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Plants for FoodPlants for Food

How do fertilisers affect plant growth?

Lesson AimsTo review key ideas about plants

for food and study how fertilisers affect plant growth.

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Learning outcomes

By the end of the lesson you should know / be able

•to link ideas about feeding relationships and photosynthesis

• that plants require a range of minerals for healthy growth

• that fertilisers supply these minerals to crop plants

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We need plants !

Write down 3 reasons to support this statement

Remember: The three main Remember: The three main types of nutrient are:types of nutrient are:

1. Nitrogen in the form Nitrates – used to make proteins

2. Phosphorus in the form of Phosphates – used to provide phosphorus to help photosynthesis and respiration

3. Potassium – helps the enzymes that are needed for photosynthesis and respiration

Remember: Lack of the three Remember: Lack of the three minerals would lead to a minerals would lead to a “Deficiency Symptom”:“Deficiency Symptom”:

Lack of nitrates:Small plant, yellow leaves

Lack of phosphates:Small roots and purple leaves

Lack of potassium:Yellow leaves with dead bits

Page 143 Page 143

• On your own :

a)What is a fertiliser?b)Answer questions 1- 3

• In groups of 3 or 4 :• Answer questions 4 -11 on newsprint

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1.What is a weed?1.What is a weed?2.What is a weedkiller?2.What is a weedkiller?3. Why are they used ? 3. Why are they used ?

• Answer question1-4 page 145• Extension questions 5-11 p\age 146

• Remember your pondweed report is due in next lesson !

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Advantages

Helping plants to growHelping plants to growFarmers can use a number of chemicals to help plants to grow:

1) Fertilisers

2) Herbicides

3) Pesticides

Disadvantages

Disrupt food chains

Provide nutrients

NPK

Too much of it can kill pond life

Kill weeds

Kill pests

Disrupt food chains

03/05/23Another disadvantage of Another disadvantage of pesticidespesticides

Insecticides can wash into a stream or lake where they are taken up by microscopic water plants. Consider the food chain:

Although the level of insecticides in the plants is small, it will build up through the food chain due to the number of organisms in each stage.

Small plants KingfisherMarine insects

Fish