ks4 biology
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KS4 Biology. Plant Nutrition. 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. How do plants get the food they need?. - PowerPoint PPT PresentationTRANSCRIPT
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KS4 Biology
Plant Nutrition
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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All living organisms need food to grow and survive.
How do plants get the food they need?
Plants are known as producers because they provide food for many other organisms.
Plants cannot move very much, so how do they get the food that they need?
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Green plants are amazing because they actually make their own food!
Green plants are the only living organisms that are able to do this.
All other organisms rely on plants because of the food that the plants make.
What is the name of the process by which plants make their own food?
Nutrition in green plants
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Plants make their own food by photosynthesis.This process is a chemical reaction that uses light energy.
What is photosynthesis?
light energy
The word photosynthesis comes from the Greek language:
“photo” means “light”“synthesis” means “putting together”
Photosynthesis just means “putting together with light”.What do green plants “put together” to make their food?
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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The raw materials for photosynthesis come from the air and the soil.
What are these raw materials called?
What else do plants need to turn carbon dioxide and water into food?
Photosynthesis: raw materials
carbondioxide
water
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Photosynthesis is a chemical reaction between carbon dioxide and water.
Energy is needed for this reaction to take place.
Where do plants get this energy from?
Photosynthesis: energy for the reaction
carbondioxide
water
light energy
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Plants use light energy from the Sun to power photosynthesis.
Where in the leaf does this reaction take place?
Photosynthesis takes place in what part of plant cells?
Photosynthesis: where it happens
carbondioxide
water
light energy
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Photosynthesis takes place in plant cells with chloroplasts.
Chloroplasts contain the green chemical called chlorophyll.
Chlorophyll absorbs the energy from sunlight that allows carbon dioxide and water to react.
What are the products of this reaction?
Photosynthesis: where it happens
carbondioxide
water
light energy
chlorophyll
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The products of the reaction between carbon dioxide and water are glucose and oxygen.
Which of these products is used by plants?
What happens to the ‘waste’ product?
Photosynthesis: products of the reaction
carbondioxide
water
glucose
oxygen
light energy
chlorophyll
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Glucose is the useful product for plants.
Some glucose is used straightaway by plant cells, some is converted to starch for storage and later used for food.
Oxygen is the ‘waste’ product. This gas is transported out of the leaf into the air.
Why is this important for humans and other living things?
Photosynthesis: products of the reaction
carbondioxide
water
oxygen
light energy
chlorophyll
glucose
oxygen
glucose
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Photosynthesis: summary
Summarize the process of photosynthesis in one sentence.
Photosynthesis is a chemical reaction which means it can also be summarized in a word equation.
What is the word equation for this vital chemical reaction?
Photosynthesis is a chemical reaction that takes place in the chloroplasts
in green plant cells, where light energy is used to convert carbon dioxide and water
into glucose and oxygen.
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Photosynthesis: word equation
carbondioxide
water
oxygen
light energy
chlorophyll
glucose
glucose
light energy
chlorophyll
carbondioxide water oxygen
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Photosynthesis: word equation activity
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Photosynthesis: chemical formulae?
Photosynthesis is a chemical reaction involving molecules.
glucose
light energy
chlorophyll
carbondioxide water oxygen
CO2 H2O O2C6H12O6
The chemical formula of a glucose molecule is C6H12O6.
What are the chemical formulae of the simple molecules that make up carbon dioxide, water and oxygen?
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Word equation to chemical equation
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Photosynthesis multiple-choice quiz
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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Leaves: maximizing photosynthesis
Leaves are the most efficient solar panels on Earth!
Why can they be called this?
Light energy is absorbed by the chlorophyll in leaves and used to carry out photosynthesis.
Leaves come in all shapes and sizes but what features do they have in common to maximize photosynthesis?
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Structure of a leaf
How are leaves designed to maximize photosynthesis?
Leaves are wide and flatto create a large surface
area and to absorb as much light as possible.
Leaves are thin so gases can reach cells easily.
Leaves have holes, called stomata, on their
underside through which gases move in and out.
Leaves have lots of veins to carry water to the cells and carry glucose away.
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Structure of a leaf activity
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Take a look inside a leaf
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What happens to the glucose?
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Testing leaves for starch – procedure
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Testing leaves for starch – experiment
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Photosynthesis and respiration
Only green plants photosynthesize,
glucose
light energy
chlorophyll
carbondioxide water oxygen
Compare the reactants, products and energy results of these two chemical reactions. How are they connected?
carbondioxideglucose oxygen water
Photosynthesis
Respiration
but respiration occurs in the cells of all living things to release energy.
(energy needed)
(energy released)
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12 a.m. 12 p.m. 12 a.m.
Photosynthesis and respiration
How will the amounts of oxygen and carbon dioxide in the air vary over 24 hours?
