CELL STRUCTURE AND FUNCTION Flashcards
Which of the following statements is a part of the classical cell theory?
a. Metabolism occurs within cells
b. The cell is the basic unit of biological organization
c. Cells are essentially the same in molecular composition
d. The cell contains hereditary information which is passed on during cell division
B. The cell is the basic unit of biological organization
What happens to the surface area to volume ratio as the cell grows?
a. It decreases
b. It increases
c. It doubles
d. It does not change
A. It decreases
// As radius increases, surface area increases as the square, but volume increases as the cube (much more rapidly)
Which of the choices can differentiate plant, fungal, and animal cells?
a. cell wall
b. ribosomes
c. cell membrane
d. all of the above
A. cell wall
// They all have the others
A plant cell was grown in a test tube containing radioactive nucleotides, the parts from which DNA is built. Later examination of the cell showed the radioactivity to be concentrated in which of the following?
a. nucleus
b. rough ER
c. smooth ER
d. central vacuole
A. nucleus
Which cell would be BEST for studying lysosomes?
a. nerve cell
b. bacterial cell
c. smooth muscle cell
d. phagocytic white blood cell
D. phagocytic white blood cell
// A lysosome is a membrane-bound cell organelle that contains digestive enzymes. Phagocytic WBCs contain the most lysosomes because they digest more material to battle bacteria, viruses, and other foreign intruders.
Which of the following factors would tend to INCREASE membrane fluidity?
a. a lower temperature
b. a greater proportion of saturated phospholipids
c. a relatively high protein content in the membrane
d. a greater proportion of unsaturated phospholipids
D. a greater proportion of unsaturated phospholipids
// Unsaturated phospholipids are smoother
Which of the following processes includes ALL the others?
a. osmosis
b. active transport
c. diffusion across a membrane
d. transport against the gradient
C. diffusion across a membrane
// Diffusion helps in the movement of substances in and out of the cells
When two solutions with identical osmotic pressure are separated by a semi-permeable membrane, no osmosis will occur. The solutions are said to be isotonic. If one solution has lower osmotic pressure than the other, it is said to be hypotonic. Why does a cell placed in hypotonic solution swell?
a. The cell loses water
b. The cell gains water
c. Water molecules move out than into the cell
d. After some time, the net movement of water is zero.
B. The cell gains water
// The cell will enlarge and swell as it absorbs water through osmosis in the hypotonic fluid
The molecules of cell membranes are arranged with their polar heads to the outside and their nonpolar tails to the inside. Where would you MOST likely find water molecules?
a. Top Head
b. Tails
c. Bottom Head
d. Both heads
D. Both Heads
// Both heads are hydrophilic.
The heads are polar, meaning they are hydrophilic and absorb the most water.
Which of the following would likely move through the lipid bilayer of a cell membrane MOST rapidly?
a. NA^+
b. ethanol
c. glycerol
d. carbon dioxide
D. carbon dioxide
//
Large uncharged polar - NO
(Ethanol)
Small uncharged polar - Yes
(Glycerol)
Small nonpolar - YES!
(NA+, O2 and CO2)
Polar molecules are oppositely charged
Nonpolar molecules are equally charged
Which of the following substances require the use of ATP?
Substance A: higher concentration in cell
Substance B: lower concentration in cell
a. substance A to enter cell
b. substance B to enter cell
c. both substances to enter cell
d, neither substance to enter cell
A. substance A to enter cell
// This is called active transport; the concentration of substance A is higher in cell so energy is needed to move it against its concentration gradient.
A concentration gradient exists when there is a region of high concentration leading to a region of low concentration
