BIOLOGY PAPER 1

• Hormones

  Chemical messages that travel through the body by blood
• The adrenal gland produces adrenaline
• The ovaries produce estrogen and progesterone
• The pituitary gland is the master gland as it regulates the secretion of other endocrine glands
• The thyroid produces thyroxine
• The pancreas produces insulin and glucagon
• The testes produce testosterone
• Adrenaline


  Used for the fight and flight response
• Insulin is produced in the pancreas
• Excess glucose is stored and changes into glycogen
• Glycogen is stored in the liver
• Carbohydrates are broken down into glucose
• The body uses glucose for energy
• After a meal, the level of blood glucose in our bodies increases


  After exercise, the level of glucose in our bodies decreases
• This happens because when we exercise, our body uses glucose for energy
• Cells


  The basic unit of all forms of life
• Structural differences between various types of cells


  • Enable them to perform specific functions within the organism
  • Controlled by genes in the nucleus
• Cell division by mitosis

  1. Produces two new identical cells

  2. Allows organism to grow
• Stem cell technology


  A new branch of medicine that allows doctors to repair damaged organs by growing new tissue from stem cells
• Eukaryotes and prokaryotes


  • Plant and animal cells (eukaryotic cells)
  • Bacterial cells (prokaryotic cells)
• Plant and animal cells (eukaryotic cells)

  • Have a cell membrane, cytoplasm and genetic material enclosed in a nucleus
• Bacterial cells (prokaryotic cells)


  • Are much smaller in comparison
  • Have cytoplasm and a cell membrane surrounded by a cell wall
  • Genetic material is not enclosed in a nucleus, it is a single DNA loop and there may be one or more small rings of DNA called plasmids
• Main sub-cellular structures


  • Nucleus
  • Cell membranes
  • Mitochondria
  • Chloroplasts in plant cells
  • Plasmids in bacterial cells
• Animal cells


  • Nucleus controls the activities of the cell
  • Cytoplasm is where most chemical reactions take place
  • Cell membrane controls the passage of substances into and out of the cell
  • Mitochondria is where most energy is released in respiration
  • Ribosomes is where protein synthesis occurs
• Plant cells


  • In addition to the parts found in animal cells, often have:

  Chloroplasts which absorb light energy to make food

  Permanent vacuole filled with cell sap
• Plant and algal cells


  • Also have a cell wall made of cellulose, which strengthens the cell
• Estimations can be used to judge the relative size or area of sub-cellular structures
• Cell specialisation


  Cells may be specialised to carry out a particular function
• Specialised plant cells


  • Root hair cells
  • Xylem cells
  • Phloem cells
• Animal and plant cells may be specialised to function within a tissue, an organ, organ systems, or whole organisms
• Electron microscope


  Has much higher magnification and resolving power than a light microscope
• Electron microscope


  • Can be used to study cells in much finer detail
  • Enables biologists to see and understand many more sub-cellular structures
• Differences in magnification and resolution

  Between a light microscope and an electron microscope
• Electron microscopy has increased understanding of subcellular structures
• Calculating magnification, real size and image size

  Magnification = size of image / size of real object
• Light microscopes

  • Can see individual cells and large subcellular structures like the nucleus
• Electron microscopes


  • Using a beam of electrons instead of a beam of light, gain a much higher resolution seeing much smaller objects e.g. the structures of mitochondria, chloroplasts, ribosomes and plasmids
• Parts of a microscope

  • Ocular Lens
  • Body Tube
  • Objectives
  • Stage Clips
• Bacteria multiply

  By simple cell division (binary fission) as often as once every 20 minutes if they have enough nutrients and a suitable temperature
• Bacteria can be grown

  In a nutrient broth solution or as colonies on an agar gel plate