Year 10 photosynthesis

7/27/2019 Year 10 photosynthesis

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Flowering Plants

Roots

Leaf

Flower

Stem


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A Leaf

Lamina

Vein

Midrib


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Leaf Structure

Waxy cuticle

Epidermis

Palisade mesophyll layer

Spongy mesophyll layer

Epidermis

Stoma

Air spaces


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Waxy Cuticle & EpidermisWaxy cuticle

Epidermis

The waxy cut ic leis a thin layer

atop the epidermis.

Its function is to reduce the w ater

lostfrom the leaf.

In arid conditions this cuticle layercan be quite thick.

Epidermis cel ls conta in no

chloroplasts not true of the

stoma cells.

They form layers on the upper and

lower surfaces of the leaf.

Their function is to prevent water

get t ing outand stopp ing unwanted

sub stances/organisms gett ing in.


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Palisade Mesophyll Layer


The pal isade mesoph yl l layeris

where most of the photosynthes isoccurs in the leaf.

The palisade cells contain a lot ofchloroplaststo help them perform

this photosynthesis.

The palisade cells are clo sely

packed togetherto maximize light

absorption.

In the leaf cross-section shown the

palisade cells are on ly found in the

upper part of th e leaf.


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Spongy Mesophyll Layer


The cells in the spongy mesophyl l

layerare not as c losely packedasthe cells in the palisade mesophyll

layer.

This creates air spacesinside the

leaf to enable gases to m ove in

and ou t.

There are not as many ch loroplastsin the spongy mesophyll cells as

there are in the palisade mesophyll

cells but photos ynthesis st i ll

occurs in the spongy m esophyl l

layer.


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Stomata


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Stomata

Stoma

There are holes found in leaves

called stomata.

These holes allows gases to

dif fuse in and out of the leaves.

A stoma is formed by two h igh ly

special ized epidermis cel ls.

These cells, called guard cel ls, are

the only epidermis cells that contain

chloroplasts.

The stomata open and close

depending upon the requirements ofthe plant.

It is through these stomata that water

leaves the leaf, the process that

powers t ranspirat ion.


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Stomata

Stoma open Stoma closed

Dur ing photo syn thesis

carbon d ioxide di f fuses in

and oxyg en di ffuses out

When the stomata are

clos ed,often at night or in

a hum id environment, th is

stops gases di f fusing in

and out o f the leaf


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Key Words

Waxy cuticle

Stomata

Air spaces

Epidermis

Palisade

mesophyll cell

Spongy

mesophyll cell

Waterproof layer atop the epidermis

Pores that allow gaseous exchange

Found in the spongy mesophyll layer,

enable gases to reach the leaf cells

One-cell thick outer layer of cells that

prevent water loss from the leaf

Contain numerous chloroplasts and aredensely packed

Loosely packed cells that do not contain

as many chloroplasts as palisade cells


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Photosynthesis

Chloroplastsare organellesof plant cells that contain a green

substance called ch lorophy l l.

Scientists believe chlorop hyl l absorbs l ight energyand this

energy is then used to make food.

The raw materials of photosynthesis are carbon dioxideand

water. The waste product of this reaction is oxygen.

The carbon dioxide required is absorbed through the stomata

in the leaves this is how the oxygen is also removed.

The water required is absorbed by the roots.

The word equation for this reaction is...

The chemical equation for this reaction is...

6H2O + 6CO2 C6H12O6 + 6O2


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Photosynthesis


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Photosynthesis

Gaseous

Exchange


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Photosynthesis

Gaseous

Exchange &Water


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Investigating Photosynthesis

Chlorophyll makes leaves green, but is

chlorophyll required for photosynthesis?

Your teacher will give you two leaves,

one is completely green.

The other leaf is called a variegated leaf.

The areas that are not green contain little

or no chlorophyll.

Both leaves have previously been destarched.

Do you know how to destarch a leaf?

Plan an investigation to discover if chlorophyll is required for

photosynthesis.How will you test to see if photosynthesis has occurred?

What do you predict your results will be?

What apparatus will you require?

What safety precautions will you need to observe?


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Is carbon dioxide required for photosynthesis?

Your teacher will give you two plants, one isenclosed in plastic and contains a chemical

that absorbs carbon dioxide.

Plan an investigation to discover if carbon

dioxide is required for photosynthesis.

What do you predict your results will be?

What apparatus will you require?

Why are two plants used?

How will you evaluate your results?

What chemical will you use to

remove carbon dioxide?


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Using Plants

Humans have used plants for thousands of years.

There are many different uses of plants by humans. The

cotton plant shown is used to produce cotton for clothing etc.


