biology

• Food groups and why humans need them

  • Carbohydrates - Provides a quick source of energy
  • Proteins - Used for growth (building) and repair of the body
  • Fats (lipids) - Provide a long store of energy, help to insulate our body, protect vital organs
  • Vitamins - Essential for keeping our body healthy
  • Minerals - Calcium strengthens bones, iron makes red blood cells
  • Fibre - Helps clean out intestines and prevent constipation
  • Water - 70% of body, needs to be replaced
• Nutritional food labels


  Tell you what is in the food, how much of each food group per 100g and per serving
• Digestion


  Food molecules are broken down into smaller molecules which can be absorbed into the blood
• Mouth


  • Teeth break down food into smaller pieces, saliva helps break down food
• Stomach


  • Has hydrochloric acid which further breaks down food and kills harmful bacteria
• Small Intestine


  • Broken down food is absorbed into the blood, walls have villi to increase surface area for absorption
• Large Intestine

  • Water is absorbed into the blood
• Enzymes


  Chemicals which speed up the chemical reactions that break down larger food molecules into smaller molecules
• Types of enzymes


  • Amylase - breaks down starch
  • Protease - breaks down proteins
  • Lipase - breaks down fats
• Active site of an enzyme

  Where the chemical reaction takes place
• Substrate


  The chemical which undergoes the chemical reaction
• Breathing


  Movement of air into and out of the lungs
• Respiration


  Chemical reaction between oxygen and glucose to make carbon dioxide and water, occurs in all body cells
• Diaphragm


  • Sheet of muscle used when breathing
• Breathing in (inhalation)


  Rib cage moves up and out, diaphragm contracts and moves downwards, volume of thorax increases, pressure in lungs decreases
• Breathing out (exhalation)


  Rib cage moves down and in, diaphragm relaxes and moves upwards, volume of thorax decreases, pressure in lungs increases
• Path of oxygen

  Enters mouth/nose, down trachea, into bronchus, into bronchiole, into alveolus, diffuses into blood
• Gas exchange in alveoli

  • Oxygen diffuses into blood, carbon dioxide diffuses into alveoli, large surface area, thin moist wall, surrounded by blood capillaries
• Blood vessels


  • Arteries - carry oxygenated blood at high pressure
  • Veins - carry deoxygenated blood at low pressure
  • Capillaries - one cell thick, connect arteries to veins
• Components of blood


  • Red blood cells - carry oxygen
  • White blood cells - fight infections
  • Platelets - clot blood
  • Plasma - liquid part that carries cells
• Heart


  • Pumps blood around the body, contains muscle tissue, has 4 chambers
• Circulation


  Right side pumps blood to lungs, left side pumps blood to body, double circulation system
• Aerobic respiration


  Respiration using oxygen to release large amounts of energy from glucose
• Anaerobic respiration

  Respiration without oxygen to release small amounts of energy from glucose
• Mitochondria


  • Organelle where energy is generated in aerobic respiration
• Lactic acid from anaerobic respiration causes muscle cramps, can only be broken down by oxygen
• Types of diseases


  • Communicable - spread from person to person, caused by pathogens
  • Non-communicable - not spread from person to person, caused by genetics or lifestyle
• Smoking


  • Main cause of lung cancer, causes breathing problems, heart disease, blocked arteries, stroke, emphysema
• Types of pathogens


  • Bacteria
  • Viruses
  • Fungi
  • Protozoa
• Diseases caused by pathogens

  • Salmonella - caused by bacteria
  • Athlete's foot - caused by fungi
  • Measles - caused by virus
• Groups of drugs


  • Depressants - decrease brain and heart activity
  • Stimulants - increase alertness and energy
  • Painkillers - block pain messages
  • Hallucinogens - distort senses
• Drugs in each group

  • Depressants: alcohol, cannabis, heroin
  • Stimulants: nicotine, ecstasy, caffeine
  • Painkillers: aspirin, paracetamol
  • Hallucinogens: LSD
• Fermentation


  Plants/microbes undergo anaerobic respiration to produce ethanol and carbon dioxide
• Photosynthesis


  Process where plants produce their own food using carbon dioxide, water and sunlight
• Chloroplasts


  • Plant cell organelles that contain chlorophyll and carry out photosynthesis
• Photosynthesis equation


  Carbon dioxide + Water → Oxygen + Glucose
• Uses of glucose from photosynthesis


  • Energy for seeds
  • Starch storage
  • Fruit production
  • Protein synthesis
  • Cellulose for cell walls
• Starch test


  Adding iodine to a leaf to check if starch is present
• Factors affecting rate of photosynthesis

  • Sunlight
  • Temperature
  • Carbon dioxide concentration
  • Water concentration
• Stomata


  • Allow air to enter and leave the leaf for photosynthesis and gas exchange