humans (6) + (5)

• diffusion = the net movement of particles from an area of high concentration to an area of low concentration until equilibrium
• osmosis = net movement of water particles from an area of high water potential to an area of low water potential through a partially permeable membrane
• active transport = movement of particles through a cell membrane of lower concentration to a region of higher concentration using energy from respiration
• rate of movement effected by: distance (short = quicker), temperature (higher = quicker), concentration gradient (shorter = quicker) , surface area to volume ratio (larger ratio = quicker)
• respiration = the release of energy from glucose
• respiration equation = C6H12O6 + 6O2 = ATP + 6CO2 + 6H2O
• ATP = energy - used for muscle contractions and growing
• aerobic respiration = uses oxygen and produces lots of ATP - needs to ventilate to provide enough oxygen
• anaerobic respiration = not enough oxygen to completely break down glucose - less ATP
• anaerobic equation in animals - glucose = lactic acid
• anaerobic equation in plants and fungi - glucose = ethanol + carbon dioxide
• build up of lactic acids = causes pain
• multicellular organisms - have small SA:V ratio = big distance so slow diffusion
• multicellular organisms use: exchange surfaces - lungs and alveoli, and transport systems - blood and circulation
• unicellular organisms - don't need transport as has big SA:V ratio - quick diffusion
• burning food practical: measure temp change of carbs - measure energy = 20 x temp change x 4.2
• alimentary canal (long pipe) = mouth - oesophagus - stomach - small intestines - pancreas - large intestines - rectum - anus
• mouth = mechanical mastication (chewing) - produces saliva in salivatory glands + amylase - pH 7
• oesophagus = connects throat to stomach
• stomach = pH 3 - HCl + protease - churns food
• small intestines (duodenum and ileum) = pH 7 - bile injected in, broken down to small molecules and absorbed
• pancreas = injects enzymes into small intestines
• large intestines = excess water is absorbed
• rectum = faeces are stored
• anus = faeces leave body
• peristalsis = wave like motions of circular muscle contractions to aid the movement of food through the gut
• bile = made in the liver and stored in the gallbladder - emulsifies fats and neutralises stomach acid
• villi = in small intestine - helps increase rate of diffusion
• villi adaptations = long finger-like structure = large surface area, good blood supply = quick absorbtion, thin = short diffusion pathway