B1 EXAM BRIEFING Tuesday 15 th May 2018, 1.30PM
CELL BIOLOGY Topic 1
Cell Biology Eukaryotic: have cell membrane, cytoplasm & genetic material in a nucleus. Prokaryotic: bacterial cells. Smaller. Genetic material not in a nucleus, single loop DNA, one or more small rings DNA (plasmids).
Specialised Cells Sperm Cell and Egg Cell Xylem cell Strengthened by lignin Ciliated epithelial Cell Root hair Cell Palisade Cell Muscle and Nerve Cells Phloem cell Guard cell Transports sugars for use/ storage. Cell sap moves to next cell through pores in end wall Red Blood Cell and White Blood Cells
Required Practical Microscopy
Required Practical Growing Bacteria IV: type OR concentration antiseptic (g/cm 3 ) DV: area of zone of inhibition cm 2 CV: size of paper disk, type of bacteria Flame the neck of bottle of culture & loop before & after spreading bacteria on agar. Soak paper disks in different types/ concentrations of antiseptic, place onto agar. Will diffuse into agar and prevent growth bacteria during incubation. Use a control- sterile water. Tape in cross, store upside down, incubate 2 days at 25 C (not anoxic or 40 C- promotes growth of harmful bacteria) Bacteria- binary fission- up to once every 20 minutes. Measure zone of inhibition πr 2.
Cell Division Binary Fission (Bacteria) Mitosis
Stem Cells Also in meristems (tips of shoots & roots) of plants. Meristem tissue can differentiate throughout life. Quick & economical. Crops with special features e.g. disease resistance cloned for large crop. Advantages Disadvantages Embryonic stem cells Embryo (first few days after fertilisation) Can differentiate into any type of cell Can treat conditions e.g. paralysis & diabetes Can differentiate into most types of adult cells Embryo would be destroyed anyway (surplus to IVF process) Therapeutic cloning- embryo produced with same genes as patient. Not rejected. Ethical or religious objection- e.g. destruction of life Risk of viral infection. Adult stem cells Can form blood cells Form fewer types of cells
Affected by; Concentration gradient, T, SA Exchange surfaces; large SA, thin membrane, efficient blood supply, ventilated Transport of substances Molecules move from an area of high concentration to low concentration. Molecules move along a concentration gradient. The movement of water molecules. Diffusion Osmosis Active Transport The movement of ions Is a passive process that requires no energy Requires energy from respiration. The movement of molecules against a concentration gradient.
Required Practical Osmosis IV: concentration sugar solution (g/cm 3 ) DV: change in mass (g) CV: initial length & mass of potato chip, volume of sugar solution (cm 3 )
CELL ORGANISATION Topic 2
Relate back to villi Digestion Amylase; starch sugar Protease; protein amino acids Lipase; fats glycerol + fatty acids Bile; emulsify fat, neutralise stomach acid
Enzymes Biological catalyst Rate of reaction Molecules gain kinetic energy Optimum temperature Enzyme is denaturing 0 10 20 30 40 50 60 70 Temperature / o C
Required Practical Enzymes & ph IV: ph of buffer solution DV: time taken to stop iodine changing black (s) CV: volume amylase (cm 3 ), volume starch (cm 3 ), temperature ( C)
Required Practical Food tests Benedict s solution test: 1. Make a solution of the substance to be tested in a boiling tube, and add Benedict's solution (blue). 2. Heat the tube gently for about 2 minutes in the waterbath. A colour change from blue to yellow/orange/red shows the presence of a simple sugar e.g. glucose. Iodine test: 1. Make a solution of the substance to be tested in a boiling tube OR place a small piece in a spotting tile. 2. Add a few drops of iodine. A colour change from orange/ brown to blue/ black shows the presence of starch. Biuret solution test: 1. Add the food to be tested into a test tube. Label. 2. Add 3 drops of Biuret reagent solution to each test tube. Shake gently to mix. 3. Note any colour change. Proteins will turn the solution pink or purple. Fat test: 1. Dissolve some ground up food in water. 2. Add 3 drops of Sudan III stain. 3. Shake gently. If fat is present there will be a redstained oil layer which will float on the surface.
