Biology B1

Biology B1

Keeping Healthy
1. Diet and Exercise
  1. Balanced Diet- Includes everything needed for a healthy body
  2. Different amounts of energy needed, based on metabolic rate
  3. Energy taken in>Energy used=Weight Lost
2. Weight Problems
  1. Eating more energy than needed causes mass to increase
  2. Obese- Very overweight
    1. Type 2 diabetes
    2. Coronary Heart diease
  3. Starvation- Very underweight
    1. Deficiency disease
3. Inheritance, Exercise and Health
  1. Inherited factors affect health factors, such as metabolic rate and cholesterol levels
  2. Regular exercise improves health as it increases metabolic rate and lowers cholesterol
4. Pathogens and Disease
  1. Pathogens- Microorganisms that cause disease
    1. Usually bacteria and viruses
  2. Reproduce rapidly, and may produce toxins
  3. Viruses reproduce inside cells damaging them
  4. Semmelweiss
    1. Discovers how disease is passed from person to person
    2. Introduces hand washing in hospitals
5. Defence Mechanisms
  1. Skin stops pathogens getting in
  2. Pathogens that do enter can be destroyed by white blood cells in the immune system
    1. Can ingest pathogens by digesting and destorying them
    2. Antibodies an attach to antigens on the pathgen to destroy it
    3. Antitoxins neutralise toxins produced by pathogens
6. Using Drugs to Treat Disease
  1. Medicines such as painkiller relieve symptoms, but don't kill pathogens
  2. Antibiotics can't kill viruses
  3. Antibiotics cure bacterial diseases by killing bateria
  4. Viruses are hard to destroy becasue thet reproduce inside cells so there is a risk of damaging the cells
7. Growing and Investigating Bacteria
  1. Bactera can be grown on agar jelly
  2. All materials used mut be sterilised
    1. Prevents unwanted microorganisms contaminating the culture
  3. Uncontaminated cultures can be used for investigations of antibiotics and disinfectants
8. Changing Pathogens
  1. Pathogens can change causing mutations
    1. These can spread rapidly due to lack of immunity to new strain
  2. New strains can cause epidemics or pandemics
    1. Epidemic- Spread of a disease within a country
    2. Pandemic Spread of a disease internationally
  3. Bacteria can develop resistance to antibiotics through natural selection
9. Immunity
  1. Vaccines immunise against disease
  2. Vaccines contain dead or inactive pathogens
    1. Encourages white blood cells to produce and remember the antibodies to destroy the pathogens
  3. Vaccination works on both bacteria and viruses
10. How do we deal with disease?
  1. Herd immunisation, vaccinating large numbers, protects society from the risk of disease
Coordination and Control
1. Responding to Change
  1. Nervous system allows reaction to surroundings
  2. Receptors in sense organs detect external stimuli
    1. Impulse sent along sensory neurone to brain
      1. Brain coordinates response, which is sent down motor neurone
        Effector then responds
2. Reflex Actions
  1. Reflex actions are automatic responses to a stimulus and usually keep us out of danger
  2. Reflex arc is similar to a normal response, but instead of going to the brain, the impulse is processed by a relay neurone in the spinal cord
  3. Between neurones there are synapses that use chemicals to pass the impulse over the gap
3. Hormones and the Menstrual Cycle
  1. Menstrual cycle lasts 28 days with ovulation at 14 days
  2. Follicle Stimulating Hormone (FSH)- Made in the Pituitary Gland and causes an egg to mature and stimulates the production of oestrogen
  3. Oestrogen- Produced by the ovaries and it inhibits the production of FSH and stimulate the production of LH and the womb lining
  4. Luteinising Hormone (LH)- Made in the Pituitary Gland and it stimulates the release of the matured egg
4. Artificial Control of Fertility
  1. The contraceptive pill may contain oestrogen and progesterone to inhibit FSH
  2. FSH can be given to help an infertile woman produce eggs
  3. Fertility Treatments
    1. Advantages
      1. Reduces family size
      2. Woman can plan pregnancies
      3. Couples that couldn't have children before can now
    2. Disadvantages
      1. Pill can cause side effects
      2. Ethical or religious implications
      3. IVF is expensive
      4. Embryos may be destroyed
5. Controlling Conditions
  1. Internal conditions of the body must stay constant
    1. Controlled by the nervous system and hormones
  2. Water, ion content, temperature and blood sugar levels are controlled
6. Hormones and the Control of Plant Growth
  1. Plants respond to light, phototropism, gravity, geotropism, and moisture, hydrotropism
  2. Auxin is the plant hormone that controls geo and phototropism
    1. In a root the auxin gathers on the underside, and makes the plant where there is less auxin to grow more, bending the root towards the ground
    2. In a shoot auxin gathers on the underside and makes the part where there is more auxin to grow, bending the shoot away from the ground
7. Using Hormones
  1. Can have side effects
  2. Misuse of plant hormones could effect the environment
Medicine and Drugs
1. Developing New Medicines
  1. Drugs are tested in labs, on animals and in clinical trial on healthy and ill patients
  2. Placebo- Don't contain a drug, are used to see if drug does have effect
    1. Double Blind Trials- Neither doctor nor patient knows which is the drug and which is the placebo, to remove bias
  3. Thalidomide, a sleeping pill, was found to cure morning sickness but caused birth defects so now treats lepsory
2. How Effective Are Medicines?
  1. Statins lower cholesterol levels and have lowered heart disease by 40%
  2. Double blind trials should be used to test non prescribed medicines to remove bias
3. Drugs
  1. Drug- A chemical the effect your behaviour or thoughts
  2. Both legal and illegal drugs may harm your body
  3. Chemicals in cannabis may cause mental illness in some
  4. Cocaine and heroin is very addictive, and you may suffer from withdrawal symptoms when trying to stop taking them
