B1 Revision

Keeping healthy

  • Metabolic rate is the rate of chemical reactions in your body and can be affected by your genes, exercise and age.
  • If you are overweight you have a risk of high blood presure, heart disease and diabetes.
  • If you are underweight you have a risk of infertility, exhaustion and a weak immune system.
  • People have high cholesterol because they eat too much saturated fats however it can genetically inherited. If your cholesterol is too high you have the risk of heart disease, you can reduce your cholesterol by taking statins, eating unsaturated food and exersice.
  • There are 2 types of pathogen, bacteria (release poisonous toxins-small) and viruses (live in cells and reproduce - really small).
  • White blood cells engulf and digest pathogens, then they release antibodies to stick to the pathogen and antitoxics to stick to toxins.
  • Antibiotics are drugs which kill bacteria, however the overuse of them can lead to bacteria becoming resistant to antibotics and can lead to mutations which are difficult to treat.
  • A vaccine works by using a small amount of dead or inactive pathogens, then your white blood cells produce antibodies which match the shape of the antigen. White blood cells can now quickly produce antibodies next time your infected.
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Coordination and control

  • Nervous system sends electrical impulses along neurons. In order it is receptor, sensory neurons, brain and spinal cord, motor neuron the to the effector (muscle or organ).
  • The reflex arc: Receptor, sensory neuron, relay neuron, motor neuron and effector (muscle or organ).
  • Plant hormone is called auxin. In phototropism, the plant responds to the light and auxin which is on the sunny side of the plant is destroyed and the shoot grow down. In gravitropism, the plant responds to gravity auxin gathers on the lower side which then leads to the roots growing more on the side with the least amount of auxin. The roots bend towards gravity.
  • Hormones in the menstrual cycle: FSH - produced in the pituitary gland and causes egg to matureOestrogen - proudced in the ovaries and causes the lining of the womb to develope. LH - produced in the pituitary gland and causes the egg to leave the ovary.
  • Your body has to control certain things in order for it to function properly:

Temperature - too hot ~ sweat, blood flow increases. too cold ~ shiver, blood flow decreases.

Water and salt - urine can show if you are dehydrated ~ clear no and dark yes. Your kidneys control your water and salt amount.

Blood sugar levels - insulin is released from pancreas if you have diabetes you have low insulin.

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Medicine and drugs

  • Drugs change the chemical reactions in your body. Legal drugs are alcohol, nicotine and caffine, illegal drugs are ecstacy, cannabis and heroin.
  • To test a new drug you research the drug, chemicals are made, tested on animals, tested on healthy people then if it goes well then it goes on to the unhealthy people.
  • A placebo is a pill that doesnt work. This is usually used on a double-blind trial when the doctor gives one person a placebo and one a working drug to see what the effect is.
  • Performance enhancing drugs like steroids are used to build muscle and enable athletes to train harder. However taking drugs to win is cheating and there can be dangerous side effects.
  • Thalimoide was a drug which was used on pregnant women to help morning sickness however it wasnt tested properly and caused birth defects, but it is now used to cure leprosy.
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Adaptation for survival

  • Plants compete for water, light, minerals and space. They use stratergies like rapid growth to reach ligth first, seed dispersal techniques and growing their roots deep and producing chemicals to stop other plants from growing.
  • Plants like cactus' adapt to dry environments by storing water in their stem, deep root system to absorb water, curling leaves to reduce surface area and having a waxy cuticle to reduce water loss. Plants also lost water through leaves by transpiration (evaporation from their leaves).
  • Animals compete for food, water, space and mates. They  use stratergies for competing for female mates by fighting and learning to dance.
  • Animals adapt to different environments, in cold areas they have thick fur to trap air, small ears so they dont lose as much heat and big paws to balance weight. In hot area they have large ears to let heat escape, thin fur to increase heat loss and hunts at night to reduce heat loss. Prey adapt by camoflage - polar bears have white fur for snow. Or have bright colours to show poison.
  • Plants and animals can be used to measure environmental change, plants like lichens are affected by acid gas pollution e.g. sulphar dioxide. and animals like invertebrates distribute themselves depending on water quality.
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Energy in biomass

Glucose + Oxygen > Carbon dioxide + Water + Energy = Respiration (GOCOWE)

Carbon dioxide + Water > Oxygen + Glucose = Photosynthesis

  • Energy is lost by respiration/movement, waste/faeces, and inedible material.
  • During decay worms, maggots and slugs eat dead material. Microbes (bacteria and fungi) digest dead material. Carbon dioxide is released into the air by respiration. Minerals released into soil which helps plants.
  • In order for something to decay the conditions need to be moist, warm and have oxygen.

Carbon cycle:

  • Photosynthesis
  • Animals taking in oxygen
  • Respiration
  • Animals dies and decays.
  • Microorganism respire.
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Variation, reproduction & new tech

  • A gene is a section of DNA, it controls a chromosome of your body. You have 46 chromosomes in the nucleus of your blood cells, arranged in 23 pairs. One of each pair is inherited from your male and one from your female. Your sex cells or gametes only have 2 chromosomes.
  • Sexual reproduction: fusion of female and male gametes, producing genetic variety in the offpsring.
  • Asexual reproduction: only one individual - no fusion of gametes. The offpsring are indentical to the parent.
  • There are two types of plant cloning, Cutting - plant dones cna be made quickly by taking cuttings from mature plants. Tissue cutting - taking small groups of cells from part of a plant and growing them under special conditions.
  • Genetic engineering - changing the genetic makeup of an organism. This can be used for making medical drugs e.g. insulin and antibodies. However, eating GM crops may have an effect on human health.
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  • Jean-Baptiste Lamaracks theory of evolution - characteristics which develop during an organism's lifetime can be passed on to the next generation.
  • Charles Darwin's theory of evolution - all organisms in a species vary and there some are more likely to survive (natural selection). The best adapted ones breed and pass on characteristics to their offspring.
  • Darwin's theory is accepted now rather than Lamaracks but it challenged the idea that God created the universe. Scientists were not convinced because they did not think their was enough evidence.
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Biology Unti 1 - Revision

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