AQA Topic 4 - Bioenergetics

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  • Created by: Grace
  • Created on: 10-05-18 13:02
What does photosynthesis use for its process?
Energy
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Give the balanced equation for photosynthesis
6CO2 + 6H2O =(light)= C6H12O6 + 6O2
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Describe the process of photosynthesis
Photosynthesis takes place in chloroplasts in green plant cells which contain pigments like chlorophyll which absorb light. Energy is transferred to the chloroplasts from the environment by light
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Complete the sentences: Photosynthesis is ______ - this means energy is transferred ____ the environment in the process
1. Endothermic 2. From
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How do plants use glucose?
1. For respiration 2. Making cellulose 3. Making amino acids 4. Stored as oils or fats 5. Stored as starch
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Describe how plants use glucose for respiration
Respiration transfers energy from glucose which enables the plant to convert the rest of the glucose into various other useful substances
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Describe how plants use glucose for making cellulose
Glucose is converted into cellulose for making strong plant cell walls
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Describe how plants use glucose for making amino acids
Glucose is combined with nitrate ions, which have been absorbed from the soil, to make amino acids which are then made into proteins for plant growth
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Describe how plants use glucose for storing oils or fats
Glucose is turned into lipids - fats and oils - for storing in seeds
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Describe how plants use glucose for storing starch
Glucose is turned into starch and stored in roots, stems and leaves for when photosynthesis isn't happening i.e the winter.
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Why do plants store glucose as starch?
Starch is insoluble so does not draw in lots of water and swell, unlike a cell with lots of glucose in
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Name the limiting factors of photosynthesis
1. Light intensity 2. Temperature 3. Concentration of CO2
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When is light often a limiting factor?
During the night
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When is temperature often a limiting factor?
In the winter
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When is CO2 often a limiting factor?
When its warm enough and bright enough
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Why can chlorophyll be a limiting factor of photosynthesis?
The amount of chlorophyll can be affected in a plant w/ a disease/environmental stress (i.e lack of nutrients) = chloroplasts to become damaged/not make enough chlorophyll = the rate of photosynthesis is reduced bc they can't absorb as much light
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Study the graphs on page 58 for 'rate of photosynthesis'
N/A
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Describe an experiment that measures the effect of light intensity on the rate of photosynthesis (1)
A source of white light is at a specific distance from the pondweed which is left to photosynthesis for a set amount of time. As it ps' the oxygen released will collect in the capillary tube. At the end the syringe is used to draw the gas bubble in
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Describe an experiment that measures the effect of light intensity on the rate of photosynthesis (2)
the tube up alongside a ruler and the length of the gas bubble is measured. This is proportional to the volume of O2 produced. The experiment is then repeated with the light at different distances.
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Why must some variables absolutely be controlled in the previous experiment?
Because it may affect the results due to other limiting factors of photosynthesis. Variables that must be controlled include temperature and time
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Complete the sentence: As distance increases, light intensity _____ which means they are _____ proportional
1. Decreases 2. Inversely
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Describe the inverse square law
Light intensity decreases in proportion to the square of the distance
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Give the equation for inverse square law
Light intensity ∝ 1 ÷ distance (squared)
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What does the inverse square law mean?
For example, if you halve the distance the light intensity will be four times greater but if you third the distance the light intensity will be nine times greater
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How do greenhouses work?
Greenhouses artificially create the ideal environment for plants by trapping the suns heat to ensure the temperature doesn't become limiting. In winter a heater may be used to keep the temperature at optimum and in the summer shades/ventilation
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Why do commercial farmers use artificial light?
Once the sun goes down, no light is being supplied to the plants. Artificial light is used to elongate the time the plants photosynthesise for
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How can farmers increase CO2 levels in their greenhouse?
By using a paraffin heater, as the paraffin burns it makes carbon dioxide as a by-product
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Give an advantage of greenhouses
Keeping plants enclosed in a greenhouse makes it easier to keep them from pests and diseases, plus farmers can add fertilisers to the soil as well to provide all the minerals for healthy growth
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Why is it important that a farmer supplies the right amount of limiting factors?
The whole process can be expensive but if everything is provided in the right amount, the plants will grow faster and harvested more often = more money. However if amounts are given which the plants do not need it would be wasting money
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Define respiration
The process which transferring energy from the breakdown of glucose and it goes on in every cell in your body continuously
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True or False: All living things respire
True
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Why do all living things respire?
It's how they transfer energy from their food to their cells
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What sort of reaction is respiration?
Exothermic because it transfers energy to the environment
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Give three examples of how organisms use the energy transferred by respiration
