Notesale: Turn your study into money

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BIOLOGY TOPIC 4
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Its word equation is:

FUEL + OXYGEN  CARBON DIOXIDE + WATER ( + ENERGY)

In the case of the candle, the fuel is the wax that the candle is made out of
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In the chemical reaction, we say that the oxygen releases the energy in
the fuel
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It is called
aerobic respiration
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With animals and people, the fuel is the food that we eat
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The chemical,
which is the fuel, is glucose (a type of sugar)
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The energy produced by respiration is used by all bodily functions
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If someone is
exercising, then they will obviously need a greater supply
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It is the blood which pumps the blood around the body
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When we exercise, the breathing rate also increases and gets deeper in order to supply the
blood with more oxygen to carry - and to remove all the carbon dioxide
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The glucose is incompletely oxidised
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In this reaction,
glucose releases energy without using any oxygen
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The
problem is that it also produces lactic acid
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When lactic acid builds up in the muscles, it eventually diffuses into the blood and is carried
to the liver
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So your body obtains a
quick burst of energy by anaerobic respiration
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Your pulse rate remains high
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This need for oxygen after
you have finished the exercise is called oxygen debt
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After 14 minutes her heart beat is
back to normal
Person B started off with heart beat of 80 beats/min
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Which person is fitter? _______

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Anaerobic respiration in plant and yeast cells

Plants also need energy for growth and other processes
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In plants the equation for anaerobic respiration:

GLUCOSE  ETHANOL + CARBON DIOXIDE (+ ENERGY)
Yeast is a single cell (fungus)
When it is kept at body temperature, 37oC and put into a glucose solution it will feed on the
sugar, grow and reproduce
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Ethanol is commonly known as alcohol
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It is used to produce
alcoholic drinks: wine, beer, vodka etc
The anaerobic respiration reaction in yeast is also used to make bread
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The carbon dioxide produced causes the dough (mixture
of flour and water) to rise
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Our metabolism is the sum of all the
reactions in a cell or the body
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g
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We obtain the glucose from the food
we eat
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Carbon dioxide and water are used to make glucose and oxygen - and - instead
of producing energy, energy is needed for the reaction to take place
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This reaction is called photosynthesis:

ENERGY FROM
SUNLIGHT

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When we eat the potatoes, or wheat etc
we have mechanisms to convert the carbohydrates back into glucose
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Photosynthesis takes place in
the chloroplasts
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It is the
chlorophyll which absorbs the energy in sunlight and converts it to the energy in glucose
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When sun shines on them, we can
see photosynthesis happening because we can see the bubbles of
oxygen produced by the leaves
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All the children will get a bag with a toy, a
dreidle, a chocolate coin and a funny hat
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You tell the organiser that you can only prepare 21 bags because there are only 21
funny hats
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In this case, the shortest
supply is the funny hats - so you can only increase the number of bags by getting
more funny hats
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If the organiser now gives you 30 more funny hats, now you can prepare _______
bags because the number of ____________________________ is now the limiting
factor
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For photosynthesis to take place, we have already learnt that we need





The light intensity
The temperature
The concentration of carbon dioxide, CO2, in the water
The amount of chlorophyll in the leaves

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For example, if a plant is grown with an ample supply of water and carbon dioxide
but is kept in a dark room then the plant will not grow well
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Increasing the amounts of water and carbon
dioxide will not help because the light is the limiting factor - and it is only by
increasing the amount of light that will increase the rate of photosynthesis
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Something else must be
the limiting factor

Light intensity

Rate of photosynthesis

High temperature

C
B

Low temperature

A

Light intensity

The graphs show the effects of increasing light intensity at different temperatures

Graph A shows that
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Farmers and crop growers will do as much as possible to maximise the yield of the crop
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They maintain plants in greenhouses which allow them to:
be grown at the optimum temperature
have extra carbon dioxide in the air for optimal growth
(by burning fuels inside the greenhouse)
provide the plants with maximum light – using artificial light if necessary
Farmers must balance these conditions without making the crops too expensive to sell at a
profit
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Uses of glucose from photosynthesis

Glucose is a high energy chemical
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g
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g
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This is made out of cellulose
o Producing amino acids which are used to produce protein
e

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