Unit 3- Life On Earth Flashcards
What are biotic factors?
Biotic factors are activities of living things.
examples of biotic factors?
Food available
Number of predators
Disease
Level of competition
What are abiotic factors?
A biotic factors are non living factors.
Examples of abiotic factors?
Temperature, rainfall, light intensity, concentration of oxygen and PH.
What is an ecosystem?
Is a natural biological unit of the environment and is made of living and non-living parts. And ecosystem contains one or more habitats.
What is grazing?
Grazing is a biotic factor that can affect spices diversity in a grassland.
What is predation?
Predation is a biotic factor that affects the numbers of both the population of a prey animal and the population of its predator because a delicate balance exists between the two.
What is a biome?
A biome is a large region of the earth that can be distinguished from other biomes by the characteristic abiotic factors that affect it, the particular animal community (fauna) and plant community (flora) that it possesses.
What is a niche?
An organisms niche is the role that it plays within a community.
What is a food chain?
A food chain is a relationship where one organism feeds on the previous one in the series and in turn provides food for the next one.
What does a food chain begin with?
Producer
What does each arrow in a food chain indicate?
Indicates the direction of energy flow.
How much energy is lost at each stage of the food chain?
90%
What is biodiversity?
Biodiversity means the total variation that exists amongst all living things on earth.
The relationship takes the form of a pyramid because?
- the energy lost at each link in the food chain limits the quantity of living matter that can be supported at the next level.
- the final consumer tends to be larger in body size than the one below it, and so on.
What is the biomass of a population?
Is its total mass of living matter.
How much of the air consists of nitrogen gas?
80%!!!
Plants absorb nitrogen from the soul in the form of?
NITRATE
What is nitrogen?
Nitrogen is a chemical element that is cycled around an ecosystem.
What happens at arrow one in the nitrogen cycle?
Decomposer bacterial bring about the decomposition of dead bodies and nitrogenous waste, releasing ammonium compounds into the soil.
What does the arrow marked 2 represent?
The process of nitrification.
What does nitrifying bacteria convert ammonium compounds into?
Nitrites and then further nitrifying bacteria convene nitrites to nitrates that can be used by plants.
What does arrow 3 represent in the nitrogen cycle?
Represents the process of denitrification. Denitrifying bacteria deprive the soil of nitrogenous compounds by breaking down nitrates and releasing nitrogen gas into the air.
Other bacteria live inside swellings called?
Nodules. On the root of leguminous plants such as pea, bean and clover.
Many types of fertilisers contain?
Nitrate to enrich the soil and bring about an increased yield of crops.
What is interspecific competition?
Occurs between members of DIFFERENT species but they compete for the SAME food.
What is intraspecific competition?
Where members of the SAME species compete for the SAME food!
What type of competition of more intense?
Intraspecific. As the competing individuals have identical needs.
Possible sources of error of a pitfall trap?
- The numbers and types of animals may not be representative of the ecosystem as a whole.
- Birds may eat trapped animals
- Some animals may eat others
Ways and which errors nah be minimised with pitfall traps?
- set up several traps
- disguise the opening with a lid such as a leaf supported on sticks
- check traps regularly or put preservative liquid such as 50% ethanol in the bottom of the traps.
What are quadrants used for?
Measuring the abundance of plants
Possible errors of quadrants?
- ten quadrants may be too small a number of samples to give a fair representation of the number of plants present in an ecosystem.
- might identify the plant wrongly
What is a mutation?
A mutation is a change in the structure or composition of an organisms genetic material.
Mutation is the only source of?
New variation amongst living things.
What is an adaptation?
Is an inherited characteristic that makes an organism well suited to its environment.
Many offspring die before reaching reproductive age as a result of factors such as?
- competition
- lack of food
- overcrowding
- inability to escape predators
- lack of resistance to disease
What is survival of the fittest?
Those offspring whose phenotypes are better adapted to their environment have a better chance of surviving, reaching reproductive age and passing on genes for favourable characteristics to their offspring.
What is a species?
A species is a group of living things that are so similar to one another genetically that they are able to interbreed and produce fertile offspring.
What is speciation?
Speciation is the formation of new species. It occurs when a population becomes isolated from the other members of its species for a very long time or permanently.
Examples of geographical isolation barriers?
Rivers, desert, a sea or a mountain change.
Examples of ecological isolation barriers?
Caused by differences in temperature, humidity or pH.
Humans have uses their expectional brainpower to?
- remove the threat of predation
- develop vast areas of land for food production
- improve public health
What is leaching?
If fertilisers from field leaches into a river or loch, it make the ware over-rich in mineral nutrients such as nitrate. This promotes a rapid growth of algae, which form an algal bloom.
What is an biological control?
The reduction of a pest population by deliberate introduction of one of its natural enemies such as a predator or a parasite.
Example of a biological control?
The use of a ladybird to clear greenfly from plants.
