9C Plants and Photosynthesis

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KS3 Biology

9C Plants andPhotosynthesis


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9C Plants and Photosynthesis

Contents

Leaes and gl!"ose

S!##ary a"tiities

$oots and water

%hat is &hotosynthesis'


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(ow do &lants grow'

Many years ago people

thought that plants ate soil

and that made them grow.

Think about it, if that really

happened then there

wouldnt be any soil left!

Plants actually grow by

#aking their own food,

not by eating soil!

So where does the stuff

that plants are made of

come from?


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(ow do &lants #ake their own food'

ne of the raw materials that plants need to make food

does come from the soil)the other comes from the air.

hat are these two raw materials called?

Plants use carbon dio"ide and water to make their own food

in a chemical reaction. hat is the name of this reaction?

"ar*on dio+ide,fro# the air-

water

,fro# the soil-


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(ow do &lants #ake their own food'

Plants make their food from carbon dio"ide and water in a

chemical reaction called...

&hotosynthesis.

The food made by photosynthesis is the sugar gl!"ose.

/+ygengas is also made as a by#product of photosynthesis.

o+ygen

gl!"ose"ar*on dio+ide,fro# the air-

water

,fro# the soil-


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(ow do &lants grow'

Plants need energyfor photosynthesis to take place.

here does this energy come from?

The energy for photosynthesis comes from the Sun.

here in a plant does photosynthesis take place?

o+ygen


water

,fro# the soil-

light energy


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(ow do &lants grow'

Plant cells in the upper surface of lea$es ha$e "hloro&lasts

which contain the green pigment called "hloro&hyll.

o+ygen


water

,fro# the soil-

light energy

%t is chlorophyll that absorbs light energy from the Sun

to make photosynthesis happen.

"hloro&hyll


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Photosynthesis s!##ary

Plants make their own food by the process of &hotosynthesis.

%n this chemical reaction, chlorophyll in plant cells absorbs lightenergy to change carbon dio"ide and water into glucose and

the by#product o"ygen.

hat is the word e&uation for photosynthesis?

gl!"ose

light energy

"hloro&hyll

"ar*ondio+ide

water o+ygen

This e&uation can be read as'

(carbon dioxide and water, in the presence of light energy

and chlorophyll, produces glucose and oxygen).


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%hat is needed for &hotosynthesis'


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Photosynthesisword e!ation a"tiity




Contents

Leaes and gl!"ose

S!##ary a"tiities

$oots and water




(ow are leaes ada&ted'

*ea$es are small +factories

that produce food for plants

by photosynthesis.

*ea$es are ada&tedso that

photosynthesis can take place.

Plants need carbon dio"ide,water, sunlight and chlorophyll

to carry out this important

process.

hat features of lea$es

make them suitable for

photosynthesis?



(ow are leaes ada&ted'

The features of leaf that make it

suitable for photosynthesis are'

leaf is *roadand flatto

capture lots of sunlight.

carry water to the leaf

and take food from the leafto the rest of the plant. -eins

also help to support the leaf.

ertain plant cells contain

"hloro&lastswith "hloro&hyll.

Small holes called sto#atain

the underside of a leaf allow

gases in and out.

eins



6nside a leaf



%hat do &lants !se gl!"ose for'

gl!"ose

Some glucose is used straight away inres&iration. Plants also carry out respiration to

release the energy they need for life processes.

Some glucose is con$erted into star"h and othersubstances for storage. These stores of energy

can be used later when the plant needs them.

Some glucose is used to make new "he#i"alssuch as proteins, sugars and fatsthat the plant

also needs to function properly.

hat do plants with the glucose made by photosynthesis?



7esting leaes for star"h




Contents

Leaes and gl!"ose

S!##ary a"tiities

$oots and water




(ow does water enter a &lant'

%ateris one of the raw materials

needed for plants to carry out

photosynthesis.

/ow does water enter a plant?

ater from the soilenters a plantthrough the roots.

0ou cant normally see them but

roots are a $ery important part of a plant.

hy are roots branched and spread out through the soil?



(ow are roots ada&ted'

1oots are branched and spread out

for two reasons'

to absorb water 2and mineral salts3

from a large amount of soil.

to anchor the plant in the soil.

Taking a closer look, roots are

co$ered in root hair "ells.

1oot hair cells ha$e thin wallsand a large s!rfa"e areato help

them absorb lots of water.

/ow are roots adapted to their 4ob?

water



%hy do &lants need water'

ater is needed by plants for photosynthesis

but this importantli&uid is also used in many

other ways'

to pro$ide dissoled #ineralsthat keep the plants healthy5

to trans&ort s!*stan"esaround the plant5

to keep the plant rigid and !&right5

to keep the plant "ool5

to allow other "he#i"al rea"tionsto occur in plant cells.

hat happens to a plant if it does not get enough water?




Contents

Leaes and gl!"ose

S!##ary a"tiities

$oots and water


8l



8lossary

"hloro&hyll The green pigment inside chloroplaststhat plants need for photosynthesis to take place.

"hloro&lastThe part of a plant cell wherephotosynthesis occurs.

gl!"ose The sugar plants make during photosynthesis.

&alisade "ell type leaf cell with lots of chloroplasts.&hotosynthesis The process by which plants use

carbon dio"ide and water to produce glucose and o"ygenin the presence of light and chlorophyll.

star"h 6"tra glucose from photosynthesis is stored asthis substance which can be tested for with iodine.

sto#ata Small holes in the lower surface of a leafthat allow gases in and out.

+yle# Tubes in $eins that carry water around a plant.

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:nagra#s

; lti l h i i


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Documents

9C Plants and Photosynthesis