Plants need energy to grow, to
replace worn out cells, to get rid of waste, and to reproduce. All
organisms get energy from food. PHOTOSYNTHESIS
is the process by which plants make food. Only plants can make food.
In this process carbon dioxide and
water combine in the presence of light to form sugar, a food.
are found in layers of protective cells on the surface of the leaf.
Gases move in and out of stomates. These openings connect to large
air spaces in the middle layer of the leaf. Carbon dioxide in the
middle layer of the leaf is available to the food-making cells of the
in the vein carries water to the food-making cells. The water comes
from the roots and the root hairs which are in the ground.
You can think of a
as a food factory. Carbon dioxide and water are the raw materials
that go into the factory. Sunlight is the energy that changes the raw
materials into the product, food in the form of sugar.
Photosynthesis is a complex process.
A series of chemical reactions change the raw materials to the food
product. The process can be shown simply by looking at the starting
materials and the end products.
WATER + CARBON
DIOXIDE + ENERGY ---> SUGAR + OXYGEN
is the process by which plants discard the materials that they don't
use. For example, in photosynthesis, when plants take in cardon
dioxide, they let out oxygen, which is what we breathe. This is how
we always have fresh air.