Heart Pacemakersmaintain resting heart rate. Natural (right atrium) & artificial. vena cava (inferior) vena cava (superior) pulmonary vein
Artificial blood = saline (no RBC). Blood & Vessels Type of blood vessel Sketch of blood vessel Structural information How does the structure link to the role played by the blood vessel Artery away Thick muscular walls. Small lumen. High pressure blood. Maintain high pressure. Capillary muscles & lungs Thin- 1 cell thick. Lumen v. small. Speed up diffusion- gas exchange. Vein towards Thin walls. Large lumen. Valves Low pressure blood. Prevent backflow of blood.
Coronary Heart Disease Fatty material reduces blood flow = lack oxygen for heart. Treatment How it works Advantages Disadvantages Statins Drug- reduce blood cholesterol Reduce blood cholesterol. Simple. Side effects inc. type 2 diabetes, confusion, liver, muscles, kidney damage. Artificial heart valves Replace failed heart valveartificial or biological (human or pig). Less likely rejected. Don t need donor. Ethical/ religious preference. Cost. Clots. Infection. Heart transplant Replace heart with one from human donor. Existing structure. Rejection- immunosuppressants. Artificial heart Replace heart with man-made heart. Less likely rejected. Don t need donor. Ethical/ religious preference. Bleeding. Infection. Can fail. Clots/strokes. No thinners. Cost. Battery replacement. Stents Tube hold open artery Lower risk heart attack Take blood thinning drugs (dangerous). Scar tissue can irritate & narrow artery.
Health = the state of physical and mental well-being. Non-communicable Diseases Factor Effect on health Disease with increased risk factor Diet (Non-contagious) Heart trouble and blood high pressure Type 2 diabetes, Obesity Anorexia, malnourished Description of disease Can t regulate blood sugar Stress High blood pressure Cardiovascular disease Heart has to pump faster/ with a greater volume, can become damaged. Smoking Tar in lungs, difficulty breathing. Heavy coughing. Depression. Cardiovascular disease Lung cancer Damaging airways, arteries and lung lining. Alcohol Damages liver Liver disease Liver (removes toxins from blood) no longer functions. Exercise Obesity, arthritis, muscle weakness, cardiovascular disease Communicable & non-communicable diseases can interact, leading to poor health
Cancer Uncontrollable mitosis = tumour Benign (not spreading/ cancerous) & Malignant (spreads to form secondary tumours)
Plant Structure Gases diffuse into and out of the leaf Transpiration: water vapour evaporates from the cells inside the leaf. This diffusion is greatest in hot, dry, windy, bright conditions. Xylem cell Strengthened by lignin Phloem cell Transports sugars for use/ storage. Cell sap moves to next cell through pores in end wall Guard cell Turgid w. water to open stoma
INFECTION & RESPONSE Topic 3
Communicable Diseases Type of pathogen Symptoms Mode of transmission Prevention (not necc. guaranteed 100% effective) Treatment Measles Virus Fever, red skin rash Inhalation of droplets Vaccination HIV Virus Flu-like illness. Body attacks immune cells. Sexual contact, exchange bodily fluids. Barrier contraception, not sharing needles Antiretroviral drugs. AIDS (late stage HIV) Immune system damaged = cancer + infections Salmonella Bacteria Vomiting, abdominal cramps Ingestion of contaminated/ uncooked food Person-to-person Cook food properly Replace fluids. Most cases pass in ~7 days. Gonorrhoea Bacteria Thick yellow/ green discharge vagina/ penis, pain urinating. STD Barrier contraception Antibiotics. Protist disease: Malaria. Vector = mosquito. Recurrent fever, death. Nets & removal of stagnant water reduce chance of being bitten.
Human Defence Systems Skin, nose, trachea, bronchi, stomach Phagocytosis: Antibody production: Antitoxin production Vaccinations
Antibiotics & Painkillers Antibiotic (e.g. penicillin) kill bacteria, cure disease. Specific. Can t kill viruses. Resistant strains emerging due to overuse. Painkillers only treat symptoms. Antivirals difficult to produce as to destroy virus must damage body tissue.
