B3, OCR 21st Century

Question 1

Species definition

Answer 1

A group of organisms that can breed together to produce fertile offspring

Question 2

Why do species adapt?

Answer 2

To increase their chance of survival

Question 3

Genetic variation

Answer 3

Differences between individuals of the same species

Question 4

Mutations in body cells

Answer 4

Little or no effect. Can lead to cancer

Question 5

Mutations in sex cells

Answer 5

Mutation will be passed on to the offspring

Question 6

Natural selection

Answer 6

“Survival of the fittest”. The process that causes evolution

Question 7

What is “Survival of the fittest”?

Answer 7

Competition between individuals for resources (E.G. food) leads to individuals evolving in order to increase their changes of survival. The mutation is passed on to offspring

Question 8

Selective breeding

Answer 8

Humans choose a feature they want to pass on, and only breed from animals or plants with that feature

Question 9

How can the process of evolution produce new species?

Answer 9

Sometimes groups of organisms of the same species become isolated from each other. Each group adapts differently, and new species are created. Factors - natural selection and environmental changes

Question 10

Can environment affect evolution?

Answer 10

Yes, species adapt to their conditions

Question 11

Evidence for evolution?

Answer 11

Fossils - show organisms getting more complex

DNA records - DNA controls the characterises of living things. All living things have evolved from the same simple life forms. The more closely related two species are, the more similar their DNA is

Question 12

Who proposed the theory of evolution?

Answer 12

Charles Darwin

Question 13

Who proposed an alternate evolution theory?

Answer 13

Lamarck - suggested a characteristic was passed on if it was used a lot by an animal, and passed on to offspring

Question 14

Biodiversity

Answer 14

Variety of life on earth

Question 15

What does biodiversity include?

Answer 15

• number of different species
• range of different types of organisms
• genetic variation between organisms of the same species

Question 16

Why is maintaining biodiversity so important?

Answer 16

• more plants we have = the more resources we have

- many new medicines have been discovered using chemicals produced by living things

Question 17

What is classification?

Answer 17

Organising organisms into groups according to similarities in their characteristics. First kingdoms, then into smaller and smaller groups

Question 18

Kingdoms

Answer 18

There are five different kingdoms into which all species on Earth can be grouped into

Question 19

What are the five kingdoms?

Answer 19

Bacteria, fungi, algae, plants, animals

Question 20

What is interdependence?

Answer 20

Organisms relying on other organisms, E.G. for food

Question 21

How do you work out the efficiency of energy transfers?

Answer 21

(Energy available to the next stage ÷ energy that was available to the previous stage) x 100

Question 22

What releases CO2 into the atmosphere?

Answer 22

• combustion
• plant respiration
• animal respiration
• decomposition

Question 23

How do carbon compounds get into plants?

Answer 23

Photosynthesis

Question 24

How do carbon compounds get into animals?

Answer 24

By eating plants

Question 25

How do carbon compounds get into the soil?

Answer 25

Decomposition of dead plants and animals

Question 26

What is the carbon cycle?

Answer 26

Cycle of carbon between the atmosphere, the soil and living things

Question 27

What is the nitrogen cycle?

Answer 27

Cycle of nitrogen between the atmosphere, the soil and living things

Question 28

What is nitrogen needed for?

Answer 28

For making proteins for growth . plants get it from the soil, but it needs to be turned into nitrates first

Question 29

What is nitrogen fixation?

Answer 29

The process of turning nitrogen from the air into nitrogen compounds (E.G. nitrates)

Question 30

Two ways of fixating nitrogen?

Answer 30

Lightning - energy in the bolt makes nitrogen react with the airnto give nitrates Nitrogen-fixing bacteria - in roots and soils

Question 31

Decomposers

Answer 31

Decompose proteins and urea and turn them into ammonia

Question 32

Nitrifying bacteria

Answer 32

Turn ammonia in decaying matter into nitrates (nitrification)

Question 33

Nitrogen-fixing bacteria

Answer 33

Turn atmospheric nitrogen into nitrogen compounds that plants can use

Question 34

Denitrifying bacteria

Answer 34

Turn nitrates back into nitrogen gas

Question 35

Non-living indicators used to measure environmental change?

Answer 35

- temperature. Taken over a long period of time could indicate that the climate of the environment is changing - nitrate level. Indicator of environmental change in a body of water - CO2 levels. Used to measure environmental changes in the air

Question 36

Living indicators of environmental change?

Answer 36

- lichen. Sensitive to levels of sukfur dioxide in the atmosphere, used to monitor air pollution - mayfly nymphs. Sensitive to levels of oxygen in water, indicator of water pollution - photoplankton. Indicator of water pollution

Question 37

Sustainability

Answer 37

Meeting the needs of today's population without harming the environment so that future generations can still meet their own needs