Unit 3: Life On Earth

Question 0

What does an ecosystem consist of?

Answer 0

All living organisms living in a particular habitat and the non-living components with which organisms interact

ECOSYSTEM = HABITAT + COMMUNITY.

Question 1

What are biomes?

Answer 1

Biomes are various regions of the planet distinguished by their climate, fauna and flora. Global distribution can be influenced by temperature and rainfall.

Question 2

What is a niche?

Answer 2

A niche is the role the organism plays within the community. It includes the use it makes of the resources in its ecosystem like light, temperature and nutrient availability and it’s interaction with other organisms in the community including competition, parasitism and predation.

Question 3

What is the total variation within a region called? (Rainforest, ocean,
Earth)

Answer 3

Biodiversity

Question 4

Give examples of abiotic factors.

Answer 4

• pH
• temperature
• soil moisture
• rainfall
• light intensity

Question 5

Give examples of biotic factors.

Answer 5

• grazing
• predation
• food availability
• disease
• competition

Question 6

How can human activities affect the biodiversity of a region?

Answer 6

• pollution (acid rain)
• habitat destruction ( deforestation)
• over harvesting of an organism ( over fishing)

Question 7

How is acid rain formed?

Answer 7

When fossil fuels are burned and gases such as sulphur dioxide are produced.

Question 8

What is grazing?

Answer 8

When herbivores feed on plants and when grazing levels are low the diversity is low as a few dominant species prevent other species growing. As grazing intensity increases, species diversity increases.

Question 9

What is predation?

Answer 9

When one organism hunts another and can effect species within an organism.

Question 10

Explain what habitat, population, community and species are.

Answer 10

Habitat -place where an organism lives
Population - all the members of one species living in a habitat
Community - all the plants, animals and microorganism living in a habitat
Species - group of organisms that can breed to produce fertile offspring

Question 11

What are biomes?

Answer 11

Geographical regions of the earth that have similar climate ie. desert biomes have extremes of temperatures and very little rainfall.

Question 12

Explain what parasitism is.

Answer 12

When one organism feeds from a host. Only the parasite benefits from the relationship, usually harmful for the host
ie. Ticks feeding on blood of animal

Question 13

What does interspecific competition mean?

Answer 13

When individuals of different species require similar resources within an ecosystem. Sometimes, it’s possible for species to reach a compromise such as feeding on different fish in a loch.

Question 14

What does intraspecific competition mean?

Answer 14

When individuals of the same species require the same resources. As a result compromise can’t be reached and this type of competition is more intense.

Question 15

Name sources of error and how to minimise them for a pitfall trap.

Answer 15

• May not be able to climb into container - container is line with soil surface
• Trapped organisms may be eaten by birds - cover trap with raised stone or leaf
• Trapped organisms may eat each other - use a preservative (50% ethanol) in traps

Question 16

Name sources of error and how to minimise them for quadrating.

Answer 16

• Not placed randomly - ensure that quadrats are thrown at random
• Some plants that are partly in the quadrat are included and others are not - establish a rule for plants that are partially included and apply consistently to all quadrats in the study

Question 17

How do you calculate % increase/decrease calculations?

Answer 17

Change in number (final value-starting)
➗
Starting value

                          ✖️100

Question 18

Name some causes of loss of biodiversity.

Answer 18

• over fishing and over hunting
• habitat destruction (deforestation)
• pollution of air and water
• endangered species due to global warming
• desertification

Question 19

What are some problems with the increasing population?

Answer 19

• requires increased food yield

- in future the worlds food production will be insufficient to feed population

Question 20

How could food production be increased?

Answer 20

• genetic modification (GM crops)

- use more fertilisers and pesticides

Question 21

What are GM crops?

Answer 21

Crops produced that have had specific changes introduced into their DNA using the methods of genetic engineering

Question 22

Give examples of GM crops

Answer 22

• GM strawberries (gene from arctic fish so they are frost resistance(
• GM sweet corn (produces poison which kills harmful insects and the gene comes from a bacteria)

Question 23

Why use fertilisers?

Answer 23

-important for providing nutrients for increasing plant growth and crop yield but applied carefully so there’s no algal blooms

Question 24

What are problems with fertilisers?

Answer 24

• can leach into fresh water increasing algal blooms
• reduces light levels killing aquatic plants
• dead algae become food for bacteria
• bacteria increase
• reduces oxygen availability to other organisms

Question 25

What are pesticides?

Answer 25

Chemicals used by farmers to protect their crops from attack by pests and diseases and competitions from other plants

Question 26

Name problems with pesticides

Answer 26

• sprayed into crops can accumulate in bodies of organisms over time
• as passed along food chains, toxicity increases and reach lethal levels
• known as bioaccumulation example DTT

Question 27

What is used as indicator species?

Answer 27

The presence or absence of certain invertebrates can be used as an indicator of water pollution levels

Question 28

What are lichens?

Answer 28

Lichens are similar organisms to algae or fungi - indicators of air pollution

Question 29

What’s desertification?

Answer 29

A process by which fertile land turns into barren land or desert

Question 30

What’s biological control?

Answer 30

Method of using a natural predator to

Control pests

Question 31

What’s bioaccumulation?

Answer 31

When toxic chemicals build up (accumulate) in the tissues of an organism over times