Which factors (limited space or overcrowding; limited food; Predators; parasite and diseased) tend to act in a density-dependent manner; Tony Sinclair (1989) many studies of density dependence in 51 populations of insects, 82 populations of large mammals, and 36 populations of small mammals and birds. Which of the following observation is most likely true?

a) Insects showed a wide variety of causes of density dependence and no one density-dependent factor was of overriding importance

b) The lesser the amount of available food, the greater the mortality of large mammals

c) Space and social interactions were more important for smaller mammals and birds, because they are more territorial

#Question id: 2242

#Unit 2. Cellular Organization

What two features of the structure of cholesterol make it somewhat amphipathic?

#Question id: 2243

#Unit 2. Cellular Organization

Features of the fluid mosaic model of membrane structure include:

A. a lipid bilayer.

B. dynamic motion of both membrane lipids and proteins.

C. proteins that may either rest on the surface or penetrate the membrane.

D. the hydrophobic core of the bilayer prevents the unassisted movement of water-soluble substances from one side to the other.

E. Covalent interactions between phospholipids, and between phospholipids and proteins, lend strength and resilience to the membrane.

Which of the following is correct?

#Question id: 2244

#Unit 2. Cellular Organization

Arrange the statements below in the proper sequence of events that occur in an action potential:

I. The resting potential is re-established.

II. A stimulus depolarizes the membrane to threshold.

III. Na+ gates open and Na+ rushes into the cell.

IV. K+ gates open and K+ rushes out of the cell.

#Question id: 2245

#Unit 2. Cellular Organization

Which of these statements is generally true of integral membrane proteins?

#Question id: 2246

#Unit 2. Cellular Organization

Which of the following statements describe(s) the typical biomembrane?

a. It may include different types of lipid molecules.

b. The lipid molecules in the membrane are attached to each other though covalent bonds.

c. All lipids and proteins in the biomembrane are equally mobile.

d. It contains a hydrophilic core.

e. It has a cytosolic face and an exoplasmic face.

#Question id: 2247

#Unit 2. Cellular Organization

When computing the osmotic pressure that must be placed across the membrane to stop the flow of water, what is the glucose osmotic equivalent of 1 M CaCl₂?