Biology B1

Biology B1

1. Keeping Healthy

   • Diet and Exercise
     • Balanced Diet- Includes everything needed for a healthy body
     • Different amounts of energy needed, based on metabolic rate
     • Energy taken in>Energy used=Weight Lost
   • Weight Problems
     • Eating more energy than needed causes mass to increase
     • Obese- Very overweight
       • Type 2 diabetes
       • Coronary Heart diease
     • Starvation- Very underweight
       • Deficiency disease
   • Inheritance, Exercise and Health
     • Inherited factors affect health factors, such as metabolic rate and cholesterol levels
     • Regular exercise improves health as it increases metabolic rate and lowers cholesterol
   • Pathogens and Disease
     • Pathogens- Microorganisms that cause disease
       • Usually bacteria and viruses
     • Reproduce rapidly, and may produce toxins
     • Viruses reproduce inside cells damaging them
     • Semmelweiss
       • Discovers how disease is passed from person to person
       • Introduces hand washing in hospitals
   • Defence Mechanisms
     • Skin stops pathogens getting in
     • Pathogens that do enter can be destroyed by white blood cells in the immune system
       • Can ingest pathogens by digesting and destorying them
       • Antibodies an attach to antigens on the pathgen to destroy it
       • Antitoxins neutralise toxins produced by pathogens
   • Using Drugs to Treat Disease
     • Medicines such as painkiller relieve symptoms, but don't kill pathogens
     • Antibiotics can't kill viruses
     • Antibiotics cure bacterial diseases by killing bateria
     • Viruses are hard to destroy becasue thet reproduce inside cells so there is a risk of damaging the cells
   • Growing and Investigating Bacteria
     • Bactera can be grown on agar jelly
     • All materials used mut be sterilised
       • Prevents unwanted microorganisms contaminating the culture
     • Uncontaminated cultures can be used for investigations of antibiotics and disinfectants
   • Changing Pathogens
     • Pathogens can change causing mutations
       • These can spread rapidly due to lack of immunity to new strain
     • New strains can cause epidemics or pandemics
       • Epidemic- Spread of a disease within a country
       • Pandemic Spread of a disease internationally
     • Bacteria can develop resistance to antibiotics through natural selection
   • Immunity
     • Vaccines immunise against disease
     • Vaccines contain dead or inactive pathogens
       • Encourages white blood cells to produce and remember the antibodies to destroy the pathogens
     • Vaccination works on both bacteria and viruses
   • How do we deal with disease?
     • Herd immunisation, vaccinating large numbers, protects society from the risk of disease

2. Coordination and Control

   • Responding to Change
     • Nervous system allows reaction to surroundings
     • Receptors in sense organs detect external stimuli
       • Impulse sent along sensory neurone to brain
         • Brain coordinates response, which is sent down motor neurone
           • Effector then responds
   • Reflex Actions
     • Reflex actions are automatic responses to a stimulus and usually keep us out of danger
     • 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
     • Between neurones there are synapses that use chemicals to pass the impulse over the gap
   • Hormones and the Menstrual Cycle
     • Menstrual cycle lasts 28 days with ovulation at 14 days
     • Follicle Stimulating Hormone (FSH)- Made in the Pituitary Gland and causes an egg to mature and stimulates the production of oestrogen
     • Oestrogen- Produced by the ovaries and it inhibits the production of FSH and stimulate the production of LH and the womb lining
     • Luteinising Hormone (LH)- Made in the Pituitary Gland and it stimulates the release of the matured egg
   • Artificial Control of Fertility
     • The contraceptive pill may contain oestrogen and progesterone to inhibit FSH
     • FSH can be given to help an infertile woman produce eggs
     • Fertility Treatments
       • Advantages
         • Reduces family size
         • Woman can plan pregnancies
         • Couples that couldn't have children before can now
       • Disadvantages
         • Pill can cause side effects
         • Ethical or religious implications
         • IVF is expensive
         • Embryos may be destroyed
   • Controlling Conditions
     • Internal conditions of the body must stay constant
       • Controlled by the nervous system and hormones
     • Water, ion content, temperature and blood sugar levels are controlled
   • Hormones and the Control of Plant Growth
     • Plants respond to light, phototropism, gravity, geotropism, and moisture, hydrotropism
     • Auxin is the plant hormone that controls geo and phototropism
       • 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
       • 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
   • Using Hormones
     • Can have side effects
     • Misuse of plant hormones could effect the environment

