Biology B1 gcse's

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Heart:Relaxes to fill with blood. Contracts to squeeze blood out. Blood Pressure: measured in mm Hg. Two measurements; eg. 120/80mm hg. Systolic(first number), when heart contracts. Diastolic(second number), when heart relaxes. Factors: -weight -stress -smoking - alcohol -diet high in fat, sugar and/or salt.High blood pressure is dangerous as blood vessels can weaken and burst, which could lead to a stroke.Low blood pressure results in poor blood circulation, which can cause dizziness,fainting and cold hands and feet. Pulse: Resting pulse, 60bpm to 100bpm. Increase in breathing rate and pulse rate because: -deliver oxygen and glocose to cells in muscles more quickly. -remove carbon dioxide more quickly.Heathly means being free from infection.Fit means how much physical activtiy you're capable of doing.Cardiovascular Efficiency means how well your heart copes and recovers with aerobic exercise. Aerobic Respiration:is the release of energy from glucose in the presence of oxygen.Word equation: Glucose+Oxygen->Carbon Dioxide+Water+Energy.Anerobic Respiration: takes place in the absence of oxygen.It quickly releases a small amount of energy through the incomplete breakdown of glucose.Word:Glucose->Latic acid+Energy.Occurs when muscles are working so hard that not enough oxygen can't be delivered to break down all the available glucose through aerobic respiration.Latic acid:toxic to cells.After anerobic exercise your heart rate stays high to remove latic acid from muscles. Deep breathing continues ensuring enough oxygen is taken in to oxidise the latic acid.

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Balanced Diet: Must contain -carbohydrates and fats to provide energy. -protein for growth and repair. To keep healthly: -minerals, eg iron to make haemoglobin in red blood cells. -vitamins to prevent scurvy. -fibre to prevent constipation. -water to prevent dehydration. BMI:Mass(kg)/Height(m).Protein molecules are long chains of amino acids:Essential amino acids taken in by eating food.Non-essential amino acids made by the body. RDA(recommended daily allowance formula: 0.75 x body mass(kg).Non-Infectious diseases can't be caught from another person.They are caused by: -poor diet. -oragan malfunction. -genetic inheritance. -cells mutating.Infectious Diseases are spread from person to person.They are caused by pathogens.Examples of pathogens are: -fungi(athlete's foot). -Viruses(flu). -Bacteria(cholera). -protozoa(dysentery).Defences Against Pathogens: -skin. -respiratory system. -stomach. -blood. If pathogens enter the body,white blood cells start fighting the invasion. The two types of white blood cells are: -Phagocytes. -Lymphocytes.Types of Vision: binocular(humans and predators)) and monocular(prey).46Chromosomes.Gametes(sex cells). Inheritance of sex: **=female XY=male.

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All cells contain: -Cytoplasm(many chemical reactions take place). -A cell membrane(Controls movement in and out of the cell). -A nucleus(controls what the cell does).-Mitochondria(respiration takes place inside).DNA is made of two strands coiled around each other in a double helix. The four bases are A,C,G and T. A bonds with T and C bonds with G. Living cells have to: -obtain oxygen,glucose,water and minerals from thire surroundings. -get rid of waste products,such as carbon dioxide, These pass through the cell membrance by diffusion. Diffusion is the movement of a substance from a region of high concentration to a region of low concentration.

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