bio

• the 4 functions of mitosis


  growth, repair, development and asexual reporduction
• definition of diffusion


  the net movement of particles from an area of higher concentration to an area of lower concentration
• definition of osmosis


  the net diffusion of water from an area of high concentration to an area of lower concentration of water across a partially permeable membrane
• definition of active transport


  the movement of substances from a dilute solution to a more concentrated solution (against the concentration gradient) (requires energy from respiration)
• specialisation of muscle cells


  can contract, they contain special protein fibers that can change their cells, and are also packed with mitochondria to provide energy for contractions
• the digestive system; the mouth


  contains enzymes in the saliva which begin to digest the starch into smaller sugar molecules
• the digestive system; the esophagus 


  food passes down into the stomach, where enzymes begin the digestion of proteins
• the digestive system; the stomach


  contains hydrochloric acid which helps enzymes, the churning action of the stomach turns food into fluid, increasing the surface area for the enzymes to digest
• the digestive system; the small intestine


  chemicals are released from the liver and pancreas, the walls release enzymes to continue the digestion of protein and lipids, and the small food molecules are absorbed into the bloodstream either by diffusion or active transport
• the digestive system; the pancreas


  releases enzymes that continue the digestion of starch and protein, and start the digestion of lipids
• the digestive system; the liver


  releases bile which helps speed up the digestion of lipids also neutralises the acid released by from the stomach
• the digestive system; the large intestine


  water is absorbed into the bloodstream
• the digestive system; the rectum and the anus


  feces are released out of the body
• what are proteins broken down by and where?

  proteases and are found in the stomach, pancreatic fluid and small intestine
• what are proteins made of?

  long chains of amino acids
• what happens to protein when we digest it?

  the protease enzymes convert the proteins back into individual amino acids which are absorbed into the bloodstream
• what happens to amino acids when they are absorbed?

  they are joined together in a different order to make human proteins
• what are carbohydrates (starch) broken down by and where?


  broken down by carbohydrases and are found in the saliva and pancreatic fluid
• what is starch made from?


  a chain of glucose molecules
• what is starch broken down by?

  the enzymes amylase
• what happens when carbohydrates are digested?

  we produce simple sugars
• what are lipids broken down by and where?

  broken down by lipase and found in the pancreatic fluid and small intestine
• what are lipids made from?

  a molecule of glycerol attached to 3 molecules of fatty acids
• where is bile made and stored?

  made in the liver and stored in the gall bladder
• what 3 things does bile do?

  speed up the digestion of lipids, converts large lipid droplets into smaller droplets (emulsification) and neutralises the stomach acid
• adaptation of the small intestine


  the interior is covered by villi which increase the surface area with microvilli even further, villi also have a very good blood supply so it can rapidly remove waste products, and a thin membrane for a short diffusion path which all increase the rate of diffusion
• on which side of the heart is the aorta and pulmonary vein?


  left
• on which side of the heart is the pulmonary artery and vena cava?


  right
• from where does de-oxygenated blood flow in the heart?

  from the vena cava in the right atrium down to the right ventricle and up the pulmonary artery to the lungs
• from where does oxygenated blood flow in the heart?


  from the pulmonary vein in the left atrium down to the left ventricle and up the aorta to the rest of the body
• what are pacemakers?

  a group of cells in the right atrium which produce small electrical impulses
• 4 features of arteries

  contain high-pressured blood, are strong and elastic, have a thick wall and muscle/elastic tissue
• 5 features of capillaries

  really small, exchange substances, takes away waste products, 1 cell thick wall for easy diffusion, and contain low pressure, slow flowing blood
• 5 features of veins 


  contain low-pressure blood, don't need to be strong, have valves that prevent blood backflow, have the biggest lumen and a small layer of fibers and smooth muscle
• function of the trachea

  contains rings of cartilage to prevent it collapsing during inhalation
• what are the alveoli?

  tiny air sacs where gases diffuse in and out of the bloodstream
• features of the alveoli


  thin walls for a short diffusion path, and a good supply of blood, once oxygen is diffused it's rapidly removed so that the concentration gradient is as steep as possible
• benign cancer


  found in one area
• malignant cancer


  these cells invade tissues and move them into the bloodstream, where they spread to other parts and form new tumours
• causes of cancer

  genetics (breast, prostate, or large intestine cancer)or lifestyle (smoking, UV)