Download The Sun and our energy sources

© 2009 Marshall Cavendish International (Singapore) Private Limited
Questions to think about…
How do plants
get their food?
What is the
source of energy
for animals?
How is the Sun
related to our energy
sources?
© 2009 Marshall Cavendish International (Singapore) Private Limited
Source of energy for animals
Let How
us follow
doesaapiece
meal of
baked potato’s
provide
us with journey
energy?
in the human body.
© 2009 Marshall Cavendish International (Singapore) Private Limited
Source of energy for animals
2.
partially
digested
potato
3. The
4.
In the
the
stomach,
small
intestine,
digestion
1.
In
mouth,
thefurther
piecethe
of potato
travels
down The
the
gullet
toisthe
takes
is
completely
place.
digested
potato
crushed
a type
potato
is chewed
into ainto
mash.
stomach.
and
of
sugar
mixed
called
with
glucose.
digestive
juices.
Saliva
helps
to digest
theGlucose
potato
It then
then
enters
moves
down
bloodstream
to the small
and
slightly.
It is the
then
swallowed.
intestine.
is
transported to the cells in the body.
© 2009 Marshall Cavendish International (Singapore) Private Limited
Source of energy for animals
• Energy is stored in food.
• The food that we eat cannot provide our
bodies with energy immediately.
• It has to be digested first.
• Glucose is the digested form of food that
provides us energy.
© 2009 Marshall Cavendish International (Singapore) Private Limited
How do plants get their food?
• Plants need energy to stay alive.
• This energy comes from the food they make.
• Plants make food in the presence of sunlight,
through the process called photosynthesis.
• During photosynthesis, energy from sunlight is
used to combine carbon dioxide and water to
make glucose and oxygen.
• Glucose, a form of sugar, is food for the plant.
© 2009 Marshall Cavendish International (Singapore) Private Limited
How do plants get their food?
• Photosynthesis
water + carbon dioxide
in the presence
of sunlight
glucose + oxygen
In this way, energy
from the Sun is passed
on to plants.
© 2009 Marshall Cavendish International (Singapore) Private Limited
How do plants get their food?
• Excess glucose is converted to starch and
stored in different parts of the plant.
• We get energy when we eat these plant parts.
Some
Otherplants
plantsstore
store Many plants store starch
temporarily in their leaves.
starch
starchinintheir
theirseeds.
roots.
Other plants store starch in
their underground stems.
lettuce
potatoes
soy beans
carrots
© 2009 Marshall Cavendish International (Singapore) Private Limited
The Sun and our energy sources
• When plant parts are
eaten by animals, the
energy stored in the plant
parts is transferred to the
animals.
• Some animals eat plants
only (plant-eaters)
• These plant-eaters get
their energy from plants.
rabbit
giraffe
zebra
© 2009 Marshall Cavendish International (Singapore) Private Limited
The Sun and our energy sources
• Other animals eat plants and animals
(plant-and-animal eaters).
• These plant-and-animal eaters get their energy
from both plants and animals.
man
raccoon
chicken
© 2009 Marshall Cavendish International (Singapore) Private Limited
The Sun and our energy sources
• Some animals eat only other animals
(animal-eaters).
• These animal-eaters get their energy from the
meat they eat.
snake
tiger
© 2009 Marshall Cavendish International (Singapore) Private Limited
The Sun and our energy sources
• Although animals that eat only animals do not eat plants,
the energy that they get can be traced back to plants.
• Since plants make food from using energy from the Sun,
the energy from the Sun is passed on from the plants to
the plant-eaters.
In this example, the
energy from the grass is
transferred to the planteater – the zebra.
© 2009 Marshall Cavendish International (Singapore) Private Limited
The Sun and our energy sources
• Eventually, this energy is passed on from
plant-eaters to animal-eaters.
Here,
is transferred
Thus,energy
food produced
by
from the
plant-eater
to the
plants
become
the source
animal-eater,
as this
of energy forsuch
animals.
lioness.
© 2009 Marshall Cavendish International (Singapore) Private Limited
© 2009 Marshall Cavendish International (Singapore) Private Limited