l eaves b4a. r esults of mustard seed experiment what differences can you see between the two sets?...

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LEAVES B4a

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O BJECTIVES Key Objective Describe the role of leaves in aiding photosynthesis Describe how the main features of the plant are linked to photosynthesis (E-G) Explain how leaves are adapted for efficient photosynthesis (C/D) Explain how the structure of a leaf palisade cell is related to its function (C/D) Identify the process by which gases travel in and out of the plant (C/D) Explain how the cellular structure of a leaf is adapted for efficient photosynthesis (A/B)

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Page 1: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

LEAVESB4a

Page 2: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

RESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences. Suggest what would happen to the cress seedlings if they

were left in the dark for another 2 weeks. Give an explanation for your suggestion.

Page 3: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

OBJECTIVESKey Objective Describe the role of leaves in aiding photosynthesis

Describe how the main features of the plant are linked to photosynthesis (E-G)

Explain how leaves are adapted for efficient photosynthesis (C/D)

Explain how the structure of a leaf palisade cell is related to its function (C/D)

Identify the process by which gases travel in and out of the plant (C/D)

Explain how the cellular structure of a leaf is adapted for efficient photosynthesis (A/B)

Page 4: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

EXPERIMENT What do you see on

the upper and lower leaf surfaces?

Suggest an explanation for your observations.

Pour some hot water into the beaker. Hold the stalk of a large leaf with a pair of

forceps and lower it into the hot water. Watch what happens to the upper and

lower surfaces.

Page 5: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

STOMATA

Page 6: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

PRACTICALS - TEARING LEAVES PAINTING LEAVESYou will need: lettuce or privet leaf glass slides cover slips microscope

Method Take a leaf such as a lettuce or

privet leaf. Tear it across so that a strip of

lower epidermis is removed. Put a small piece of the torn strip

onto a glass slide. Add a drop of water and a cover

slip. Look at it under the microscope. Repeat the procedure with a strip

torn off the upper epidermis.

You will need: lettuce or privet leaf forceps clear nail varnish glass slides cover slips microscope

Method Paint the upper and lower surfaces

of a leaf with a thin layer of clear nail varnish. Allow it to dry.

Using forceps, peel off the dried nail varnish.

Put a piece from each surface on a microscope slide.

Add a drop of water and a cover slip. Look at it under a microscope.

While you are waiting for the varnish to dry complete w/s B4a4 using the blue OCR book

Page 7: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences
Page 8: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

FOR G-E: Identify the chloroplasts, vacuole and cell wall in a plant cell. State that chloroplasts absorb light energy for

photosynthesis. State that photosynthesis occurs mainly in the leaves. Describe the entry points of materials required for

photosynthesis: water through roots; carbon dioxide through leaf pores.

Describe the exit point of materials produced in photosynthesis: oxygen through leaf pores.

 KEY WORDS: chlorophyll; cuticle; guard cell; lower epidermis; palisade

mesophyll; spongy mesophyll; stomata; upper epidermis; vein

Page 9: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

FOR C/D Name and locate the parts of a leaf:

cuticle; upper and lower epidermis; palisade and spongy mesophyll layers; stomata and guard cells; veins.

Explain how leaves are adapted for efficient photosynthesis: broad so large surface area; thin so short distance for gases to travel; contain chlorophyll to absorb light; have a network of veins for support and transport; stomata for gas exchange.

State that the exchange of gases is by diffusion. Explain how the structure of a leaf palisade cell is related to

its function: contains many chloroplasts.

Page 10: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

FOR A*-B: Explain how the cellular structure of a leaf is

adapted for efficient photosynthesis: epidermis is transparent; palisade layer at the top containing most of the

chloroplasts; air spaces in the spongy mesophyll allow

diffusion between stomata and photosynthesising cells;

internal surface area / volume ratio very large.

Page 11: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

LEAVES ARE DESIGNED FOR ONE THING ONLY – MAKING FOOD

In order to do this they must be able to draw in water and carbon dioxide gas.

They must also be able to trap sunlight.

Page 13: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

THEY HAVE ‘HOLES’ IN THE LEAVES TO ALLOW CARBON DIOXIDE IN AND OXYGEN OUT. THESE ARE STOMATA.

Page 14: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

THERE ARE VEINS IN THE LEAVES TO TRANSPORT WATER AND SUGAR AROUND.

Page 15: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

MANY OF THE CELLS ARE PACKED WITH CHLOROPLASTS WHICH CONTAIN A LIGHT TRAPPING PIGMENT- CHLOROPHYLL.

Page 16: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

THERE IS A WAXY LAYER ON TOP TO STOP WATER BEING LOST FROM THE LEAF.

Page 17: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

PLENARY Draw this diagram of a Marram grass leaf.

Page 18: L EAVES B4a. R ESULTS OF MUSTARD SEED EXPERIMENT What differences can you see between the two sets? Suggest why a lack of light caused these differences

MARRAM GRASS IS FOUND ON SAND DUNES.1) Add the two missing labels (D)2) What does the waxy cuticle do? (C)3) How does the position of the stomata

help this plant? (C)4) Why are there no stomata on the outer

surface of the leaf? (B)5) Explain the function of the hairs on the

inner surface of the leaves? (A)6) Explain how having sunken stomata

will affect gaseous exchange in the plant, and why this would be an advantage to the plant. (A*)