KS4 Plant Nutrition. Plant Nutrition презентация

More about photosynthesis

Contents

How do plants make food?

Multiple-choice quiz

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?

Nutrition in green plants

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?

More about photosynthesis

Contents

How do plants make food?

Multiple-choice quiz

Photosynthesis: raw materials

carbon
dioxide

water

Photosynthesis: energy for the reaction

carbon
dioxide

water

light energy

Photosynthesis: where it happens

carbon
dioxide

water

light energy

Photosynthesis: where it happens

carbon
dioxide

water

light
energy

chlorophyll

Photosynthesis: products of the reaction

carbon
dioxide

water

glucose

oxygen

light
energy

chlorophyll

Photosynthesis: products of the reaction

carbon
dioxide

water

oxygen

light
energy

chlorophyll

glucose

oxygen

glucose

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.

CO2

H2O

O2

C6H12O6

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?

More about photosynthesis

Contents

How do plants make food?

Multiple-choice quiz

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?

Leaves are wide and flat
to 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.

Photosynthesis

Respiration

but respiration occurs in the cells of all living things to release energy.

(energy needed)

(energy released)

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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How do plants make food?

Multiple-choice quiz

The rate of photosynthesis

light

The rate of photosynthesis varies depending on three main factors:

How do these factors affect the rate of photosynthesis?

carbon dioxide

temperature

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?

Carbon dioxide and the rate of photosynthesis

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.

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 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.

As the amount of light increases, so does the rate. The limiting factor is light.

light intensity

rate of photosynthesis

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

As the amount of carbon dioxide goes up, so does the rate. The limiting factor is carbon dioxide.

concentration of
carbon dioxide

rate of photosynthesis

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

As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature.

temperature

rate of photosynthesis

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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Contents

How do plants make food?

Multiple-choice quiz

Just like humans, plants need a balanced diet
that includes small amounts of mineral elements.

What mineral elements do they need?

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?

making leaves

making roots

making flowers and fruit

making chlorophyll

What are the sources of minerals in the soil?

Why do farmers add fertilizers to their soil?

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?

lower leaves yellow and dead

weak stem

upper leaves
pale green

small roots

purple leaves

poor flower
and fruit growth

yellow leaves
with dead spots

upper leaves normal (leaves turn yellow from bottom upwards)

lower leaves pale green or yellow

making leaves

making roots

making flowers
and fruits

making chlorophyll

stunted growth and
yellow leaves

poor roots and
purple leaves

yellow leaves with
dead spots

leaves turn yellow
from the bottom

More about photosynthesis

Contents

How do plants make food?

Multiple-choice quiz