Living Things and Their Environment

Question 1

Define the main key terms: ecology, habitat, population, community, ecosystem.

5 marks

Answer 1

• Ecology is the study of ecosystems.
• Habitat is the place or the location where an organism (or a biological population) lives.
• Population is how many of a species lives in an area.
• Community is an interacting group of various species in a common location.
• An ecosystem is how communities interact with each other.

Question 2

What factors influence environment?

7 marks

Answer 2

• Temperature
• Oxygen
• pH
• Water
• Pressure
• Radiation
• Nutrients

Question 3

Give an example of and explain an organism that has adapted to its environment.

5 marks

Answer 3

A polar bear is suited to its environment because:
* Its white fur helps it blend in with snow and ice
* Its small ears reduce heat loss
* Its large size reduces surface area, therefore reducing heat loss
* Its large paws spread its weight on the ice

Question 4

What causes changes in population sizes?

4 marks

Answer 4

• Immigration
• Emigration
• Lack/abundance of food
• Predators

Question 5

List and describe four factors limiting population growth.

8 marks

Answer 5

1. Predators - if a species is preyed on, it cannot grow as quickly.
2. Food availability - not enough food = less population growth.
3. Competition - more competition = less growth.
4. Birth rate - more births = more growth.

Question 6

Give an example of a food chain. Name the organisms at all trophic levels.

8 marks

Answer 6

Producer ==> Primary consumer ==> Secondary consumer ==> Tertiary consumer/Apex predator
Grass ==> Grasshopper ==> Snake ==> Hawk

Question 7

What is the role of decomposers in a food chain?

2 marks

Answer 7

Decomposers break down dead biomass into nutrients that can be used by plants.

Question 8

All energy in a food chain comes from the Sun, but only ……….% of energy is passed on to each level of the food chain.

1 mark

Answer 8

10%

Question 9

Green plants get their energy from 1)………., and animals get their energy from 2)………. .

Answer 9

1. Photosynthesis
2. Respiration

Question 10

Write out the word equation for aerobic an anaerobic respiration.

Answer 10

Aerobic
Glucose + Oxygen ====> Carbon dioxide + Water (+ energy)

Anaerobic
Glucose ====> Lactic acid (+ some energy)

Anaerobic in yeast
Glucose ====> Carbon dioxide + Ethanol (alcohol) (+ some energy)