2d-Movement of substances into and out of cells Flashcards
What are the three main processes by which substances move into and out of cells?A: The three processes are:
Diffusion: Movement of particles from an area of high concentration to an area of low concentration.
Osmosis: Movement of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane.
Active Transport: Movement of particles against the concentration gradient using energy from ATP.
How do surface area, volume, distance, temperature, and concentration gradient affect the rate of movement?A:
Surface Area to Volume Ratio: A larger ratio increases the rate of diffusion and osmosis.
Distance: Shorter distances increase the rate of movement.
Temperature: Higher temperatures provide more kinetic energy, increasing the rate of movement.
Concentration Gradient: A steeper gradient increases the rate of diffusion and osmosis.
What is diffusion and why is it important in living organisms?
A: Diffusion is the passive movement of particles from high to low concentration. It is essential for gas exchange (oxygen and carbon dioxide) and the transport of nutrients (e.g., glucose and amino acids).
What is osmosis and why is it essential for cells?
A: Osmosis is the movement of water molecules across a partially permeable membrane. It is vital for maintaining cell turgor pressure in plants and regulating water balance in animal cells
What is active transport and why do cells need it?
A: Active transport uses ATP energy to move substances against their concentration gradient. It is essential for absorbing nutrients (e.g., glucose in the intestines) and maintaining ion balance (e.g., sodium and potassium ions in nerve cells).
Investigate Diffusion and Osmosis
Living System: Potato Cylinder Experiment
Method: Cut potato cylinders of equal size, measure their initial mass, and place them in solutions of different concentrations (e.g., distilled water, sugar solutions). After a set time, remove, blot dry, and measure their final mass.
Positive Result: If the potato gains mass, water has entered the cells by osmosis (hypotonic solution).
Negative Result: If the potato loses mass, water has left the cells by osmosis (hypertonic solution).
Neutral Result: No change in mass indicates an isotonic solution where water movement is balanced.
Investigate Diffusion and Osmosis
Non-living System: Visking Tubing Experiment
Non-living System: Visking Tubing Experiment
Method: Fill Visking tubing (which acts as a partially permeable membrane) with a glucose solution, immerse it in water, and test the external solution for glucose using Benedict’s solution.
Positive Result: If glucose is detected outside the tubing (blue to brick-red), diffusion has occurred.
Negative Result: No color change indicates glucose has not diffused
