17/04/2018. AQA Science Trilogy and Triple Biology Paper 1

Transcription

1 AQA Science Trilogy and Triple Biology Paper 1

2 B1 Cells and Cell Transport Starter: Mark your homework exam questions and show me your revision notes. Hwk: Complete week 2 of revision timetable making revision notes and complete exam questions (Weds)

3 Microscopes Light Microscopes Light microscope enable us to see images of microscopic objects by magnifying them, which we cannot see with the naked eye. Electron Microscopes Electron microscopes use an electron beam focused by electromagnets to view specimens which cannot be seen with light microscopes.

4 1 micrometre is one millionth of a metre.

5 Microscope Calculations 1. What is the total magnification of an image if the microscopes has an eyepiece of x10 magnification and an objective of x40 magnification? 2. Calculate the actual size of the object if the size of the image is 0.25cm and the magnification is x40?

6 A Typical Animal Cell 1) Cytoplasm - this is where the reactions happen and these are controlled by enzymes 2) Nucleus controls the cell s activities 3) Cell Membrane controls what comes in and out 4) Ribosomes protein synthesis happens here 5) Mitochondria - energy is released here during respiration

7 A Typical Plant Cell: Cell wall made of cellulose which strengthens the cell Cell membrane controls what comes in and out Large vacuole contains sap and helps support the cell Chloroplasts (containing chlorophyll) this is needed for photosynthesis Nucleus controls what the cell does and stores information Cytoplasm Chemical reactions happen here

8 Eukaryotic and Prokaryotic Cells Prokaryotic Cells: Have DNA but NOT enclosed in a nucleus. Have cytoplasm and cell membrane enclosed in a cell wall. Smaller than Eukaryotic cells. Example is bacteria. Eukaryotic cells: Have DNA enclosed in a nucleus Have cell membrane and cytoplasm Example is an animal cell.

9 Specialised animal cells I.D: Function: Features: Red Blood Cell Carries oxygen around the body No nucleus and large surface area What are their jobs and how are they specialised to carry them out? Think about how they are different! I.D: Function: Features: Sperm Cell Travel and fertilise Egg.???

10 Specialised animal cells I.D: Function: Features: Nerve Cell Carry electrical impulses in the nervous system Lots of dendrites to connect to other cells, long axon to carry impulse, nerve endings which transmit chemical across synapse.

11 Specialised plant cells Food Photosynthetic cell Called sieve plates Outer walls are dead cells. Cells contain mitochondria to provide energy to transport the food. Root hair cell

12 Diffusion Summary Diffusion is when particles spread from an area of high concentration to an area of low concentration. The particles move along a concentration gradient and this process takes no energy (it s a passive process ). Diffusion can be accelerated by increasing the temperature of the particles, which makes them move faster or increasing the concentration gradient.

13 Diffusion in the Body Cells use diffusion to swap the oxygen they need for the carbon dioxide they no longer want: Oxygen diffuses in Out goes waste CO 2 Other examples of where diffusion happens in humans: Alveoli in the lungs Villi in the intestines

14 Diffusion in Villi In the intestine, large food molecules are broken down into smaller ones that then diffuse into the blood through villi in the intestine. Villi also have a very good blood supply to increase concentration gradient and a large surface area to increase the rate of diffusion. They have tiny folds in their cell membrane called microvilli, which increase the surface area.

15 Osmosis Osmosis is a special kind of diffusion. It s when water particles diffuses from a dilute area to a concentrated solution through a partially permeable membrane (i.e. one that allows water to move through but not anything else): Water Sugar solution In this example the water molecules will move from left to right (along the concentration gradient) and gradually into the sugar solution.

16 Potato cells Strong sugar solution Medium sugar solution Weak sugar solution

17 Osmosis in Animal and Plant cells If cells absorb too much or not enough water they may swell or shrivel, causing them to work less efficiently.

18 Investigating Osmosis in plant cells 1. Using a cork borer cut potato cylinders to the same size and remove ends. 2. Wipe with paper towel to remove excess moisture. 3. Record the length and mass of each potato core. 4. Set up test tubes containing different concentrations of sugar solution. 5. Place a potato cylinder in each test tube and leave for 1 hour. 6. Remove from the test tube and wipe with paper towel. 7. Weigh and measure the length and calculate the change in mass and length.

