B7- Biology across the ecosystem

A summary of the 21st century science module B7- Biology across the ecosystem

  • Created by: R_Hall
  • Created on: 07-06-11 16:14

Living Organisms are Interdependant

  • All organisms are dependant on the energy from the Sun .
  • Plants absorb a small percentage of this energy for photsynthesis- this energy is stored in chemicals which make up the cells.
  • Autotroph- An organism that produces its own organic compounds.
  • Heterotrophs- An organism that must eat other organisms for its source of organic compounds.
  • Energy is transferred between organisms in an ecosystem when organisms are eaten and when dead organisms and waste is fed on by decay organism
  • Energy passes out of a food chain- it is used for life processes in the organism, escapes as heat, excreted as waste and is uneaten. This limits the length of food chains.
  • Soil is composed of biomass (living and dead organisms), inorganic materials, air and water (with dissolved mineral ions).
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  • In photosynthesis, light energy is absorbed by chlorophyll, energy used to rearrange the atoms of CO2 and H2O to produce glucose.
  • This glucose may be converted into chemicals needed for growth of plant (cellulose, protein, chlorophyll), converted into starch for storage or used in respiration to release energy.
  • Starch is a better storage molecule than glucose because it is insoluble and has little effect of the osmotic balance of the cell.
  • Energy released by respiration may be used to synthesise polymers required by the plant cell (glucose to starch and cellulose, or glucose to nitrate to amino acids to proteins).
  • Plant roots absorb nitrates by active transport.
  • Rate of photosynthesis may be limited by low levels of heat, CO2 and light.
  • Most scientists agree that human activity is causing an increased level of atmospheric CO2.
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Heterotrophic Nutrition

  • Symbiosis- Any association between 2 organisms (clownfish and sea anemone).
  • Commensalism- A relationship between 2 organisms of different species where one gains, and the other neither gains nor loses (seed pods on clothes).
  • Parasitism is a close association between 2 organisms which is beneficial to the parasite, but harmful to the host.
  • Tapeworms have adapted an enzyme-resistant cuticle to protect from digestion.
  • Parasites are important causes of human disease and have an impact on food production.
  • The evolution of a parasite is closely linked to that of the host.
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Sickle-cell Anaemia

  • Sickle-cell anaemia is a genetic disorder caused be a faulty recessive allele of the gene that codes for haemoglobin.
  • Haemoglobin is the protein that carries O2 molecules in red blood cells.
  • Red blood cells with sickle-cell haemoglobin are stretched into a rigid "sickle" shape.
  • These rigid red blood cells get stuck in small blood cells, causing acute pain and extreme tiredness.
  • Carriers of the sickle-cell allele have a higher resistance to malaria than people who do not- sickle-cell trait.
  • Where malaria is common, natural selection favours people with sickle-cell trait- the frequency of the sickle-cell allele is higher in these areas.
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Living Factories

  • Bacteria and fungi make many useful organic compounds very efficiently.
  • Bacteria any fungi can be grown on a large scale (fermentation) to include-
  • Production of antibiotics- Fungus grows in a tank of nutrient solution and the antibiotic is secreted into the solution.
  • Production of single-cell protein- Microorganisms can be grown from simple starting nutrients, they reproduce quickly. Microbial biomass is grown for food called single-cell protein.
  • Enzymes for food manufacture (rennin)- Most rennin for cheese comes from industrially grown fungi.
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Genetic Modification and Testing

  • The main steps of genetic modification=
  • 1.Isolating and replicating the required gene.
  • 2. Transferring the gene into a new cell.
  • 3. Use of a vector (virus or plasmid.)
  • Genetic modification includes bacterial synthesis of drugs and hormones (insulin) and disease resistance in crop plants.
  • There are economic,social and ethical implications for the release of genetically modified organisms.
  • The use of DNA technology in genetic testing=
  • 1. Isolating DNA from white blood cells.
  • 2. Production of gene probe.
  • 3. Use of UV or autoradiography to locate gene probe
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Aerobic and Anaerobic respiration

  • Energy is released from food chemicals in the process of respiration.
  • Aerobic respiration requires oxygen.
  • Anaerobic respiration takes place in muscle cells where there is a shortage of oxygen, and leads to a build up of lactic acid.
  • Oxygen is needed to break down the lactic acid (oxygen debt).
  • Aerobic respiration releases more energy per glucose molecule than anaerobic respiration.
  • Anaerobic respiration may be advantageous to human being and other organisms in certain conditions (predator running after prey).
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Muscles and ATP

  • Energy released during respiration is used to synthesise a chemical called ATP- the "energy currency" of living things.
  • Muscle tissue contracts when provided with energy (ATP) from respiration.
  • During exercise, respiration in muscle cells increases to provide additional energy for movement.
  • Muscle cells require a faster supply of O2 and glucose, and removal of CO2- this need is met by increasing heart and breathing rates.
  • "Normal" measurements for factors such as heart rate and blood pressure are given within a range, and that individuals vary.
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Blood and Blood types

  • Components and functions of the blood=
  • 1. Red Blood Cells- transporting oxygen.
  • 2. White Blood Cells- fighting infection.
  • 3. Platelets- blood clotting at injury sites.
  • The ABO blood type system describes antigens on the surface of red blood cells and antibodies in the blood plasma.
  • For blood transfusions the donor and recipient must be matched to avoid clotting.
  • ABO blood type is determined by a single gene with 3 alleles (A, B, O).
  • A and B are co-dominant, O is recessive to both.
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Structure of the Circulatory system

  • Double circulation- A circulatory system where the blood passes through the heart twice for every complete circulation of the body.
  • Valves act like one-way doors to keep the blood flowing in 1 direction- stop it flowing backwards.
  • Tissue fluid is formed as blood passes through capillary beds.
  • This assists the exchange of chemicals by diffusion between capillaries and tissues (to include O2, CO2, glucose and urea).
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Skeletal System and Sport Injuries

  • Vertebrates have an internal skeleton for support and movement.
  • Muscles can only move bones at a joint by contraction, operate in antagonistic pairs.
  • The specific properties of ligaments (tough and elastic), cartilage (smooth) and tendons (tough and inelastic) enable them to function effectively.
  • Common injuries can be caused by excessive exercise (to include sprains, dislocations, torn ligaments or tendons).
  • The symptoms of sprains can include redness, swelling, bruising and pain.
  • A physiotherapist is used to prescribe exercises for injuries to treat skeletal-muscular injuries.
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Folllowing a Training Programme

  • Factors in a person's medical or lifestyle history should be disclosed before treatment begins or exercise regime starts (medication, alcohol, tobacco).
  • This information on general health is needed to decide on the best programme or treatment.
  • Regular contact between trainers and clients is needed to make sure that the programme is being successful
  • Personal medical and fitness info must be recorded and stored accurately and made available to others on the health/fitness team
  • Treatments often have side-effects and are weighed against the benefits
  • There are many ways to achieved a target- cure, recovery, rehabilitation or enhanced fitness
  • Any assessment of progress needs to take into account the accuracy of the monitoring technique and the reliability of the data obtained
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honor mason


Really helpful, thanx :)

alex colton


very interesting and really helped well done

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