Photosynthesis:Nutrition:Biology Chapter 6

Photo = light

• Photosynthesis is the process that plants undergo in order to transform solar energy into chemical energy stored in the bonds of sugar molecules

Equation Of Photosynthesis
                                               sunlight
Carbon dioxide gas + Water  ----------> glucose + oxygen
                                             chlorophyll

Function Of Leaf Structure

Leaves

• the main photosynthesis organs of a plant which adopted to carry out photosynthesis efficiently

• It grows so that they overlap each other as little as possible.This management called a leaf mosaic which enables leaves to receive as much light as possible

• Plant can detects the direction of light so that their leaves are always absorb the maximum amount of light

• A leaf consists of a flat,thin lamina which is joined to the stem by a petiole

• Xylem transports water absorbed and Phloem transports organic product

• Both the upper and lower surfaces of a leaf consists of a protective layer of epidermis

• The outer surface of both epidermis is coated by cuticle,which helps prevent excessive water loss

• The epidermis of a leaf has tiny pores called stomata which flanked by guard cell

• Inside a leaf are a few layers of cell collectively called mesophyll

• In the leaves of dicotyledons,the mesophyll can be divided into:
• a)Palisade Mesophyll              b)Spongy Mesophyll

Adaptation Of Photosynthesis

Land Plants

Hibiscus sp.
- more stomata on the lower epidermal layer than on the upper epidermal layer

- shiny layer of wax covers the epidermis

- transculent layer of epidermis

- high chloroplast density in the palisade mesophyll layer that faces the sun

- network of veins within the leaf

Desert Plants

Cactus sp.
- leaves in the form of needles

- have succulent stems

- have fewer stomata on their stems

- stomata are sunken into the epidermis

- waxy and thick cuticle covers the epidermis

- have green stems

Floating Plants

Nymphae sp.
- leaf tissues are full of air spaces

- have flat leaves

- all stomata located only on the upper epidermis

- waxy cuticle covers the upper epidermis

- transparent layer of epidermis cells

- palisade layer have a lot of chloroplast

Aquatic Plants

Hydrilla sp.
- no stomata

- many small leaves

- tissues full of air spaces

- very little or no cuticle on outer surface of epidermis