19 Active Transport In diffusion substances moved along a concentration gradient. In active transport, substances move against a concentration gradient: Outside cell Inside cell This process takes energy and this comes from respiration. It enables cells to take in substances even though they are in very small concentrations. Root hair cells take in nutrients using active transport. Cell membrane Words concentration, energy, respiration, nutrients

20 B2 Cell differentiation and replication Starter: Mark your homework questions. Hwk: Complete week 3 and 4 of revision timetable, including notes on each topic and exam questions (Tues 17 th April)

21 Cells, Genes and Chromosomes Chromosomes contain the genetic information (genes) and are normally found in pairs in the nucleus (humans have 23 pairs, so a total of 46 chromosomes). They are replicated every time a cell divides by mitosis.

22 Mitosis vs. Meiosis Mitosis: 1. Used for growth and repair of cells 2. Produces a clone 3. Cells with identical number of chromosomes and genetic information are produced Meiosis: 1. Used to produce gametes for sexual reproduction occurs in the testes and ovaries 2. Each daughter cell has half the number of chromosomes of the parent During meiosis copies of the genetic information are made and then the cell divides twice to form four daughter cells.

23 Stages of mitosis Mitosis: Stage 1: The longest phase. The parent cell grows larger and carries out normal cell activity. Its DNA is replicated to form 2 copies of each chromosome and the number of sub cellular structures increases ie. ribosomes. Stage 2: Mitosis occurs 1 set of each chromosome is pulled to each end of the dividing cell. The nucleus divides. Stage 3: Cytoplasm and cell membrane divides to form two identical daughter cells.

24 Cell differentiation During the development of a multi-celled organism an unspecialised cell, called a Stem cell, differentiates to form specialised cells that carry out a particular function: In animals, most cell differentiation happens at an early stage (during foetal development). In plants, most cell differentiation can happen throughout its life. White blood cell Ciliated epithelial cell Nerve cell (neurone) Egg cell (ovum)

25 Cell differentiation Stem cells from meristems can be used to produce clones of plants quickly and cheaply. Eg. For protection from extinction or high crop yield. Unspecialised cells in plants are known as meristems. They are found in the stem and root, allowing mitosis to take place continuously. Plant cells do not differentiate permanently, they can redifferentiate, but animal cells cannot.

26 Stem Cells A stem cell is an unspecialised cell that can differentiate to become a specialised cell. It can be found in embryos or bone marrow. These cells can be used to treat certain conditions but the use of these cells is very controversial. Embryonic stem cells can be cloned from unused embryos in IVF treatment and used to differentiate into MOST type of specialised cells eg nerve cells to replace damaged nerves. STEM CELL Meristems in plants can differentiate into any type of plant cell throughout its life. Adult stem cells are found in bone marrow and can differentiate into some specialised cells such as blood cells.

27 Stem cell research Stem cells are cells that have not yet specialised: In therapeutic cloning an embryo is produced with the same genes as the patient. Embryo Cloned embryos Adv of Stem cells: No risk of rejection by the body as it is a tissue match. Dis of Stem cells: Ethical or religious objections destroying a potential life. Risk of transfering viral infections. The ethical issue: Should these embryos be treated as humans?

28 B3. Organisation and digestive system

29 Cells, tissues, organs and systems Basically, all living things are made up of cells A group of CELLS with similar structure and function makes up a TISSUE A group of TISSUES performing a specific function makes up an ORGAN A group of ORGANS working together makes up an ORGAN SYSTEM A group of ORGAN SYSTEMS working together make up an ORGANISM

30 Another example Here s another example in humans: Muscle cells Muscle tissue Organ Organ System Organism

31 Examples of Plant Tissue 1) Epidermal tissue, which covers the plant 2) Mesophyll, where photosynthesis occurs 3) Xylem and phloem, which are used to transport substances around the plant

32 An example organ: The Stomach Consider one of the body s most important organs the stomach: The stomach contains many different types of tissue, including: 1) Muscular tissue, to contract and churn up the contents 2) Glandular tissue, to produce digestive juices 3) Epithelial tissue, to cover and protect the outside of the stomach

