Unit 4 Learning Catalytics

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

1. glycogen

2. proteins

3. nucleic acids

4. lipids

2. proteins

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures?

1. They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.

2. They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume.

3. They must block water and small molecules to regulate the exchange of matter and energy with their environment.

4. They are composed of a mixture of lipids and nucleotides.

1. They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.

The membranes of winter wheat are able to remain fluid when it is extremely cold by _____.

1. increasing the percentage of cholesterol molecules in the membrane

2. increasing the percentage of unsaturated phospholipids in the membrane

3. cotransport of glucose and hydrogen

4. decreasing the number of hydrophobic proteins in the membrane

2. increasing the percentage of unsaturated phospholipids in the membrane

Which of the following processes includes all others?

1. passive transport

2. transport of an ion down its electrochemical gradient

3. osmosis

4. facilitated diffusion

1. passive transport

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same..

Refer to the figure. If you examine side A after three days, you should find _____.

1. decrease in the concentration of NaCl and glucose and an increase in the water level

2. no change in the concentration of NaCl and glucose and an increase in the water level

3. decrease in the concentration of NaCl and a decrease in the water level

4. decrease in the concentration of NaCl, an increase in water level, and no change in the concentration of glucose

3. decrease in the concentration of NaCl and a decrease in the water level

Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? The animal cell is in _____.

1. hypotonic solution, and the plant cell is in an isotonic solution

2. an isotonic solution, and the plant cell is in a hypertonic solution

3. an isotonic solution, and the plant cell is in a hypotonic solution

4. hypertonic solution, and the plant cell is in an isotonic solution

3. an isotonic solution, and the plant cell is in a hypotonic solution

What kinds of molecules pass through a cell membrane most easily?

1. large and hydrophobic

2. small and hydrophobic

3. large polar

4. ionic

2. small and hydrophobic

Suppose that the cell is secreting insulin, a protein hormone, via exocytosis. Which statement most accurately describes why this mechanism of transport is ideal for insulin secretion?

1. Proteins are small and diffuse readily through the phospholipid bilayer.

2. Proteins are large molecules that cannot be transported efficiently across the membrane via transport proteins.

3. Exocytosis provides a mechanism for the passive transport of large proteins.

4. Small molecules such as polypeptides are transported much more efficiently via bulk transport.

2. Proteins are large molecules that cannot be transported efficiently across the membrane via transport proteins.

Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from ____.

1. bacterium

2. an animal but not a plant

3. nearly any eukaryotic organism

4. a plant but not an animal

3. nearly any eukaryotic organism

Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely involved in this disease?

1. ysosomes

2. Golgi apparatus

3. ribosomes

4. mitochondria

4. mitochondria