Leaves

Pages 578; 595 - 597

A. Function

CO2 + H20 C6H12O6 + O2

carry out photosynthesis1. specialized organs that

B. Parts of the Leaf

the upper & lower surface of the

leaf that functions in protection

2. Epidermis - single layer on

1. Cuticle - thin, waxy outer layer

that prevents the loss of too

much water

Parts of the Leaf

(food)

b. Phloem - transports sugar

a. Xylem - transports water

4. Vein - bundles of vascular tissues

3. Mesophyll - area where there are cells with chloroplasts; area of photosynthesis

Parts of the Leaf5. Stomata - tiny pores on the lower surface that allows carbon dioxide to enter and water & oxygen to exit the leaf during photosynthesis; allows oxygen to enter and water & carbon dioxide to exit the leaf during respiration

Parts of the Leaf6. Guard Cells - opens & closes

the stomata; regulates gas

exchange and water loss

stomata closed

stomata open

* More than 90% of the water taken up by the roots are lost to the atmosphere as water vapor (through the stomata); this is called transpiration

cuticle

upper

epidermis

lower

epidermis

vascular tissues

(xylem & phloem)

guard cellsstomata

mesophyll

Leaf Adaptation:

collect sunlight (tropical)3. Broadleaf: large, flat leaves to

reduce water loss2. Pine Needles: thin and waxy to

photosyntheticreduce water loss; they are not

1. Cactus: “thorns” are thin to

Leaf Adaptation:

enzymescontains rainwater and digestiveto “funnel” insects; the “pitcher”

a. pitcher plant: leaves are shaped

4. Carnivorous:

Pitcher Plant

Pitcher Plant

Leaf Adaptation:

digestive enzymes

secretions (which trap insects) and

b. sundew: leaves have sticky

sundew

Leaf Adaptation:

release digestive enzymestrap the animals inside andare hinged; they fold up & and

c. Venus Flytrap: leaf blades

Venus Fly Trap

Venus Fly Trap

Leaf Adaptation:

insects (ex. nicotine)growth and development of

5. Chemical Defenses: chemicals

on leaves that kill or disrupt the