33 An example system: The Digestive System The whole point of digestion is to break down our food so that we can get the bits we need from it. Basically, here s how it works: 1) Glands such as the salivary gland and the pancreas produce digestive juices 2) Digestion occurs in the stomach (churns and breaks down food) and small intestine (absorbs glucose and nutrients) 3) Bile is produced by the liver and helps break down fats 4) Glucose is absorbed in the small intestine 5) Water is absorbed in the large intestine, leaving behind the faeces

34 Villi also have a very good blood supply to increase concentration gradient and a large surface area to increase the rate of diffusion. They have tiny folds in their cell membrane called microvilli, which increase the surface area. Diffusion in Villi In the intestine, large food molecules are broken down into smaller ones that then diffuse into the blood through villi in the intestine. How is the small intestine adapted for diffusion?

35 Required Practical: Food tests

36 The digestive system The whole point of digestion is to break down our food so that we can get the bits we need from it The main foods affected are CARBOHYDRATES these are broken down into GLUCOSE. Hydrochloric acid is produced in the stomach to kill bacteria. Digestion also depends on enzymes...

37 Introduction to Enzymes 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. These molecules are then folded to create a certain shape. Proteins are used in hormones, antibodies and muscle tissue. The enzyme s active site is shaped to fit a specific substrate. This shape of the active site can be destroyed by high temperatures or the wrong ph which means the enzyme will no longer work: Enzyme Substrate

38 Enzymes Enzymes work best in certain conditions: Enzyme activity Enzymes are denatured beyond 40 O C Could be protease (found in the stomach) Could be amylase (found in the intestine) 40 0 C Temp ph ph 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.

39 Enzymes Required Practical Amylase breaks down starch into glucose. Explain how the following equipment (and other equipment) could be used to investigate the affect of ph, temperature and concentration affect enzyme controlled reactions.

40 The products from digestion are used to build new carbohydrates, lipids and proteins as well as glucose being used in respiration. Bloodstream Enzymes in digestion Enzymes can be produced by the body to help digestion. When they come into contact and react with food they break it down into smaller pieces which can then pass into the blood: Amylase (produced in the mouth, pancreas and small intestine) breaks starch (a carbohydrate) down into glucose: Protease (produced in the stomach, pancreas and small intestine) breaks proteins down into amino acids: Lipase (produced in the pancreas and small intestine) breaks fats (lipids) down into fatty acids and glycerol:

41 Bile and The Liver Bile is a chemical produced in the liver and stored in the gall bladder. It has 2 functions: 1) It is alkaline to neutralise stomach acid so that enzymes can work. 2) It emulsifies ( breaks down fats to form small droplets to increase the surface area of the fats. This will increase the rate of fat break down by lipase: Fat globules Fat droplets

42 B4 Organising animals and plants

43 The four parts of blood 1. RED BLOOD CELLS contain haemoglobin and carry oxygen around the body. They have no nucleus and a large surface area. 2. PLATELETS small bits of cells that lie around waiting for a cut to happen so that they can clot (for a scab). 3. WHITE BLOOD CELLS kill invading pathogens by producing antibodies or engulfing the microbe. These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO 2 and glucose as well as taking away waste products to the kidneys

44 Arteries, veins and capillaries Arteries carry high pressure blood away from the heart. They have smaller lumen and no valves. Capillaries have thin walls (one cell thick) to allow glucose and oxygen to pass through. Also used to connect arteries to veins. Lumen Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.

45 The Heart The heart is basically a muscle with four main chambers:

46 The Heart 1. Deoxygenated blood (i.e. blood without oxygen) enters through the vena cava into the right atrium 4. Oxygenated blood from the lungs enters through the pulmonary vein into the left atrium 2. It s then pumped through a valve into the right ventricle 5. It s then pumped through another valve into the left ventricle 3. It s then pumped through another valve up to the lungs through the pulmonary artery 6. It s then pumped out of the aorta to the rest of the body

47 Double Circulation 1) Blood gets pumped from the heart to the lungs and picks up oxygen. The haemoglobin in the cells becomes oxyhaemoglobin 5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again 2) The blood is then taken back to the heart 3) The heart pumps the blood to the intestine (where oxygen and glucose are removed). The oxyhaemoglobin is split up into oxygen and haemoglobin 4) and to the rest of the body (where oxygen is also removed)

48 Heart disease Arteries can narrow due to cholesterol and other factors. If this happens a stent may be needed:

49 Mending the Heart What are the pros and cons of using the following artificial products?

50 The Respiratory System The bigger the organism, the more difficult it is to exchange materials. How are a human s lungs adapted for this purpose?

