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12/04/2015 OCR Additional Science B4 The Processes of Life M Barker Shirebrook Academy.

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Presentation on theme: "12/04/2015 OCR Additional Science B4 The Processes of Life M Barker Shirebrook Academy."— Presentation transcript:

1 12/04/2015 OCR Additional Science B4 The Processes of Life M Barker Shirebrook Academy

2 12/04/2015 B4.1 How do Chemical Reactions take place in living things?

3 12/04/2015 Photosynthesis Introduction Basically, photosynthesis is the process through which a plant makes large food molecules using carbon dioxide and water and it happens in plants as well as some micro organisms: That’s a nice plant. I’m going to put it in the sun and give it lots of water and air… CO 2 H2OH2O

4 12/04/2015 Respiration Introduction I enjoy taking samples using quadrats. In order to do this, I need energy. Where does this energy come from? All living things, including plants, get their energy from respiration. Respiration is basically the process of breaking down the large food molecules that were probably originally made in plants.

5 12/04/2015 Enzyme use in nature Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes. Photosynthesis is catalysed by enzymes in the cells. Enzymes are proteins that speed up chemical uses. Here are two important natural uses for them:

6 12/04/2015Enzymes Enzymes are biological catalysts. They help the reactions that occur in our bodies by controlling the rate of reaction. An enzyme is basically a protein molecule made up of long chains of amino acids. Cells make enzymes according to the instructions carried in their genes. The enzyme’s shape helps another molecule “fit” into it: This shape can be destroyed by high temperatures or the wrong pH: Enzyme Substrate

7 12/04/2015 The “Active Site” EnzymeSubstrate Active site

8 12/04/2015 Enzymes are denatured beyond 40 O CEnzymes Enzymes work best in certain conditions: Enzyme activity TemppH 40 0 C Could be protease (found in the stomach) Could be amylase (found in the intestine) Enzymes are used in industry to bring about reactions at normal temperatures and pressures that would otherwise be expensive. However, most enzymes are denatured at high temperatures and can be costly to produce.

9 12/04/2015 B4.2 How do Plants make food?

10 12/04/2015 Travels up from the roots WATER CARBON DIOXIDE Enters the leaf through small holes on the underneath SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen Photosynthesis – the 4 things you need

11 12/04/2015 Carbon dioxide + _____ glucose + _____ 6CO 2 + 6H 2 0C 6 H 12 O 6 + 6O 2 Sunlight Chlorophyll Sunlight Chlorophyll The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________. Words – respiration, starch, water, oxygen, energy Photosynthesis equations

12 12/04/2015 What is the glucose used for? 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule 2) Glucose can be used to make cellulose for cell walls… 3) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Cellulose Proteins Glucose can also be used for respiration, either by the plant or by what eats it!

13 12/04/2015 A Typical Plant Cell: Cell wall – made of cellulose which strengthens the cell Cell membrane – controls what comes in and out Nucleus – controls what the cell does and stores genetic info for making proteins Large vacuole – contains sap and helps support the cell Cytoplasm – Chemical reactions happen here Chloroplasts – contains chlorophyll and enzymes for photosynthesis reactions

14 12/04/2015 2 common nutrients… Nitrates:  Used to make proteins  Lack of it leads to stunted growth Magnesium:  Used to make chlorophyll  Lack of it leads to yellow leaves

15 12/04/2015Diffusion Diffusion is when something travels from an area of high concentration to an area of low concentration. For example, consider the scent from a hamburger… The “scent particles” from this hamburger are in high concentration here: Eventually they will “diffuse” out into this area of low concentration: Carbon dioxide and oxygen pass in and out of leaves by diffusion.

16 12/04/2015 Diffusion Summary Diffusion is when particles spread from an area of high concentration to an area of ___ concentration. The particles move along a “concentration _____” and this process takes no _____ (it’s a “passive” process”). Diffusion can be accelerated by increasing the _______ of the particles, which makes them move _______. Words – faster, low, gradient, temperature, energy

17 12/04/2015Osmosis Osmosis is a “special kind of ___________”. It’s when water diffuses from a __________ area to a less concentrated area through a partially permeable _________ (i.e. one that allows water to move through but not anything else): WaterSugar solution In this example the water molecules will move from left to right (along the concentration ______) and gradually _____ the sugar solution. Plants use osmosis to take in water through their roots. Words – membrane, concentrated, dilute, diffusion, gradient

18 12/04/2015 Strong sugar solution Medium sugar solution Weak sugar solution Potato cells

19 12/04/2015 Active Transport In diffusion substances moved along a concentration gradient. In active transport, substances move against this gradient: Outside cellInside cell This process takes ______ and this comes from ___________. It enables cells to take in substances even though there are in very small __________. Root hair cells take in ______ using active transport. Cell membrane Words – concentration, energy, respiration, nutrients

20 12/04/2015 Carbon dioxide diffuses into the leaf through holes in the bottom surface. Diffusion and Active Transport in plants More concentrated Less concentrated Mineral …while plant nutrients are taken in by root hair cells using active transport.

