IB Biology

• What is the smallest unit of life?


  Cells are the smallest unit of life
• What evidence supports the idea that all cells come from preexisting cells?

  Observations on cell division and reproduction, and Pasteur's experiments on microbes
• What is the role of DNA in cells?


  DNA contains the blueprint for growth, development, and behavior
• What is differentiation in cells?

  Differentiation is the process by which cells develop into specialized types
• What are the functions of life in cells?

  • Metabolism: Chemical reactions inside the cell
  • Response: Perceiving and responding to stimuli
  • Homeostasis: Maintaining a constant internal environment
  • Growth: Irreversible increase in size
  • Reproduction: Producing offspring
  • Excretion: Removing toxic waste
  • Nutrition: Obtaining nutrients for energy and growth

  
• What are stem cells?


  Stem cells are unspecialized cells that can differentiate into specialized cells
• What is the significance of pluripotent stem cells?

  Pluripotent stem cells can become any type of cell in the body
• How do adult stem cells differ from embryonic stem cells?

  Adult stem cells are multipotent and can only differentiate into a limited range of cells
• What are the sources of stem cells?

  • Embryonic stem cells: Pluripotent, can become any cell type
  • Adult stem cells: Multipotent, found in tissues like liver, skin, and bone marrow
  • Umbilical cord stem cells: Multipotent
• What is the process of differentiation in cells?

  Differentiation involves cells expressing some genes while not expressing others
• What is the structure of prokaryotic cells?

  Prokaryotic cells lack a membrane-bound nucleus and organelles
• What are the main components of eukaryotic cells?

  • Membrane-bound nucleus
  • Membrane-bound organelles (e.g., mitochondria, Golgi apparatus)
  • Cytoplasm
  • Plasma membrane
• What is the function of the plasma membrane?

  The plasma membrane controls the movement of substances into and out of the cell
• What is the role of mitochondria in cells?


  Mitochondria are the site of aerobic respiration
• What is the function of ribosomes?


  Ribosomes are responsible for protein synthesis
• What is the function of the Golgi apparatus?

  The Golgi apparatus modifies, stores, and packages proteins
• What is the structure of the cell wall in plant cells?

  The cell wall helps maintain the shape of the cell and regulates turgor pressure
• What is the role of chloroplasts in plant cells?

  Chloroplasts are the site of photosynthesis
• What are the main differences between prokaryotic and eukaryotic cells?

  • Prokaryotic cells: No membrane-bound nucleus or organelles, smaller size, DNA is circular and naked
  • Eukaryotic cells: Membrane-bound nucleus and organelles, larger size, DNA is linear and associated with histones

  
• What is the structure of the plasma membrane?

  The plasma membrane is semi-permeable and made up of phospholipids
• What is the function of membrane proteins?

  Membrane proteins facilitate various functions such as transport, communication, and enzymatic activity
• What is diffusion?

  Diffusion is the passive movement of particles from high concentration to low concentration
• What is osmosis?

  Osmosis is the movement of water molecules from a lower solute concentration to a higher solute concentration
• What is active transport?

  Active transport is the movement of substances against a concentration gradient, requiring energy
• What are the steps involved in active transport using protein pumps?

  1. Molecule enters at specific protein pump
  2. Molecule binds to the site
  3. Protein changes shape using energy from ATP
  4. Pump opens on the other side and releases the molecule
  5. Returns to original shape

  
• What is the sodium-potassium pump?

  The sodium-potassium pump is an example of active transport that moves sodium out and potassium into the cell
• What are vesicles used for in cells?

  • Moving large quantities of substances
  • Transporting materials through cytosis
• What is the process of osmosis?

  Positive movement of water molecules from a lower solute concentration to higher solute concentration through a partially permeable membrane
• What happens in a hypertonic solution?

  Water diffuses out because the outside has more solutes
• What characterizes an isotonic solution?

  It has equal solute concentrations inside and outside the cell
• What occurs in a hypotonic solution?

  Water diffuses in because the inside has more solutes
• What is active transport?

  Substances absorbed against the concentration gradient requiring energy
• What energy source is used in active transport?

  ATP released by the cell through cellular respiration
• What are protein pumps?

  Integral proteins that allow substances into and out of the cell using ATP
• How do protein pumps operate?

  A molecule binds to a specific site, causing the protein to change shape and transport the molecule
• What is the role of vesicles in cellular transport?

  They are used for moving large quantities of substances through cytosis
• What is endocytosis?


  It takes in a substance by surrounding it with membrane
• How does exocytosis function?

  It involves vesicles fusing with the plasma membrane to release substances
• What substances can be released through exocytosis?

  Hormones, enzymes, water, and waste
• What is the role of ribosomes in protein synthesis?

  Ribosomes produce proteins which enter the rough endoplasmic reticulum (rER)