1. To build up larger molecules from smaller ones i.e amino acids to proteins 2. In animals its used to allow the muscles to contract so they can move around 3. In mammals and birds the energy is used to keep their body temperature steady in the cold
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Define metabolism
Metabolism all all the chemical reactions in an organism
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What are most reactions controlled by? What do they form?
In a cell there are lots of chemical reactions happening simultaneously which are controlled by enzymes, many of the reactions link together to form bigger reactions
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Give 3 examples of large molecules being made from smaller ones
1. Lipid molecules are each made from one molecule of glycerol and three fatty acids 2. Glucose is combined with nitrate ions to make amino acids which are then made into proteins 3. Glucose joined to form glycogen(animal),cellulose or starch(plant)
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Give 2 examples of large molecules being broken down into smaller ones
1. Glucose is broken down in respiration to transfer energy to power all reactions to make molecules 2. Excess protein is broken down in a reaction to produce urea which is then excreted in urine
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Complete the sentence: Aerobic respiration involves _____
Oxygen
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What is the most effective way to transfer energy from glucose?
Aerobic respiration
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Where do most aerobic respiration reactions happen?
Mitochondria
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Give the balanced equation for aerobic respiration
C6H12O6 + 6O2 = 6CO2 + 6H2O
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What respiration is used the most
Aerobic, it occurs frequently in plants and animals
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When is anaerobic respiration used?
When you're doing vigorous oxygen, your body can't always supply enough oxygen to your muscles. They begin to do both anaerobic and aerobic respiration
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Complete the sentence: Anaerobic respiration involves _____ ______
Lactic acid
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Define anaerobic respiration
It's respiration without oxygen thats the incomplete breakdown of glucose which makes lactic acid
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Give the word equation for anaerobic respiration
Glucose = lactic acid
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Why is anaerobic respiration less efficient?
It transfers less energy than aerobic respiration because glucose isn't fully oxidised (because it doesn't combine with oxygen) so is only useful in emergencies i.e allow your muscles to keep going for longer
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Why is anaerobic respiration different in plants and yeast?
They produce ethanol and carbon dioxide instead of lactic acid
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Give the worded equation for anaerobic respiration in plants and yeast
Glucose = ethanol + carbon dioxide
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What is anaerobic respiration in yeast cells called?
Fermentation
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Why is fermentation useful?
In the food/drinks industry it is used to make bread and alcoholic drinks as in bread-making the CO2 makes the bread rise and in wine/beer fermentation produces alcohol
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Why do muscles need respiration? Why is this increased with exercise?
Muscles need energy from respiration to contract and when you exercise some of your muscles contract more frequently than normal so you need more energy which comes from increased respiration
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What does this increase of muscle contraction in exercise mean for cells? How does this happen?
It means that the cells have to be supplied with more oxygen. Therefore your breathing rate and breath volume increase to get more oxygen into the blood and your heart rate increases to get this oxygenated blood around the body faster
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Complete the sentences: As oxygenated blood moves around the body at an ______ rate, ____ is removed at the same pace
1. Increased 2. CO2
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Why is anaerobic respiration bad?
Lactic acid builds up in the muscles which gets painful. Long periods of exercise also causes muscle fatigue - the muscles get tired and then stop contracting efficiently
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What is an oxygen debt?
An oxygen debt is the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells. Oxygen reacts with the lactic acid to form harmless CO2 and water
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What leads to an oxygen debt?
After resorting to anaerobic respiration during exercise, when you stop exercising you'll have an oxygen debt
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Why do you have an oxygen debt?
You have provide the oxygen that you didn't get to your muscles in time because your lungs, heart and blood couldn't keep up with the demand earlier on
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What does an oxygen debt mean for you physically after exercise?
It means you have to keep breathing heavily after you stop exercising to get more oxygen into your blood which is transported to the muscle cells
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How can you tell if there are still high levels of lactic acid and CO2 in your body?
If your pulse and breathing rate stay high
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Describe the other way your body copes with the high level of lactic acid
The blood which enters your muscles transports the lactic acid to the liver where it is converted back to glucose
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Describe an investigation for the effect of exercise on the body
Measuring breathing rate by counting breaths and heart rate by taking the pulse at various intervals i.e sitting down for 5 minutes, 5 minutes after gentle walking, 5 minutes after running etc
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Other cards in this set

Card 2

Front

Give the balanced equation for photosynthesis

Back

6CO2 + 6H2O =(light)= C6H12O6 + 6O2

Card 3

Front

Describe the process of photosynthesis

Back

Preview of the front of card 3

Card 4

Front

Complete the sentences: Photosynthesis is ______ - this means energy is transferred ____ the environment in the process

Back

Preview of the front of card 4

Card 5

Front

How do plants use glucose?

Back

Preview of the front of card 5
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