Bio unit 3.3

Phtosynthesis

When a cell captures energy in the sunlight and uses it to make food

Factors that affect the rate of photosynthesis

light intensity, carbon dioxide concentration and temperature

Where does photosynthesis occur?

chloroplasts in the leaves of a plant

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Granum

stack of thylakoids

outer membrane of chloroplast

permeable to small organic molecules

inner membrane of chloroplast

The inner plasma membrane composed of a phospholipid bilayer.

Thylakoids

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.

stroma

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.

Chemical equation for photosynthesis

6CO2 + 6H2O ------> C6H12O6 + 6O2

Palisade mesophyll-

This layer of cells

is located near the top of the leaf and

is

characterized by tightly packed

photosynthetic cells.

Spongy mesophyll—

This part of the

leaf includes photosynthetic cells full

of

chloroplasts, but it also includes air

space between many of the cells.

Epidermis—

This layer of cells at the very

top and bottom of the leaf has small cells

that are tightly linked together. The

epidermis creates a boundary between

the leaf and its environment.

Stoma (plural: stomata)—

This is a pore or small hole,

usually found in the bottom

of a leaf.

Guard cells—

These are cells found on either side of a

stoma that can control

Whether the stoma is open or

closed.

Vascular bundle—

The vascular

bundles of the leaf are

primarily composed of two

types of cells:

Xylem cells-

responsible

for transporting water (and

minerals dissolved in

it) from the roots.

Phloem cells

responsible

for transporting glucose made

in the cells of the

leaf to other locations in the

plant where the glucose is

needed.

visible spectrum

portion of the electromagnetic spectrum that we can see

chlorophyll

principal pigment of plants and other photosynthetic organisms (green)

leaf anatomy

Upper epidermis Palisade mesophyll

Spongy mesophyll Vascular bundles

xylem phloem

Lower epidermis

photosynthetic pigments

Chemicals that absorb light energy and use it to carry out photosynthesis. Contained in thylakoid membranes in chloroplast. Examples are chlorophyll a, chlorophyll b, carotenoids, xanthophylls, and phycobilins.

chlorophyll absorbs

blue and red light

Carotenoids

An accessory pigment, either yellow, orange or red, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.

carotenoids absorb

blue and green light