Which plasma membrane component can be either found on its surface or embedded in the membrane structure?
In addition to a plasma membrane, eukaryotic cell organelles, such as mitochondria, 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 increases the fluidity of the membrane?
- its head
- saturated fatty acid tail
- unsaturated 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 primary function of carbohydrates attached to the exterior of 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.
What do double bonds in phospholipid fatty acid tails contribute to?
- the fluidity of membranes
- the hydrophobic nature of membranes
- the hydrophilic nature of membranes
- preventing high temperatures from increasing fluidity of membranes
Identify the principal force driving movement in diffusion.
- concentration gradient
- membrane surface area
- particle size
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 a nephron into the collecting duct of the kidney
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.
Which of the following questions can be asked about organisms that live in fresh water?
- Will their bodies take in too much water?
- Can they control their tonicity?
- Can they survive in salt water?
- Will their bodies lose too much water to their environment?
Which of the following explains why active movement of molecules across membranes must function continuously?
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.
How does the sodium-potassium pump make the interior of the cell negatively charged?
- by expelling anions
- by pulling in anions
- by expelling more cations than it takes in
- By taking in and expelling an equal number of cations.
What is the difference between primary and secondary active transport?
- Primary active transport is indirectly dependent on ATP, while secondary active transport is directly dependent on ATP.
- Primary active transport is directly dependent on ATP, while secondary active transport is indirectly dependent on ATP.
- Primary active transport does not require ATP, while secondary active transport is indirectly dependent on ATP.
- Primary active transport is indirectly dependent on ATP, while secondary active transport does not require ATP
What happens to the membrane of a vesicle after exocytosis?
- It leaves the cell.
- It is disassembled by the cell.
- It fuses with and becomes part of the plasma membrane.
- It is used again in another exocytosis event.
In what important way does receptor-mediated endocytosis differ from phagocytosis?
- It transports only small amounts of fluid.
- It does not involve the pinching off of membrane.
- It brings in only a specifically targeted substance.
- It brings substances into the cell, while phagocytosis removes substances.