1. Plant Nutrition How do plants make food? What is photosynthesis?
Contents
Plant Nutrition
How do plants make food?
What is photosynthesis?
More about photosynthesis
The rate of photosynthesis
Minerals from the soil
Multiple-choice quiz

2. What do plants need for a balanced diet?
Plants need carbon dioxide and water for photosynthesis.
Do they need any other nutrients to keep healthy?
Just like humans, plants need a balanced diet
that includes small amounts of mineral elements.
What mineral elements do they need?

3. What minerals do plants need?
Plants need mineral elements for healthy growth.
Some of the most important minerals needed by plants are:
nitrogen
nitrates
phosphorus
phosphates
potassium
potassium ions
magnesium
magnesium ions
How do plants obtain these minerals?
The mineral elements are found in salts dissolved in water.
Plants obtain minerals when they absorb water from the soil.
What type of salt are each of these elements found in?

4. What are minerals needed for?
How do plants use these mineral elements?
Mineral element
How mineral is used in plants
nitrogen (N)
phosphorus (P)
potassium (K)
magnesium (Mg)
making leaves
making roots
making flowers and fruit
making chlorophyll

5. Plant and minerals – summary activity

6. Where do minerals come from?
What are the sources of minerals in the soil?
Rocks: The minerals in rocks are slowly dissolved by slightly acidic rainwater. These minerals are washed into the soil.
Natural fertilizers: Animal faeces and the decay of dead plants and animals return minerals to the soil.
Artificial fertilizers: These
contain a ready-made mixture
of the minerals needed by plants.
Why do farmers add fertilizers to their soil?

7. Not enough minerals!
What happens if plants do not get enough minerals?
Plants do not grow properly if they are deprived of minerals and begin to look unhealthy.
If a plant does not get enough of a mineral it is said
to have a mineral deficiency.
Do mineral deficiencies affect a plant in the same way?

8. Mineral deficiency – no nitrogen!
Nitrogen is used for making leaves and is probably the most important mineral for plant growth.
What is the effect of nitrogen deficiency?
upper leaves
pale green
lower leaves yellow and dead
weak stem

9. Mineral deficiency – no phosphorus!
Phosphorus is used for making roots and is important for all the other minerals used by plants.
What is the effect of phosphorus deficiency?
purple leaves
small roots

10. Mineral deficiency – no potassium!
Potassium is used for making flowers and fruit, so crops are given extra potassium before they start to fruit.
What is the effect of potassium deficiency?
poor flower
and fruit growth
yellow leaves
with dead spots

11. Mineral deficiency – no magnesium!
Magnesium is used for making chlorophyll and so is vital for the process of photosynthesis.
What is the effect of magnesium deficiency?
upper leaves normal (leaves turn yellow from bottom upwards)
lower leaves pale green or yellow

12. Mineral deficiency experiment

13. Plant and minerals summary
Complete this table of plant mineral needs and deficiencies.
Mineral
Use in plant
Deficiency signs
nitrogen
phosphorus
potassium
magnesium
making leaves
stunted growth and
yellow leaves
making roots
poor roots and
purple leaves
making flowers
and fruits
yellow leaves with
dead spots
making chlorophyll
leaves turn yellow
from the bottom