Paper 1

• Cells


  The basic building blocks of life that can replicate independently
• Multicellular organisms like animals and plants contain many cells that divide to grow or replace dead cells, not to create new organisms
• Bacteria are single-celled prokaryotic organisms
• Subcellular structures common to animal and plant cells


  • Cell membrane
  • Nucleus
  • Cytoplasm
  • Mitochondria
  • Ribosomes
• Plant cells

  • Have a rigid cell wall made of cellulose
  • Contain a permanent vacuole with cell sap
  • Contain chloroplasts for photosynthesis
• Bacterial cells

  • Lack mitochondria and chloroplasts
  • Have a single circular strand of DNA instead of a nucleus
  • May have additional plasmids
  • May have flagella for movement
• Photosynthesis occurs in the chloroplasts of plant cells, using chlorophyll to absorb light energy
• Aerobic respiration in mitochondria releases energy for cells
• Key groups of living organisms

  • Animals
  • Plants
  • Fungi
  • Protists
  • Bacteria
  • Viruses
• Animals

  • Multicellular
  • Heterotrophs
  • Reproduce sexually
• Plants

  • Multicellular
  • Autotrophs (get energy from sun via photosynthesis)
• Fungi

  • Some are multicellular, some are unicellular
  • Heterotrophs (get energy from other organisms)
  • Use saprotrophic nutrition (secrete digestive enzymes, absorb nutrients)
  • Some have a mycelium body made of hyphae
  • Some are pathogens that can cause disease
• Protists

  • Mostly unicellular
  • Some are autotrophs (can photosynthesize), some are heterotrophs (consume other organisms)
  • Some are pathogens that can cause disease (e.g. malaria)
• Bacteria


  • Unicellular
  • Some can photosynthesize but don't have chloroplasts
  • Most feed off other living or dead organisms
  • Estimated to have more species than all other kingdoms combined
  • Some are pathogens that can cause disease, but most are harmless or helpful
• Viruses


  • Tiny particles, not cells
  • Have a protein coat surrounding genetic material (DNA or RNA)
  • Can only reproduce by infecting and using other living cells
  • Always act as parasites and cause harm to the host organism
• Eukaryotes (animals, plants, fungi, protists) have DNA in chromosomes and a nucleus, while prokaryotes (bacteria) have loose DNA and no nucleus
• Viruses are much smaller than prokaryotic cells, around 10-100 times smaller
• Characteristics of living things (organisms)

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Acronym for characteristics of living things

  Mrs gran
• Non-living things may have some of these features, but only living things have all seven
• Movement


  Ability of organisms to move, either the whole organism or just part of it
• Respiration


  Chemical reactions that break down nutrient molecules to release energy for metabolism
• Sensitivity


  Ability to detect and respond to changes in the internal or external environment
• Growth


  Permanent increase in size and dry mass of an organism
• Reproduction


  Process that makes more of the same kind of organism
• Excretion


  Removal of waste products of metabolism and substances in excess of requirements
• Nutrition


  Taking in of materials for energy, growth and development
• All living organisms are made up of one or more cells
• Viruses are not considered living organisms because they do not meet all seven characteristics
• Nanometers


  Smallest unit of length you need to know
• Units of length

  • Nanometers
  • Micrometers
  • Millimeters
  • Meters
  • Kilometers
• Each unit is 1,000 times bigger or smaller than the one next to it
• Converting between units of length

  1. Divide by 1,000 to convert to a larger unit

  2. Multiply by 1,000 to convert to a smaller unit
• Converting 6 millimeters

  • 6 millimeters = 0.006 meters = 0.000006 kilometers
  • 6 millimeters = 6,000 micrometers = 6,000,000 nanometers
• To convert between non-adjacent units, convert in steps
• • Naked eye can see down to 100 micrometers
  • Light microscope can see down to 500 nanometers
  • Electron microscope can see down to 0.1 nanometers
• Centimeters


  10 millimeters, 100 centimeters in a meter
• Converting centimeters

  1. Divide by 100 to get meters

  2. Multiply by 10 to get millimeters
• Converting 30 centimeters


  • 30 cm = 300 mm = 300,000 micrometers = 300,000,000 nanometers
• Microscopy


  The use of microscopes