51 Diffusion in the lungs Oxygen diffuses in and carbon dioxide diffuses out of blood in the lungs: CO 2 Alveoli have three things that help them to do this job: a massive surface area, a moist lining that is only one cell thick and a very good blood supply.

52 Ventilation Note the role the diaphragm has in helping us to breathe:

53 Diffusion and Active Transport in plants Mineral More concentrated Less 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.

54 Root hair cells Plant roots are made of root hair cells which have two features that help them to take in water and nutrients: Root hair cells Large surface area Thin cell membrane

55 Structure of the Leaf How do all of these features help gas exchange in plants? Large surface area Thin structure Network of veins Lots of air spaces Stomata

56 Water loss Water loss through the stomata is biggest on a hot, dry, windy day. Plants that live in these conditions often have a thicker waxy layer.

57 Controlling water loss Carbon dioxide enters a leaf through the. These cells are also responsible for controlling the content of the The cells control how wide the stomata opens (if at all). If too much water is being lost through the stomata then the guard cells will to prevent further loss. Water and carbon dioxide enter here No more water and carbon dioxide allowed in Words water, close, stomata, guard, leaf

58 Transport in plants xylem and phloem Xylem vessels are made from dead plant cells and are used by the plant to transport water and soluble mineral salts from the roots to the stem and the leaves. Phloem are tubes made from long columns of living cells and are used by the plant to transport dissolved food to the whole plant for respiration and storage.

59 Transpiration 1) Water evaporates through the stomata 2) Water passes back into the leaf through xylem vessels by osmosis 3) Water is then pulled upwards through the xylem tissue 4) This is replaced by water entering from the root tissue 5) Water enters root hair cells by osmosis to eventually replace the water lost through respiration

60 Factors affecting Transpiration

61 B5 Communicable Diseases Starter: Mark your homework. Hwk: Complete week 5 of revision (tues)

62 Health Health is the state of your physical and mental wellbeing. Major causes of ill health can be caused by communicable (transferred) and non communicable (not transferred) diseases. Your health can also be affected by: Diet Stress Gender Ethnicity Financial status

63 Microbes Microbes are micro organisms that can cause diseases. They can enter the body in a number of ways: What ways can you think of? They can be spread by air and breathed in through the mouth or nose They can be spread by water and food and be eaten or drunk. or other natural openings They can be spread by direct contact and can enter through cuts or bites in the skin

64 Disease A disease is any condition where the body isn t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease): Bacteria 1/1000 th mm big Living cells (some are harmless) Clone themselves quickly. Affected by antibiotics May produce toxins, making you feel ill. Examples: food poisoning, tetanus, Use the information to explain why viruses cannot be treated by antibiotics. Viruses 1/1,000,000 th mm big Genetic info inside a protein coat Not affected by antibiotics Release poisons Replicate inside your cells damaging your cells. Examples: colds, flu, polio,

65 Required Practical: Growing micro organisms Method: 1) Sterilise the inoculating loop 2) Dip the loop in the bacteria and spread it across the agar 3) Secure (but don t seal) the lid with tape and store upside down. Questions: 1) Why are you sterilising the loop? 2) What does the agar do? 3) Why is the lid not sealed all the way around? 4) Culture at 25 degrees in school autoclave. 4) Why would you not want to culture your bacteria at 37 O C?

66 Required Practical: Preventing bacterial growth. To prevent bacteria growth we can use the following: Antibiotics for inside the body. Antiseptics for outside the body Disinfectants for object surfaces. Binary Fission (cell replication) can occur as frequently as every 20 minutes. When investigating the effectiveness of different antibiotics, you can compare them by calculating the zone of inhibition around each antibiotic disc. To do this you calculate the cross sectional area: TTr 2 The larger the zone of inhibition, the more effective the antibiotic.

