Biology B1

Diet and Exercise
1. Carbohydrates, fats and proteins
  1. Used to release energy and provide nutrients to build cells
2. Mineral ions and vitamins
  1. Small amounts needed for cells to function
3. Malnourishment is too much or too little food
4. Metabolic Rate
  1. Is affected by your amount of muscle, how much exercise you do and some inherited factors
  2. The rate at which chemical reactions are carried out
5. Inherited factors such can affect things such as cholesterol
Defence against diseases
1. Pathogens
  1. Bacterium release toxins and some can invade and destroy blood cells (Smaller than our cells)
  2. Viruses take over a cell's DNA and cause cells to make toxins and damage them in the process (Much smaller than bacteria)
2. Immune system
3. Ignaz Semmelweis discovered hand washing prevented the spread of diseases in pregnant women
4. Vaccinations
  1. A small amount of dead/inactive pathogen is injected - this causes white blood cells to produce antibodies - if you are infected by the pathogen later your body can react quickly so you don't become ill
5. Mutations
  1. Epidemic - A widespread occurrence of an infectious disease in a community at a particular time
  2. Pandemic - (of a disease) prevalent over a whole country or the world.
  3. A new strain of pathogen is produced - antibodies don't recognise it - new strains could spread rapidly
  4. Antibiotic resistance
    1. Mutations create antibiotic-resistant strains - antibiotics kill regular bacteria but resistant bacteria survise and reproduces - this must be treated with a new more powerful antibiotic - with no new antibiotic it may spread
6. Antibiotics
  1. Medicines used to kill BACTERIAL pathogens
  2. e.g.penicillin
  3. Certain bacteria can only be killed by specific antobiotics
Nervous system
1. Receptors
  1. Stimulus - Change in surroundings
  2. Nervous System - Detects stimuli and coordinates a response
  3. Response - Change in an organism's behaviour due to a stimulus
2. Responses
  1. Reflex actions are automatic and involve very few neurones
  2. 1.A receptor cell produces and electrical pulse because of a stimulus 2.The impulse passes along a sensory neurone to the central nervous system 3.It goes to a relay neurone in the central nervous system 4.it then passes to a motor neurone 5.Finally it passes to the effector e.g.the arm
Control in the human body
1. Internal conditions
  1. Water content is lost: when we breathe out (Lungs), when we sweat to cool down (Skin) and in urine (Kidneys)
  2. Ion content is lost: when we sweat (Skin) and when we urinate (Kidneys)
2. Menstrual cycle
  1. Hormones
    1. FSH - Produced in Pituitary glands - Matures the egg - Stimulates the production of oestrogen
    2. LH - Produced in the pituitary glands - Cause the release of an egg - Inhibits Oestrogen
    3. Oestrogen - Produced in the ovaries - Builds up the womb lining - Inhibits production of FSH and stimulates the production of LH
  2. Birth control - Contain oestrogen or progesterone (reduces headaches for women) which means no eggs mature so no eggs are ready to be released
3. Increasing fertility
  1. IVF - Fertilisation outside of a woman's body
  2. Fertility drugs - contain FSH and LH which stimulate eggs to mature and be released
Control in plants
1. Phototropism - Growth in response to light
2. Gravitropism - Growth in response to gravity
3. Auxin (Plant growth hormone produced in the shoot or root tip) grows on the shaded side of a stem to elongate the cells and cause the plant to bend towards the light
4. Auxin is used in weedkiller and essentially grows the plant so big it cannot recieve the nutrients required and dies
Drugs
1. Chemicals which affect how the body works
2. Trials
  1. 1.In the laboratory: The drug is tested on cultures of cells, cultures of tissues and then animals
  2. 2.Clinical trials stage 1: Very small dose is tested on a healthy volunteer
  3. 3.Clinical trials stage 2: A patient with the disease is given different doses of the drug to find the optimum dose and if it works
  4. Placebo - A substance that has no therapeutic effect, used as a control in testing new drugs
  5. Double blind trials - When neither the patient or doctor know if the patient is receiving a placebo so the metal effect doesn't affect the results
