B4 - The Processes of Life

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Cambridge IGCSE Biology Flashcards on B4 - The Processes of Life, created by franimal on 11/04/2013.

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Question Answer
What are the seven processes carried out by all living things? Movement, respiration, sensing, growth, excretion, feeding and reproduction.
What do enzymes do? Catalyse or speed up certain reactions.
What are enzymes made of? They're proteins, long molecules made up of long chains of amino acids.
Why is the type of amino acid in the enzyme important? Different amino acids fold into different shapes. What shape the enzyme is dictates what it does.
What is the lock and key model? A model for how a specific molecule has a specific shape, which fits into a corresponding enzyme during a reaction.
What part of the enzyme must the molecule fit into? The active site.
What happens to an enzyme if it gets too hot? It denatures - a permanent change where the active site deforms and the molecule no longer fits.
What is the temperature an enzyme works best at called? The optimum temperature.
What is the balanced equation for photosynthesis? 6 CO2 + 6 H20 = C6H1206 + 6 O2
What does chlorophyll do? Absorbs sunlight energy and uses it to kick-start photosynthesis.
What are the three ways glucose is used in plants? For making other chemicals needed for cell growth, storing energy in starch molecules and releasing energy in respiration.
What is diffusion? The movement of molecules from a high to a low concentration.
Diffusion doesn't need energy to work. What is this called? A passive process.
What are the stomata in plants, what are they for and why do they work? Tiny holes on the underside of a leaf that allow carbon dioxide out and oxygen in by diffusion. When the oxygen concentration is high in the leaf, the oxygen naturally diffuses out, with the opposite true for CO2.
What is osmosis? A specific type of diffusion that moves water into and out of cells.
Why is the cell membrane so important in osmosis? Partially permeable membranes allow small molecules such as water through but not big molecules such as glucose.
What is the main function of osmosis in plants? Forming the 'skeleton' of the plant by driving water from the roots, up the stem and into the leaves where it's used for photosynthesis.
Why is starch insoluble? If the plant stored glucose as glucose, the cells would bulge with water that travelled by osmosis into the glucose filled area.
Why is nitrogen needed in plants? To combine with glucose to make amino acids to make proteins.
In what form is nitrogen taken in by the plant? As nitrate ions.
Where and how are nitrate ions taken in by the plant? They're absorbed by the root hair cells, using active transport.
Why is active transport used instead of diffusion? Nitrates are in a higher concentration in the roots than in the soil - diffusion would carry them out, not in.
How does active transport work? A carrier protein in the cell membrane traps molecules and then releases them into the plant.
What factors effect the rate of photosynthesis? Light intensity, carbon dioxide and oxygen levels, water, chlorophyll.
Why do farmers try to ensure their plants have no limiting factors? The less limiting factors the faster the plant grows, the faster it grows the better the crop, the better the crop the higher the profits.
What is a quadrat and a transect? A quadrat is a square frame thrown randomly into an area so the plant life can be sampled fairly. A transect is a line of quadrats at regular intervals.
What are mitochondria? An organelle in animals and plants where respiration takes place.
What is aerobic respiration? The process of glucose reacting with oxygen to release energy and produce carbon dioxide and water.
How is anaerobic respiration in animals different from aerobic respiration? (3 points) It occurs when the body can't get oxygen to the cells fast enough, it produces lactic acid not CO2 and H2O, and is very, very inefficient.
How is anaerobic respiration in plants different from anaerobic respiration in animals? (1 point) Instead of lactic acid, ethanol and carbon dioxide are released.
When do humans use plant and microorganism respiration to their own advantage? Brewing, baking, yoghurt and cheese making. Alcohol, vinegar, biofuels and biogas.
How is biogas produced? Waste from humans or animals is broken down by bacteria, and the anaerobic respiration produces methane.
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