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Photosynthesis
Respiration
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How do plants get the food they need?
All living organisms
need food to grow
and survive.
Plants are known as
producers because
they provide food for
many other organisms.
Plants cannot move
very much, so how
do they get the food
that they need?
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Nutrition in green plants
Green plants are amazing
because they actually
make their own food!
Green plants are the
only living organisms
that are able to do this.
All other organisms rely
on plants because of the
food that the plants make.
What is the name of the
process by which plants
make their own food?
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What is photosynthesis?
Plants make their own food by photosynthesis.
This process is a chemical reaction that uses light energy.
light energy
The word photosynthesis comes
from the Greek language:
“photo” means “light”
“synthesis” means “putting together”
Photosynthesis just means “putting together with light”.
What do green plants “put together” to make their food?
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Photosynthesis: raw materials
The raw materials
for photosynthesis
come from the air
and the soil.
What are these raw
materials called?
What else do plants
need to turn
carbon dioxide
and water into food?
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carbon
dioxide
water
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Photosynthesis: energy for the reaction
Photosynthesis is a
chemical reaction
between carbon
dioxide and water.
light
energy
Energy is needed
for this reaction to
take place.
Where do plants
get this energy
from?
carbon
dioxide
water
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Photosynthesis: where it happens
Plants use light
energy from the
Sun to power
photosynthesis.
light
energy
Where in the leaf
does this reaction
take place?
Photosynthesis
takes place in what
part of plant cells?
carbon
dioxide
water
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Photosynthesis: where it happens
Photosynthesis takes
place in plant cells
with chloroplasts.
light
energy
Chloroplasts contain
the green chemical
called chlorophyll.
Chlorophyll absorbs
the energy from
sunlight that allows
carbon dioxide and
water to react.
What are the products
of this reaction?
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chlorophyll
carbon
dioxide
water
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Photosynthesis: products of the reaction
The products of the
reaction between
carbon dioxide and
water are glucose
and oxygen.
light
energy
chlorophyll
Which of these
products is used
by plants?
What happens to the
‘waste’ product?
carbon
dioxide
oxygen
glucose
water
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Photosynthesis: products of the reaction
Glucose is the useful
product for plants.
Some glucose is used
straightaway by plant
cells, some is
converted to starch
for storage and later
used for food.
light
energy
chlorophyll
carbon
Oxygen is the ‘waste’
dioxide
product. This gas is
transported out of the
leaf into the air.
Why is this important
for humans and other
living things?
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oxygen
glucose
water
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Photosynthesis: summary
Summarize the process of photosynthesis in one sentence.
Photosynthesis is a chemical reaction
that takes place in the chloroplasts
in green plant cells, where light energy
is used to convert carbon dioxide and water
into glucose and oxygen.
Photosynthesis is a chemical reaction which means it can
also be summarized in a word equation.
What is the word equation for this vital chemical reaction?
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Photosynthesis: word equation
light energy
carbon
dioxide
water
glucose
oxygen
chlorophyll
light
energy
chlorophyll
carbon
dioxide
oxygen
glucose
water
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Photosynthesis: word equation activity
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Word equation to chemical equation
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Photosynthesis multiple-choice quiz
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Energy for life
Every living cell in your body needs energy. The average
adult has about 50 million million cells – that’s a lot of energy!
energy
Where does all this energy come from?
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In body cells, the energy needed for life comes from the
chemical energy stored in glucose. We eat to obtain
energy from food (plants).
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What is needed for releasing energy?
Burning is a chemical reaction in which energy is released
in the form of heat.
What other substance is needed for energy to be released
from this fuel?
fuel
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oxygen
?
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What does the body need for releasing energy?
The body’s energy-releasing process depends on the
digestive system and the breathing system.
What are the substances supplied by these systems?
glucose is the fuel
supplied
? by
the digestive system
oxygen
is supplied
?
by
the breathing system
How does the body’s energy-releasing process compare
with releasing energy from wood?
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Transport around the body
Glucose and oxygen enter the body
in different ways, but are needed at
the same destinations.
Where are these substances needed
and how do they get there?
Glucose and oxygen are
transported around the body
by the circulatory system.
Blood flowing in blood vessels
takes these important substances
to where they are needed – the
body’s cells.
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The body’s energy-releasing process
In the body’s cells, the chemical energy stored in glucose
is usually released by a chemical reaction with oxygen.
What is this energy-releasing process called?
respiration
glucose
oxygen
energy
Why does every living cell need a constant supply of
glucose and oxygen?
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What is respiration?
Respiration is the process used by the body’s cells
to release the chemical energy stored in glucose.
When oxygen is involved in this energy-releasing process,
it is called aerobic respiration.
What do you think aerobic means?
aerobic = ‘with oxygen’
Aerobic respiration is an efficient process that generates
enough energy to supply the whole body.
Our bodies perform aerobic respiration most of the time,
as long as the supply of oxygen remains high enough.
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Waste products of aerobic respiration
Aerobic respiration releases energy that is useful.
This process is a chemical reaction between glucose and
oxygen which also generates waste products.
glucose
oxygen
?
?
energy
Breathing in obtains the oxygen needed for aerobic
respiration. How does the body get rid of the waste products?
Breathing out removes the waste products of aerobic
respiration.
How can the waste products of this reaction be identified?
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Aerobic respiration: summary
Summarize the process of aerobic respiration in a sentence.
Aerobic respiration is a chemical reaction
that takes place in all living cells,
in which glucose reacts with oxygen
to produce carbon dioxide and water
and stored chemical energy is released.
Aerobic respiration is a chemical reaction so it can also be
summarized in a word equation.
What is the word equation for this vital chemical reaction?
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Aerobic respiration: word equation
glucose
oxygen
carbon
dioxide
water
energy
energy
glucose
oxygen
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carbon
dioxide
water
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Aerobic respiration: word equation activity
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What is aerobic respiration?
Respiration is the process used by the body’s cells
to release the chemical energy stored in glucose.
When oxygen is involved in this energy-releasing process,
it is called aerobic respiration.
What do you think aerobic means?
aerobic = ‘with oxygen’
Aerobic respiration is an efficient process that generates
enough energy to supply the whole body.
Our bodies perform aerobic respiration most of the time,
as long as the supply of oxygen remains high enough.
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Photosynthesis and respiration
Only green plants photosynthesize, but respiration occurs
in the cells of all living things to release energy.
Photosynthesis (energy needed)
light energy
carbon
dioxide
water
glucose
oxygen
chlorophyll
Respiration (energy released)
carbon
glucose
oxygen
dioxide
water
Compare the reactants, products and energy results of
these two chemical reactions. How are they connected?
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Photosynthesis and respiration
How will the amounts of oxygen and carbon dioxide
in the air vary over 24 hours?
amount of
oxygen
amount
of gas
in the air
amount of
carbon dioxide
12 a.m.
12 p.m.
12 a.m.
What overall effect do photosynthesis and respiration have
on the levels of oxygen and carbon dioxide in the air?
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