UNIT 3 bio review Flashcards
Term: Diffusion
Definition: The movement of molecules from an area of higher concentration to an area of lower concentration.
Term: Selectively permeable
Definition: A property of cell membranes that allows some substances to pass through while blocking others.
Term: Indicators
Definition: Substances that change color or properties in the presence of specific chemicals, used to test for their presence.
Term: Dialysis tubing
Definition: A synthetic, semi-permeable membrane used in experiments to model the cell membrane.
Term: Starch
Definition: A large carbohydrate molecule that is too big to pass through a selectively permeable membrane.
Term: Glucose
Definition: A small, simple sugar molecule that can pass through a selectively permeable membrane.
Term: Starch indicator
Definition: Iodine solution, which turns blue-black in the presence of starch.
Term: Glucose indicator
Definition: Benedict’s solution, which changes color (e.g., orange) when heated in the presence of glucose.
Term: Controls
Definition: Experimental setups that remain constant to ensure reliable comparisons.
Term: Cytoplasm
Definition: The jelly-like substance inside cells where organelles are suspended and metabolic reactions occur.
Term: Cell membrane
Definition: The thin, flexible barrier that surrounds the cell, controlling the entry and exit of substances.
Term: Cell wall
Definition: A rigid outer layer in plant cells, providing structure and protection.
Term: Osmosis
Definition: The movement of water molecules through a selectively permeable membrane from an area of low solute concentration to high solute concentration.
Term: Wet mount
Definition: A slide preparation technique in which a sample is placed in a drop of liquid on a slide and covered with a cover slip.
Term: Cover slip
Definition: A thin, flat piece of transparent material placed over a specimen on a microscope slide.
Question: What does hydrophobic mean?
Answer: Water-repelling; refers to the tails of phospholipids in the cell membrane.
Question: What does hydrophilic mean?
Answer: Water-attracting; refers to the heads of phospholipids in the cell membrane.
Question: What are the functions of the cell membrane?
Answer: Protects the cell, controls the movement of substances in and out, and supports communication between cells.
Term: Passive transport
Definition: The movement of substances across the cell membrane without using energy.
Term: Facilitated diffusion
Definition: Passive transport of molecules across a membrane through protein channels.
Term: Hypotonic
Definition: A solution with a lower solute concentration compared to another solution, leading to water entering the cell.
Term: Hypertonic
Definition: A solution with a higher solute concentration compared to another solution, leading to water leaving the cell.
Term: Isotonic
Definition: A solution with equal solute concentration compared to another solution, resulting in no net water movement.
Term: Active transport
Definition: The movement of substances against a concentration gradient, requiring energy (ATP).
Term: Endocytosis
Definition: The process by which cells engulf substances into vesicles to bring them into the cell.
Term: Exocytosis
Definition: The process of vesicles fusing with the cell membrane to release substances outside the cell.
Question: Explain the Diffusion Through a Membrane lab.
Answer: The lab demonstrates diffusion and osmosis using dialysis tubing. Glucose and iodine can pass through the membrane, while starch cannot.
Question: What is the role of starch and glucose indicators?
Answer: Starch indicator (iodine) detects starch by turning blue-black; glucose indicator (Benedict’s solution) detects glucose by turning orange when heated.
Question: How do you prepare a wet mount?
Answer: Place the sample on a slide, add a drop of water, and carefully place a cover slip at an angle to avoid air bubbles.
Question: What happens to glucose and starch in the lab setup?
Answer: Glucose moves out of the tubing into the surrounding solution; starch remains inside because it is too large to pass through.
Question: What happens to a plant cell in salt water?
Answer: The cell shrinks as water leaves due to osmosis, and the membrane pulls away from the cell wall (plasmolysis).
Question: What happens to a plant cell in pure water?
Answer: The cell swells as water enters by osmosis, but the cell wall prevents it from bursting.
