Ecology 1

Question 1

What is ‘ecology’?

Answer 1

The study of the interactions between organisms and their environment.

Question 2

What is meant by the ‘biosphere’?

Answer 2

That part of the planet containing (living) organisms.

Question 3

What is an ‘ecosystem’?

Answer 3

A group of clearly distinguished organisms that interact with their environment as a unit. (e.g. grassland ecosystem, mild temperatures and low rainfall)

Question 4

What is a ‘habitat’ defined as?

Answer 4

The place where an organism lives. (e.g. school field)

Question 5

What is meant by the ‘population’ of an ecosystem?

Answer 5

All the members of a species living in an area.

Question 6

Define ‘community’.

Answer 6

All the different populations in an area.

Question 7

What is the difference between abiotic and biotic factors? Give examples of both.

Answer 7

‘Abiotic’ refers to non-living factors. (e.g. light intensity) ‘Biotic’ refers to living factors. (e.g. predation)

Question 8

What is the difference between ‘climatic’ and ‘edaphic’ factors?

Answer 8

Climatic factors refer to long-term weather. Edaphic factors refer to soil-related factors, such as soil pH.

Question 9

What is the difference between producers and consumers?

Answer 9

Producers carry out photosynthesis (make their own food). Consumers are organisms that take in energy from another organism (do not make their own food).

Question 10

What is meant by a ‘grazing’ food chain? Give an example.

Answer 10

A sequence of organisms in which each one is consumed by the next in the chain.

Question 11

What is a ‘trophic level’?

Answer 11

A feeding stage in a food chain.

Question 12

What is a ‘pyramid of numbers’?

Answer 12

It is a pyramid that represents the proportion of each trophic level based on their population in a food chain.

Question 13

What is a ‘niche’ in terms of ecology?

Answer 13

The (functional) role an organism plays in its community.

Question 14

Explain what is meant by ‘nutrient recycling’ and give two instances of this process.

Answer 14

• The way in which elements are exchanged between the living and non-living parts of an ecosystem.
• The Carbon Cycle and Nitrogen Cycle are examples of ‘nutrient recycling’.

Question 15

Outline what happens in the Carbon cycle.

Answer 15

1. Carbon dioxide is taken from the atmosphere by plants who use it for photosynthesis.
2. If plants decay ‘incompletely’, then fossil fuels will be formed, which can be burned to release CO₂ back into the atmosphere.
3. If the plants die normally, their remains are decomposed by by micro-organisms which again releases CO₂.
4. If the plants are eaten by animals, the animals respire, and die, both processes leading to release of CO₂.
5. Those parts of the animals (bones, teeth, etc.) that cannot be broken down by micro-organisms are slowly weathered releasing CO₂ to the environment.

Question 16

Outline what happens in the Nitrogen cycle.

Answer 16

1. Nitrogen in the atmosphere is converted to nitrates (NO₃^-) by nitrogen-fixing bacteria/lightning.
2. These are absorbed by plants to make their proteins.
3. Plants can die directly or be eaten by animals which die, both being decayed by bacteria and fungi of decay.
4. They form nitrogenous compounds in the soil (NH₃, etc.), which are converted to nitrites and then nitrates by nitrifying bacteria.
5. Some of the nitrates formed are absorbed by plants.
6. Denitrifying bacteria convert the remaining nitrates to N₂ gas again.

Question 17

Define ‘pollution’.

Answer 17

Any harmful addition to the environment.

Question 18

Give an example of domestic pollution. State a possible solution.

Answer 18

• CFCs in aerosols cause ozone layer depletion.
• Use of HFCs instead in aerosols will prevent this depletion.

Question 19

Define ‘conservation’?

Answer 19

The wise management of exisitng natural resources (maintain biodiversity, prevent exitinction, etc.)

Question 20

Give an example of conservation.

Answer 20

• In the fishing industry, overfishing is combatted by using nets with larger meshes to prevent smaller fish from being caught (they go on to survive and reproduce).
• Fishing quotas for certain species have also been used extensively.

Question 21

Give an example of waste management.

Answer 21

• In agriculture, waste produced by farm animals is spread over land to provide nutrients to crops. If this slurry runs into lakes, it can cause ‘eutrophication’ (lack of oxygen due to algal growth) and marine life dies.
• To prevent this, slurry is spread on dry land during the summer (no run-off).

Question 22

Name a role of micro-organisms in waste management.

Answer 22

They are used in landfill sites to decompose organic (biodegradable) matter. They are spread over waste in the form of soil.