Plants and Photosynthesis

How do plants make their own food?

Plants are autotrophic – This means they make their own food.

The way plants make their own food is through a process called Photosynthesis

One of the raw materials that plants need to make food does come from the soil, the other comes from the air.

What are these two raw materials called?

Plants use carbon dioxide and water to make their own food in a chemical reaction. What is the name of this reaction?

carbon dioxide (from the air)

water (from the soil)

Photosynthesis

Plants need energy for photosynthesis to take place. Where does this energy come from?

The energy for photosynthesis comes from the Sun.

Where in a plant does photosynthesis take place?

carbon dioxide (from the air)

water (from the soil)

light energy

Photosynthesis takes place in the chloroplast found in plant cells.

Notice that plant cells have many chloroplast in them.

What are the products of photosynthesis?

What type of energy transformation occurs during photosynthesis?

oxygen

Glucose (chemical energy)

carbon dioxide (from the air)

water (from the soil)

light energy (radiant )

Radiant / light energy to chemical energy

Plant cells in the upper surface of leaves have chloroplasts which contain the green pigment called chlorophyllchlorophyll. .

oxygen

glucosecarbon dioxide

(from the air)

water (from the soil)

light energy

It is chlorophyllchlorophyll that absorbs light/radiant energy from the Sun to make photosynthesis happen.

chlorophyll

Plants make their own food by the process of photosynthesis.

In this chemical reaction, chlorophyll in plant cells absorbs light energy to change carbon dioxide and water into glucose and the by-product oxygen.

What is the word equation for photosynthesis?

glucose

light energy

chlorophyll

carbondioxide water oxygen

This equation can be read as:“carbon dioxide and water, in the presence of light energy and chlorophyll, produces glucose and oxygen”.

Cellular Respiration

• Mitochondria give animal and plant cells energy by breaking down glucose to release energy.

• Cellular respiration is a process that uses the products of photosynthesis to produce energy.

• What part of the cell helps produce energy?

• What process produces energy?

Cycle of Carbon Dioxide and Glucose

Cellular Respiration:C6H12O6 + 6O2 → 6CO2 + 6H2O

Photosynthesis:6CO2 + 6H2O + energy from the sun→C6H12O6 + 6O2

Leaves are small ‘factories’ that produce food for plants by photosynthesis.

Leaves are adapted so that photosynthesis can take place.

Plants need carbon dioxide, water, sunlight and chlorophyll to carry out this important process.

What features of leaves make them suitable for photosynthesis?

The features of leaf that make it suitable for photosynthesis are:

A leaf is broad and flat to capture lots of sunlight.

carry water to the leaf and take food from the leaf to the rest of the plant. Veins also help to support the leaf.

Certain plant cells contain chloroplasts with chlorophyll.

Small holes called stomata in the underside of a leaf allow gases in and out.

Veins

How does water enter a plant?

Water is one of the raw materials needed for plants to carry out photosynthesis.

How does water enter a plant?

Water from the soil enters a plant through the roots.

You can’t normally see them but roots are a very important part of a plant.

Why are roots branched and spread out through the soil?

How are roots adapted?Roots are branched and spread out for two reasons:

to absorb water (and mineral salts) from a large amount of soil.

to anchor the plant in the soil.

Taking a closer look, roots are covered in root hair cells.

Root hair cells have thin walls and a large surface area to help them absorb lots of water.

How are roots adapted to their job?

water

Why do plants need water?

Water is needed by plants for photosynthesis but this important liquid is also used in many other ways:

to provide dissolved minerals that keep the plants healthy;

to transport substances around the plant;

to keep the plant rigid and upright;

to keep the plant cool;

to allow other chemical reactions to occur in plant cells.

What happens to a plant if it does not get enough water?

Glossarychlorophyll – The green pigment inside chloroplasts

that plants need for photosynthesis to take place.chloroplast – The part of a plant cell where

photosynthesis occurs.glucose – The sugar plants make during photosynthesis.palisade cell – A type leaf cell with lots of chloroplasts.photosynthesis – The process by which plants use

carbon dioxide and water to produce glucose and oxygen in the presence of light and chlorophyll.

starch – Extra glucose from photosynthesis is stored as this substance which can be tested for with iodine.

stomata – Small holes in the lower surface of a leaf that allow gases in and out.

xylem – Tubes in veins that carry water around a plant.