What overall effect do photosynthesis and respiration have on the levels of oxygen and carbon dioxide in the air?
amount of gas
in the air
amount of oxygen
amount of carbon dioxide
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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Photosynthesis is a chemical reaction and so has a rate.
Is the rate of photosynthesis always the same?
The rate of photosynthesis
light
glucose
light energy
chlorophyll
carbondioxide water oxygen
The rate of photosynthesis varies depending on three main factors:
How do these factors affect the rate of photosynthesis?
carbon dioxide temperature
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Light and the rate of photosynthesis
Light energy has to be absorbed by chlorophyll for photosynthesis to take place.
glucose
light energy
chlorophyll
carbondioxide water oxygen
The brighter the light, the more light energy there is, so will photosynthesis be faster or slower?
More light energy means that photosynthesis will be faster.
If light intensity is too high plant cells can be damaged.How is photosynthesis affected if this happens?
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Investigating photosynthesis – apparatus
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Investigating photosynthesis – experiment
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Investigating photosynthesis – results
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Carbon dioxide is one of the raw materials used by plants to make their food.
Carbon dioxide and the rate of photosynthesis
glucose
light energy
chlorophyll
carbondioxide water oxygen
The concentration of carbon dioxide in the air (0.03%) is actually quite low.
Why is the concentration of carbon dioxide in commercial greenhouses often raised to about 0.1%?
More carbon dioxide means more photosynthesis, so plants make more food and grow quicker.
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Photosynthesis is controlled by enzymes.Enzymes usually work best at warmer temperatures.
Temperature and the rate of photosynthesis
glucose
light energy
chlorophyll
carbondioxide water oxygen
Why is the rate of photosynthesis slower on a sunny day in winter compared to in summer?
If the temperature gets too hot (above 40 °C), plant enzymes begin to break down and are destroyed or denatured.
Why does photosynthesis stop under such conditions?
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What is the ideal combination of factors for the maximum rate of photosynthesis?
What is a limiting factor?
enough light enough carbon dioxide
ideal temperature (not too hot or cold)
How is the rate affected if one of these factors is restricted?
If one of the factors is restricted, the rate of photosynthesis will be below the maximum possible rate.
The restricted factor controls how quickly photosynthesis occurs and so limits the rate. It is called the limiting factor.
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Photosynthesis and light – limiting factors
How does the amount of light affect the rate of photosynthesis on this labelled graph?
As the amount of light increases, so does the rate. The limiting factor is light.
light intensity
rate
of
ph
oto
syn
thes
is
Here, increasing the amount of light has no affect on the rate. The limiting factor is now carbon dioxide or temperature.
What must be increased for the rate to increase?
1
2
1
2
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Photosynthesis and carbon dioxide – limiting factors
How does the amount of carbon dioxide affect the rate of photosynthesis on this labelled graph?
As the amount of carbon dioxide goes up, so does the rate. The limiting factor is carbon dioxide.
concentration of carbon dioxide
rate
of
ph
oto
syn
thes
is
Here, increasing the amount of carbon dioxide has no affect on the rate. Light or warmth is now the limiting factor.
What must be increased for the rate to increase?
1
2
1
2
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Photosynthesis and temperature – limiting factors
How does temperature affect the rate of photosynthesis on this labelled graph?
1. As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature.
temperature
rate
of
ph
oto
syn
thes
is
0oC 45oC
Most plant enzymes are destroyed at about 45°C. Here, photosynthesis stops and the rate falls to zero.What is the limiting factor?
1
2
1
2
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Limiting factors activity
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Limiting factors in the greenhouse
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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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?
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What minerals do plants need?
Plants need mineral elements for healthy growth.
Some of the most important minerals needed by plants are:
The mineral elements are found in salts dissolved in water.Plants obtain minerals when they absorb water from the soil.
How do plants obtain these minerals?
nitrogen
potassium ions
phosphorus
potassium
magnesium magnesium ions
phosphates
nitrates
What type of salt are each of these elements found in?
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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
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Plant and minerals – summary activity
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Where do minerals come from?
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.
What are the sources of minerals in the soil?
Why do farmers add fertilizers to their soil?
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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?
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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?
lower leaves yellow and dead
weak stem
upper leaves pale green
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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?
small roots
purple leaves
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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
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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
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Mineral deficiency experiment
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Plant and minerals summary
Mineral Use in plant Deficiency signs
nitrogen
phosphorus
potassium
magnesium
Complete this table of plant mineral needs and deficiencies.
making leaves
making roots
making flowersand fruits
making chlorophyll
stunted growth and yellow leaves
poor roots and purple leaves
yellow leaves with dead spots
leaves turn yellow from the bottom
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The rate of photosynthesis
Minerals from the soil
Plant Nutrition
What is photosynthesis?
More about photosynthesis
Contents
How do plants make food?
Multiple-choice quiz
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Multiple-choice quiz