Photosynthesis. Synthesizing food from light

Transcription

1 Photosynthesis Synthesizing food from light 7.5A recognize that radiant energy from the Sun is transformed into chemical energy through the process of photosynthesis

2 Consider a Hamburger.. It contains meat that was once a part of a cow. Where did the cow get the energy to make the muscle that became meat? A cow must take in food, such as plants, that already contain chemical energy. So where do plants get this energy?

3 The sun through the process of photosynthesis!

4 Let s go over a few terms Energy is the ability to do work Forms of energy potential and kinetic Tell me what you know about potential and kinetic energy

5 Kinetic and Potential Energy Potential Energy is stored energy. Kinetic Energy is the energy of motion.

6 Potential Energy Stored energy due to an object's position or chemical composition

7 Kinetic Energy Energy in motion.

8 Energy changes - As energy travels through the universe, it changes from one type or form to another. This is known as energy transformation Lets take a look at the types.

9 Energy Transformation is: The change of energy from one form to another. Example: Energy Transformation

10 Types of energy we will focus on: Of all of the forms or types of energy that exist, we will focus on just three: Chemical energy, mechanical energy and light (radiant) energy

11 Chemical Energy Energy STORED in matter because of its CHEMICAL bonds. It is released during a chemical reaction. Examples: Battery Digestion Burning Wood/Fuel

12 Chemical Energy Chemical Energy is required to bond atoms together. And when bonds are broken, energy is released.

13 Chemical Energy Fuel and food are forms of stored chemical energy.

14 Mechanical Energy Energy that an object has because of its movement or position. Examples: Moving Cars Waterfalls Running Sound

15 Radiant or light Energy Type of energy from the sun. Energy carried by ELECTROMAGNETIC RADIATION. Radiant=LIGHT (but it Isn t always visible) Examples: Visible Light/Sunlight (What you see) X-Rays (invisible) Microwaves (invisible) UV Light (invisible)

16 Law of Conservation of Energy The law states: Energy cannot be created nor destroyed. What does this mean? It means that energy can only change its form from one type to another. The energy of the world is a constant because the total amount of the energy does not change.

17 Law of Conservation of Energy For example: Let s look at a flashlight. It runs on batteries. The battery has chemical energy. When the flashlight is turned on, the chemical energy is first transformed into electrical energy and then into light energy.

18 Law of Conservation of Energy Another example: Sunlight absorbed by plants. This radiant or light energy is converted into food (chemical energy) by the plant going through photosynthesis.

19 Photosynthesis photo = LIGHT synthesis = BUILD Photosynthesis means building with Light The process through which plants make their own food through a chemical change.

20 What are chemical changes and chemical reactions? Chemical change is when you start with one molecule and turn it into another. Chemical reaction is: when two or more molecules interact and the molecules change. Bonds between atoms are broken and created to form new molecules.

21 Chemical reaction ex:

22 The Chemical change A chemical reaction takes place in plants in which light energy is converted to chemical energy in the form of food Food = Carbohydrates are used by all living things as fuel for energy. It is the means by which the energy in sunlight becomes usable to living things.

23 So Where does photosynthesis occur? Photosynthesis occurs in the leaves of a plant. Inside the leaf lots of cells!

24 Parts of a plant cell Chloroplast Mitochondria Stomata -

25 Close up of plant cell: The chloroplast the chloroplast has chlorophyll in it (the chemical that makes plants green). Chlorophyll allows the plant to absorb radiant energy or sunlight.

26 Close up of plant cell: The mitochondria the organelle that generates (make) the energy in the cell

27 Close up of plant cell: The stomata this is the cell part that releases the waste oxygen and takes in carbon dioxide.

28 All of these parts work together to capture sunlight and to convert this radiant energy into chemical energy or glucose (sugar).

29 The Chemical Reaction Explained (what happens at the molecular level): Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into glucose. Oxygen is released in this reaction. What do all of these letters and numbers mean?

30 Elemental or atomic symbol reminder! If you don t know what these symbols are, you need to spend some time studying the periodic table! C = O = H = Carbon Oxygen Hydrogen These elements constantly recombine to form molecules.

31 Reading a chemical molecule:

32 Let s take a closer look

33 Make a small T chart: Reactants Products

34 Some simple steps to understand chemical formula terms Reactants what goes in to the chemical reaction (the first part) Products what is made after the chemical reaction occurs (the second part)

35 six molecules of carbon dioxide plus six molecules of water produce one molecule of sugar plus six molecules of oxygen Reactants Energy (sunlight) Products 6CO 2 + 6H 2 O Radiant Energy C 6 H 12 O 6 + 6O 2 From the air Write the formula down! Water taken up by roots Glucose Energy Fuel Oxygen

36 Note how each of the raw materials (reactants) end up in the chloroplasts so that the whole photosynthesis process can happen.

37 Pay attention to what happens to the products of photosynthesis.

38 What about oxygen? If you noticed before, oxygen is released as a product that is NOT used by the plant. This is known as a by-product or waste Who does use oxygen?

39 Earth Guide

40 What do plants do with the energy? As a result of photosynthesis, plants meet their immediate need for energy to grow, develop, respond, and reproduce. The food not used right away is stored by plants in their roots, stems, leaves, fruit, or flowers

41 The glucose is very useful for the plant Can be converted into fats and oils for the seeds Can be joined together to make cellulose for the cell walls Can be converted to fructose for the fruit glucose Can be combined with nutrients from the soil to make proteins for the new Can be used in respiration to release energy can be joined together to make starch for storage

42 The Importance of Plants Photosynthesis in plants and a few bacteria is responsible for feeding nearly all life on Earth. It does this by taking energy from the sun and converting it into a storable form, usually glucose, which plants use for their own life processes. Animals that consume plants also make use of this energy, as do those that consume those that consume plants, and so on to the top of the food chain.

43 Our Part As important a job as making all of the world's food is, there's another vital function that photosynthesis performs: It generates the oxygen that oxygenbreathing animals need to survive. But here we animals repay the favor. We exhale the carbon dioxide that plants need for photosynthesis.

44 Respiration (not the breathing kind) Cellular respiration is the process in which nutrients are converted in useful energy in the cell. This useful energy is known as sugar. Different organisms make different types of sugars Some examples are glucose and fructose

45 Cellular Respiration Animals like us need energy which is obtained from sugars. This process of obtaining energy from sugar is known as respiration. Respiration occurs in the mitochondria of cells. So now that the plant has made the sugar energy, it needs to use it. But how does it do this?

46 Photosynthesis and Respiration are reverse operations! Photosynthesis: making the energy Respiration: using the energy

47 Comparison Photosynthesis Food is formed (made) Energy from the sun stored in glucose Carbon dioxide taken in Oxygen given off Goes on only in light Occurs in presence of chlorophyll Respiration Food broken down (used) Energy stored in organic molecules is released Carbon dioxide given off Oxygen taken in Goes on day and night Occurs in all living cells

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