B4 Revision

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What are the seven life processes?
Mrs Gren - Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.
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What are enzymes?
Catalysts that speed up chemical reactions in living organisms. They are proteins.
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What are proteins?
Large molecules made up of long chains of amino acids.
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Explain the four steps of a Lock and Key model?
1) An enzyme has an active site. 2) The reaction takes place in the active site. 3) Only the correct molecule fits in the active site. 4) The product leaves the active site. The enzyme can be used again.
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How do enzymes work?
They break down large molecules or join small molecules together.
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Why do we need enzymes?
Because our bodies would not be able to create chemical reactions fast enough at 37 degrees, so enzymes are catalysts and they speed up these chemical reactions to keep us alive.
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What happens if the temperature in the human body is raised to 40 degrees?
Enzymes are denatured, which means their active site shape changes so the molecule no longer fits.
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How does the pH affect enzymes?
The pH can break down the bonds holding together the protein chains, so this results in the active site changing shape.
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What is the balanced chemical equation for photosynthesis?
6CO2 + 6H2O (+light energy) = C6H12O6 + 6O2.
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What is the word equation for photosynthesis?
Carbon dioxide + water = glucose + oxygen.
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Where does photosynthesis take place?
Chloroplasts.
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Why are chloroplasts green?
They contain a green pigment called chlorophyll.
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Describe the 3 main stages of making glucose from photosynthesis?
1) Light energy is absorbed by chlorophyll. 2) Atoms from water and carbon dioxide are rearranged. 3) Molecules of glucose are made.
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What are the three ways glucose is used in plants?
1) Making other chemicals needed for cell growth. 2) Storing energy in starch molecules. 3) Releasing energy in respiration.
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Where are Stomata found and what do they do? How does diffusion help them?
Stomata allow carbon dioxide into the leaf and oxygen out of the leaf. They are tiny holes found on the underside of the leaf. Diffusion drives these gases from high to low concentrations.
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What do partially permeable cell membranes do?
They let some molecules through them but not others.
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What is osmosis?
The diffusion of water across a partially permeable membrane.
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What does osmosis do in plants?
It drives water up the plant stem and regulates where the water in the plant goes.
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Why is glucose stored as starch?
Because if it was stored in cells as glucose then the water would move into the cell and it would burst. Starch is insoluble so it's okay.
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How do plants take nitrogen from the soil?
They take it as nitrate ions through root hair cells.
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What is active transport?
Active transport is when cells use the energy from respiration to transport molecules across the membrane.
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Give an example of active transport?
When plants take in nitrates against their diffusion gradient.
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When is active transport used?
When a cell needs to take in molecules that are in higher concentration inside the cell than outside.
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What are the five limiting factors in photosynthesis?
Sunlight, chlorophyll, water, temperature and carbon dioxide.
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What is aerobic respiration used for?
Every day respiration.
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What is the word equation for aerobic respiration?
Glucose + oxygen = Water + carbon dioxide (+energy released).
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What is the balanced symbol equation for aerobic respiration?
C6H12O6 + 6O2 = 6CO2 + 6H2O.
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What is anaerobic respiration used for?
When lots of energy is needed for short bursts of time.
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What is the word equation for anaerobic respiration?
Glucose = Lactic Acid (+energy).
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Where does anaerobic respiration occur in plants and microorganisms?
Germinating seeds and yeast.
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What is the word equation for anaerobic respiration in plants and microorganisms?
Glucose = Ethanol + Carbon dioxide (+energy released).
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Name two useful products from respiration?
Bioethanol (from sugar) and biogas (from waste).
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Other cards in this set

Card 2

Front

What are enzymes?

Back

Catalysts that speed up chemical reactions in living organisms. They are proteins.

Card 3

Front

What are proteins?

Back

Preview of the front of card 3

Card 4

Front

Explain the four steps of a Lock and Key model?

Back

Preview of the front of card 4

Card 5

Front

How do enzymes work?

Back

Preview of the front of card 5
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