67 Microbes: How to prevent their spread How can we prevent the spread of disease? Coughing and sneezing into tissues and then destroying them. Isolating infected individuals Destroying vectors Having vaccinations Good hygiene eg handwashing.

68 Salmonella food poisoning Gonorrhoea Measles HIV Tobacco Mosaic Virus Malaria Rose Black Spot Pathogen Type Bacteria Bacteria Virus Virus Virus Protist Fungi symptom s of disease Vomiting and diarrhoea Burning pain when urinating and yellow discharge from sexual organs Fever and skin rash Mild flu like symptoms, then years later turns to AIDS, attacking your own immune system Leaves change colour from green to yellow in a mosaic pattern, so no photosynthesis can occur. Fever, vomiting, death Black or purple spots on leaves. Leaves turn yellow and drop off plant so it can not photosynthesis e. treatment of disease Antibiotics Antibiotics None, but vaccine given to prevent it. No cure. Antiviral drugs used to slow down development of AIDs. No cure Antimalarial drugs treat symptoms. Using fungicides how disease is spread Undercooke d food Unprotected sexual contact Airborne when infected person sneezes Transmitted through body fluids such as unprotected sexual contact Contact between plants or through insects. Mosquito acts as a vector Air, water and direct contact by gardeners how pathogen spread can be prevented Cook food thoroughly Use condoms Vaccines Use condoms Good pest control Mosquito nets, killing vectors, antimalarial drugs Removing and destroying leaves and using fungicides.

69 Microbes: our defence against them Our bodies have four major defence mechanisms against invading microbes: What do you think they are? The skin acts as a barrier The breathing organs produce mucus to cover the lining of these organs and trap the microbes If our skin is cut platelets seal the wound by clotting Our blood contains white blood cells

70 Fighting disease If microbes enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS: White blood cells do 3 things: 1) Phagocytosis: They engulf the microbe 2) Antibody production: They produce antibodies to neutralise the microbe 3) Antitoxin production: They produce antitoxins to neutralise the toxins produced by microbes

71 Producing antibodies You re going down Step 1: The white blood cell sees the pathogen (microbe) Step 2: The cell produces antibodies to fit the pathogen Step 3: The antibodies fit onto the pathogens and cause them to clump Step 4: The pathogens are eaten by the white blood cells

72 More about plant diseases Plant diseases can be detected by: Stunted growth Spots on leaves Areas of decay Growths Malformed stems or leaves Discolouration Presence of pests Identification of plant diseases can be done by: Referring to a gardening manual Taking infected plants to a lab to identify the pathogen Using testing kits that contain monoclonal antibodies.

73 Plant disease Rose Black spot: Produce black spots on leaves and leaves fall off. Caused by fungi. Treated with fungicides Plant damage Nitrate deficiency: Leads to reduction in chlorophyll, so can t photosynthesise and causes stunted growth Solution: Fertilisers. Aphids: Insects which suck the sap, reducing growth rate. Eaten by ladybirds. Tobacco mosaic virus: Produces yellow mosaic pattern on leaves. No treatment. Caused by virus. Magnesium ions deficiency: Magnesium ions are used to make chlorophyll, lack of magnesium leads to chlorosis of leaves (yellow leaves).

74 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

75 Plant defence response How do plants defend themselves from disease? Physical defences against microorganisms: Cellulose cell walls Tough waxy cuticle on leaves Layer of dead cell around stems (bark on trees) which fall off. Chemical defences: Antibacterial chemicals produced. Poisons to deter herbivores. Mechanical adaptations: Thorns and hairs deter animals. Leaves which curl or droop when touched. Mimicry to trick animals.

76 B6. Preventing and treating disease

77 Fighting disease NATURAL IMMUNITY This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy. ARTIFICIAL IMMUNITY 1) A vaccine with dead microbes is injected the body is tricked into producing antibodies ready for the real thing. The antibodies then remember the microbe and are able to produce the antibodies again quickly if they come into contact with the microbe again. Discuss how you think a vaccine protects you from illness, then feedback.

