B3, OCR 21st Century Flashcards
Species definition
A group of organisms that can breed together to produce fertile offspring
Why do species adapt?
To increase their chance of survival
Genetic variation
Differences between individuals of the same species
Mutations in body cells
Little or no effect. Can lead to cancer
Mutations in sex cells
Mutation will be passed on to the offspring
Natural selection
“Survival of the fittest”. The process that causes evolution
What is “Survival of the fittest”?
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
Selective breeding
Humans choose a feature they want to pass on, and only breed from animals or plants with that feature
How can the process of evolution produce new species?
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
Can environment affect evolution?
Yes, species adapt to their conditions
Evidence for evolution?
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
Who proposed the theory of evolution?
Charles Darwin
Who proposed an alternate evolution theory?
Lamarck - suggested a characteristic was passed on if it was used a lot by an animal, and passed on to offspring
Biodiversity
Variety of life on earth
What does biodiversity include?
- number of different species
- range of different types of organisms
- genetic variation between organisms of the same species
Why is maintaining biodiversity so important?
- more plants we have = the more resources we have
- many new medicines have been discovered using chemicals produced by living things
What is classification?
Organising organisms into groups according to similarities in their characteristics. First kingdoms, then into smaller and smaller groups
Kingdoms
There are five different kingdoms into which all species on Earth can be grouped into
What are the five kingdoms?
Bacteria, fungi, algae, plants, animals
What is interdependence?
Organisms relying on other organisms, E.G. for food
How do you work out the efficiency of energy transfers?
(Energy available to the next stage ÷ energy that was available to the previous stage) x 100
What releases CO2 into the atmosphere?
- combustion
- plant respiration
- animal respiration
- decomposition
How do carbon compounds get into plants?
Photosynthesis
How do carbon compounds get into animals?
By eating plants
How do carbon compounds get into the soil?
Decomposition of dead plants and animals
What is the carbon cycle?
Cycle of carbon between the atmosphere, the soil and living things
What is the nitrogen cycle?
Cycle of nitrogen between the atmosphere, the soil and living things
What is nitrogen needed for?
For making proteins for growth . plants get it from the soil, but it needs to be turned into nitrates first
What is nitrogen fixation?
The process of turning nitrogen from the air into nitrogen compounds (E.G. nitrates)
Two ways of fixating nitrogen?
Lightning - energy in the bolt makes nitrogen react with the airnto give nitrates
Nitrogen-fixing bacteria - in roots and soils
Decomposers
Decompose proteins and urea and turn them into ammonia
Nitrifying bacteria
Turn ammonia in decaying matter into nitrates (nitrification)
Nitrogen-fixing bacteria
Turn atmospheric nitrogen into nitrogen compounds that plants can use
Denitrifying bacteria
Turn nitrates back into nitrogen gas
Non-living indicators used to measure environmental change?
- 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
Living indicators of environmental change?
- 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
Sustainability
Meeting the needs of today’s population without harming the environment so that future generations can still meet their own needs
