Biology Notes for Aqa Essay

Metabolic Rate- How quickly the chemical reactions (metabolism) are taking place within cells * In a balanced diet, you need- -Carbohydrates to build cells and to release energy. -Minerals and Vitamins in small amounts to keep the body functioning. -Water because we lose 70% form sweat, breath, tears, urine, faces etc. -Fiber to prevent constipation and bowel cancer. * Malnutrition- eating a diet which is not balanced which can lead to being overweight (obese), underweight or deficiency diseases (Rickets etc) * Pathogens-

Infectious diseases carried by microorganisms which can be passed form one person to another. * Bacteria- Single-celled organisms. Cause diseases by reproducing rapidly once inside the body (Splitting). They produce Toxins * Viruses- Take over the cells as they reproduce, damaging and destroying them, very rarely produces toxins. * How the body protects from Pathogens: -Skin covers body and acts as a barrier. -Scabs- Platelets in your blood quickly help to form a clot which dries into a scab which stops Pathogens. -Mucus- when you breathe, you draw air loaded with Pathogens.

However, your breathing organs produce a sticky liquid. -Stomach Acid- When the mucus gets swallowed into the gut, stomach destroys the pathogens * Immune System- White blood cells can protect us by: -Ingestion-Some white blood cells actually take in Pathogens, destroying and preventing them form causing disease -Antitoxins- Some white blood cells produce Antitoxins. These counteract the toxins (poisons) released by Pathogens -Antibodies- White blood cells release a chemical called an Antibody, which destroys the Pathogen.

A unique antibody is released to destroy each type of Antibody * Mutations- Random/Naturally occurring changes which happen in the ones of organisms which change their characteristics * Immunity- Our white blood cells are able to make the right antibody quickly * Injections- Small amounts of dead or inactive pathogens are put into your body. The antibodies destroy the dead/inactive pathogens without any risk of you getting the disease. You are then immune to future infections by the same pathogens.

It now responds rapidly and makes the correct antibody as if you had already had the disease Coordination and Control * Control Systems- -Nervous System- responds to a Stimulus and is very quick -Hormones- Chemical messenger and is secreted by Glands and is slow * Reflex Action- An automatic ,unconscious and rapid response to a stimulus by our Nervous System I. E. Moving our hands away from a fire Nervous System- -Receptor Cells- React to a Stimulus -Neuroses (Nerve Cells)- Carry the Nerve impulse -CANS (Spinal cord/Brain) – Coordinates our response to the Nerve Impulse [Relay Neuron. Synapse- Gaps between two neuroses. Chemical released to cross gap. The chemicals trigger a new nerve impulse in the next neuron. Effecter- Responds either by Muscles or Glands * Menstrual Cycle- A women’s fertility is controlled by hormones secreted by Glands FISH- Secreted by Pituitary Glands. Makes eggs mature in the ovaries and stimulates the ovaries to produce Estrogen -Estrogen- Secreted by the Ovaries. Stimulates the lining of the womb for pregnancy and stimulates Pituitary Glands to make LA. LA-Stimulates the release of a mature egg form one of the ovaries in the middle of the Menstrual Cycle- Ovulation -As the estrogen levels rise, they inhibit (slow down the production of FISH and encourage the production of LA * Controlling Fertility -Pill- Low dose of Estrogen with Progesterone stop unpleasant side effects- this inhibits FISH production (eggs don’t mature) Fertility Drugs- IV and Drugs containing FISH and LA * – controlled by the Nervous system and hormones Homeostasis – It controls levels of water, salt ions, blood sugar and temperature * Hormones -Plant growth affected by light, moisture and gravity -Again- Controls plant hormones- -Photocopies- a plant will bend towards a source of light -Gravitations- a plant will grow upwards (Against gravity) – Isotropic- a plant root will grow downwards (with gravity) Plant Photocopies and Gravitations is caused by an uneven distribution of Again in plant roots and shoots Drugs Uses- -Recreation I. E. Alcohol, Nicotine, Cannabis and Cocaine -Sport- They can improve sporting performance I. E. Steroids and Stimulants -Medicine- Treat someone/ aid recovery I. E.

Paramedical and Stains -Stains- It lowers cholesterol, reducing the risk of a stroke or heart attack by 25%-40%. But one side effect is it damages the liver and some patients go back to eating fatty foods because they don’t think they will be affected by strokes or heart attacks Problems- -Addiction- Alters chemical process and can lead to dependency- Heroin and Cocaine -Thalidomide- Medicine produced in the ass’s and originally used as a sleeping pill. When it was discovered it stop sickness during pregnancy, doctors allowed pregnant women to use it, but then the number of deformed babies increased. When it was withdrawn, the number of deformed babies decreased.

Used now to treat Leprosy and some kinds of cancer Mental Illness- Depression (Schizophrenia) which is associated with Cannabis Heart and Circulatory Problems- Cocaine, Heroin and Cannabis is associated with Heart and Circulatory problems Gateway Drugs- Lead to harder drugs- Cannabis- Heroin? More problems are caused by legal drugs I. E. Nicotine and Alcohol * Trials