Week 3 Quiz

In the plasma membrane's phospholipid bilayer, which part of each phospholipid faces the watery fluid inside and outside the cell?

Select one.

• The nonpolar tails, which turn toward the water
• The phosphate heads, which are attracted to water
• The tails on the outside and the heads on the inside
• The membrane proteins, which replace the heads at each surface

A cell needs more of a protein. Reading structure to function, which organelle builds proteins?

Select one.

• The ribosome
• The Golgi apparatus
• The mitochondrion
• The lysosome

Which organelle modifies, sorts, and packages products from the rough ER and ships them in vesicles?

Select one.

• The ribosome
• The mitochondrion
• The Golgi apparatus
• The smooth ER

Salt is sprinkled on salad leaves, and the leaves go limp as a puddle forms in the bowl. In this example of osmosis, what crosses the leaf cells' membranes?

Select one.

• Salt, moving into the cells
• Salt and water, moving in opposite directions
• Proteins, leaving through channels
• Water, moving out toward the salt

In Dataset C (illustrative), a model cell with an inside of 300 mOsm/L is placed in a 100 mOsm/L bath. Reading from the cell's side, what happens?

Select one.

• The bath is hypertonic, water moves out, and the cell shrinks
• The bath is isotonic, and there is no net water movement
• The bath is hypotonic, water moves in, and the cell swells
• The bath is hypotonic, water moves out, and the cell shrinks

In Dataset C (illustrative), the same 300 mOsm/L model cell is placed in a 500 mOsm/L bath. Which reading is right from the cell's side?

Select one.

• Hypertonic bath, water moves out, the cell shrinks
• Hypotonic bath, water moves in, the cell swells
• Hypertonic bath, water moves in, the cell swells
• Isotonic bath, no net movement, the cell stays the same

The 300 mOsm/L solution from Dataset C is diluted into twice its volume. Using C₁V₁ = C₂V₂, what is the new concentration, and how does it read for the 300 mOsm/L model cell?

Select one.

• 600 mOsm/L, hypertonic to the cell
• 300 mOsm/L, isotonic to the cell
• 150 mOsm/L, hypertonic to the cell
• 150 mOsm/L, hypotonic to the cell

For each ATP it spends, what does the sodium-potassium pump move?

Select one.

• Two sodium ions out and three potassium ions in
• Three sodium ions out and two potassium ions in
• Three sodium ions in and two potassium ions out
• Three sodium ions out and three potassium ions in

True or false: an IV fluid is mixed to be hypotonic, so that water moves into the body's cells and keeps them full.

True or false.

• True
• False

Select every process that is passive transport, moving a substance from higher to lower concentration with no ATP spent.

Select every option that applies.

• Diffusion
• The sodium-potassium pump
• Facilitated diffusion
• Exocytosis
• Osmosis
• Phagocytosis