78 Using Antibiotics Antibiotics can be used to kill bacteria. However, there are two problems: 1) Overuse of antibiotics can lead to bacteria becoming resistant (e.g. the MRSA superbug ). This means that antibiotics must be used sparingly. 2) Antibiotics have no effect on a virus, like the common cold. It is difficult to kill a virus without damaging body tissue. A virus is usually allowed to run its course.

79 Using Painkillers Painkillers are drugs used to relieve the symptoms of disease but without killing the pathogens, for example: Paracetamol Aspirin Ibuprofen

80 Discovering drugs Traditionally drugs were extracted from plants and microorganisms. Aspirin originates from Willow. Heart drug Digitalis originates from foxglove plant. Most new drugs are synthesised by chemists, however, their starting point may still be a chemical extracted from a plant. Penicillin was discovered by Alexander Fleming from Mould. It was extracted by Florey and Chain.

81 Researching new medicines What makes a good medicine?

82 Developing drugs Preclinical Testing Clinical trials: Testing on cells and animals Healthy volunteers, checking for side effects. Small group with disease, checking for effectiveness, dosage & side effects. Large group with disease, checking for effectiveness & side effects.

83 What is a placebo? Placebos Clinical trials can be done in different ways: 1) Blind trials Patients do not know which drugs they are taking a real drug or a placebo 2) Double blind trial Neither the doctors or the patients know if they are taking the real drug Placebos offer an ethical dilemma as a patient might be sick and still be given a dummy pill. Also, you might notice if you had a placebo as you wouldn t get the side effects of normal drugs...

84 Making monoclonal antibodies Monoclonal antibodies are proteins produced to target specific cells or chemicals in the body. Lymphocytes make antibodies but don t clone. Tumours rapidly clone but don t make antibodies. Combining these produces a hybridoma cell, capable of producing a specific antibody and cloning itself.

85 Uses of monoclonal antibodies Monoclonal antibodies bind to specific antigens (proteins), this means they can be used in a number of ways: Pregnancy tests by binding to HCG hormone Diagnosis of disease binding to the antigens of cancer cells. They carry a marker for doctors to see where they have built up. Detecting infections in blood fluids bind to antigen of bacteria found in blood to detect infections like syphilis.

86 Uses of monoclonal antibodies in treatment. Monoclonal antibodies are increasingly being used to treat cancers. There are 3 ways they can be used: Use them to block receptors on the surface of cancer cells so they stop growing. Get them to carry toxic drugs to the cancer cells that stop them growing. This attacks the cancer cells directly without harming other cells. Trigger the white blood cells to recognise, attack and destroy cancer cells.

87 Advantages & Disadvantages of monoclonal antibodies Advantages Targets specific cells, so your own cells are not harmed. Targets specific cells so can be used to treat wide range of illnesses. In the future could be cheaper than developing new drugs (although currently expensive) Disadvantages Not yet widely used as have not proven as successful as expected. Using mouse antibodies triggered an immune response in humans. It is difficult to produce the correct antibody and attach an appropriate drug.

88 B7 Non communicable diseases

89 Cancer and carcinogens A tumour is a mass of abnormally growing cells. There are two types of tumour. Benign tumours: Growths of abnormal cells contained in place, usually within a membrane. They don t invade other parts of the body. Malignant Tumours: Malignant tumours are cancers. They invade neighbouring tissues and spread to different parts of the body in the blood, where they form secondary tumours. Causes of Cancer: Genetic risk. Exposure to carcinogens causing mutations in cells. This could be caused by exposure to: smoking or asbestos Ionising radiation ie UV light. Radioactive materials Nuclear radiation Medical and dental x rays.

90 Smoking is a causal mechanism for lung cancer, not just a correlation. This is clear from the time delay between consumption and illness and has also been proven through medical research. Smoking Cigarettes contain a number of harmful drugs. Drug Nicotine Tar Carbon Monoxide Effect Addictive Carcinogenic Poisonous gas leading to the shortage of oxygen in the body, can lead to low birth weight and stillbirth in pregnant smokers. Smoking also narrows blood vessels, increases heart rate and damages lining of the arteries. This makes heart disease more likely.

