Photosynthesis and plant cells Photosynthesis and plant cells.

Photosynthesis and Photosynthesis and plant cellsplant cells

PhotosynthesisPhotosynthesis

A definition:

Photosynthesis is the process a plant uses to make food and grow.

Four things are needed for photosynthesis:

Travels up from the roots

WATER

CARBON DIOXIDE

Enters the leaf through small holes on the underneath

SUNLIGHT

Gives the plant energy CHLOROPHYL

L Where the chemical reactions happen

The word and chemical equations for photosynthesis:

Carbon dioxide + water glucose + oxygen

6CO2 + 6H20 C6H12O6 + 6O2

Sunlight

Chlorophyll

Sunlight

Chlorophyll

Four factors affect Four factors affect photosynthesis:photosynthesis:

1. More light = Faster rate of photosynthesis.

2. Water – if Lack of water slows photosynthesis down.

3. Temperature – Hot temperatures slows photosynthesis down.

4. CO2 – more carbon dioxide, photosynthesis happens faster.

Leaf Stomata (plural Stoma)• Microscopic “mouths” in leaves that let

CO2 in and water & O2 out.

• Stomata can close by swelling the “lips” or guard cells.

• Why would they need to close?

Photosynthesis happens in the “palisade” cells in

the leaf:

Palisade

cells

Close up on a palisade Close up on a palisade cell:cell:

Cell wall

Cell membrane

NucleusLarge vacuole

Cytoplasm

Chloroplasts (containing chlorophyll)

How do Plant Roots Work?• Paper towels can

absorb more water if they have larger surface area!

• Roots also work by using a large surface area.

• What makes the water move into the roots?

• Diffusion!

Plant roots are made of “root hair cells” which have a large surface area and a thin cell membrane to help absorb minerals and water:

Thin cell membrane

Large surface area

Plant growthPlant growth

Plants grow using food they make through photosynthesis. So what else do they need?

Plants also need three important minerals to keep healthy. They absorb these through their roots.

3 types of nutrients:3 types of nutrients:

1. Nitrates – used to make proteins

2. Phosphates –to help photosynthesis and respiration

3. Potassium – helps build enzymes the plant needs