4. Legal and Illegal Drugs
  1. Medicinal Drugs- Used to control disease and can only be prescribed by a doctor
  2. Recreational Drugs- Used only for pleasure and affect the brain and nervous system
  3. Recreational drugs can be legal like caffeine or alcohol or illegal like cannabis or heroin
  4. Impact of legal drugs greater than illegal drugs as they are more readily avaliable
5. Does Cannabis Lead to Hard Drugs?
  1. Obtaining cannabis from dealers may put people in contact with harder drugs
  2. Chemicals in cannabis can cause mental illness particularly in teenagers
6. Drugs in Sport
  1. Some athletes use illegal performance enhancing drugs such as steroids to give them an unfair advantage in competitions
    1. Most would consider this unethical
Adaptation and Survival
1. Adapt and Survive
  1. Organisms get necessary materials for survival from their surroundings and other organisms
  2. Organisms are adapted to survive in the conditions they normally live
  3. Some microorganisms, extremophiles, are adapted to live in the most extreme environments
2. Adaptation in Animals
  1. Adaptations help an animal survive
  2. Animals in cold climates are usually large with small surface area: volume ratio, and vice versa for hot climates
  3. Coat colour may to provide year round camoflage
3. Adaptation in Plants
  1. Plants lose water vapour from stomata on the leafs surface
  2. To conserver water plants reduce the surface area of leaves, store water and have extensive root systems
4. Competition in Animals
  1. Animals compete for: food, water, territory and mates
  2. The best adapted animals are good competitors
5. Competition in Plants
  1. Plants compete for: water, light, space and nutrient and mineral ions from the soil
6. How do you survive?
7. Measuring Environmental Change
  1. Environmental changes the distribution of organisms
    1. Changes can be caused by living factors, arrival of a new predator or disease, or non-living factors, temperature and rainfall
  2. Environmental changes can be measured with using non living indicators such as thermometers or rain gauges
  3. Organisms, indicator species, can used to disclose pollution levels
8. Impact of Change
  1. Distribution of organisms can be affected by living and non living factors
  2. Data on the effect of environmental change isn't always easy to interpret
Energy in Biomass
1. Pyramids of Biomass
  1. Main source of energy for organisms is the sun's radiation
    1. Green plants turn the light energy to chemical energy during photosynthesis
  2. Biomass- Amount of dry living mass in an organism
  3. Biomass at each stage of the food chain is less than the previous stage
2. Energy Transfers
  1. Less energy is available at each stage of the food chain as it is lost through movement, waste and into the surroundings
    1. The rest is used for growth
3. Decay Processes
  1. Organisms take nutrients from the environment which are returned when they die
  2. Decay is started by detritus feeders who produce waste materials that are then eaten by microorganisms called decay organisms
  3. Decay happens quicker in warm moist aerobic conditons
4. Carbon Cycle
  1. Carbon cycle is the constant recycling of carbon in nature
  2. Carbon dioxide is removed from the atmosphere during photosynthesis
  3. Respiration and combustion return carbon dioxide to the atmosphere
5. Recycling Organic Waste
  1. Recycling organic waste reduces landfill and methane, and recycles nutrients in the waste
Variation, Reproduction and New Technology
1. Inheritance
  1. Offsprings have similar characteristics to their parents
  2. Genes are passed in gametes from parents to offsrprings
  3. Genes control characteristics of your body
2. Types of Reproduction
  1. Clones are produced during asexual reproduction, where no gametes join
  2. Clones- Genetically identical copies of one parent
  3. Sexual reproduction involves the joining of gametes from two parents leading to a variety of offsprings
3. Genetic and Environmental Differences
  1. Difference within a species can be because of genetic factors due to differences in the genes they have inherited, and environmental factors such as diet and exercise
  2. Clones may have differences due to environmental causes
4. Cloning
  1. Plant clones can be made quickly and easily by making a cutting
  2. A tissue culture could be made by taking some cells from the plant and growing them in special conditions
  3. Animals can be cloned by putting a nucleus in an empty egg and placed in a surrogate mother
5. Adult Cell Cloning
  1. Scientists have used adult cell cloning to clone animals such as Dolly the sheep
  2. The nucleus of a cell is placed into an empty egg cell and transplanted in to a host mother, creating a clone
6. Genetic Engineering
  1. Genetic engineering transfers a gene for one organism to another to give a desired characteristic
  2. Enzymes are used to cut a gene from a chromosome and is then inserted in another
  3. Genes must be transferred at an early stage of development
7. Making Choices About Technology
  1. Disadvantages
    1. Long term affects of eating GM crops aren't known
    2. Could reduce or contaminate the gene pool
    3. 'Playing' God
  2. Advantages
    1. May provide cures for genetic disorders
    2. Produces medical drugs
    3. Crops are resistant to herbicides and insects
Evolution
1. Theories About Evolution
  1. It is thought all life developed from simple organisms that lived 3 billion years ago
  2. Darwin suggested evolution takes place by a process of natural selection over many years
2. Accepting Darwin's Ideas
  1. Darwin's theory was only gradually accepted
3. Natural Selection
  1. Natural selection means the fittest organisms survive to breed
  2. If a gene mutates the new characteristics may allow and organism to survive better
4. Classification and Evolution
  1. Comparing similarities and differences allow classification of organisms
  2. Classification allows evaluation of evolutionary relationships

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