AP Biology Unit 2 Review Qs

Which plasma membrane component can be either found on its surface or embedded in the membrane structure?

• carbohydrates

• cholesterol

• glycolipid

• protein

In addition to a plasma membrane, a eukaryotic cell has organelles, such as mitochondria, that also have membranes. In which way would these membranes differ?

• The proportion of phosphate within the phospholipids will vary.

• Only certain membranes contain phospholipids.

• Only certain membranes are selectively permeable.

• The proportions of proteins, lipids, and carbohydrates will vary.

Which characteristic of a phospholipid, shown here, increases the fluidity of the membrane?

• cholesterol

• its head

• saturated fatty acid tail

• double bonds in the fatty acid tail

How would an organism maintain membrane fluidity in an environment where temperatures fluctuated from very high to very low?

• Greater proportion of unsaturated phospholipids in membranes.

• Greater proportion of saturated phospholipids in membranes.

• Greater proportion of carbohydrates in membranes.

• Greater proportion of proteins in membranes.

According to the fluid mosaic model of the plasma cell membrane, what is the location of carbohydrates in the cell membranes?

• Carbohydrates are in contact with the aqueous fluid both inside and outside the cell.

• Carbohydrates are present only on the interior surface of a membrane.

• Carbohydrates are present only on the exterior surface of a membrane.

• Carbohydates span only the interior of a membrane.

Identify the principal driving movement in diffusion, such as depicted here.

• concentration gradient

• membrane surface area

• particle size

• temperature

Which of the following is an example of passive transport across a membrane?

• the movement of H+ into a thylakoid disc during photosynthesis

• the uptake of glucose in the intestine

• the uptake of mineral ions into root hair cells of plants

• the movement of water from the descending loop of a nephron into the interstitium

Water moves via osmosis across plasma cell membranes in which direction?

• from an area with a high concentration of other solutes to a lower one

• from an area with a high concentration of water to one of lower concentration

• from an area with a low concentration of water to one of higher concentration.

• throughout the cytoplasm

What problem is faced by organisms that live in fresh water?

• They will have higher concentrations of body solutes.

• Without compensating mechanisms, their bodies tend to take in too much water.

• They have no way of controlling their tonicity.

• Their bodies tend to lose too much water to their environment.

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Why must active transport of molecules across plasma membranes function continuously?

• Diffusion cannot occur in certain cells.

• Diffusion is constantly moving solutes in opposite directions.

• Facilitated diffusion works in the same direction as active transport.

• Not all membranes are amphiphilic.