B4 It's A Green World

Carbon Dioxide + Water --> Glucose + Oxygen

Features of Leaves for Efficient Photosynthesis.

- large surface area exposed to light

- Thin: CO2 and water vapour have short distance to travel to reach the cells where it's needed.

- Contain lots of chlorophyll  (pigment that absorbs light energy for photosynthesis)

- Network of veins that deliever water and other nutrients to all of the leaf

- Upper Epidermis is transparent, so light can pass through easily to the palisade layer.

DIFFUSION IS THE NET MOVEMENT OF PARTICLES FROM AN AREA OF HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION

- Diffusion of gas within leaves is vital for photosyntheisis. 

- CO2 diffuses into the leaves.

- Oxygen and Water Vapour diffuse out the leaf

- O2 is made as a waste product of photosynthesis.

- Some O2 is is used in respiration, the rest diffuses out of the leaf, via the stomata

- At night, photosynthesis does NOT take place. Lots of CO2 is made in respiration, lots of O2 is used up. At night, diffusion is mainly CO2 diffusing out and O2 diffusing in.

Osmosis is the movement of water molecules across a partially permeable membrane from an area of high concentration to an area of low concentration.

-Osmosis is basically diffusion of water.

- 'Partially Permeable Membrane' is a membrane that only allows certain substabnces to diffuse through it. (eg./ water can pass through, but not glucose)

-There is a net movement of water molecules during osmosis.

- When plants have plenty of water, the cells take water in by osmosis. The cells become swollen- or turgid.