B3 - Life on Earth

When do scientists estimate that life on Earth began?
3500 million years ago
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Why are some species isolated from one another?
So they cannot interbreed
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How would two organisms develop differently?
They can be isolated from eachother and placed in different environments. Different mutations can cause new features. Natural selection works on the new features so they are passed on. Then, environmental differences can cause more mutations.
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What is the evidence for evolution?
Fossil records and DNA
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How do fossil records show evidence for evolution?
They show species getting more and more complex over time.
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How does DNA show evidence for evolution?
Scientists can use similarities and differences in the DNA of two same species organisms to work out how life has evolved.
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Charles Darwin had the theory of:
Evolution by natural selection
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How did Charles Darwin form his theory?
Making many observations and applying creative thought to his findings.
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What was the name of the other scientist who had a theory about Evolution?
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What did Lamarck argue?
If a characteristic was used a lot by a certain animal it would become more developed. The aquired characteristic would then be passed down to offspring.
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What is an example of how Larmarck's theory would work?
If a rabbit did a lot of running and developed big leg muscles, the rabbit's offspring would also develop big leg muscles.
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Why was Larmack's theory rejected?
Aquired characteristics don't have a genetic basis therefore they cannot be passed on.
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What are the three things biodiversity includes?
1) The number of different species on Earth. 2) The range of different types of organisms 3) The genetic variation between organisms of the same species
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Why is maintaining biodiversity important? (Give 2 reasons)
1) The more plants we have available, the more resources there are for developing food crops. 2) Many new medicines have been discovered using chemicals produced from living things.
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Why is the rate of extinction in species increasing?
There is a correlation between the growth of the world's population and the number of species extinctions.
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How have humans caused direct extinction?
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How have humans caused indirect extinction?
Destroying an organisms habitat or introducing a new species it can't compete with.
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What is 'Classification'?
Organising organisms into groups
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What 3 factors do scientists use to classify organisms?
1) Physical features 2) Similarities in characteristics 3) Similarities in genetics (such as DNA)
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What are the 5 different kingdoms?
1) Bacteria 2) Funghi 3) Algae 4) Plants 5) Animals
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As you go down the groups in a classification, the number of types of organisms in each one ..........
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As you go down the groups in a classification, the number of characteristics the organisms have in common ............
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Why is classification useful?
Shows the evolutionary relationships between different organisms.
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What is the role of an organism's environment?
Provides factors that are essential for life
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What 4 main things are provided by an organism's environment?
1) Light 2) Food 3) Oxygen 4) Water
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What happens if one fof the main factors provided by an organism's environment is in short supply?
The species that need it must compete for it. Those who dont get it will die. This limits the size of the population in their habitat.
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What is 'Interdependence'?
When organisms depend upon other organisms (usually for food)
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Where does nearly all the energy in an ecosystem come from?
The sun
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What do plants do with light energy from the Sun?
They use a small percentage and store it by converting it to chemicals which make up plant cells.
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How is energy transferred within an ecosystem?
When animals eat plants and other animals; when decomposers feed on parts of dead organisms and waste materials.
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What happens to some of the energy at each stage?
it is lost
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How is most of the energy eventually lost?
As heat or waste products
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Why don't we see food chains with more than 5 stages?
So much energy is lost at each stage that there's not enough left to support more organisms past this point.
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How do you calculate efficiency?
(Energy available to the next stage / Energy that was available at the previous stage) x100
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In an energy flow diagram, what do the numbers show?
The amount of energy available to the next stage of the food chain.
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How do you work out how much energy has been lost at each stage?
Energy available at next stage - energy available at previous stage
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What unit do you display efficiency in?
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The first non-living indicator is........... (begins with a T)
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How does temperature act as a non-living indicator?
Temperature measurements taken over a long period of time can indicate that the climate of the environment is changing (eg. Global warming)
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What is the second non-living indicator? (Begins with an N)
Nitrate level
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How does nitrate level act as an indicator of environmental change?
It works in a body of water. An increase in this level could be because of sewage or fertilisers entering the water, showing that it is being polluted.
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What is the third non-living indicator? (Begins with a C)
Carbon Dioxide level
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How does the Carbon Dioxide level act as a non-living indicator?
an increase in Carbon Dioxide could be caused by human activities such as burning fossil fuels. Increasing CO2 also means an increase in the rate of global warning.
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What is the first living indicator? (Begins with an L)
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How do Lichen act as living indicators?
Air pollution can be monitored by looking at particular types of lichen which are sensitive to levels of CO2 in the atmosphere. The number and type of lichen at a particular location indicate how clean the air is.
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What is the second living indicator? (Begins with M, then N)
Mayfly Nymphs
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How do Mayfly Nymphs act as living indicators?
When bacterial population increases in a river due to polution, oxygen is used up. Mayfly nymphs are sensitive to levels of oxygen in the water. If you find them in the water, the water is clean.
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What is the third living indicator for measuring environmental change? (Begins with a P)
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How do Phytoplankton act as a living indicator?
They live in water. Populations increase when levels of nitrates and phosphates in the water increase. Adding fertilisers and sweage causes increase in nitrates and phosphates. More algae therefore indicates water pollution.
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Define 'Sustainability'
Meeting the needs of today's population without harming the nevironment so that future generations can still meet their own needs.
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What does loss of biodiversity mean for future generations?
They won't be able to get the things they need from the environment that we can get today.
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Give an example of unsustainable living
Large-scale monoculture crop production is where farmers grow only one type of crop. Doesn't help maintain biodiversity. A single type of crop will therefore support fewer species.
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What could the extinction of some species mean for humans in the future?
Reduction in ability to produce food or find new medicines.
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Why is it unsustainable to throw packaging materials away? (Give 3 reasons)
1) The resources that have gone into making the material can't be reused so they aren't available to future generations. 2) Lots of energy has been used to make the packaging materials 3) Most waste thrown to landfill sites; taking up space
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What is the first way we can improve sustainability of packaging materials and why does this work?
Using renewable materials as the resources can be replaced.
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Give an example of a renewable resource we can use and how it is renewable.
We can use paper and card to improve sustainability as we can replant the trees.
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What is the second way we can improve sustainability of packaging materials?
Using less energy
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Why would using less energy be sustainable?
The environment isn't damaged as much because less energy from burning fossil fuels is required.
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What is the third and final way packaging materials can be made more sustainable?
Creating less pollution
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Using an example, how does creating less pollution lead to more sustainable packaging?
Using biodegradable packaging creates less pollution (Eg wood,) which rots away easily.
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What is, overall, the most sustainable thing to do in terms of packaging?
Use less packaging material
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Other cards in this set

Card 2


Why are some species isolated from one another?


So they cannot interbreed

Card 3


How would two organisms develop differently?


Preview of the front of card 3

Card 4


What is the evidence for evolution?


Preview of the front of card 4

Card 5


How do fossil records show evidence for evolution?


Preview of the front of card 5
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