ch4&5

• key requirements of being multicellular

  the same DNA, ability to communicate with other cells, be adjoined to other cells, have specialised cells
• four levels of organisation

  specialised cell, tissue, organ, system
• sources of stem cells in animals

  embryos, some adult tissues
• sources of stem cells in plants

  meristem tissues
• gene expression definition


  when the information stored in genes is used to build structures in the cell, determines how it will differentiate and function
• xylem function


  transports water and inorganic nutrients absorbed from soil
• phloem function


  transports dissolved sugars and some other molecules (not water)
• benefit of having dead cells to transport water

  greater amounts, efficiency
• mesophyll


  contain cells with many chloroplasts for photosynthesis
• upper epidermis


  waxy cuticle to protect leaves
• lower epidermis


  lower part of leaf surface containing guard cells that control the stomata
• formula for photosynthesis


  12H2O + 6CO2 -----> C6H12O6 + 6O2 + 6H2O
• stomata function


  allow gas exchange when open (guard cells control it - open is flacid, closed is turgid)

  the rate of stomatal opening influences the rate of photosynthesis
• extra- vs intra-cellular water transport

  extra- - between cell walls

  intra- - within the cytoplasms (plasmodesmata)
• osmosis (passive) use


  water travels down the concentration gradient due to high concentration of water in the soil
• active transport use


  most dissolved mineral ions
• diffusion (passive) use


  uptake of potassium and phosphate ions is dependent on the rate of water uptake
• transpiration definition


  movement of water molecules from the roots to the stomatal pores

  if continuous - transpiration streaming
• factors affecting transpiration


  humidity, temperature, wind, light
• translocation definition


  movement of organic solutes (C, H, + O)
• source definition


  compounds such as glucose would have leaves
• sink definition


  regions that need the compounds
• heterotroph definition


  any organism that needs to ingest other organisms to gain energy
• use of carbohydrates


  energy for cellular respiration
• use of lipids


  required for the plasma membrane
• use of amino acids

  range of cellular functions
• use of vitamins


  assist in chemical reactions
• use of minerals


  building blocks for body structures
• use of water


  solvent for biochemical reactions
• mechanical digestion


  physical breakdown of food molecules so that chemical digestion can occur faster
• chemical digestion


  enzymes that break down molecules into smaller subunits
• three enzymes


  amylases (carbs)

  proteases (proteins)

  lipases (lipids)
• mouth digestive function


  chamber for food

  produce saliva for lubrication

  produce amylase for carb breakdown

  teeth and tongue - mechanical digestion
• oesophagus digestive function


  forms long, thin tube for passage of food to the stomach

  peristaltic muscle movement to push food to stomach
• gall bladder digestive function

  stores bile that emulsifies lipids
• pancreas digestive function


  glucagon and insulin production

  enzyme production
• liver digestive function


  production and secretion of bile

  emulsification of fats
• stomach digestive function


  production of gastric juices

  production of pepsimegon

  HCl production

  mucus production to protect lining

  peristalsis to churn food
• small intestine digestive function

  absorption of nutrients and water

  perstalsis for movement
• function of the caecum


  fermentation chamber (hindgut fermenters - two types of faeces)