91 Modern diets and health problems Poor diet can lead to obesity. Obesity increases the risk of diabetes, high blood pressure and heart disease. % obesity in the UK This happens when the body is taking in more energy then it is burning. Describe the relationship shown in the graph and suggest ways we could change this trend.

92 Alcohol Alcohol (ethanol) is poisonous but the liver can usually break it down before permanent damage occurs. Alcohol is addictive and can lead to liver damage. It can cause: Cirrhosis of the liver, destroying liver tissues so it no longer functions. Cancer as it is a carcinogen. Brain damage and death. Drinking during pregnancy can lead to low birth weight, miscarriage, still birth. Could also cause deformities as the liver and organs don t develop properly.

93 Photosynthesis the 4 things you need Basically, photosynthesis is the process through which a plant makes its own food using carbon dioxide and water: SUNLIGHT WATER Travels up from the roots Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen CARBON DIOXIDE Enters the leaf through small holes (stomata) on the underneath

94 Photosynthesis equations Carbon dioxide + Water Sunlight Chlorophyll glucose + Oxygen Sunlight 6CO 2 + 6H 2 0 C 6 H 12 O 6 + 6O 2 Chlorophyll The GLUCOSE produced by photosynthesis is used by the plant for energy (through respiration). It is stored in the plant as starch.

95 Required Practical: Factors affecting photosynthesis How does light intensity affect rate of photosynthesis? How does temperature affect rate of photosynthesis? Which of these practicals would produce the most valid results? Explain.

96 Limiting Photosynthesis What factors could limit the rate of 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

97 Drawing graphs of these factors 1. Temperature Photosynthesis is controlled by enzymes these are destroyed at temperatures above 40 0 C 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 CO 2

98 Other than respiration 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 Glucose molecules Cellulose 3) Glucose can be combined with nitrates to make proteins (for growth) Glucose molecules Proteins 4) Glucose can be converted into lipids (fats or oils) to store in seeds Glucose molecules Lipid structure

99 Encouraging Photosynthesis Using knowledge of limiting factors, explain how plant growth is encouraged in a greenhouse or hydroponics:

100 B9 Respiration

101 (Aerobic) Respiration All living organisms have to move, grow, keep warm etc. Each of these life processes needs ENERGY. Respiration is the process our bodies use to produce this energy: The glucose we need comes from food and the oxygen from breathing. Water and carbon dioxide are breathed out. The MAIN product of this equation is energy. Respiration happens in mitochondria in cells.

102 The Effect of Exercise Heart rate/min Breathing rate/min Rest Exercise Recovery mins 10 mins 15 mins 20 mins During exercise the following things happen: heart rate increases, breathing rate and breathing volume increases and arteries supplying muscles dilate. These three things all help muscles to get the oxygen and

103 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.

104 Anaerobic respiration in animals Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing oxygen: Glucose lactic acid + a bit of energy This happens when the body can t provide oxygen quick enough for aerobic respiration to take place. Anaerobic respiration produces energy much quicker than aerobic respiration but only produces 1/20 th as much. Lactic acid is also produced, and this can build up in muscles causing fatigue and an oxygen debt. Blood flowing through the muscles transports the lactic acid to the liver where it is converted back to glucose using the oxygen from the oxygen debt to convert the lactic acid into glucose and carbon dioxide. The oxygen debt is the amount of extra oxygen needed after exercise to oxidise the accumulated lactic acid & remove it from cells.

105 Anaerobic respiration in plants and yeast cells Anaerobic respiration also occurs in plants and yeast cells. It does not produce lactic acid. Anaerobic respiration in yeast cells is known as fermentation and is used in the manufacture of ethanol and bread.

106 Metabolism and the Liver Metabolism is the sum of all reactions that take place in the cell. The energy produced in respiration is used in metabolism to synthesise new molecules. This includes: Converting glucose to starch, glycogen and cellulose. Making lipids from glycerol and 3 fatty acid molecules. Building amino acids from nitrate ions and glucose, then synthesising proteins. Respiration Breaking down excess proteins into urea for excretion. Role of the Liver The liver has many different metabolic functions: Detoxifying poisonous substance ie ethanol from alcohol drinks. Passing broken down products such as urea into the blood for excretion. Breaking down worn out blood cells Breaking down lactic acid.