Unit 3 - Life on earth

Question 1

What is a habitat?

Answer 1

Where an organism lives.

Question 2

What is a population?

Answer 2

The total number of living organisms of one type/species living in a habitat.

Question 3

What is a community?

Answer 3

A community is made up of all the living organisms of all types in an ecosystem.

Question 4

What is an ecosystem?

Answer 4

An ecosystem consists of all the organisms living in a habitat and the non-living components with which the organisms interact. This includes the interactions of organisms in food webs.

Question 5

What is a species?

Answer 5

A group of similar organisms who can reproduce to produce fertile offspring.

Question 6

What is Biodiversity?

Answer 6

The term used to describe the variety of living things found in an ecosystem.

Question 7

What is a herbivore?

Answer 7

An animal that eats plants

Question 8

What is a carnivore?

Answer 8

An animal that eats other animals

Question 9

What is an omnivore?

Answer 9

An animal that eats both plants and other animals

Question 10

What is a producer?

Answer 10

A green plant that produces food by photosynthesis

Question 11

What is a consumer?

Answer 11

An animal that eats other organisms for energy

Question 12

What is a predator?

Answer 12

An animal which hunts and eats other animals

Question 13

What is a prey?

Answer 13

An animal which hunts and eats other animals

Question 14

What is a niche?

Answer 14

The role an animal plays within it’s community

Question 15

What is photosynthesis?

Answer 15

A series of enzyme controlled reactions occurring in green plant cells

Question 16

What happens in the first stage of photosynthesis?

Answer 16

In the light reactions stage, light is trapped by chlorophyll in chloroplast. The light is the converted into ATP and the light splits water taken in from the roots into hydrogen and oxygen. Oxygen then diffuses out of the plant as a waste product and the two raw material hydrogen and ATP are carried on to the next stage.

Question 17

What happens in the second stage of photosynthesis?

Answer 17

In carbon fixation, CO2 in the atmosphere diffuses into the plant and meets the two raw materials from the light reactions hydrogen and ATP. The hydrogen and the carbon dioxide fuse together with the energy provided by the ATP to produce glucose

Question 18

What can the glucose from photosynthesis be used for?

Answer 18

The chemical energy in the sugar is used in respiration, stored as starch or used to make cellulose for the plants cell walls (structural). The plant can also make fat and proteins from these carbohydrates.

Question 19

How do plants get nitrates and what do they use them for?

Answer 19

Plants absorb nitrates dissolved in soil water through their roots and are needed to synthesise amino acids which are needed by both plants and animals to synthesise proteins

Question 20

What is a mutation?

Answer 20

A mutation is a random change to genetic material, they occur spontaneously and are the only source of new alleles

Question 21

What does mutation create?

Answer 21

Mutations create variation within a population making it possible to evolve and change overtime in response to changing environmental conditions

Question 22

What is speciation?

Answer 22

• Speciation is the formation of a new species and occurs after part of a population becomes isolated by an isolation barrier which could be geographical ecological or behavioural/reproductive.
• Different mutations occur in each sub-population and natural selection selects for different mutations in each group due to different selection pressures.
• Each sub-population evolves until they become so genetically different they are two different species which can no longer reproduce to produce fertile offspring.