biology paper 1

• nucleus: contains genetic material
• cell membrane: can control what substance can pass in and out of the cell
• cytoplasm: where chemical reaction takes place
• mitochondria: provides cells with energy they need to function
• ribosomes: site of protein synthesis
• rigid cell walls: provides support and structures the cell
• permenant vacuole: contains sap, a mixture of sugars, salt and water
• chloroplast: where photosynthesis takes place
• bacteria cells
• • bacteria cells
  • do not have nucleus
  • do not have mitochondria
  • do not have chloroplast
• plasmid- antibiotic resistance
• circular strand of DNA- genes needed to reproduce
• where is bile produced?

  by the liver
• what is an enzyme?

  biological catalyst, made of protein which can speed up reactions, without being used up
• cells

  basic function + structural units in a living organism
• what is a tissue

  a group of cells of structure and function working together for a particular purpose
• what is an organ

  group of different tissues working together to perform a particular function
• organ systems

  group of organs with related functions, working together to perform bodily functions in an organism
• mouth

  mechanical digestion taking place
• salivary glands

  chemical digestion using the enzyme amylase
• stomach

  foods mechanically digested by chiming (muscular contraction)
• enzymes e.g pepsin

  low optimum pH- hydrochloric acid
• small intestine

  enzymes which are adapted to a more alkaline pH
• bile

  produced in the liver

  stored in gall bladder

  neutralize stomach acid

  emulsifies fats
• enzyme

  1. substrate has a complimentary shape to the active site of the enzyme
  2. substrate binds to the active site forming an enzyme - substrate complex
  3. bonds are broken in the substrate
  4. the products are realised and the enzyme is recycled
• biological catalyst

  made of protein which can speed up a reaction without getting used up
• enzyme effects (temperature)

  as temp increases, the rate of reaction increases until after the optimum temp

  the active site will then denature, lowering the rate of reaction
• enzyme effectors (pH)

  the optimum pH of an enzyme is where it is most active

  above or below the optimum pH can cause the enzyme to denature
• food tests - starch

  chemical- iodine

  positive result- blue- black

  negative result- stays orange
• food tests- glucose
• food test- glucose

  chemical- benedicts reagent

  extra step- heat up with water bath

  positive reult- traffic light colours
• food test - protein

  chemical- biuret solution

  positive result- purple

  negative result - blue
• food test- fats (lipids)

  chemical- sudan III

  positive result- brick red

  negative result- no red
• artaries

  transport blood AWAY from the heart
• arteries

  tick wall that are elastic, allows it to with stand high blood pressure
• veins

  transport blood TO the heart

  thin walls, contains valves to prevent the back flow of blood
• capillaries

  found all around the body e.g muscles
• capillaries

  very thin walls which are 'leaky' allowing substances to leave the blood to reach body tissues
• double circulatory system

  • right side of the heart sends blood to the lungs
• double circulatory system

  • the left side of the heart sends blood to the body