Exploring Osmosis Through Animation

The video tutorial explains diffusion as the movement of molecules down a concentration gradient, allowing small molecules like oxygen and carbon dioxide to cross the plasma membrane. It highlights osmosis, a special case of diffusion involving water molecules. The tutorial discusses how urea, a large polar molecule, affects water movement across membranes, leading to changes in water levels. It concludes with an explanation of isotonic, hypertonic, and hypotonic solutions based on osmotic concentrations.

What is the net movement of molecules down a concentration gradient called?

• Osmosis

• Diffusion

• Facilitated Diffusion

• Active Transport

Which small molecules are allowed to cross the plasma membrane through diffusion?

• Sugars and Proteins

• Oxygen and Carbon Dioxide

• Ions and Glucose

• Amino Acids and Nucleotides

Why can't most polar molecules freely cross the lipid membrane?

• They are non-polar

• They are hydrophobic

• They are too small

• They are too large and polar

What is the special case of diffusion that involves water molecules called?

• Osmosis

• Endocytosis

• Facilitated Diffusion

• Active Transport

Why can't urea diffuse across the membrane?

• It is non-polar

• It is too small

• It is both large and polar

• It is hydrophobic

What happens to the number of free water molecules when urea is added to one side of a membrane?

• It increases

• It fluctuates

• It decreases

• It remains the same

What causes the water level to rise on the side with urea molecules?

• Urea molecules are moving to the other side

• More water molecules are entering than leaving

• More water molecules are leaving than entering

• The membrane is impermeable to water

What term describes solutions with equal osmotic concentrations?

• Hypertonic

• Hypotonic

• Isotonic

• Isometric

Which solution has a higher concentration of solutes?

• Isometric

• Hypertonic

• Isotonic

• Hypotonic