Flowering Plants
2.17 Describe the process of photosynthesis and understand its importance in the conversion of light energy to chemical energy.
Photosynthesis is the process in which energy- from the sunlight- is used to create glucose.
Basically: Light energy > Chemical energy |
2.18 Write the word equation and the balanced chemical symbol equation for photosynthesis.
2.19 Understand how varying carbon dioxide concentration, light intensity and
temperature affect the rate of photosynthesis.
Carbon Dioxide
If there is insufficient carbon dioxide a plant will not be able to photosynthesis to its full potential. Because there is less carbon dioxide- less reactant- there has to be less product being made. |
Light intensity
If the light is at a low intensity the rate of photosynthesis is lowered because the energy that the light provides is less, so the reaction is slowed down. A higher light intensity will enable photosynthesis to happen faster. |
Temperature
In colder temperatures the rate of photosynthesis will decrease. If the temperature is too high however, the plant will not be able to photosynthesise. |
2.20 describe the structure of the leaf and explain how it is adapted for
photosynthesis.
Basic Adaptations
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Complex Adaptations
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2.21 Understand that plants require mineral ions for growth and that
magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids.
As well as water and sunlight, plants require mineral ions to grow.
Different mineral ions do different things, two key examples of this are:
Different mineral ions do different things, two key examples of this are:
- Magnesium ions:
- Which are needed for chlorophyll.
- Nitrate ions:
- Which are needed for amino acids.
2.22 Describe experiments to investigate photosynthesis, showing the evolution
of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll.
Experiment to investigate production of Starch:
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Experiment using Pond Weed:
Place plant under water and vary the different factors (light, carbon dioxide, chlorophyll).
The gas which the plant gives off as part of photosynthesis is oxygen. This amount of oxygen the plant is giving off can be measured by counting the bubbles. |
Humans
2.24 Identify sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of the diet.
Carbohydrates
Fats (lipids)
Vitamin A
Dietary fibre
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Proteins
Vitamin C & Iron
Vitamin D & Calcium
Water
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2.26 Describe the structures of the human alimentary canal and describe the
functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas.
2.27 Understand the processes of ingestion, digestion, absorption, assimilation
and egestion.
Digestion: process in which large insoluble molecules of food are broken down into smaller ones.
Absorption: the process by which soluble molecules produced by digestion are taken from the gut (occurs mostly in the small intestine.) The soluble products of digestion are then transported to the various tissues by the circulatory system.
Assimilation: the cells of the tissues that absorb the molecules for use.
Egestion: removal of waste (undigested products) as faeces.
Excretion: removal of waste products that have been in the body.
Absorption: the process by which soluble molecules produced by digestion are taken from the gut (occurs mostly in the small intestine.) The soluble products of digestion are then transported to the various tissues by the circulatory system.
Assimilation: the cells of the tissues that absorb the molecules for use.
Egestion: removal of waste (undigested products) as faeces.
Excretion: removal of waste products that have been in the body.
2.28 Explain how and why food is moved through the gut by peristalsis.
Peristalsis: the contractions of two sets of muscles in the walls of the gut. One set runs along the gut, while the other set circles it. Their wave-like contractions create a squeezing action, moving down the gut.
Muscles move food because mechanical action is needed to get food through the system.
Muscles move food because mechanical action is needed to get food through the system.
2.29 Understand the role of digestive enzymes, to include the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases.
Enzymes break down food into useful things that our bodies need. Different enzymes break down different components of our food.
Amylase and maltase > starch > glucose
Proteases > proteins > amino acids
Lipases > lipids > fatty acids and glycerol.
Amylase and maltase > starch > glucose
- Happens in mouth
Proteases > proteins > amino acids
- Happens in stomach and small intestine
Lipases > lipids > fatty acids and glycerol.
- Happens in small intestine
2.30 Understand that bile is produced by the liver and stored in the gall bladder,and understand the role of bile in neutralising stomach acid and emulsifying lipids.
- Bile is produce by the liver and stored in the gall bladder.
- Enzymes in the small intestine work best in alkaline conditions but the food is acidic after being in the stomach.
- Bile is alkaline and so when it is released into the small intestine it enables the enzymes to work.
- Bile also emulsifies fat; this gives it a larger surface area, which means that it is easier for lipases to work.
2.31 Describe the structure of a villus and explain how this helps absorption of the products of digestion in the small intestine.
The Villi can be found in the small intestine. They are raised lumps on the inside of the small intestine. Food diffuses into the blood stream through these surfaces.
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