Chemistry

• Prokaryotic cells


  Smaller, simpler cells without membrane-bound organelles or a nucleus
• Eukaryotic cells


  Larger cells with a nucleus and membrane-bound organelles, found in plants, animals, and fungi
• Differences between animal and plant cells


  • No cell wall
  • No chloroplasts
  • Small vacuoles
  • Many lysosomes
  • Numerous mitochondria (animal)
  • Cell wall
  • Chloroplasts
  • Large vacuoles
  • Lysosomes rare
  • Few mitochondria (plant)
• Nucleus


  Contains the genetic material DNA, essential for the cell to function
• Nucleolus


  Found within the nucleus and contains RNA
• Endoplasmic reticulum


  A network of flattened membranes used mainly for the transport of proteins
• Types of endoplasmic reticulum


  • Rough - with ribosomes attached
  • Smooth - no ribosomes, processes lipid synthesis
• Vacuole


  General storage and disposal of substances, larger in plant cells
• Cell membrane


  A 'selective barrier' that allows certain substances to pass through and prevents others from entering the cell
• Fluid mosaic model of the cell membrane


  Phospholipids provide barriers, peripheral proteins form temporary bonds, channel proteins allow ions/water flow, carrier proteins involved in active transport, glycoproteins for cell-cell recognition, cholesterol restricts molecule passage
• Light microscope


  Ocular lens 10x, objective lens 4x, 10x, 40x, 100x, can see nucleus and chloroplast but not organelles
• Concentration gradient


  Higher concentration of particles in one area than another
• Surface area to volume ratio


  Smaller single-celled organisms have a high ratio, allowing effective diffusion of oxygen and materials
• Hypotonic


  Lower solute concentration, e.g. dehydration when not drinking enough water
• Enzymes


  Proteins that control cellular reactions, speed up reactions by forming substrate-enzyme complexes, can break down or build up molecules, control processes like photosynthesis and respiration
• High temperatures


  Causes more collisions for reactions to occur
• Photosynthesis


  Process used by plants and other organisms to convert light energy into chemical energy
• Cellular respiration


  Process in which organisms use oxygen to break down food molecules to get chemical energy, can occur aerobically or anaerobically
• Aerobic cellular respiration occurs in the mitochondria and produces a lot of ATP per glucose molecule, while anaerobic respiration produces less ATP
• Three domains of life


  • Archaea
  • Bacteria
  • Eukaryotes
• Unicellular organisms


  Contain only one cell, either prokaryotic or eukaryotic
• Colonial organisms


  Made up of a group of identical single-celled organisms
• Multicellular organisms


  Made up of many different types of specialised cells
• Plant structures


  • Vascular - with xylem and phloem
  • Non-vascular - without xylem and phloem
• Movement of water in xylem


  Due to properties of water like cohesion, adhesion, and transpiration creating tension
• Heterotrophs


  Consumers that consume organic matter, including animals, humans, bacteria, archaea, protists, and fungi
• Autotrophs


  Producers that make their own food from inorganic substances like carbon dioxide, usually plants
• Gas exchange in plants


  Occurs through stomata and lenticels, stomata open in light and close in dark to balance gas exchange and water conservation
• Gas exchange in animals


  Movement of gases between the external environment and internal environment, different animals have specialised structures like lungs, gills, or tracheae
• Respiratory system in humans


  Nose, windpipe, voice box, airway, alveoli in lungs where gas exchange occurs
• Circulatory system


  Cardiovascular system of heart, blood, and blood vessels, and lymphatic system of tissues and organs producing white blood cells
• Blood components


  • Red blood cells
  • White blood cells
  • Platelets
• Blood vessels


  • Arteries
  • Capillaries
  • Veins
• Heart


  Four-chambered, with atria and ventricles, left ventricle has thicker wall to pump blood around body
• Circulatory systems


  • Open - fluids mix freely, found in invertebrates
  • Closed - blood contained in vessels, found in vertebrates
• Sampling techniques


  Quadrats to estimate plant cover, mark-release-recapture to estimate animal populations
• Cane toads were introduced to Australia as biological control for cane beetles, but became an invasive species with no natural predators, increasing in population due to positive selection pressures
• Prickly pear was introduced to Australia as a food source, and its population increased rapidly as it was well-suited to the arid climate and removal methods were ineffective
• within the sample is counted. This process allows an understanding of the population.
• Quadrat sampling


  A method by which organisms in a certain area of the habitat are counted directly. It is used to estimate population abundance, density, frequency and distribution. The position is chosen by random.