Only $2.99/month

AP Bio Chapter 2 AP Questions

Terms in this set (6)

Cholesterol is a naturally occurring substance that helps regulate the fluidity of a cell's plasma membrane. A cholesterol molecule can be represented as having a polar head and a nonpolar region, as shown in the figure.

The figure presents a cholesterol molecule. A black dot indicates the polar head, which is attached to a nonpolar region that is represented by a sequence of four hexagons or a pentagon, each of which shares one side with the previous and/or next component of the region.
Which of the following models shows how cholesterol molecules most likely interact with the phospholipid bilayer of a cell's plasma membrane?

A
The figure presents a phospholipid bilayer and cholesterol molecules. The polar head of each cholesterol molecule is situated between the heads of the phospholipids, and the nonpolar region extends out and away from the membrane.

B
The figure presents a phospholipid bilayer and cholesterol molecules. Each cholesterol molecule lies flat against the outer surface of the membrane so that the polar head and nonpolar region of each molecule are both in contact with the phospholipid heads.

C
The figure presents a phospholipid bilayer and cholesterol molecules. The cholesterol molecules are located in the interior of the membrane and separate the two layers of the bilayer from each other.

D
The figure presents a phospholipid bilayer and cholesterol molecules. The polar head of each cholesterol molecule is situated between the heads of the phospholipids, and the nonpolar region extends into the interior of the membrane between the phospholipid tails.
Figure 1 presents a dialysis bag immersed in a beaker of water.
Figure 1

A student is using dialysis bags to model the effects of changing solute concentrations on cells. The student places one dialysis bag that contains 25 mL of distilled water into each of two beakers that are filled with 200 mL of distilled water. (Figure 1). The membrane of each dialysis bag membrane contains pores that allow small solutes such as monoatomic ions to pass through but are too small for anything larger to pass. After 30 minutes, 5 mL of a concentrated solution of albumin (a medium-sized, water-soluble protein) is added to one of the two beakers. Nothing is added to the other beaker. After two more hours at room temperature, the mass of each bag is determined. There is no change in the mass of the dialysis bag in the beaker to which no albumin was added.

Which of the graphs below best represents the predicted change in mass over time of the dialysis bag in the beaker to which albumin was added?

A
The figure presents a graph in the coordinate plane. The horizontal axis is labeled Time, in minutes, and the numbers 0 through 150, in increments of 30, are indicated. The vertical axis is labeled Relative Mass of Dialysis Bag. The axis has an arrowhead at the top end, and no numbers are indicated along it. The graphed line begins at 0 minutes, about halfway up the vertical axis, and extends horizontally to the right until it ends at 150 minutes. A label indicates Albumin Added at 30 minutes.

B
The figure presents a graph in the coordinate plane. The horizontal axis is labeled Time, in minutes, and the numbers 0 through 150, in increments of 30, are indicated. The vertical axis is labeled Relative Mass of Dialysis Bag. The axis has an arrowhead at the top end, and no numbers are indicated along it. The graphed line begins at 0 minutes, about halfway up the vertical axis, and extends horizontally to the right until 30 minutes. A label indicates Albumin Added at 30 minutes. The graphed line starts to move downward and to the right at 30 minutes until it ends at 150 minutes, just above the horizontal axis.

C
The figure presents a graph in the coordinate plane. The horizontal axis is labeled Time, in minutes, and the numbers 0 through 150, in increments of 30, are indicated. The vertical axis is labeled Relative Mass of Dialysis Bag. The axis has an arrowhead at the top end, and no numbers are indicated along it. The graphed line begins at 0 minutes, about one third of the way up the vertical axis, and moves upward and to the right until it is about halfway up the vertical axis at 30 minutes. A label indicates Albumin Added at 30 minutes. The graphed line then moves downward and to the right until it ends at 150 minutes, about one third of the way up the vertical axis.

D
The figure presents a graph in the coordinate plane. The horizontal axis is labeled Time, in minutes, and the numbers 0 through 150, in increments of 30, are indicated. The vertical axis is labeled Relative Mass of Dialysis Bag. The axis has an arrowhead at the top end, and no numbers are indicated along it. The graphed line begins at 0 minutes, about halfway up the vertical axis, and extends horizontally to the right until 30 minutes. A label indicates Albumin Added at 30 minutes. The graphed line then moves upward and to the right until it ends at 150 minutes, near the top of the vertical axis.
Two competing hypotheses exist regarding the cell membrane structure. One hypothesis states that membrane structure is static and membrane components throughout the bilayer are rigidly bound. Alternatively, the other hypothesis states that cell membranes are a fluid mosaic in which membrane components may drift within the bilayer around the surface of the cell. An experiment is set up in which membrane proteins of two different cells are fluorescently labeled with two different colors and then fused as shown in Figure 1.

The figure presents a model of a cell fusion experiment. There are two cells, and the membranes of each cell have proteins embedded in them. The membrane proteins in one cell are colored grey, and the membrane proteins in the other cell are colored black. The figure shows the grey cell and the black cell beginning to merge.
Figure 1. Model of initiation of cell fusion experiment

Which of the following results, one hour after membrane fusion, best supports the alternative hypothesis that the cell membrane is a fluid mosaic?

A
The figure presents a model of a cell. The membrane of the cell has only grey proteins embedded in it.

B
The figure presents a model of a cell. The membrane of the cell has only black proteins embedded in it.

C
The figure presents a model of a cell. The membrane of the cell has both grey proteins and black proteins embedded in it. The black proteins are concentrated in one area of the cell membrane, and the grey proteins are concentrated in a separate area of the cell membrane.

D
The figure presents a model of a cell. The membrane of the cell has both grey proteins and black proteins embedded in it. The grey proteins and black proteins are distributed throughout the cell membrane, and are not concentrated in particular areas.