21 12/04/2015 Encouraging Photosynthesis Using knowledge of limiting factors, explain how plant growth is encouraged in a greenhouse:

22 12/04/2015 Limiting Photosynthesis 1.Temperature – the best temperature is about 30 0 C – anything above 40 0 C will slow photosynthesis right down 2.CO 2 – if there is more carbon dioxide photosynthesis will happen quicker 3.Light – if there is more light photosynthesis happens faster What factors could limit the rate of photosynthesis?

23 12/04/2015 Drawing graphs of these factors 1. Temperature Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 40 0 C 2. Carbon dioxide 3. Light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO 2 Photosynthesis increases at first but is then limited by a lack of increase in temp or light

24 12/04/2015 Fieldwork techniques Recording light levels Using quadrats Fieldwork techniques also involve using a key to identify plants.

25 12/04/2015 B4.3 How do living organisms obtain energy?

26 12/04/2015 Uses for energy from respiration Animals and plants have many uses for the energy they generate from respiration: 1)To perform the life processes, such as moving, _____ etc 2)To build up body _______ 3)To maintain a constant body ___________ (warm-blooded mammals only) 4)To build up sugars, ________ and other nutrients in plants 5)Active __________ Words – nitrates, tissue, proteins, transport, growing

27 12/04/2015Synthesis 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule “Synthesis” means “making large molecules out of small ones”. Two examples: 2) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Proteins

28 12/04/2015 Respiration Introduction I enjoy taking samples using quadrats. In order to do this, I need energy. Where does this energy come from? Our energy comes from a process called respiration, which basically involves turning food and oxygen into energy and this reaction is controlled by enzymes.

29 12/04/2015 (Aerobic) Respiration Words – breathing, energy, grow, respiration, food, mitochondria All living organisms have to move, _____, reproduce etc. Each of these life processes needs ENERGY. ___________ is the process our bodies use to produce this energy: Glucose + oxygen water + carbon dioxide + ENERGY The glucose we need comes from ______ and the oxygen from _________. Water and carbon dioxide are breathed out. The MAIN product of this equation is _________. Respiration happens in _________ in cells.

30 12/04/2015 Muscles and exercise When we exercise our muscles are supplied with more oxygen and glucose, increasing the rate of respiration. Muscles store glucose as glycogen which can then be converted back into glucose during exercise.

31 12/04/2015 Anaerobic respiration Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________: This happens when the body can’t provide oxygen quick enough for __________ respiration to take place. Anaerobic respiration produces energy much _______ than aerobic respiration but only produces 1/20 th as much. Anaerobic respiration can also take place in other low-oxygen conditions, such as plant roots in _________ soil or bacteria in ________ wounds. Words – oxygen, aerobic, quicker, puncture, waterlogged Glucose lactic acid + a bit of energy

32 12/04/2015 Making Ethanol Ethanol is an important chemical. Many countries are increasing the amount of ethanol put into their petrol supplies: Ethanol is another product of anaerobic respiration in plant cells and some micro organisms: Ford Escape E85 – runs on 85% ethanol Sugar ethanol + carbon dioxide + energy

33 12/04/2015Bacteria Consider a bacteria cell in more detail: Bacteria – containing cytoplasm and a membrane surrounded by a cell wall. The genes are NOT in a distinct nucleus. The cell contains a number of features, including: 1)Chromosomal DNA, containing the genetic info of the cell 2)Plasmid DNA, containing extra information such as defence mechanisms 3)Flagella, which helps the cell move

34 12/04/2015 The Structure of Bacteria Bacteria also have plasmids (circular strands of DNA) that can be copied and move between different bacteria. This means that resistance to antibiotics can be passed on without the need for reproduction.

35 12/04/2015 4) 2) Respiration in Cells Notice that plant and animal cells (and bacteria) have many features that help respiration: Mitochondria – contain enzymes for respiration reactions Cell Membrane – controls what comes in and out Cytoplasm - where enzymes are made Nucleus – carries genetic info for making enzymes 1) 3) In bacteria cells, this job is done by circular DNA

36 12/04/2015 Using Anaerobic Respiration Anaerobic respiration in micro organisms is used to make fuels through: 1)Manure or other waste that can be used to release methane (biogas) 2)Corn or sugar cane that can be broken down in a fermenter to produce alcohols like bio-ethanol. Anaerobic respiration is also used in fermentation to make bread and alcohol.


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