Topic 2 - Bio

• What is the primary function of the cell membrane?

  It acts as a selectively permeable barrier controlling the passage of substances in and out of the cell.
• What is the structure of the cell membrane?

  It consists of a phospholipid bilayer with embedded intrinsic and extrinsic proteins.

  
• How does the cell membrane function as a barrier?

  It separates the internal and external environments of the cell.
• What are the main components of the nucleus?

  The nucleus contains nuclear pores, nucleolus, DNA, and a nuclear envelope.

  
• What is the function of the nucleolus?

  The nucleolus is responsible for making ribosomes.
• What occurs at the nuclear pores?

  Nuclear pores allow the movement of substances to and from the cytoplasm.
• What is the primary function of mitochondria?

  Mitochondria are the site of aerobic respiration and produce ATP.
• What is the structure of mitochondria?

  Mitochondria have a double membrane with the inner membrane folded into cristae.
• What type of DNA do mitochondria contain?

  Mitochondria contain small, circular DNA.
• What is the function of chloroplasts?

  Chloroplasts absorb light for photosynthesis to produce organic molecules like glucose.
• What is the structure of chloroplasts?

  Chloroplasts have thylakoid membranes stacked to form grana, linked by lamellae.

  
• What is the function of the Golgi apparatus?

  The Golgi apparatus modifies proteins received from the RER and packages them into vesicles for transport.
• What is the structure of lysosomes?

  Lysosomes are types of Golgi vesicles containing digestive enzymes.
• What is the function of ribosomes?

  Ribosomes are the site of translation in protein synthesis.
• What is the structure of the rough endoplasmic reticulum (RER)?

  The RER is a system of membranes with bound ribosomes and is continuous with the nucleus.

  
• What is the structure of the smooth endoplasmic reticulum (SER)?

  The SER is a system of membranes with no bound ribosomes.

  
• What are the differences between prokaryotic and eukaryotic cells?

  Prokaryotic cells are smaller, lack membrane-bound organelles, and have circular DNA not associated with histones.
• What is the structure of the cell wall in plants, fungi, and bacteria?

  In plants, it is made of cellulose; in fungi, it is made of chitin; and in bacteria, it is made of murein.
• What is the function of the cell vacuole?

  The cell vacuole makes cells turgid, provides structural support, and serves as a temporary store for sugars and amino acids.
• What are the features of viruses?

  Viruses are non-living, acellular, contain genetic material, a capsid, and attachment proteins.
• What is the purpose of cell fractionation?

  Cell fractionation breaks open cells and removes debris so organelles can be studied.
• What is the process of homogenisation?

  Homogenisation is the process by which cells are broken open so organelles are free to be separated.
• What conditions are required for homogenisation?

  Conditions include cold temperature to reduce enzyme activity, isotonic solutions to prevent osmosis, and buffered solutions to resist pH changes.
• What is differential centrifugation?

  Differential centrifugation separates organelles according to their density by spinning at increasing speeds.
• What is the mitotic index?

  The mitotic index is used to determine the proportion of cells undergoing mitosis, calculated as a percentage or decimal.

  
• What is the fluid mosaic model?

  The fluid mosaic model describes the lateral movement of membranes with scattered embedded intrinsic and extrinsic proteins.
• What role does cholesterol play in the cell membrane?

  Cholesterol restricts lateral movement of the membranes, adds rigidity, and prevents water and dissolved ions from leaking out.
• What is simple diffusion?

  Simple diffusion is the net movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.
• What is facilitated diffusion?

  Facilitated diffusion is a passive process using protein channels or carriers to move substances down the concentration gradient.
• What is osmosis?

  Osmosis is the net movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane.
• What is a hypertonic solution?

  A hypertonic solution has a more negative water potential than the cell, causing water to move out of the cell by osmosis.
• What is a hypotonic solution?

  A hypotonic solution has a more positive water potential than the cell, causing water to move into the cell by osmosis.
• What is an isotonic solution?

  An isotonic solution has the same water potential as the cell, resulting in no net movement of water.
• What is water potential?

  Water potential is the pressure created by water molecules, measured in kPa and represented by the symbol ψ.
• What is active transport?

  Active transport is the process of moving substances against their concentration gradient, requiring energy.
• What is the role of protein carriers in the cell membrane?

  Protein carriers bind with molecules, causing a change in shape that enables the molecule to be released to the other side of the membrane.
• What are protein channels in the cell membrane?

  Protein channels are tubes filled with water that enable water-soluble ions to pass through the membrane.
• What is the significance of selective channel proteins?

  Selective channel proteins only open in the presence of certain ions, allowing for regulated transport.
• What is the function of colored pigments in vacuoles?

  Colored pigments in vacuoles attract pollinators.
• What is the purpose of calibrating the eyepiece graticule?

  Calibration is required each time the objective lens is changed to determine the distance between each division at that magnification.