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B7: Biology Across the Ecosystem Biology in Action A. Blackford Revision is important! WARNING • This PowerPoint is not a substitute for active revision using notes, the workbook and revision guide. • You also need to do plenty of past papers to get exam practice. • Good luck! Harvesting the sun • Most of the energy used by living things ultimately came from the sun • Plants harvest this energy by PHOTOSYNTHESIS. They are AUTOTROPHS • Animals are HETEROTROPHS and need to eat ready made food. Cycles in Nature • Energy flows through the living system • Nutrients (like CARBON and NITROGEN) are CYCLED in the system Trapping Sunlight Energy • What happens to the light energy that hits the leaf? 60% wrong wavelength 5% passes straight through 33% lost as heat energy 35% absorbed By chlorophyll 2% to new growth Leaves are green because RED and BLUE light is absorbed for use in photosynthesis and GREEN light passes through or is reflected. Photosynthesis The Equation for Photosynthesis Carbon dioxide + Water 6CO2 6H2O Light energy Chlorophyll • Light energy splits water into hydrogen and oxygen • The reaction takes place in CHLOROPLASTS Glucose C6H12O6 + Oxygen 6O2 What is the glucose used for? • Glucose is a carbohydrate • It is the starting point for FATS, PROTEINS (with nitrates from the soil) other carbohydrates and CELLULOSE (for the cell wall) • Changed into starch for storage (starch does not upset the OSMOTIC balance of the cell). • For energy from respiration 18 energy e.g. seed germination other sugars GLUCOSE protein cytoplasm starch cellulose cell walls storage e.g. starch in potato fruits The rate of Photosynthesis • Changing the light intensity changes the rate of photosynthesis – up to a point! Light is NOT limiting the rate of photosynthesis (something else is) Light is limiting the rate of photosynthesis Increasing light intensity Limiting factors (carbon dioxide) Light is limiting all the way along this line. Increasing the CO2 concentration increases the final rate of photosynthesis Light is NOT limiting the rate here. Carbon dioxide IS. Compensation point • At the compensation point the amount of carbon dioxide produced by respiration is equal to the amount of oxygen being produced by photosynthesis • Plants cells produce CO2 all the time (from respiration) • There are two compensation points each day The carbon cycle Vegetation Feeding relationships Oak tree Insect Sparrow Kestrel Producers 1o Consumer 2o Consumer 3o Consumer Producers Herbivore Carnivore Carnivore 1st trophic level 2nd trophic level 3rd trophic level 4th trophic level Increasing Size (usually) Decreasing Number (usually) Pyramids of number or biomass? • Counting the number of organisms along a food chain will usually give a pyramid of numbers (but not always) Pyramid of biomass If the total mass of the organisms at different trophic levels are taken a pyramid of biomass is produced Life underground • Soil organisms are responsible for recycling nutrient such as nitrogen • They are responsible for the decay of dead animals and plants Soil microbes Bacteria Fungi Approx numbers per gram of soil 1 000 000 000 1 000 000 Nematodes 500 000 Flatworms 100 000 Insects 5000 Living together 1 • Commensalism • One organism benefits but the other isn’t harmed e.g. seeds sticking to the fur of animals for dispersal. • Mutualism • Both organisms in a relationship benefit e.g. clown fish are protected by anemone tentacles and they drop bits of food that the anemone feeds on (see your revision guide for more examples) Living together 2 • Parasitism • Only one of the organisms benefit from this arrangement, the other is harmed by it. These are dust mites in a human eye lash follicle. They are 0.4 mm long. Most people have some. They LOVE makeup and will thrive if it is not taken off properly at night! Human parasites • These can get into the body by: • Food or water • Through nose, mouth, anus, genitial and urinary tracts • Insect bites • Burrowing under the skin Tapeworms 1 • • • • • • • • Live in the human gut Can be very long (10m for fish tapeworm) Their head and suckers grip the gut wall They have a thick skin (cuticle) so they are not digested They can respire anaerobically They have male and female organs They produce huge numbers of egg (6m a year from cow tapeworm The head (scolex) constantly produces new ‘segments’ that break off from the tail Tapeworms 2 • Tapeworm eggs must develop in the muscles of other animals (pig, cows, fish) before infecting humans • The tapeworms form a cyst in the muscle • Humans eat undercooked or raw meat and the tapeworm develops in the gut. Tapeworms in the stomach of a dog Malaria • Caused by a microscopic animal called a protozoan • Transmitted by mosquitoes (they are the VECTORS for this disease). • 300-500 million infected worldwide, annual deaths 2 million Sickle cell anaemia • This is a genetic disorder caused by a recessive allele. • Faulty haemoglobin is made that changes shape at low oxygen concentrations • This causes the red blood cells to ‘sickle’ and clog capillaries. • Sickle cell anaemia protects heterozygous individuals from malaria so the allele is more common in areas that have endemic malaria ‘Sickled’ red blood cell Normal red blood cell Inheriting sickle cell anaemia Parent 1 Parent 2 • The sickle cell allele is recessive (A is normal and a is the sickle allele) • Aa individuals are carriers • aa individuals are