Life on Earth

What is an ecosystem?

all of the living organisms and the non-living components in a habitat

What is a species?

organisms which interbred to produce fertile offspring

What is biodiversity?

Variety and abundance of living organisms in an ecosystem

What is a community?

all of the organisms living in a particular habitat

What is a population?

the number of one species living in a particular habitat

What is an autotroph?

an organism which can make its own food (green plants)

What is a heterotroph?

an organism which eats other organisms for energy

What is a herbivore?

an animal which only eats plants

What is a carnivore?

an animal which only eats animals

What is an omnivore?

an animal that eats both animals and plants

What is a predator?

an animal which hunts and eats other animals

What is prey?

an animal which is hunted and eaten by other animal

What is a food chain?

a food chain is a simple feeding relationship and it always starts with a producer

If an organism’s food source decreases/is removed from the food web, their numbers will…?

If an organism gains a new predator/ predators number increase, their number will…

If an organism’s competitor decreases in numbers or a predator decreases in number, their number will…?

What is a niche?

The role that an organism plays within a community

What does a niche include?

• The resources the organism requires in is ecosystem, such as light

• The organisms interactions with other organisms in the habitat, such as competition

• The conditions it can tolerate, such as temperature

Why might competition occur between plants?

• light

• space

• water

• soil nutrients

Why might competition occur between animals?

• food

• mates

• shelter

• water

What is interspecific competition?

Competition between two different species, they compete for one or a few resources

What is intraspecific competition?

Between the same species, they compete for all of the same resources and this type is more intense.

What is a biotic factor?

a living factor, for example, grazing

What is an abiotic factor?

a non-living factor, for example, temperature

Why do scientists take samples?

to find out the variety and number of organisms living there.

What is an indicator species?

an indicator species tell us about the level of pollution in an area by their presence or absence

What is stage one of photosynthesis?

Light reaction

What traps light during photosynthesis and where does it go?

Chlorophyll traps light into the chloroplasts.

What is chemical energy used to make during photosynthesis?

ATP

What happens to oxygen during photosynthesis?

It is diffused from the cell and out of the leaf

Water is split apart to produce what during photosynthesis?

Oxygen and Hydrogen

What are passed down to stage 2 of photosynthesis?

Hydrogen and ATP

What is stage 2 of photosynthesis called?

Carbon Fixation

What is used to produce glucose in photosynthesis?

Hydrogen, carbon dioxide are used with ATP.

What is sugar used for in plants?

• the chemical energy in sugar can be used for respiration.

• the sugar can be converted into other substances such as starch and cellulose.

What are the three limiting factors that can limit the rate of photosynthesis?

• Temperature

• Light intensity

• Carbon dioxide

The arrows in a food chain show the directions of…?

energy flow

The amount of energy available…what… as you move along a food chain?

Most of the energy during a food chain is lost from what?

• heat

• movement

• undigested materials

What is a pyramid of numbers used for?

Pyramid of numbers shows the relative number of each organism at each level of a food chain.

During harvest of soil what is lost that needs to be replaced after?

Nitrogen

Nitrogen is replaced by what after harvest?

• fertiliser

• compost

• manure

What can be used to reduce the use of fertiliser?

Genetically modified crops

What do plants make from nitrogen?

amino acids

What do animals eat plants (and other animals) for?

amino acids to make protein synthesis happen

What happens during the nitrogen cycle?

• Nitrogen is recycled through a set of processes called the nitrogen cycle.

• Bacteria and fungi are vital to the nitrogen cycle

What is a pesticide?

• pesticides are sprayed onto crops and can kill plants and animals which reduce crop yield.

What is bioaccumulation?

when pesticides build up in the bodies or organisms over time

What is a mutation?

• a random change to genetic material

• this changes the order of the DNA bases and can result in missing proteins or produce different proteins

The rate of mutations increases with..?

• radiation

• UV light

• X-rays

• Gamma rays

What is natural selection?

• when a species produces more offspring than their environment can support, some individuals die because of factors such as predation, food shortage or disease.

• Some individuals are better adapted to their environment do to inherited characteristics that give them a selective advantage.

What is speciation?

• speciation is the process which forms a new species

• speciation occurs after part of a population becomes isolated by an isolation barrier.

What are three isolation barriers?

• Geographical barrier

• Ecological barrier

• Behavioural barrier