Topic 7 - Ecology

Question 1

What is an ecosystem?

Answer 1

Ecosystem:

— The interaction of a community of living organisms and non-living parts of their environment.

Question 2

Define the terms:

• – Habitat
• – Population
• – Community
• – Biotic factors
• – Abiotic factors

Answer 2

• – Habitat: where an organism lives
• – Population: all the organisms of one species living in an environment
• – Community: the entire population of different species living in an environment
• – Biotic: the living factors of an environment
• – Abiotic: the non-living factors of an environment

Question 3

What resources do plants and animals compete for to survive?

Answer 3

Plants:

• – Mineral ions
• – Water
• – Light
• – Space

Animals:

• – Food
• – Water
• – Mates
• – Territory

Question 4

What is interdependence?

Answer 4

Interdependence:
— When species depend on other species for things such as food, water, shelter etc. If species are removed then it can have an effect on the entire community.

Question 5

What is a stable community?

Answer 5

Stable community:

— When all the species and environmental factors are in balance so population sizes remain fairly constant.

Question 6

Give examples of abiotic factors.

Answer 6

Abiotic factors:

• – Temperature
• – Light intensity
• – Carbon dioxide level for plants
• – Moisture levels
• – Wind intensity and direction
• – Oxygen level for aquatic animals
• – Soil pH and mineral content

Question 7

Give examples of biotic factors.

Answer 7

• – Predators
• – Competition
• – Pathogens
• – Food availability

Question 8

What is a producer?

Answer 8

Producer:

— An organism that makes its own food using energy from the sun. This is usually a green plant or algae.

Question 9

What is biomass? How is biomass energy transferred?

Answer 9

Biomass:

— The mass of living material. It is transferred when consumers eat other organisms

Question 10

What is the order of the food chain?

Answer 10

Producers - Primary consumer - Secondary consumer - Tertiary consumers

Question 11

What are prey and predators?

Answer 11

Prey:
— Organisms hunted and killed by a consumer. It is eaten by the predator.

Predator:
— Consumers that hunt and kill other animals

Question 12

What factors affect rate of decay of microorganisms?

Answer 12

Temperature:
— Warmer conditions = faster rate of decay

Oxygen availability:
— Many organisms require oxygen to decay

Water availability:
— Moister environment = faster rate of decay

Number of decay organisms:
— More microorganisms and detritus feeders = faster rate of decay

Question 13

Explain the carbon cycle.

Answer 13

• – Carbon dioxide is taken in by plants for photosynthesis
• – Plants respire and return some carbon dioxide into the atmosphere
• – Burning of fossil fuels adds carbon dioxide into the atmosphere
• – Animals feed on plants which transfer carbon compounds into fats and proteins in their bodies. The carbon then moves through the food chain.
• – Animals respire and return carbon into the atmosphere as carbon dioxide.
• – Plants, animals and algae die and are decayed by detritus feeders and microorganisms feed on their remains. These then respire and return carbon into the atmosphere.
• – Animals produce waste which is broken down by detritus feeders and microorganisms.

Question 14

How is biogas made?

Answer 14

• – Lots of different microorganisms decay plant and animal waste anaerobically which produces methane gas as a fuel
• – Made in a fermenter called a digester or generator.
• – Generator needs to be kept at a constant temperature.

Question 15

Compare both types of generators.

Answer 15

Batch generator:

• – Biogas in small batches
• – Manually loaded with waste

Continuos generators:

• – Makes biogas all the time
• – Waste is continuously fed in
• – Biogas produced at a steady rate
• – More suited for large-scale projects

Question 16

An increasing population causes an increase in waste management. What effect does this have on the environment? Explain each effect in detail.

Answer 16

Waste and chemical materials produce more pollution in water, in land and on air.

Water: Affect rivers, lakes and oceans which affect aquatic life and humans that rely on them for survival
Land: Toxic chemicals are used for farming. Nuclear waste is buried underground and household waste is dumped in landfill sites which are burned.
Air: Smoke and acidic gases released into the atmosphere pollute the air e.g. sulfur dioxide produces acid rain

Question 17

How do humans reduce land availability?

Answer 17

The land is used for:

• – building
• – quarrying
• – farming
• – dumping waste

Question 18

How does destoying peat bogs add carbon dioxide to the atmosphere?

Answer 18

Plants in bogs don’t fully decay as there is not enough oxygen therefore the partly-rotted plants build up to form peat. Carbon is stored in the plants in the peat. Peat bogs are drained to use as farmland or used as garden compost. This reduces the area of the habitat which decreases biodiversity.

The decay or burning of peat as fuel adds carbon dioxide into the atmosphere.

Question 19

What are some of the biological consequences of global warming?

Answer 19

— Increase in temperature
— Wider distribution of animal and plant species which causes a lack of biodiversity
— Change in migration patterns of birds
— Water expands and ice melts causing rising sea levels

Question 20

What contributes to global warming?

Answer 20

— Burning of fossil fuels which increases levels of carbon dioxide in the atmosphere.
— Decay adds methane to the atmosphere
— Methane and carbon dioxide are greenhouse gases and they absorb energy from the sun as they act like an insulating layer

Question 21

How is biomass transferred between tropic levels?

Answer 21

Consumers eat other plants and animals which transfers about 10% of biomass to the next tropic level

Question 22

What are the causes for a loss of biomass?

Answer 22

• – Organisms don’t eat every single part of the organism they are consuming
• – Not all ingested material is absorbed as some are egested in faeces
• – Some absorbed material is lost as waste

Question 23

What biological factors affect food security?

Answer 23

Factors affecting food security:

• – Increasing population
• – Changing diets in developed countries therefore scarce foods are transported around the world
• – New pests and pathogens affect farming
• – Changes in environmental conditions affect farming
• – High costs of agricultural inputs so it is hard to maintain food production
• – Conflict

Question 24

How can food production be made more efficient?

Answer 24

• – Limit movement of livestock and keep them in a temperature-controlled environment therefore less energy is used by the livestock. This results in more energy for growth so more food is produced.
• – Raise some livestock in small pens or cages which restricts their movement
• – Feed livestock high-protein food to increase growth