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Exercise 1: Complete the Table

Broccoli

Potato

CabbageCarrot

Lettuce

Stem Root Leaf Flower

Rhubarb

Turnip

Cauliflower

Celery

BroccoliRhubarb

Celery

Potato

Turnip

Lettuce

Cabbage Cauliflower

Carrot


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Exercise 2: The Leaf

1. _____ 2. ______

3. _______

Midrib

Vein

Lamina

Stalk

Extension of the stalk into the leaf

The blade of the leaf

Attaches the leaf to the stem

Branch-off from the midrib

Vein Lamina

Midrib


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Exercise 3: Label the Parts of a Plant

4. ______

2. _______

1. _______

3. _____

Roots

Leaves

Flower

Stem


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Exercise 4: Label the Parts of a Plant

Flower

Roots

Leaf

Stem


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Exercise 5: Leaf Structure1. ___________

2. ___________

3. ______________________

5. _____________________

7. __________

6. ________

4. __________

Waxy cuticle

Epidermis



Epidermis

Stoma

Air space


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Exercise 6: Link the Boxes

Waxy cuticle

Stomata

Air spaces Waterproof layer atop

the epidermis

Pores that allow

gaseous exchange

Found in the spongymesophyll layer, enable

gases to reach the leaf

cells


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Exercise 7: Link the Boxes

Epidermis

Palisade

mesophyll cell

Spongy

mesophyll cell

Contain numerous

chloroplasts and are densely

packed, where most of the

photosynthesis occurs

Loosely packed cells that do

not contain as many

chloroplasts as palisade cells

One-cell thick outer layer

of cells that prevent

water loss from the leaf


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Exercise 8: Short Questions - Leaf

1. What do we call the continuation of the leaf stalk into the leaf-

blade?

2. What do we call the specially adapted cells that form holes in the

leaves to allow gaseous exchange?

3. What are these holes/pores called?

4. What is the name of the waxy waterproof layer found on top of the

epidermis?

5. What is the lamina?

Midrib

Guard cells

Stomata

Cuticle

The leaf-blade


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Exercise 9: Short Questions - Leaf

1. What do we call the outer one-cell thick layer of cells that contain

no chloroplasts?

2. What is the function of this layer?

3. What are two differences between palisade mesophyll cells

(PMC) and spongy mesophyll cells (SMC)?

4. By what process does carbon dioxide enter and leave leaves?

The epidermis

To prevent water loss and to stop substances and

organisms entering the leaf

SMC more loosely packed, less chloroplasts

Diffusion

PMC more densely packed, more chloroplasts


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Exercise 10: Insert the Missing Words

Chloroplasts__________of plant cells that contain a green

substance called__________.

Scientists believe chlorophyll absorbs_____energy and this

energy is then used to make_____.

The raw materials of photosynthesis are carbon dioxide and

_____. This waste product of this reaction is_______.The carbon dioxide required is absorbed through the_______

in the leaves this is how the oxygen is also removed.

The water required is absorbed by the_____.

roots organelles light food

water chlorophyll oxygen stomata

organelles

chlorophyll

light

food

water oxygenstomata

roots


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Exercise 11: Short Questions - Photosynthesis

1. Which organelles in plant cells contain a green substance called

chlorophyll?

2. Which two raw materials are required by green plants for

photosynthesis?

3. What is the waste product of photosynthesis?

4. How does this waste product leave the plant during the day?

5. What process requires this waste product to enable green

plants to release energy from their food?

Chloroplasts

Water and carbon dioxide

Oxygen

Through the stomata

Respiration


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Exercise 12: Short Questions Plant Nutrition

1. What do we call the process whereby green plants make

glucose using light energy and the raw materials carbon dioxideand water?

2. During the night many green plants perform another process

whereby they release the energy from their food they have

made. What do we call this process?

3. The sugar glucose, the product of photosynthesis, is changed to

starch when it is being stored by the plant. Why?

4. What is the chemical formula of glucose?

Photosynthesis

Respiration

Glucose is soluble in water, starch is insoluble in water.

By storing the food starch it means it is easier for the

plant to keep the food in the required place

C6H12O6


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Exercise 13: Short Questions Plant Nutrition

1. What is the word equation for photosynthesis?

2. What is the chemical equation for photosynthesis?

3. Name the arrowed organelle.

4. Which substance does this organelle

contain that allows green plants to

absorb the Suns light energy for the

process of photosynthesis?

6H2O + 6CO2 C6H12O6 + 6O2

Chloroplast

Chlorophyll


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Exercise 14: Variegated Leaf

A destarched variegated plant was left in a sunny garden during

the day for several hours.

At the end of this period a leaf was taken from the plant and

tested for starch.

The results are shown below

Variegated leaf

before starch test

Variegated leaf

after starch test

Explain the resu lt observed (8 marks )


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Exercise 15: Products of Photosynthesis

Some destarched pondweed was set-up as below.

A bright lamp was placed nearby for two hours.

Before lamp

turned on

After six hours of

lamp shining

Explain the resu lt observed (6 marks )

The following results were observed at the end of this period.


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Exercise 16: Short Questions

1. What is a variegated leaf?

2. Draw a diagram of a variegated leaf.

3. What is the chemical test for starch?

4. How do you destarch a green plant?

Parts of the leaf do not contain chlorophyll, other parts do

Starch turns orange/brown iodine solution purple/black

You leave it in the dark for several days so that its food

stores (starch) are exhausted


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Exercise 17: Label the Leaf Parts

A

BC

A. _______________

B. _______________

C. _______________

Lamina

Vein

Midrib

I t ti 1


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I t ti 2


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I t ti 3


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I t ti 4


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I t ti 13


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Year 10 photosynthesis