Which plasma membrane component can be found either 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 the membranes
- greater proportion of saturated phospholipids in the membranes
- greater proportion of carbohydrates in the membranes
- greater proportion of proteins in the membranes
Which of the following is true for carbohydrates?
- 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.
- Carbohydrates 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
- the prevention of high temperatures from increasing the 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 in which direction?
- from an area with a high solute concentration 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 fish that live in freshwater?
- They have higher concentrations of body solutes.
- Without compensating mechanisms, their bodies would take in too much water.
- They have no way of controlling their tonicity.
- Their bodies could 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?
Why must active transport 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 the membrane.
- It brings in only a specifically targeted substance.
- It brings substances into the cell, while phagocytosis removes substances.