Plants Nutrition
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Transcript of Plants Nutrition
Content Photosynthesis Energy for the reaction Raw materials Products of the reaction Word equation Chemical equation Structure of leave Stomata The rate of photosynthesis Carbon dioxide Light Temperature Limiting Factors Carbon dioxide-limiting Factors Light-limiting Factors Temperature-limiting Factors Minerals Dificiency Nitrogen Phosphorus Potassium Magnesium Fertilisers (NPK) Greenhouse production Reference Questions
How do plants get the food they need?All living organisms need food to grow and survive.
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 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.
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?
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
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
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
light energy
chlorophyll
oxygen
glucose
Photosynthesis: summary
Summarize the process of photosynthesis in one sentence.
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: chemical formulae?
Photosynthesis is a chemical reaction involving molecules.
glucose
light energy
chlorophyll
carbondioxide water oxygen
CO2 H2O O2C6H12O6
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.
Stomata
Stomata is a pore, found in the epidermis of leaves, stems and other organs that is used to control gas exchange.
The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening.
Open in the morning. Close at night.
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
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?
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.
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?
What is a limiting factor?
A factor present in an environment that controls a process, particularly the growth, abundance or distribution of a population of organisms in an ecosystem.
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
pho
tosy
nth
esis
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
pho
tosy
nthe
sis
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
phot
osy
nthe
sis
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
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
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.
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
Fertilisers (NPK)
• Fertilisers make crops grow faster and bigger so that crop yields are increased. They're minerals, which must first dissolve in water so that plants can absorb them through their roots.
• Fertilisers provide plants with the essential chemical elements needed for growth particularly nitrogen, phosphorus and potassium. The proportions of these elements in a fertiliser are often shown as N:P:K = 15:30:15.
Greenhouse production Farmers can use their knowledge of factors limiting the rate of
photosynthesis to increase crop yields. This is particularly true in greenhouses, where the conditions are more
easily controlled than in the open air outside: The use of artificial light allows photosynthesis to continue beyond
daylight hours. Bright lights also provide a higher-than-normal light intensity.
The use of artificial heating allows photosynthesis to continue at an increased rate.
The use of additional carbon dioxide released into the atmosphere inside the greenhouse also allows photosynthesis to continue at an increased rate.
Reference
• www.google.com• https://www.google.co.th/search?
q=fertilisers+npk&espv=2&biw=1366&bih=623&source=lnms&tbm=isch&sa=X&ei=ZPFAVZ-wOY6juQShn4H4Dg&ved=0CAcQ_AUoAQ#tbm=isch&q=fertilisers+
• http://feeco.com/npk-fertilizer-what-is-it-and-how-does-it-work/
• http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway_pre_2011/chemical/fertilisersrev1.shtml
• http://en.wikipedia.org/wiki/Fertilizer• www.bbcbitesize.com• Biology for Cambridge IGCSE (Book)• Others Books for Biology IGCSE
Plant and minerals (Question)
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
Questions
1. Write down the balanced chemical equation for photostnthesis. On the equation identify the sources of energy, raw material, and by-product.
2. Write down the word equation for photosynthesis3. Define: Limiting factor Stomata Fertilisers NPK