobic respiration is used by plants for photosynthesis to produce glucose and oxygen.
3. Makes glucose for energy
   - Plants make glucose
   - Organism can feed on plants to obtain energy