ks4 plant nutrition (boardworks)

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KS4 Biology

Plant Nutrition


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


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?


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


Plants make their own food by photosynthesis.This process is a chemical reaction that uses light energy.


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?




Plant Nutrition



Contents




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


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


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


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


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


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


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.


Photosynthesis: word equation

carbondioxide

water

oxygen

light energy

chlorophyll

glucose

glucose

light energy

chlorophyll

carbondioxide water oxygen


Photosynthesis: word equation activity


Photosynthesis: chemical formulae?

Photosynthesis is a chemical reaction involving molecules.

glucose

light energy

chlorophyll


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?


Word equation to chemical equation


Photosynthesis multiple-choice quiz




Plant Nutrition



Contents




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?


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.


Structure of a leaf activity


Take a look inside a leaf


What happens to the glucose?


Testing leaves for starch – procedure


Testing leaves for starch – experiment


Photosynthesis and respiration

Only green plants photosynthesize,

glucose

light energy

chlorophyll


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)


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




Plant Nutrition



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Photosynthesis is a chemical reaction and so has a rate.

Is the rate of photosynthesis always the same?


light

glucose

light energy

chlorophyll


The rate of photosynthesis varies depending on three main factors:

How do these factors affect the rate of photosynthesis?

carbon dioxide temperature


Light and the rate of photosynthesis

Light energy has to be absorbed by chlorophyll for photosynthesis to take place.

glucose

light energy

chlorophyll


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?


Investigating photosynthesis – apparatus


Investigating photosynthesis – experiment


Investigating photosynthesis – results


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


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.


Photosynthesis is controlled by enzymes.Enzymes usually work best at warmer temperatures.

Temperature and the rate of photosynthesis

glucose

light energy

chlorophyll


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?


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.


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


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


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


Limiting factors activity


Limiting factors in the greenhouse




Plant Nutrition



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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?


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?


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


Plant and minerals – summary activity


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?


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?


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


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


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


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


Mineral deficiency experiment


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




Plant Nutrition



Contents



ks4 plant nutrition (boardworks)

Education

word photosynthesis

photosynthesis leaves

photosynthesis contents

process of photosynthesis

power photosynthesis

green plants

chemical equation

green chemical