key concepts

• What are the main structures of an animal cell?

  • Nucleus: stores genetic information (DNA)
  • Cell membrane: controls entry and exit of substances
  • Mitochondria: responsible for respiration and energy production
  • Ribosomes: make essential proteins
  • Cytoplasm: where chemical reactions occur
• What additional structures do plant cells have compared to animal cells?


  • Cell wall: provides strength and protection
  • Vacuole: stores cell sap
  • Chloroplasts: involved in photosynthesis
• How does a bacterial cell differ from plant and animal cells?

  • Bacterial cells have:
  • Flagellum for movement
  • DNA floating in cytoplasm (not in a nucleus)
  • Plasmid loops (extra DNA)
• What are the two categories of cells mentioned?

  Prokaryotic cells and eukaryotic cells.
• What characterizes prokaryotic cells?


  They are smaller, simpler, and have no nucleus.
• What characterizes eukaryotic cells?

  Eukaryotic cells are bigger, more complex, and have a nucleus.
• What is cell differentiation?


  It is the process where cells switch genes on or off to develop specialized characteristics.
• What are gametes and their characteristics?


  • Gametes: sperm and egg cells
  • Specialized cells with a haploid nucleus (23 chromosomes)
  • Fuse together to form a zygote
• What is the role of the axon in the sperm cell?


  • Filled with enzymes to help break down the egg cell
• What is the role of cilia in ciliated epithelial cells?


  • Hair-like structures that help move substances along in organs
• What are the main components of a light microscope?


  • Eyepiece lens
  • Stage clips
  • Course and fine focus wheels
  • Objective lenses
  • Stage
  • Light
• When were light microscopes invented?


  In the 1500s.
• How do light microscopes work?


  They pass beams of light through the specimen.
• What is the resolution of light microscopes compared to electron microscopes?


  Light microscopes have a relatively low resolution compared to electron microscopes.
• Why can't electron microscopes view living cells?


  Because they work in a vacuum, which cells cannot survive.
• How do you find total magnification in a microscope?


  By multiplying the magnification of the eyepiece lens by the magnification of the objective lens.
• How do you calculate magnification?


  By dividing the image size by the real size.
• What are enzymes and their functions?


  • Biological catalysts made by living things
  • Speed up reactions
  • Not living; they are molecules
  • Have a substrate that fits into the active site
• Why are enzymes considered highly specific?


  Because only one type of substrate can fit into the enzyme's active site.
• What are the two types of enzyme reactions?


  • Breakdown: larger molecules into smaller ones
  • Synthesis: smaller molecules into larger ones
• What happens to enzymes if the temperature is too low?


  They do not have enough energy to work properly.
• What is denaturation in enzymes?


  It is when the shape of the active site changes, preventing catalysis.
• What effect does pH have on enzymes?


  If the pH goes off in either direction, the enzyme begins to denature.
• How can enzyme activity be increased?


  By increasing the substrate concentration until all active sites are full.
• What is the Benedict's test used for?


  • To test for reducing sugars
  • Add Benedict's reagent and heat gently
  • Positive test: colored precipitate (blue = low, orange-red = high sugar concentration)
• What is the Biuret test used for?


  • To test for proteins
  • Add potassium hydroxide and copper sulfate
  • Positive test: solution turns purple
• What is the emulsion test used for?


  • To test for lipids
  • Add ethanol, shake, pour into water
  • Positive test: water turns milky
• What is the iodine test used for?


  • To test for starch
  • Add iodine to the sample
  • Positive test: blue-black color
• How is calorimetry used to measure energy in food?


  • Set up: retort stand, clamp, copper cup, thermometer, tongs, Bunsen burner
  • Burn food under copper cup with water
  • Measure temperature change
  • Calculate energy: mass of water (g) × temperature change × 4.2
• What is diffusion?


  It is the movement of particles from a higher to a lower concentration.
• What is osmosis?


  • Movement of water molecules from high to low concentration
  • Occurs through a partially permeable membrane
  • Special case of diffusion
• How does osmosis work with solute concentrations?


  • Water moves from higher water concentration (lower solute) to lower water concentration (higher solute)
  • Aims to balance concentrations
• What type of cells are animal and plant cells?

  They are eukaryotic cells
• What is a characteristic of prokaryotic cells?

  They are much smaller than eukaryotic cells
• What additional structures do bacterial cells have?

  Cell wall, single circular DNA, plasmids
• What are organelles?

  Structures in a cell with different functions
• Where do aerobic respiration reactions occur?

  In the mitochondria
• Where does protein synthesis occur?

  In the ribosomes
• What is the function of flagella in bacterial cells?

  Allows bacteria to move
• What adaptations do root hair cells have?

  Large surface area, large vacuole, many mitochondria