Week 4 Quiz

A microscope shows a cell with a plasma membrane, cytoplasm, DNA, and ribosomes. Which further clue decides whether the cell is prokaryotic or eukaryotic?

Select one.

• Whether it has ribosomes that build proteins
• Whether its DNA sits inside a true nucleus
• Whether it has a plasma membrane at its border
• Whether it has DNA anywhere inside it

A eukaryotic cell makes a protein it will send outside itself. Which organelle modifies, sorts, and ships that protein toward the plasma membrane?

Select one.

• The lysosome
• The nucleus
• The smooth endoplasmic reticulum
• The Golgi apparatus

Which of these structures does a typical leaf cell of a plant have? Select all that apply.

Select every option that applies.

• Chloroplasts
• Mitochondria
• A cell wall
• A nucleoid in place of a nucleus
• No ribosomes at all

In the phospholipid bilayer of a plasma membrane, where do the water-fearing phospholipid tails sit?

Select one.

• Tucked inward, between the two rows of heads
• Facing the watery fluid outside the cell
• Facing the watery cytoplasm inside the cell
• Sticking out on both faces of the membrane

The plasma membrane is built mainly from phospholipids. To which class of macromolecules do phospholipids belong?

Select one.

• Carbohydrates
• Proteins
• Lipids
• Nucleic acids

A cook sprinkles salt on a crisp lettuce leaf, and the leaf goes limp. Read from the lettuce cells' side, what happened?

Select one.

• The salty film was hypotonic, so salt moved into the cells
• The salty film was hypertonic, so water moved out of the cells
• The salty film was isotonic, so water moved in and out equally
• The salty film was hypotonic, so water moved out of the cells

In the course's cube-cell model, the side grows from 1 to 4 units. What happens to the surface-area-to-volume ratio, and why?

Select one.

• It rises, because the bigger cube has much more surface
• It stays the same, because surface and volume both grow
• It falls, because volume grows faster than surface area
• It falls, because the surface area of the cube shrinks

A sugar crosses a membrane through a carrier protein, moving from where it is plentiful to where it is scarce, and the cell spends no ATP. Which kind of transport is this?

Select one.

• Facilitated diffusion, a form of passive transport
• Active transport, because a protein is involved
• Osmosis, because a substance crosses the membrane
• Active transport, because it moves down the gradient

The sodium-potassium pump spends 1 ATP per cycle to move 3 Na⁺ out and 2 K⁺ in. How many ions does it move in 4 cycles?

Select one.

• 8 Na⁺ out and 12 K⁺ in
• 3 Na⁺ out and 2 K⁺ in
• 4 Na⁺ out and 4 K⁺ in
• 12 Na⁺ out and 8 K⁺ in

A model cube cell has a side of 3 units, so its surface area is 6 × 3 × 3 = 54 square units and its volume is 3 × 3 × 3 = 27 cubic units. What is its surface-area-to-volume ratio, written in simplest form?

Select one.

• 54:27, left as surface to volume
• 2:1, from 54 ÷ 27 = 2
• 1:2, from 27 ÷ 54
• 3:1, from 6 ÷ 2 = 3