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KS4 Biology Plant Nutrition.

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Presentation on theme: "KS4 Biology Plant Nutrition."— Presentation transcript:

1 KS4 Biology Plant Nutrition

2 Plant Nutrition How do plants make food? What is photosynthesis?
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

3 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?

4 Nutrition in green plants
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?

5 What is photosynthesis?
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?

6 Plant Nutrition How do plants make food? What is photosynthesis?
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

7 Photosynthesis: raw materials
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? carbon dioxide water

8 Photosynthesis: energy for the reaction
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? light energy carbon dioxide water

9 Photosynthesis: where it happens
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? light energy carbon dioxide water

10 Photosynthesis: where it happens
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? light energy chlorophyll carbon dioxide water

11 Photosynthesis: products of the reaction
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? light energy chlorophyll carbon dioxide oxygen glucose water

12 Photosynthesis: products of the reaction
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? light energy chlorophyll carbon dioxide oxygen oxygen glucose glucose water

13 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 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?

14 Photosynthesis: word equation
light energy carbon dioxide water glucose oxygen chlorophyll light energy chlorophyll carbon dioxide oxygen glucose water

15 Photosynthesis: word equation activity

16 Photosynthesis: chemical formulae?
Photosynthesis is a chemical reaction involving molecules. glucose light energy chlorophyll carbon dioxide water oxygen CO2 H2O C6H12O6 O2 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?

17 Word equation to chemical equation

18 Photosynthesis multiple-choice quiz

19 Plant Nutrition How do plants make food? What is photosynthesis?
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

20 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?

21 Structure of a leaf How are leaves designed 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.

22 Structure of a leaf activity

23 Take a look inside a leaf

24 What happens to the glucose?

25 Testing leaves for starch – procedure

26 Testing leaves for starch – experiment

27 Photosynthesis and respiration
Only green plants photosynthesize, but respiration occurs in the cells of all living things to release energy. Photosynthesis (energy needed) glucose light energy chlorophyll carbon dioxide water oxygen Respiration (energy released) carbon dioxide glucose oxygen water Compare the reactants, products and energy results of these two chemical reactions. How are they connected?

28 Photosynthesis and respiration
How will the amounts of oxygen and carbon dioxide in the air vary over 24 hours? amount of oxygen amount of gas in the air amount of carbon dioxide 12 a.m p.m a.m. What overall effect do photosynthesis and respiration have on the levels of oxygen and carbon dioxide in the air?

29 Plant Nutrition How do plants make food? What is photosynthesis?
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

30 The rate of photosynthesis
Photosynthesis is a chemical reaction and so has a rate. Is the rate of photosynthesis always the same? glucose light energy chlorophyll carbon dioxide water oxygen The rate of photosynthesis varies depending on three main factors: light carbon dioxide temperature How do these factors affect the rate of photosynthesis?

31 Light and the rate of photosynthesis
Light energy has to be absorbed by chlorophyll for photosynthesis to take place. glucose light energy chlorophyll carbon dioxide 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?

32 Investigating photosynthesis – apparatus

33 Investigating photosynthesis – experiment

34 Investigating photosynthesis – results

35 Carbon dioxide and the rate of photosynthesis
Carbon dioxide is one of the raw materials used by plants to make their food. glucose light energy chlorophyll carbon dioxide 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.

36 Temperature and the rate of photosynthesis
Photosynthesis is controlled by enzymes. Enzymes usually work best at warmer temperatures. glucose light energy chlorophyll carbon dioxide 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?

37 What is a limiting factor?
What is the ideal combination of factors for the maximum rate of photosynthesis? 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.

38 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. 1 2 2 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? rate of photosynthesis 1 light intensity

39 Photosynthesis and carbon dioxide – limiting factors
How does the amount of carbon dioxide affect the rate of photosynthesis on this labelled graph? 1 As the amount of carbon dioxide goes up, so does the rate. The limiting factor is carbon dioxide. 2 2 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? rate of photosynthesis 1 concentration of carbon dioxide

40 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. rate of photosynthesis 2 Most plant enzymes are destroyed at about 45°C. Here, photosynthesis stops and the rate falls to zero. What is the limiting factor? 2 1 0oC temperature 45oC

41 Limiting factors activity

42 Limiting factors in the greenhouse

43 Plant Nutrition How do plants make food? What is photosynthesis?
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

44 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?

45 What minerals do plants need?
Plants need mineral elements for healthy growth. Some of the most important minerals needed by plants are: nitrogen nitrates phosphorus phosphates potassium potassium ions magnesium magnesium ions How do plants obtain these minerals? The mineral elements are found in salts dissolved in water. Plants obtain minerals when they absorb water from the soil. What type of salt are each of these elements found in?

46 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

47 Plant and minerals – summary activity

48 Where do minerals come from?
What are the sources of minerals in the soil? 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. Why do farmers add fertilizers to their soil?

49 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?

50 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? upper leaves pale green lower leaves yellow and dead weak stem

51 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? purple leaves small roots

52 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

53 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

54 Mineral deficiency experiment

55 Plant and minerals summary
Complete this table of plant mineral needs and deficiencies. Mineral Use in plant Deficiency signs nitrogen phosphorus potassium magnesium making leaves stunted growth and yellow leaves making roots poor roots and purple leaves making flowers and fruits yellow leaves with dead spots making chlorophyll leaves turn yellow from the bottom

56 Plant Nutrition How do plants make food? What is photosynthesis?
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

57 Multiple-choice quiz


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