Notes

• Why does the breathing rate increase when exercising

  • to increase the amount of oxygen entering the blood via diffusion
  • so muscle cells get more oxygen for aerobic respiration and release more energy
  • increased breathing rate also gets rid of excess carbon dioxide in the body made by aerobic respiration
  • more oxygen delays the start of anaerobic respiration preventing lactic acid and oxygen debt
• Describe how the small intestine is adapted for efficient absorbtion

  • Has villi and microvilli which increase the surface area for absorbtion
  • walls of the villi and capillaries are one cell thick - providing a short diffusion pathway for molecules to move from gut to blood
  • The good blood supply helps maintain the concentration gradient
  • has lots of mitochondria in surface cells for for aerobic respiration to release energy for active transport
• why in drug trials would a scientist use placebo and double- blind trials to increase validity ?

  placebo takes into account the psychological effects or using a placebo for comparison for treatment Vs no treatment therefore its a control

  double- blind trials - to avoid bias
• Describe how the human body prevents pathogens from entering ?

  
  

  - The skin acts as a barrier and secretes sebum which repels pathogens from entering the platelets in the blood clot the blood to stop pathogens entering through cuts , if the skin barrier is compromised

  - the mucus in the nose and hairs traps pathogens from entering the trachea and bronchus when breathing. The cilia move the mucus up and out by a cough.
• Describe the body deals with pathogens inside the body ?

  • phagocytes injest the pathogen which kills the pathogens white blood cells produced antitoxin which neutralise toxins by binding to the toxins B lymphocytes produce antibodies which help destroy the pathogens white blood cells produced memory cells which provide immunity against reinfection of a specific pathogen / disease
• how are the human lungs adapted for exchange of gases ?

  • large capillary network around the alveoli - good blood supply to move oxygen in blood supply move carbon dioxide out to the lungs maintains a concentration gradient
  • many alveoli - increased surface area to volume ratio increasing rate of diffusion
  • capillaries around the alveoli one cell thick providing short diffusion pathway oxygen and carbon dioxide to move around
  • constant breathing mechanism moves air in and out brings fresh oxygen for the deoxygenated blood and removes carbon dioxide maintaining the concentration gradient
• What are the factors that affect the rate of transpiration ?  

  • Increase temp - increases transpiration water particles gain energy move faster increases diffusion and evaporation through stomata
  • Increase humidity - decreases transpiration decreases diffusion , concentration difference ( more water in air than leaf )
  • Increase air flow - increases transpiration as faster air removes particles from the surface of the leaf, decreasing water concentration in air, faster diffusion
  • Increase light intensity - the stomata open for more gas for photosynthesis , more water evaporated
• What is therapeutic cloning ?

  • Sperm or eggs from the adult that needs treatment is fertilised with another egg / sperm to form a zygote
  • Cell divides to form an embryo and the inner layer contains embryonic stem cells
  • Stem cells are gathered and cultured
  • Stem cells then differentiate to form specialised cells or tissues
  • Transplanted to the patient.
• What are the different type of substrates in our body ?

  • Carbohydrates - simple sugars like glucose and sucrose and complex carbohydrates ( long chains of simple sugars) - starch and cellulose
  • Lipids - 3 molecules of fatty acids with molecule of glycerol
  • Proteins - long chains of amino acids ( shape of amino acids determines the protein )
• What are enzymes and lock and key theory ?

  • Enzymes = biological catalyst ( doesn't get used up) large proteins) that speed up a reaction
  • An enzyme has a specific active site for a specific substrate, once the substrate is found, substrate fits into active site of enzyme, substrate splits into products and leaves active site
• Factors that effect enzyme action ?

  • Higher temperature = molecules gain more energy and collide more often. Optimum temperature = greatest rate of reaction. If the temperature increases too much the active site of the enzyme gets denatured and substances are broken down
  • Each enzyme works in different pH levels - folded shape of protein enzyme molecule is held by forces, change in pH affects forces which changes shape of the active site
• How does the digestives system work ?

  • Large insoluble molecules of starch, lipids, and protein and broken down by digestives enzymes into soluble molecules to be absorbed into bloodstream in small intestine
  • Amylase= salivary glands, pancreas ,small intestine - catalyses digestion of STARCH into Sugars ( in mouth and small intestine )
  • Protease = stomach , pancreas, small intestine - proteins into amino acids( in stomach and small intestine)
  • Lipase = pancreas and small intestine - lipids into fatty acids and glycerol
• How does the body create acidic and alkali conditions ?

