AP Bio Chapter 7

What are 2 examples of carbohydrates in cell-cell recognition?

1. Developing embryo 2. Organ transplants

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? A. Membrane carbohydrates function primarily in cell-cell recognition B. Carbohydrates on the plasma membrane are typically short between 2 and 5 monosaccharides C. Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane D. The carbohydrate composition of most eukaryotic plasma membranes is quite similar E. carbohydrates are only found associated with the membranes of prokaryotic cells

A

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein? A. A large polar molecule B. A small nonpolar molecule C. A large nonpolar molecule D. Dissolved gases such as oxygen or carbon dioxide E. any of the above would easily diffuse through the membrane

A

What is an aquaporin?

A channel protein that allows the entry of water molecules

A selectively permeable membrane separates 2 solutions. Water is able to pass through this membrane; however, sucrose (a disaccharide) and glucose (a monosaccharide) cannot pass. The membrane separates 0.2 molar sucrose solution from 0.2 molar glucose solution. With time, how will the solutions change? A. Water enters the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose B. Nothing happens because the 2 solutions are isotonic to one another C. After the sucrose dissociates into two monosaccharides, water will move via osmosis to the side of the membrane that contains the dissociated sucrose. D. Water leaves the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose. E. the sucrose solution is hypertonic and will gain water because the total mass of sucrose is greater than that of glucose.

B

The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution? A. Distilled water B. 1.0M C. 0.8M D. 0.4M E. 150mM

B

Which of the following exhibits selective permeability between a cell and its external environment? A. Chloroplasts B. The plasma membrane C. Mitochondria D. Lysosomes E. endoplasmic reticulum

B

The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true? A. The mosaic aspect of the membrane is due to the glycosylation of inner leaflet phospholipids B. Only phospholipids are capable of moving in the membrane C. The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect D. The fluid aspect of the membrane describes its structure at normal temperatures, and the mosaic aspect describes the behavior of the membrane as the temp. is lowered E. the fluid aspect is due to the behavior of phospholipids, and the mosaic aspect is due to the presence of carbohydrates

C

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process? A. Passive transport B. Active transport C. Exocytosis D. Endocytosis E. Osmosis

D

Which of the following molecules is most likely to passively diffuse across the plasma membrane? A. Hemaglobin B. DNA C. Glucose D. Carbon dioxide E. sodium ion

D

Which of the following statements about diffusion is true? A. It always requires integral proteins of the cell membrane B. It is very rapid over long distances C. It requires expenditure of energy by the cell D. It is a passive process E. it occurs when molecules move from a region of lower concentration to higher concentration

D

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells? A. The red blood cell would burst, and the plant cell would shrink B. The red blood cell would shrink, and the plant cell would gain water C. Seawater is isotonic to both cells, therefore, neither cell will change as there will be no movement of water into or out of the cells D. Both cells would gain water by osmosis; the red blood cell would burst, and the plant cell would increase in turgor pressure E. both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would away from the cell wall

E

Which of the following statements about cotransport of solutes across a membrane is correct? A. In cotransport, both solutes that are being transported are moving down their chemical gradients B. Cotransport involves the hydrolysis of ATP by the transporting protein. C. A cotransport protein is commonly an ion channel D. The sodium-potassium pump is an example of a cotransport protein E. cotransport proteins allow a single ATP-powered pump to drive the active transport of many different solutes

E

penetrate the hydrophobic interior of the lipid bilayer; all the way across membrane

Integral proteins

Cholesterol molecules help the mosaic proteins to ______ _____

Keep shape

Not embedded in lipid bilayer, appendages loosely bound to the surface of the membrane; often to exposed parts of integral proteins

Peripheral proteins

Describe the fluid mosaic model.

Phospholipid bilayer with their hydrophobic and hydrophilic regions; it moves around as a fluid; proteins embedded in phospholipids give it a mosaic appearance

when a cell loses water to a hypertonic environment

Plasmolysis

Who proposed the fluid mosaic model?

Singer and Nicholson

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the membrane would carbohydrates most likely be found?

The outside (external) surface of the membrane

What is membrane potential? Which side of the membrane is positive?

Voltage across the membrane; opposite charges on it Outside- + Inside- -

Are transport proteins specific? Cite an example that supports your response.

Yes, they are specific about what type of molecule they will carry into a cell