Differences of individuals in the same species is variation.

Variation: genetic factors (dimples,eye colour) , environmental factors (hair, scars)

Genes have info for you too be formed. Genes control different characteristics

Chromosomes- 2 DNA strands

Genes are in chromosomes, chromosomes are in nucleus, nucleus are in every cell.

DNA molecules- how everything should function/form. Genes issue instructions. Cells carry it out by making proteins.Structual p –growth/repair

Functional p- enzymes speed up reactions.

Humans have 23 pairs of chromosomes.

Sex cells have single chromosomes.

23 from dad , 23 from mum

Alleles- different versions of a gene e.g. dimples (dad-no d’s, mum d’s)

2 alleles same- homozygous 2 alleles different heterozygous

Dominant alleles recessive allele

Genes can be influenced by environmental factors.

Female sex chromosome: XXMale sex chromosome: XY

If egg cell is fertilised by Y its male, fertilised by X its female.

Rare disorders can be caused by a faulty allele. i.e. Huntington's disease :affects nervous system, damages nerve cells, clumsy, forgetful, mood, concentration

Huntington allele is dominant, cystic fibrosis alleles is recessive. (carrier)

Genetic testing can be used to detect faulty alleles. Fluid surrounding fetus can be tested (small risk) effect of information. results could be used to discriminate.

People may be turned down for jobs or insurance

Embryo selection can prevent babies with genetic disorder through IVF. Ova/eggs are fertilised and tested healthy ones are put in the uterus. PGD- embryos multiple to 8 cells then 1 tested.

Pre- selection can reduce variation.

Asexual- single cell organisms can reproduce by dividing (clones) most plant/animals can produce this way. Natural clones: embryo separate or twins.

Plants naturally produce clones when they form blubs or runners. (store)

Stem cells can develop into any type of cell. They can be used to replace tissue. e.g. Parkinson's disease. 2 types of stem cells: adult and embryonic.

Adult stem cells taken from places that can repair themselves like bone marrow or umbilical cord blood.

Stem cells can also be taken from a developing embryo. This idea is very controversial but the government allow it but

under regulations to avoid misuse.

Biology: B1 revision cards

You and your genes

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Biology: B2revision cards

Keeping healthy

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Infections are caused by: microorganisms damaging cells, producing poison/toxin. Antimicrobial drugs (antibiotics) can treat this. They kill microorganism or slow them down. (inhabitation)

Examples of microorganism: bacteria (TB), fungi (athlete's foot), viruses(cold/flu)Antibiotics don’t work on viruses. Microorganism can be everywhere. Our body is ideal due to: warmth, nutrients, moisture.

Microorganisms can multiply rapidly and you only see symptoms when there is a considerable amount of infection. If a

microorganism gets into you’re body your immune system is activated.

One type of whit blood cell engulfs and ingest the microorganism and its then destroyed.Another white blood cell become sensitised to the antigens on the microorganism and produces antibodies which lock on the antigens making them easy for the white blood cells to digest.

White blood cells produce specific antibodies for specific infections. Memory cells remember this then if reinfected it can fight the infection quicker (natural immunity).

Vaccinations help your body to come immune to some antibodies. A weakened /dead version of the infection is injected into a person. Some vaccines are redeveloped due to mutation of infections.

People don’t have to be vaccinated but if a lot decide not to more are at risk.

Bacteria and fungi can become resistant to antimicrobials due to mutation: new strains.

Resistance to drug(superbugs). To stop this only take drugs when necessary, complete every course.

Clinical trials compare a old and new drug.

Clinical trial are tested on healthy people to see if a drug is good and safe for others.

drugs have to be tested for safety and effectiveness. They do this by testing it on cells (no ones harmed but doesn’t show effect on whole organism, growing cells is wrong. Then tested of animals(animals can die, react differently to humans)

Placebos- are fake/ harmless drugs

Blind test- patients doesn’t know drugs given to stop biasness. Double-blind test- patients nor doctor knows drugs given. Open-label trial- everyone knows. Long-term trial- making sure treatment is effective in the long-term

If you have too much water your urine will be dilute if you have to little water your urine will be concentrated a hormone called ADH controls this

Water input (food, drinks, respiration) water output (excretion, breathing, sweating). Stability of internal environment is called homeostasis.

Heart- right side pumps blood to lungs, left side pumps blood everywhere else. Main vessels are: vein (blood back to heart, thin walls, elastic), arteries (blood to organs, thick walls, elastic), capillaries (blood between arteries and veins, narrow, one layer thick).

Heart disease usually caused by lifestyle (smoking, stress, diet, alcohol). This happens when fat builds up clocking the flow of blood heart doesn’t get nutrients or oxygen. Blood pressure can monitor risk of heart disease.

Water level monitored by receptors cells in brain, brain sends info to effectors, pituitary glands responds, hormone released.

Drugs like alcohol and ecstasy effect the production of ADH

Biology: B3revision cards

Life on earth

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Cactus: leaves are spines and thick outer layer to reduce water loss. Wide roots to store water.

Fish; gills to take in O2 ,fins to move easily, swim bladder maintain position in water.

Life is organised into kingdoms based on organism features. E.g. animal K

Biodiversity is the variety of life when an animal is extinct the genetic code is lost.

First molecules either came from conditions on earth, deep sea or an external source. Evidence in gas clouds.

Food chain energy: sun, autotroph, herbivore, carnivore, decompose.

Species (similar organisms adapt to their environment to help them survive.

Evolution from natural selection.Evolution- slow continual change over time results in adapted creatures.

reduce landfill site: recycling, biodegradable material ( cardboard, cellulose carrier bags). These are all good but its better to reduce waste. Because energy is required to discard of material also transport costs.

All materials in the world are recycled. Energy cant be created or destroyed

Life started on earth 3500 million years ago. Species are organisms that can breed.

Meters to measure levels of gases i.e. O2 or living organisms as indicators.

Energy loss: respiration, excretion, bone, fur. Less energy at each stage limit to food chain length.

Nitrogen cycle: animals eat protein(nitrogen), nitrogen is excreted, animal decompose,

Environmental changes can also effect the food web i.e. less greens grow.Food chains are inter-related and shows animals have varied dietsIf they cant adapt they

may become extinct: increase competition, new predator, new disease

The sun is the mains source of energy plants use the energy to photosynthesis. Energy is transferred.

If something becomes extinct another animal is at risk. Because of they are dependant on each other.

Fossils are made from materials that have not decayed that are compressed under ground.

Detritivores feed on dead organisms.

An ecosystem is a place with self-sustained organisms and their surroundings. Autotrophs: make their food, heterotrophs: cant make food. Eats plants primary consumer, eat meat secondary/ tertiary consumers

Animals compete for resources. food chains show feeding relationships between organisms. When organisms eat each other energy is passed along but some is lost.

Carbon cycle: removed by photosynthesis, animals eat protein, plants/animals respire, combustion, decomposition.

Equation: 80/800 x 100 = 10%

The rate of extinction is rising because of humans: destroying the environment of killing them off.

All organism share certain traits( cellular structure), and genetic code. Fossil fuels support this and DNA evidence.

Managing the needs of people without damaging the earth- sustainability

Selective breeding is when animals produce offspring with desirable characteristics. For examples looks or produce. (man made)

Examples of change is in moths they adapted to the bark of trees because of pollution some are dark some are light.

Survival of the fittest- best offspring survive genes passed on. Only variation can be passed on if mutation has occurred in the sex cells.

Lamarck’s theory is that animals adapt to their environment