3. Thalidomide - Developed as a sleeping pill - Used to control morning sickness in women - Caused severe limb abnormalities in babies - Thalidomide is now used to treat leprocacy
4. Statins - Reduce the risk of cardiovascular disease in people with high cholesterol
5. Recreational drugs
  1. Cannabis - Usually burned and breathed in, can cause mental illnesses
  2. Addiction - When the drug makes the person dependent on it and when the drug is no longer taken withdrawal symtoms occur
6. Drugs in sport
  1. Stimulants - increase the rate of bodily functions e.g. faster heart rate so muscles receive oxygen and sugar faster
  2. Anabolic steroids - stimulate muscle growth
7. Social effects - Can harm people around them, could relax people, right to freedom
Adaptations
1. Competition
  1. Plants compete for light, space, water and nutrients
  2. Animal compete for food, territory and mates for reproduction
2. Animals in the Arctic - Small surface area to reduce heat loss, white colour for camouflage in snow, thick fur and fat to insulate and large feet to increase grip
3. Animals in Deserts - Large water stores to remain hydrated, large surface area to lose heat quickly, thick fur on top to insulate from sun's heat
4. Extremophiles
  1. Live in high levels of salt
  2. Live in high temperatures
  3. Live in high pressures
5. Indicators
  1. Bloodworms indicate polluted water
  2. Mayfly larvae indicate unpolluted water
  3. The colour of a lichen can indicate the pollution in the air
Energy in Biomass
1. Light energy from Sun - Energy captured by plants - Photosynthesis occurs - Chemical energy is stored in cells
2. Biomass at each stage reduces due to respiration
Decay
1. Occurs when an organism has died, it returns materials to the enviroment
2. It is performed by microbes: Most active when warm, moist and high levels of oxygen
The carbon cycle
Genes
1. Genes control the characteristics of the body
2. Environment (e.g. scars) and genes (e.g. eye colour) effect your variations
3. Half your genes are inherited from your father and half from your mother
Reproduction
1. Plants
  1. Asexual - No fusion of gametes (sex cells), only one parent, no mixing of genetic information and all offspring have the same genes as parent and each other
2. Animals
  1. Sexual - Gamete from other fuses with gamete from father, mixed genetic information from each parent and offspring have different combinations of genes, so varying characteristics
3. Cloning
  1. Tissue culture - A few plant cells are taken and cultured into an identical plant
  2. Embryo transplants - All offspring are identical and are developed from a single embryo
  3. Adult cell cloning
4. Genetic engineering
  1. The transfer of a gene from one organism to another so the organism receives the desired characteristics
    1. The wanted gene is removed from a chromosome using enzymes - the gene is inserted into the nucleus of a cell in the other organism - the cell of the second organism now posses this gene
  2. Issues
    1. Economic - Is the cost worth it
    2. Social - Are there benefits for society
    3. Ethical - Is it morally right
  3. Crops
    1. Crops have been modified to: resist attack by insects and resistance to herbicides so only weeds are killed
    2. Herbicide resistant crops may transfer the gene to weeds so weeds are no longer killable
    3. Herbicide kills wild flowers so less food for insects thus the whole food chain
    4. Insecticide-resistant pests may develop and become resistant to insecticide
    5. Modified crops could harm human life
Evolution
1. Darwin's theory
  1. Natural selection
  2. Individuals have varying characteristics - Some variations are better suited to certain environments - Individuals with more suitable variations survive and reproduce - The next generation have the developed genes for the environment
2. Lamarck's Theory
  1. Inheritance of characteristics
  2. Environmental factor e.g. weight training - Causes certain characteristics e.g. increased muscles size - These characteristics are inherited by the offspring e.g. young have large muscles
3. Classification
  1. Organisms are grouped as plant, animal or micro-organism based on their charcteristics
  2. All organisms developed from simple life forms over 3 billion years ago
  3. Evolutionary trees are used to show relationships between organisms

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Biology B1

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