biology paper 1

• Organelles

  • Cytoplasm
  • Nucleus
  • Cell membrane
  • Mitochondria
  • Ribosomes
  • Chloroplast
  • Cell wall
  • Vacuole
• Cytoplasm


  Where chemical reactions take place
• Nucleus


  Contains genetic material (genes & chromosomes) & controls cell activity
• Cell membrane

  Controls what enters & leaves the cell
• Mitochondria


  Organelles that contain the enzymes for respiration, and where most energy is released in respiration
• Ribosomes


  Tiny structures where protein synthesis occurs
• Chloroplast


  Site of photosynthesis in plants
• Cell wall


  Strengthen plant cell's
• Vacuole


  Store of water & nutrients in plant cells
• Mitosis


  1. Stage 1: Cell spends most of its life in interphase

  2. Stage 2: DNA condenses into chromosomes

  3. Stage 3: Nuclear membrane disappears, spindle threads form

  4. Stage 4: Chromosomes lie on equator of cell

  5. Stage 5: Chromosome splits, chromatids move to opposite poles

  6. Stage 6: Nuclear membrane forms around daughter chromosomes
• Diffusion


  Movement of a substance from an area of high concentration to an area of low concentration, happens in liquids and gases due to random particle movement
• Cell cycle


  In eukaryotes, divided into interphase and mitotic phase. Interphase is when cell grows and DNA replicates, mitotic phase is cell division
• Osmosis is the movement of water or other solvent through a semi - membrane from a region of low solute concentration to a region of high solute concentration
• Osmosis is passive transport, meaning it does not require energy to be applied
• Stem cells


  • From a recently dead embryo can be grown in special solutions
  • From an embryo can grow into any type of tissue
  • May grow out of control to form cancers
  • Large numbers can be grown in the laboratory
  • Patients treated with stem cells need to take drugs for the rest of their life to prevent rejection
  • Collecting and growing stem cells is expensive
• Active transport


  Movement of molecules across a membrane from a region of their lower concentration to a region of their higher concentration, against the concentration gradient, requires cellular energy
• Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled. Bacteria are an example of prokaryotes, which do not contain a nucleus or membrane-bound organelles
• Specialised plant cells


  • Palisade mesophyll
  • Spongy mesophyll
  • Guard cells
  • Phloem sieve tubes
  • Phloem companion cells
  • Xylem vessels
  • Meristem
• Specialised animal cells


  • Circulatory system cells
  • Excretory system cells
  • Muscular system cells
  • Nervous system cells
  • Respiratory system cells
  • Reproductive system cells
  • Skeletal system cells
• Chromosomes


  Carry genetic information in a molecule called DNA
• Mitosis ensures that when a cell divides, each new cell produced has the same genetic information
• Genes


  Sections of a chromosome that contain the code for the production of a particular protein
• A human cell has 46 chromosomes
• Electron microscopes


  • Use a beam of electrons instead of light rays
  • Scanning electron microscopes have a large field of view to examine surface structure
  • Transmission electron microscopes can examine thin slices of cells and have a maximum magnification of around 1,000,000
• Growing bacteria


  1. Use an inoculating loop to transfer bacteria, sterilise before and after use

  2. Inoculate agar plate, secure lid with tape, label and date

  3. Incubate at 25°C for 24-48 hours to encourage growth without human pathogens
• Therapeutic cloning


  • Involves replicating human embryos to harvest stem cells
  • Uses somatic cell nuclear transfer to transfer DNA into an egg cell
  • Allows use of individual's own cells to treat disease without risk of rejection
• Animal tissues


  • Epithelial
  • Connective
  • Muscular
  • Nervous
• Plant tissues


  • Vascular
  • Epidermal
  • Ground
  • Meristematic
• Exchange surfaces


  • Need for organisms to take in food, oxygen, water, and remove waste
  • Small organisms exchange substances over their body surface by diffusion
  • Surface area defines absorption rate, volume defines substance needs
• Gaseous exchange surfaces


  • Need good ventilation, circulation, large surface area, moist surface, short diffusion distance, concentration gradient to allow gas movement
• Testing for starch


  Add iodine solution, turns blue/black in presence of starch
• Testing for sugars


  Use Benedict's solution, turns red-brown in presence of reducing sugars
• Testing for proteins


  Grind sample, dissolve in water, filter, add Biuret solution, turns purple in presence of proteins
• Digestive system organs


  • Mouth
  • Oesophagus
  • Stomach
  • Small intestine (duodenum, ileum)
  • Large intestine
  • Rectum
  • Anus
  • Liver
  • Gallbladder
  • Pancreas
• Blood components

  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Pulmonary artery

  Right side
• Aorta

  Left side
• Heart valve

  Tendons attached to valve & heart wall
• Pulmonary vein

  Left atrium
• Enzymes

  • Protein molecules in cells which work as catalysts
  • Speed up chemical reactions in the body, but do not get used up in the process
  • Almost all biochemical reactions in living things need enzymes
  • With an enzyme, chemical reactions go much faster than they would without the enzyme