Key concepts in bio

• What are plasmids?

  Small rings of DNA coding for extra genes
• What is the process of differentiation in cells?

  Cells gain new structures suited to their role
• How do sperm cells aid reproduction?

  They carry male DNA to the egg cell
• What are stem cells capable of?

  They can differentiate throughout their life
• What adaptations do sperm cells have for swimming?

  Streamlined head and long tail structure
• What is the function of the acrosome in sperm cells?

  It contains enzymes to break down egg membrane
• What type of nucleus do sperm cells have?

  Haploid nucleus with 23 chromosomes
• What is the role of egg cells in reproduction?

  To accept sperm and develop into an embryo
• How does the egg cell's membrane function during fertilization?

  It becomes impermeable after one sperm enters
• Why do egg cells have many mitochondria?

  To provide energy for the developing embryo
• What is the function of ciliated epithelial cells?

  To waft bacteria trapped by mucus to the stomach
• How do root hair cells function in plants?

  They absorb water and minerals from the soil
• What adaptation do root hair cells have for absorption?

  Large surface area due to root hairs
• What is the role of xylem cells in plants?

  To transport water and minerals from roots to shoots
• How do xylem cells adapt to withstand water pressure?

  Lignin is deposited in spirals in the cells
• What is the function of phloem cells in plants?

  To carry products of photosynthesis to all parts
• What structures do phloem cell walls form?

  Sieve plates for substance movement
• How do electron microscopes differ from light microscopes?

  They use electrons for higher magnification
• Who first observed cells in cork?

  Robert Hooke in 1665
• What is the maximum magnification of a light microscope?

  Approximately 2000x
• What is the resolving power of a light microscope?

  200nm affects resolution detail
• What are the two types of electron microscopes?

  Scanning and transmission electron microscopes
• What is the magnification of a scanning electron microscope?

  Up to 2,000,000x
• What is the resolving power of a transmission electron microscope?

  0.2nm for detailed organelles
• Why are electron microscopes important for studying viruses?

  They can identify structures smaller than bacteria
• What is the formula for magnification of a light microscope?

  Eyepiece magnification x objective magnification
• How do you calculate the size of an object?

  Size of image / magnification
• What is standard form used for?

  To simplify large or small numbers
• What does the prefix 'centi' mean?

  Multiply unit by 0.01
• What does the prefix 'milli' mean?

  Multiply unit by 0.001
• What does the prefix 'micro' mean?

  Multiply unit by 0.000001
• How can estimations be useful in biology?

  To approximate quantities without counting
• How do you estimate the number of dandelions in a field?

  Count in a sample and multiply by area
• What is the total magnification of a microscope with 10x eyepiece and 40x objective lens?

  400x total magnification
• What is the first step in preparing a slide for microscopy?

  Take a thin layer of cells from sample
• Why are chemical stains used in microscopy?

  To make parts of the specimen more visible
• What is the Lock and Key Hypothesis?

  Substrate shape matches active site shape
• What happens when an enzyme binds to a substrate?

  It forms an enzyme-substrate complex
• Why is the shape of an enzyme important?

  It determines the enzyme's function
• What do enzymes do in biological reactions?

  They increase the rate without being used up