affected A a A a AA Aa Normal Carrier Aa aa Carrier Affected Living factories • Antibiotics • Penicillin made by the fungus Penicillium which is grown in huge fermenters and the fungus secretes the antibiotic into the liquid • Enzymes • Rennin can come from cows stomachs or fungus and is used in cheese manufacturing • Microbes for food • Microbes for food is called single celled protein (SCP) • Quorn is pressed fungal hyphae Genetic modification (GM) • Genes are taken from one species and added to another (e.g. human insulin genes added to bacteria to produce insulin) • Human genes are added to bacterial PLASMIDS • These are added to another bacterial cell which will produce the human chemical Genetic modification (GM) • Genes are taken from one species and added to another in plant crops this may be resistance to disease Against GM crops For GM crops Genes could make plant produce toxins Food safety organisations check for these GM crops may irreversibly change the ecosystem Farmers may benefit from healthier crops and lower costs Poor farmers can’t afford the seed. Crops are infertile Some GM technology shared and yield is bigger EU consumers won’t buy the products Consumers in other countries will buy the products Genetic testing • Gene probes are used to test for some ‘faulty’ genes • Faulty genes stick to the probe. These can be seen by • UV – a fluorescent molecule sticks to the DNA and glows under UV light • Autoradiography – gene probe made from radioactive DNA which blacken Xray film Blood White blood cell Fight infection. Some produce antibodies, others engulf invaders Red blood cell Carry oxygen in haemoglobin as OXYHAEMOGLOBIN Also present Platelets Cell fragment that trigger blood clotting (not shown here) Plasma The liquid part of blood which also carries nutrients and hormones Blood Types ABO system • Giving a patient an incompatible transfusion will cause their blood to clot and kill them! • Plasma antibodies will make this happen • Blood group O is the universal donor (why) • Blood group AB is the universal recipient (why) Inheriting blood groups • There are 3 different alleles for this gene • A is co-dominant with B • A and B are dominant over O • Everyone has 2 of these alleles • • • • AO and AA are blood group A BO and BB are blood group B AB is blood group AB OO is blood group O Predicting blood groups Examples of how blood groups are inherited Parent with blood group AB O A B A AO BO AB Group A Group B AO BO Group A Group B Parent with blood group B(O) Parent with blood group O(O) O Parent with blood group A(O) B Group AB O AO Group A O BO Group B OO Group O The heart • The heart is really 2 pumps side by side • 2 upper chambers are the atria • 2 lower chambers are the ventricles • Blue represents deoxygenated blood • Red represents oxygenated blood Aorta (to body) Vena cava (from body) Pulmonary artery (to lungs) Pulmonary vein (from lungs) Right atrium Left atrium Valve Right ventricle Left ventricle Arteries and Veins • Arteries have • Thick walls • A pulse (pressure waves from the heart beat) • Veins have • Thinner walls than arteries as the pressure is lower • Valves to stop blood flowing backwards Capillaries • Have walls one cell thick • Have very small diameter (about the size of a red blood cell) • Have walls that ‘leak’ • Oxygen and nutrients are taken to the cells • Carbon dioxide and waste, like urea, go back into the vessels Double circulation • For every trip around the body and lungs , blood must pass through the heart TWICE LUNGS Blood is OXYGENATED START RA pumps blood into the RV R VENTRICLE Pumps blood to the lungs END Deoxygenated blood returns To RA L. ATRIUM Pumps blood to LV Oxygenated blood returns to the heart L.VENTRICLE Pumps blood to the rest of the body CAPILLARIES Blood loses oxygen in the capillaries Respiration • Aerobic respiration Glucose + C6H12O6 Oxygen 6O2 Carbon dioxide + Water 6CO2 • Aerobic respiration takes place in MITOCHONDRIA 6H2O Lungs and diffusion • Lungs are efficient at getting oxygen into the lungs because them make diffusion efficient • • • • Thin walls to the alveoli Large surface area Ventilation of the lungs Diffusion gradient kept high • Good blood supply Anaerobic respiration • Respiration without oxygen In Plants and Yeast Glucose Carbon dioxide + Ethanol In Human Muscles Glucose Lactic acid In both cases some energy is produced (but not as much as in aerobic respiration) and is used to make ATP, the energy currency of the cell Exercise and the oxygen debt • Lactic acid builds up during strenuous exercise • Removing it from the muscles requires oxygen • The amount needed is the oxygen dept The skeleton • The skeleton has a number of jobs to do • Protects vital organs (brain, spine ovaries) • Makes red blood cells in the marrow of ‘long bones’ • Stores the minerals calcium and phosphorus • Forms a system of levers with muscles attached for movement Knee joint structure Muscle Femur Tendon (thigh bone) Tough and nelastic attaches muscle to bone Cartilage Smooth, covers The end of bones To help movement Patella (knee cap) Ligaments Synovial fluid Made by synovial Membrane. Lubricates and Nourishes the joint Tough elastic tissue holding bones together Tibia (shin bone) Moving the arm Sports injuries • Remember RICE • • • • Rest (immobilise the injury) Ice (anaesthetic apply covered) Compression (snugly bandage the injury) Elevation (raise limb to drain fluid) • During recover • Simple stretching • Aerobic exercise The End