IGCSE Revision- Biology
Chapter 6- Plant nutrition
6.1 Making carbohydrates using light energy
PLANT NUTRITION
- Plants make their own food by photosynthesis
CHLOROPHYLL
- In chloroplasts, water and carbon dioxide react together to make carbohydrates
and oxygen
- Chlorophyll is able to capture the sunlight, and after it has done that it passes on
the energy to water and carbon dioxide molecules. The energy makes these
molecules react together to make glucose
THE PHOTOSYNTHESIS EQUATION
- Carbon dioxide + water → glucose + oxygen
Sunlight and chlorophyll
- 6CO2 + 6H2O → C6H12O6 + 6O2
HOW A PLANT USES CARBOHYDRATES
- Some of the glucose is used to transfer energy around the plant
- For example, energy is needed to move mineral ions into the root hairs by active
transport
- Sometimes plants make more glucose than they need. When this happens, the
glucose is stored as starch to be used for later
- Starch isn’t soluble in water, so they aren’t involved in any chemical reactions
that take place in the plant
- For transport, the plant changes sugar into larger molecules called sucrose
- The sucrose is transported around the plant by phloem tubes
- Plants produce cellulose to make cell walls
- Plants also produce nectar, so that animals will carry away the gametes of
flowers
- Some of the glucose is turned into amino acids, so that can be turned into
proteins for growth
- Glucose can also be used to make chlorophyll (with magnesium and nitrate ions)
6.2 Leaves
THE STRUCTURE OF A LEAF
- A leaf consists of a broad, lat part which is attached to the leaf by a leaf stalk
- Inside the leaf stalk there are collections of parallel tubes called vascular bundles
- The vascular bundles carry substances to and from the leaf
- Chlorophyll is spread out on membranes, so a lot of sunlight can reach the leaf
Chapter 6- Plant nutrition
6.1 Making carbohydrates using light energy
PLANT NUTRITION
- Plants make their own food by photosynthesis
CHLOROPHYLL
- In chloroplasts, water and carbon dioxide react together to make carbohydrates
and oxygen
- Chlorophyll is able to capture the sunlight, and after it has done that it passes on
the energy to water and carbon dioxide molecules. The energy makes these
molecules react together to make glucose
THE PHOTOSYNTHESIS EQUATION
- Carbon dioxide + water → glucose + oxygen
Sunlight and chlorophyll
- 6CO2 + 6H2O → C6H12O6 + 6O2
HOW A PLANT USES CARBOHYDRATES
- Some of the glucose is used to transfer energy around the plant
- For example, energy is needed to move mineral ions into the root hairs by active
transport
- Sometimes plants make more glucose than they need. When this happens, the
glucose is stored as starch to be used for later
- Starch isn’t soluble in water, so they aren’t involved in any chemical reactions
that take place in the plant
- For transport, the plant changes sugar into larger molecules called sucrose
- The sucrose is transported around the plant by phloem tubes
- Plants produce cellulose to make cell walls
- Plants also produce nectar, so that animals will carry away the gametes of
flowers
- Some of the glucose is turned into amino acids, so that can be turned into
proteins for growth
- Glucose can also be used to make chlorophyll (with magnesium and nitrate ions)
6.2 Leaves
THE STRUCTURE OF A LEAF
- A leaf consists of a broad, lat part which is attached to the leaf by a leaf stalk
- Inside the leaf stalk there are collections of parallel tubes called vascular bundles
- The vascular bundles carry substances to and from the leaf
- Chlorophyll is spread out on membranes, so a lot of sunlight can reach the leaf
