Biology B4

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What is the equation for estimating population size?
number in first sample x number in second sample / number in second sample which were previously marked
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How are ecosystems self supporting?
They contain nearly everything they need to maintain themselves, water nutrients and essential elements are all recycled within the ecosystem. The only outside source is energy which usually comes from the sun.
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How is the distribution of organisms affected by abiotic factors?
Organisms are adapted to survive in certain physical conditions so are more likely to survive and repruce.
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What is zonation?
The gradual change in the distribution of species across a habitat.
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What is the difference between a natural ecosystem and an artificial one?
Natural ecosystems maintain themselves without human interference, with a higher biodiversity (native woodlands and natural lakes). Artificial ecosystems are created and maintained by humans (forestry plantations and fish farms).
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What are the two stages involved in photosynthesis?
First, light energy is used to split water into oxygen gas and hydrogen ions. Then carbon dioxide gas combines with the hydrogen ions to make glucose and water.
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Name three ways plants use glucose.
Respiration, making cell walls (glucose converted into cellulose), making proteins (glucose combined with nitrates to make amino acids which are made into proteins).
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What did Priestley's experiment show about plants?
He found that plants produce oxygen.
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What are the three limiting factors the control the rate of photosynthesis?
Light, carbon dioxide and temperature.
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What is diffusion?
The net movement of particles from an area of higher concentration to an area of lower concentration.
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What does the rate of diffusion depend on?
Distance, concentration difference and surface area.
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Name three ways leaves are adapted for diffusion.
They are broad so there is a large surface area for diffusion. They are thin so the carbon dioxide and water vapour only have to diffuse a short distance. The lower surface of the leaf is full of stomata which control the level of gas in and out.
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Name two ways leaves are adapted to absorb light.
The cells with the most chloroplasts are in the palisade layer near the top where they get the most light. The upper epidermis is transparent so the light can pass through to the palisade layer.
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What is osmosis?
The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
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What is lysis and crenation in an animal cell?
Lysis- the cell takes in too much water and bursts. Crenation- the cell loses too much water and shrivels up.
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What do phloem tubes transport?
Food
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What do xylem vessels take up?
Water
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What is transpiration? And why is it important to a plant?
It is the water loss from a plant and it is important as it provides a constant water supply for photosynthesis and creates turgor pressure.
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What four things increase the rate of transpiration?
An increase in light intensity, temperature and air movement and a decrease in air humidity.
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How are leaves adapted to reduce water loss?
A waxy cuticle on the upper epidermis, more stomata on the lower, darker side of the leaf and having fewer, smaller stomata on the leaf.
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What are the four main minerals needed for healthy growth?
Nitrates, phosphates, potassium (NPK) and magnesium.
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How does active transport work?
It uses energy from respiration to help the plant pull minerals into the root hair against the concentration gradient ( low to high).
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What increase the rate of decay?
Warmer temperature, more water and more oxygen.
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What are detritivores?
Detritivores feed on dead and decaying material, they break it up into smaller bits giving a bigger surface area for decomposers to work on, speeding up decay.
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What are saprophytes?
Saprophytes work by extracellular digestion- they feed by secreting digestive enzymes on the material outside their cells which break down the material into smaller bits to then be reabsorbed.
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What are the six ways to reduce rate of decay?
Canning, cooling, freezing, drying, adding salt/sugar and adding vinegar.
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What does intensive farming allow us to do?
Produce lots more food from lots less land, which means a huge variety of foods all yer round at low prices.
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How can intensive farming destroy the environment?
Fertilisers can cause eutrophication and removal of hedges can lead to soil erosion and loss of habitat.
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What is bio-accumulation?
As a pesticide is eaten at the first stage of the food chain, it can then not be broken down so builds up in the animals as it passes up the food chain, leading to death as the end as the animals has too much pesticides.
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Name five methods of organic farming.
Using organic fertilisers, crop rotation, weeding, varying seed planting times and biological control.
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Other cards in this set

Card 2

Front

How are ecosystems self supporting?

Back

They contain nearly everything they need to maintain themselves, water nutrients and essential elements are all recycled within the ecosystem. The only outside source is energy which usually comes from the sun.

Card 3

Front

How is the distribution of organisms affected by abiotic factors?

Back

Preview of the front of card 3

Card 4

Front

What is zonation?

Back

Preview of the front of card 4

Card 5

Front

What is the difference between a natural ecosystem and an artificial one?

Back

Preview of the front of card 5
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