Discovery & Development Drugs Traditional technique Drugs extracted from plants & microorganisms; Digitalis (heart): foxgloves. Aspirin (painkiller): willow. Antibiotic (penicillin): Penicillium mould. Modern technique Tested for toxicity, efficacy & dose. Preclinical trials on cells, tissues, live animals. Clinical trials on healthy volunteers & patients. Very low does. Further clinical trials establish optimum dose. Double blind trials inc. placebo. Results scrutinised by peer review.
Monoclonal Antibodies Stimulate mouse lymphocytes to produce partic. antibody Single clone of cells. Antibodies specific to binding site of one protein antigentarget specific chemical/ cells in body. Lymphocytes + tumour = Clone hybridoma : many antibodies Hybridoma can produce antibodies Collect & purify antibodies
Uses of Monoclonal Antibodies Pregnancy tests (see next slide). Labs; measure levels hormones/ chemicals in blood, detect pathogens Research; locate/ identify specific molecules in cell/ tissue- bind to fluorescent dye Treat some diseases: cancer; bind to radioactive substance/ toxic drug/ chemical which stops cells growing and/or dividing. Delivers substance to cancer cells without damaging others. More side effects than expected therefore not as widely used as hoped.
Pregnancy Tests Using Monoclonal Antibodies HCG
Plant Diseases & Defence TMV: Tobacco Mosaic Virus. Many species inc. tomatoes. Discoloured leaves = lack of photosynthesis = poor growth. Rose black spot: Fungus. Spots on leaves, often turn yellow & drop off. Photosynthesis reduced. Spread by water/ wind/ tools. Treat with fungicide / removing affected leaves. Bacteria & insects e.g. aphids can also spread disease. Identification by manual/ website, lab, testing kits. Deficiencies: Nitrate = stunted growth (lack of ions for protein), Magnesium = chlorosis (lack of ions for chlorophyll, no longer green). Physical defences resist invasion microorganisms: Cellulose cell walls, tough waxy cuticle, layers dead cells on stems (bark) can fall off Chemical defences: Antibacterial chemicals, poisons deter herbivores Mechanical adaptations: Thorns/ hairs deter animals, leaves droop/ curl on touch, mimicry tricks
BIOENERGETICS Topic 4
Photosynthesis Uses of Glucose: Respiration (to release energy from glucose) Endothermic. Energy transfer = light. Starch Storage (chains of glucose that are insoluble, for use when no photosynthesis) Protein Synthesis (used in amino acids along with nitrates from the soil) Cellulose for Cell Walls (made up of glucose makes them strong) Seeds (stored as oils and fats in seeds). Limiting factors: Temperature, light intensity, carbon dioxide concentration, amount of chlorophyll. Greenhouses produce optimum growth conditions to maximise growth & maintain profit.
Required Practical Rate of Photosynthesis IV: distance between lamp & pondweed (cm) DV: number bubbles in 1 minute CV: size & mass piece pondweed (g), temperature ( C) Pondweed upside down so oxygen can leave stem. Can be placed in waterbath- heat shield to minimise effect of T. Light intensity: inverse square law.
Respiration Process of transferring energy from glucose. Occurs in every cell. Energy for chemical reactions (build larger molecules), movement, keeping warm. Aerobic Mitochondria. Exothermic Anaerobic Exothermic Incomplete oxidation of glucose = less energy transferred. Anaerobic in yeast (fermentation) Alcohol & bread..
Response to Exercise, Metabolism During Exercise Inc. demand for energy Inc. heart rate, breathing rate, breath vol. = supply muscles with more oxygenated blood If insufficient oxygen: anaerobic resp. Build up of lactic acid. Long periods vigorous exercise = muscle fatigue, stop contracting efficiently. Blood flow through muscles transports lactic acid to liver- converted back into glucose. Oxygen debt = amount extra oxygen req. after exercise to remove accumulated lactic acid from cells. Metabolism Sum of all reactions in cell/ body. Energy transferred by respiration used for continued enzyme controlled processes that synthesis new molecules: Glucose starch (sugars carbohydrates) Glucose glycogen Glucose cellulose Amino acids protein 1x Glycerol + 3x fatty acids lipids Excess protein urea