biology paper 1

• eukaryotic cells

  are complex and include animal and plant cells
• prokaryotic cells

  smaller and simpler, include bacteria
• plant cells

  all plus extra: cell wall, permanent vacuole, chloroplasts
• magnification formula


  image size/real size
• preparing light microscope


  select lowest power objective lense

  use coarse adjustment knob to move up stage

  look down the eyepiece, use coarse knob to adjust stage and focus

  adjust focus with fine focus knob for a clear image

  if higher magnification needed, swap for high powered objective lense
• nerve cell


  rapid signalling, long to cover more distance, form networks around body
• muscle cells


  for contraction, contain lots of mitochondria to help generate energy
• root hair cells


  cells on the surfaces of plant roots, grow into long hairs, help plant absorb water and mineral ions
• phloem and xylem cells


  transport substances, xylem cells are hollow
• chromosomes


  contain genetic information in the nucleus
• how can stem cells preserve rare plant species?

  they can quickly produce clones of the whole plant cheaply and quickly

  can have desired features for farmers

  can grow more plants of rare species
• diffusion


  spreading out of particles from area of HIGH to LOW concentration
• osmosis 


  the movement of water molecules across a partially permeable membrane from an area of high to low water concentration
• active transport


  substances absorbed from a lower to higher concentration
• job of the lungs

  transfer oxygen to the blood and remove waste carbon dioxide from it
• what is the cell cycle

  body cells divide to produce new cells
• substances that CAN diffuse through cell membranes

  smaller ones like glucose and amino acids
• substances that CAN NOT diffuse through cell membranes

  starch and proteins
• how is the villi adapted for absorbing food

  large surface area to absorb food into the blood faster
• cells - tissues - organs - organ systems
• organ


  group of tissues that work to make a certain function
• what is a catalyst

  a substance that increases the speed of a reaction without being changed or used up in the reaction
• if starch is present....

  the iodine solution will change from brown orange to blue black
• proteases convert proteins into....

  amino acids
• lipases convert proteins into....

  amino acids
• where is bile produced

  in the liver
• where is bile stored

  in the gall bladder before its released into the small intestine
• salivary glands

  produce amylase enzyme in the saliva
• stomach


  produces protease enzymes, releases hydrochloric acid to kill bacteria
• pancreas


  produces protease, amylase and lipase enzymes, releases them into the small intestine
• liver

  where bile is produced, neutralises stomach acid and emulsifies fats
• gall bladder

  where bile is stored before released to the small intestine
• large intestine

  excess water from food is stored
• rectum

  where poo is stored before being released through the anus
• Benedicts test for sugars


  prepare a food sample and transfer 5cm3 to a test tube

  prepare a water bath set to 75 degrees

  add 10 drops of Benedictus solution using pipette

  leave for 5 mins

  if sugar is present it will turn from blue to yellow or brick red
• Iodine solution for starch


  prepare food sample of 5cm3 to a test tube

  add iodine solution

  if the sample contains starch it will go from brown orange to blue black
• Biuret test for proteins


  prepare food sample 2cm3

  add buret solution

  if proteins are present solution will change from blue to purple
• alveoli


  carries out gas exchange in the body
• double circulatory system

  1. right ventricle pumps deoxygenated blood to the lungs to take in oxygen, blood returns to the heart
  2. left ventricle pumps oxygenated blood to the other organ, blood gives out oxygen and deoxygenated blood returns to the heart to be pumped again
• valves

  make sure blood pumps in the right direction and gas valves to prevent backflow