Title: Leaves
1Leaves
2What are the functions of leaves?
- Capture light
- Exchange gases
- Provide a site for photosynthesis
- Some leaves store food and water
- Some form new plants and provide support
3Why does a plant need photosynthesis?
- PHOTO means light
- SYNTHESIS means to make or form something from
- SO.Photosynthesis is a plant making something
(food) from light.
4Photosynthesis definition
- a process by which plants combine water and
carbon dioxide in the presence of chlorophyll and
sunlight and produce carbohydrates and release
oxygen.
5Why is photosynthesis important?
- Light is the most important source of energy for
living things. Photosynthesis converts light
into nutrients that can be used by plants and
animals. - Releases oxygen
6Recipe for Photosynthesis
- 6CO2 12H2O sunlight gt
- 6O 2 C6 H12O 6 6H2 OOr in English
- Carbon Dioxide Water in Sunlight gt
- Oxygen Sugars/Food Water
7There are two parts of photosynthesis--the light
and dark reactions.
- The light reactions produce chemical energy from
light. - The dark reactions convert carbon dioxide into
carbohydrates.
8Leaves gas exchange
- Oxygen, Carbon Dioxide, and Water exchanged from
Stomata - Pores (stomata) open in day to transpire H2O and
allow gases to enter - Close during dry conditions to prevent H2O loss.
91. Leaves External Parts
A. Petiole- leaf stalk or part that connects leaf
to stem.
Petiole
10B. Blade- the large, flat part of a leaf.
C. Midrib- the large center vein.
Midrib
11D. Veins- the structural framework of leaf. Act
like pipes to carry water nutrients
Veins
12E. Margin- the edge of leaf.
Margin (edge of the leaf)
13- F. Cutin fatty (waxy) substance in many plant
cell walls on outer surface of epidermal cell
walls - - forming a Cuticle a protective covering on
a green leaf that helps hold in moisture - (this gives the leaf a glossy appearance)
14G. Stipule tiny leaf-like structures at the
base of a petioleH. Axil the angle made by
the petiole and the stem of the plant.
15(No Transcript)
16Leaves Internal Parts
A. Upper and lower epidermis- skin of the leaf
that prevents the loss of too much moisture.
B. Stomates- small openings under the leaf for
breathing or transpiration (also called stoma or
stomata)
17(Internal Parts-continued)
C. Guard cells- open and close stomates
D. Chloroplasts- small green particles that
contain chlorophyll, give leaves their green
color and are necessary for photosynthesis