What’s in a Leaf

What’s the relationship between structure and function in a leaf?

Model 1 – Leaf Sun-Catcher

1) Sun (energy), Water (liquid), Carbon Dioxide

2) Water (gas), Oxygen, Sugars

3) Water

4) Central Vein

5) Water has changed from a liquid to a gas.

Equation for Photosynthesis

6) Using above equation:

a) Reactants? Carbon Dioxide and Water

b) Reactants enter? Carbon Dioxide through stomata (underside of leaf), Water through roots to stem (xylem) and then central vein of leaf

c) Products? Sugars and Oxygen

d) Products exit? Oxygen through the stomata, Sugars through the veins

7) Matter OR Energy ?Solar (light) Energy

Chemical Energy

(C-C and C-H bonds)

Model 2 – Cross Section of a Leaf

8) Layers: CuticleUpper epidermis (skin)Palisade mesophyll (middle)Spongy mesophyll (middle) Lower epidermis (skin) Cuticle

9) Vein positiona) Model 1 - Central vein in

middle with other veins branching off

b) Model 2 – Between palisadeand spongy mesophyll

Model 2 – Cross Section of a Leaf

10)Veins: get water to all parts of the plant … the leaf requires water to help make sugar

11)Sunlight entersWater enters (liquid)Carbon dioxide entersSugar exitsOxygen exits

Water (gas) exits Xylem (liquid water)

Phloem (sugar)

12)Palisade mesophyll and guard cells have chloroplasts

13)Palisade and guard cells (chloroplastsconduct photosynthesis)

14)Chlorophyll (green pigment) are mostly in Palisade mesophyll

15)Light goes through cuticle and upper epidermis

16)Palisade mesophyll have lots of chloroplasts, arranged vertically, tightly packed, and larger.

17) More cells = More chloroplasts = More photosynthesis

18)Most light is absorbed before reaching the spongy mesophyll

19)If Upper epidermis had chloroplast it would decrease light reaching the Palisade layer

20)Epidermis functions like skin to protect what’s inside a leaf

21)The cuticle is “water-tight” to prevent water from escaping. Water must be used for the plant to photosynthesize.

22)Lower surfacea) Stoma is between guard cellb) Stoma is an openingc) Water can exit through the

stoma when open … good or bad?

23)Guard cells regulate the opening and closing of the stoma just like “gates”

24)Stoma open = access to more air space

25)Air space = oxygen, carbon dioxide, water

26)Stomata are closed … what happens?

Water and Oxygen stay in the plant. Upside?

Carbon Dioxide cannot enter. Downside?

26)Cuticle and stomata work together. How so?

Water regulation!

28 & 29

•Use your sentences tracing the pathway or reactants entering the leaf and products exiting the leaf to draw a picture of the equation of photosynthesis.

Extension Questions

30)Plants with larger leaves … advantage or disadvantage?

31)Cacti … what structures give an advantage or disadvantage?

32)Aquatic plants … adaptations?

33)Knowledge of Plant Cellsa) Water storage?

a) Large Vacuole

b) Sugar destination?b) Go to mitochondria (energy)

c) Cell wall function?c) Structure and strength so leaf is

lifted up toward the light