3. Medicine and Drugs

   • Developing New Medicines
     • Drugs are tested in labs, on animals and in clinical trial on healthy and ill patients
     • Placebo- Don't contain a drug, are used to see if drug does have effect
       • Double Blind Trials- Neither doctor nor patient knows which is the drug and which is the placebo, to remove bias
     • Thalidomide, a sleeping pill, was found to cure morning sickness but caused birth defects so now treats lepsory
   • How Effective Are Medicines?
     • Statins lower cholesterol levels and have lowered heart disease by 40%
     • Double blind trials should be used to test non prescribed medicines to remove bias
   • Drugs
     • Drug- A chemical the effect your behaviour or thoughts
     • Both legal and illegal drugs may harm your body
     • Chemicals in cannabis may cause mental illness in some
     • Cocaine and heroin is very addictive, and you may suffer from withdrawal symptoms when trying to stop taking them
   • Legal and Illegal Drugs
     • Medicinal Drugs- Used to control disease and can only be prescribed by a doctor
     • Recreational Drugs- Used only for pleasure and affect the brain and nervous system
     • Recreational drugs can be legal like caffeine or alcohol or illegal like cannabis or heroin
     • Impact of legal drugs greater than illegal drugs as they are more readily avaliable
   • Does Cannabis Lead to Hard Drugs?
     • Obtaining cannabis from dealers may put people in contact with harder drugs
     • Chemicals in cannabis can cause mental illness particularly in teenagers
   • Drugs in Sport
     • Some athletes use illegal performance enhancing drugs such as steroids to give them an unfair advantage in competitions
       • Most would consider this unethical

4. Adaptation and Survival

   • Adapt and Survive
     • Organisms get necessary materials for survival from their surroundings and other organisms
     • Organisms are adapted to survive in the conditions they normally live
     • Some microorganisms, extremophiles, are adapted to live in the most extreme environments
   • Adaptation in Animals
     • Adaptations help an animal survive
     • Animals in cold climates are usually large with small surface area: volume ratio, and vice versa for hot climates
     • Coat colour may to provide year round camoflage
   • Adaptation in Plants
     • Plants lose water vapour from stomata on the leafs surface
     • To conserver water plants reduce the surface area of leaves, store water and have extensive root systems
   • Competition in Animals
     • Animals compete for: food, water, territory and mates
     • The best adapted animals are good competitors
   • Competition in Plants
     • Plants compete for: water, light, space and nutrient and mineral ions from the soil
   • How do you survive?
   • Measuring Environmental Change
     • Environmental changes the distribution of organisms
       • Changes can be caused by living factors, arrival of a new predator or disease, or non-living factors, temperature and rainfall
     • Environmental changes can be measured with using non living indicators such as thermometers or rain gauges
     • Organisms, indicator species, can used to disclose pollution levels
   • Impact of Change
     • Distribution of organisms can be affected by living and non living factors
     • Data on the effect of environmental change isn't always easy to interpret

5. Energy in Biomass

   • Pyramids of Biomass
     • Main source of energy for organisms is the sun's radiation
       • Green plants turn the light energy to chemical energy during photosynthesis
     • Biomass- Amount of dry living mass in an organism
     • Biomass at each stage of the food chain is less than the previous stage
   • Energy Transfers
     • Less energy is available at each stage of the food chain as it is lost through movement, waste and into the surroundings
       • The rest is used for growth
   • Decay Processes
     • Organisms take nutrients from the environment which are returned when they die
     • Decay is started by detritus feeders who produce waste materials that are then eaten by microorganisms called decay organisms
     • Decay happens quicker in warm moist aerobic conditons
   • Carbon Cycle
     • Carbon cycle is the constant recycling of carbon in nature
     • Carbon dioxide is removed from the atmosphere during photosynthesis
     • Respiration and combustion return carbon dioxide to the atmosphere
   • Recycling Organic Waste
     • Recycling organic waste reduces landfill and methane, and recycles nutrients in the waste

6. Variation, Reproduction and New Technology

   • Inheritance
     • Offsprings have similar characteristics to their parents
     • Genes are passed in gametes from parents to offsrprings
     • Genes control characteristics of your body
   • Types of Reproduction
     • Clones are produced during asexual reproduction, where no gametes join
     • Clones- Genetically identical copies of one parent
     • Sexual reproduction involves the joining of gametes from two parents leading to a variety of offsprings
   • Genetic and Environmental Differences
     • 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
     • Clones may have differences due to environmental causes
   • Cloning
     • Plant clones can be made quickly and easily by making a cutting
     • A tissue culture could be made by taking some cells from the plant and growing them in special conditions
     • Animals can be cloned by putting a nucleus in an empty egg and placed in a surrogate mother
   • Adult Cell Cloning
     • Scientists have used adult cell cloning to clone animals such as Dolly the sheep
     • The nucleus of a cell is placed into an empty egg cell and transplanted in to a host mother, creating a clone
   • Genetic Engineering
     • Genetic engineering transfers a gene for one organism to another to give a desired characteristic
     • Enzymes are used to cut a gene from a chromosome and is then inserted in another
     • Genes must be transferred at an early stage of development
   • Making Choices About Technology
     • Disadvantages
       • Long term affects of eating GM crops aren't known
       • Could reduce or contaminate the gene pool
       • 'Playing' God
     • Advantages
       • May provide cures for genetic disorders
       • Produces medical drugs
       • Crops are resistant to herbicides and insects

7. Evolution

   • Theories About Evolution
     • It is thought all life developed from simple organisms that lived 3 billion years ago
     • Darwin suggested evolution takes place by a process of natural selection over many years
   • Accepting Darwin's Ideas
     • Darwin's theory was only gradually accepted
   • Natural Selection
     • Natural selection means the fittest organisms survive to breed
     • If a gene mutates the new characteristics may allow and organism to survive better
   • Classification and Evolution
     • Comparing similarities and differences allow classification of organisms
     • Classification allows evaluation of evolutionary relationships