Unit 3: Life On Earth Flashcards Preview

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Flashcards in Unit 3: Life On Earth Deck (32):

What are biomes?

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


What does an ecosystem consist of?

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



What is a niche?

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.


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



Give examples of abiotic factors.

- pH
- temperature
- soil moisture
- rainfall
- light intensity


Give examples of biotic factors.

- grazing
- predation
- food availability
- disease
- competition


How can human activities affect the biodiversity of a region?

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


How is acid rain formed?

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


What is grazing?

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.


What is predation?

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


Explain what habitat, population, community and species are.

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


What are biomes?

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


Explain what parasitism is.

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


What does interspecific competition mean?

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.


What does intraspecific competition mean?

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.


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

•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


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

•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


How do you calculate % increase/decrease calculations?

Change in number (final value-starting)

Starting value



Name some causes of loss of biodiversity.

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


What are some problems with the increasing population?

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


How could food production be increased?

- genetic modification (GM crops)
- use more fertilisers and pesticides


What are GM crops?

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


Give examples of GM crops

- 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)


Why use fertilisers?

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


What are problems with fertilisers?

- 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


What are pesticides?

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


Name problems with pesticides

- 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


What is used as indicator species?

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


What are lichens?

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


What's desertification?

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


What's biological control?

Method of using a natural predator to
Control pests


What's bioaccumulation?

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