  • Stomach walls - produce hydrochloric acids ( kills bacteria)
  • Liver PRODUCES Bile and its STORED in gallbladder - creates alkaine conditions as it neutralises stomach acid , emulsifies fats to increase surface area for lipase to act upon
• What is blood plasma and what does it contain ?

  • liquid plasma = red blood cells, white blood cells, platelets,
  • Blood plasma = transports carbon dioxide from organ to lungs, soluble digestion productions from small intestine to organs and Urea from liver to kidneys
  • Red blood cells - biconcave disc , no nucleus, red = haemoglobin combines with oxygen in lungs = oxyhaemoglobin splits in organs
  • Platelets - fragments of cells , no nucleus
• How does blood clotting work

  • Reaction causes fibrinogen to change into fibrin
  • Fibrin forms network of fibres to trap platelets and form a clot
  • Clot dries to scab
• What are the different blood vessels

  • Arteries - blood AWAY from heart - thick walls , and thick layer of muscle and elastic tissue - small lumen
  • Veins - blood TO the heart, thinner walls have valves to prevent backflow and large lumen
  • Capillaries - one cell thick walls - carry blood to organs
• How does the heart work.

  • Deoxygenated blood enters VENA CAVA to the right atrium
  • Right atrium contracts to move the blood to the right ventricle
  • Right ventricles contract and pushes blood to the pulmonary artery takes deoxygenated blood to lungs - valves prevent backflow
  • Pulmonary vein brings oxygenated blood from lungs which moves to the left atrium to left ventricle which pushes blood to aorta to carry blood around the body
• What happens when you breathe in

  • Intercostal muscles contact - ribcage - up and out
  • Diaphragm flatten
  • Volume of thorax increases
  • Pressure in throat decreases air is drawn in lungs
• What happens when you breath out ?

  • Intercostal muscles of ribcage and diaphragm relax
  • Diaphragm is domed and ribcage moves down and I
  • Volume in throat decreases
  • Pressure and air is forced out
• What are the different plant tissue ?

  • Epidermal - tissue which covers thr plant
  • Palisade mesophyll - has many chloroplasts for photosynthesis
  • Spongy mesophyll - air spaces with large surface area for diffusion of gases
  • Xylem - transports water and dissolved mineral ions from root to plant
  • Phloem - transports dissolved sugars from leaves to rest of the plant
• Stents

  • Metal mesh tubes inserted in arteries to keep them open and allow blood to flow through
  • Effective in lowering the risk of a heart attack
  • Recovery time from surgery is quick
• Enzymes

  • 
Biological catalysts, substances that increase the rate of reaction without being used up
• Pacemaker

  • 
Group of cells in right atrium that provide electrical stimulation to make the heart beat
• • Pathogens
  • 
Microorganisms that cause infectious disease, including viruses, bacteria, protists and fungi
• Bacteria

  • Small
  • Multiply very quickly through dividing by a process called binary fission
  • Produce toxins that can damage cells
• Measles

  
 Symptoms: Fever and red skin rash, can lead to other problems such as pneumonia (lung infection), encephalitis (brain infection) and blindness How it is spread: Droplet infection How it is being prevented: Vaccinations for young children to reduce transmission
• Salmonella food poisoning

  Symptoms: Fever, stomach cramps, vomiting, diarrhoea (all caused by the toxins they secrete) How it is spread: These bacteria can be found in raw meat and eggs, unhygienic conditions How it is being prevented: Poultry are vaccinated against Salmonella, keeping raw meat away from cooked food, avoid washing it, wash hands and surfaces when handling it, cook food thoroughly
• Producing Monoclonal Antibodies

  1. Inject antigen into mice - stimulates B lymphocytes to produce antibodies

  2. They are combined with tumour cells (do not make antibodies but divide rapidly), to form a cell called a hybridoma

  3. The hybridoma can divide to produce clones of itself, which all produce the same antibody

  4. The antibodies are collected and purified
• How can CHD cause a heart attack ?

  • CHD causes restricted blood flow as fatty acid blocks the arteries
  • Less oxygen reaches the heart
  • Prevents heart muscles from respiring
• Compare anaerobic respiration in yeast cells and muscle cells

  • Both release small amounts of energy - incomplete breakdown of glucose
  • Yeast produces CO2 but muscle cells don't
  • Yeast produces ethanol but muscle cells produced lactic acid
• How can pancreatic cancer cause weight loss ?

  • Less enzymes are produced by the pancreas
  • Large soluble molecules aren't broken down and digested
  • Less glucose is absorbed into the bloodstream
  • Low glucose levels means more Body fat is converted by glucagon for respiration