OCR Additional Science 10/04/2017 B4 The Processes of Life OCR Additional Science M Barker Shirebrook Academy

B4.1 How do Chemical Reactions take place in living things? 10/04/2017 B4.1 How do Chemical Reactions take place in living things?

Photosynthesis Introduction 10/04/2017 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… CO2 H2O

Respiration Introduction 10/04/2017 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 Respiration is basically the process of breaking down the large food molecules that were probably originally made in plants.

Enzyme use in nature 10/04/2017 Enzymes are proteins that speed up chemical uses. Here are two important natural uses for them: Photosynthesis is catalysed by enzymes in the cells. Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes.

Enzymes 10/04/2017 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. Enzyme The enzyme’s shape helps another molecule “fit” into it: Substrate This shape can be destroyed by high temperatures or the wrong pH:

The “Active Site” 10/04/2017 Active site Enzyme Substrate

Enzymes are denatured beyond 40OC 10/04/2017 Enzymes work best in certain conditions: Enzymes are denatured beyond 40OC Could be protease (found in the stomach) Could be amylase (found in the intestine) Enzyme activity Temp pH 400C 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.

B4.2 How do Plants make food? 10/04/2017 B4.2 How do Plants make food?

Photosynthesis – the 4 things you need 10/04/2017 SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen WATER Travels up from the roots CARBON DIOXIDE Enters the leaf through small holes on the underneath

Photosynthesis equations 10/04/2017 Carbon dioxide + _____ glucose + _____ 6CO2 + 6H20 C6H12O6 + 6O2 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

What is the glucose used for? 10/04/2017 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… Glucose molecules Cellulose 3) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Proteins Glucose can also be used for respiration, either by the plant or by what eats it!

A Typical Plant Cell: 10/04/2017 Cell wall – made of cellulose which strengthens the cell Cell membrane – controls what comes in and out Chloroplasts – contains chlorophyll and enzymes for photosynthesis reactions 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

2 common nutrients… Nitrates: Magnesium: Used to make proteins 10/04/2017 Nitrates: Used to make proteins Lack of it leads to stunted growth Magnesium: Used to make chlorophyll Lack of it leads to yellow leaves

Carbon dioxide and oxygen pass in and out of leaves by diffusion. 10/04/2017 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.

Words – faster, low, gradient, temperature, energy Diffusion Summary 10/04/2017 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

Words – membrane, concentrated, dilute, diffusion, gradient Osmosis 10/04/2017 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): 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. Water Sugar solution Words – membrane, concentrated, dilute, diffusion, gradient

Strong sugar solution Medium sugar solution Potato cells 10/04/2017 Strong sugar solution Medium sugar solution Potato cells Weak sugar solution

Words – concentration, energy, respiration, nutrients Active Transport 10/04/2017 In diffusion substances moved along a concentration gradient. In active transport, substances move against this gradient: Outside cell Inside 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. Words – concentration, energy, respiration, nutrients Cell membrane

Diffusion and Active Transport in plants 10/04/2017 Mineral Less concentrated More concentrated Carbon dioxide diffuses into the leaf through holes in the bottom surface. …while plant nutrients are taken in by root hair cells using active transport.

Encouraging Photosynthesis 10/04/2017 Using knowledge of limiting factors, explain how plant growth is encouraged in a greenhouse:

Limiting Photosynthesis 10/04/2017 What factors could limit the rate of photosynthesis? Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down CO2 – if there is more carbon dioxide photosynthesis will happen quicker Light – if there is more light photosynthesis happens faster

Drawing graphs of these factors 10/04/2017 1. Temperature Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 400C 2. Carbon dioxide Photosynthesis increases at first but is then limited by a lack of increase in temp or light 3. Light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO2

Recording light levels Fieldwork techniques 10/04/2017 10/04/2017 Recording light levels Using quadrats Fieldwork techniques also involve using a key to identify plants.

B4.3 How do living organisms obtain energy? 10/04/2017 B4.3 How do living organisms obtain energy?

Uses for energy from respiration 10/04/2017 Animals and plants have many uses for the energy they generate from respiration: To perform the life processes, such as moving, _____ etc To build up body _______ To maintain a constant body ___________ (warm-blooded mammals only) To build up sugars, ________ and other nutrients in plants Active __________ Words – nitrates, tissue, proteins, transport, growing

Synthesis 10/04/2017 “Synthesis” means “making large molecules out of small ones”. Two examples: 1) Glucose (sugar) can be used to make long chains of insoluble starch… Glucose molecules Starch molecule 2) Glucose can be combined with nitrates to make proteins (for growth)… Glucose molecules Proteins

Respiration Introduction 10/04/2017 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.

(Aerobic) Respiration 10/04/2017 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. Words – breathing, energy, grow, respiration, food, mitochondria

Muscles and exercise 10/04/2017 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.

Anaerobic respiration 10/04/2017 Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________: Glucose lactic acid + a bit of energy 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 1/20th 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

Sugar ethanol + carbon dioxide + energy Making Ethanol Ford Escape E85 – runs on 85% ethanol 10/04/2017 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: Sugar ethanol + carbon dioxide + energy

Bacteria Consider a bacteria cell in more detail: The cell contains a number of features, including: Chromosomal DNA, containing the genetic info of the cell Plasmid DNA, containing extra information such as defence mechanisms Flagella, which helps the cell move 10/04/2017 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 Structure of Bacteria 10/04/2017 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.

In bacteria cells, this job is done by circular DNA Respiration in Cells 10/04/2017 Notice that plant and animal cells (and bacteria) have many features that help respiration: 1) Cytoplasm - where enzymes are made In bacteria cells, this job is done by circular DNA 2) Nucleus – carries genetic info for making enzymes 3) Cell Membrane – controls what comes in and out 4) Mitochondria – contain enzymes for respiration reactions

Using Anaerobic Respiration 10/04/2017 10/04/2017 Anaerobic respiration in micro organisms is used to make fuels through: Manure or other waste that can be used to release methane (biogas) 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.