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Problem 1
Label the structures in this diagram of an animal cell. Review the functions of each of these organelles.
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Problem 2
The ultrastructure of a chloroplast is best studied using a
a. Light microscope
b. Scanning electron microscope
c. Transmission electron microscope
d. Light microscope and fluorescent dyes
Problem 3
The cells of an ant and an elephant are, on average, the same small size; an elephant just has more of them. What is the main advantage of small cell size? (Explain your reasoning.)
a. A small cell has a larger plasma membrane surface area than does a large cell.
b. Small cells can better take up sufficient nutrients and oxygen to service their cell volume.
c. It takes less energy to make an organism out of small cells.
d. Small cells require less oxygen than do large cells.
Problem 4
Which of the following clues would tell you whether a cell is prokaryotic or eukaryotic?
a. The presence or absence of a rigid cell wall
b. Whether or not the cell is partitioned by internal membranes
c. The presence or absence of ribosomes
d. Both b and c are important clues
Problem 5
Which of the following is one of the major components of the plasma membrane of a plant cell?
a. Phospholipids
b. Cellulose fibers
c. Collagen fibers
d. Pectins
- What four cellular components are shared by prokaryotic and eukaryotic cells?
Problem 6
- Describe two different ways in which cilia can function in organisms.
Problem 7
Problem 8
In which cell would you find the most lysosomes?
a. Pancreatic cell that secretes digestive enzymes
b. Ovarian cell that produces estrogen (a steroid hormone)
c. Muscle cell in the thigh of a long-distance runner
d. White blood cell that engulfs bacteria
Problem 9
In which cell would you find the most smooth ER?
a. Pancreatic cell that secretes digestive enzymes
b. Ovarian cell that produces estrogen (a steroid hormone)
c. Muscle cell in the thigh of a long-distance runner
d. White blood cell that engulfs bacteria
Problem 10
In which cell would you find the most rough ER?
a. Pancreatic cell that secretes digestive enzymes
b. Ovarian cell that produces estrogen (a steroid hormone)
c. Muscle cell in the thigh of a long-distance runner
d. White blood cell that engulfs bacteria
Problem 11
In which cell would you find the most mitochondria?
a. Pancreatic cell that secretes digestive enzymes
b. Ovarian cell that produces estrogen (a steroid hormone)
c. Muscle cell in the thigh of a long-distance runner
d. White blood cell that engulfs bacteria
- In what ways do the internal membranes of a eukaryotic cell contribute to the functioning of the cell?
Problem 12
Problem 13
Is this statement true or false?
'Animal cells have mitochondria; plant cells have chloroplasts.'
Explain your answer, and describe the functions of these organelles.
- Describe the structure of the plasma membrane of an animal cell. What would be found directly inside and outside the membrane?
Problem 14
Problem 15
Imagine a spherical cell with a radius of 10 μm. What is the cell's surface area in μm²?
Its volume, in μm³? (Note: For a sphere of radius r, surface area = 4πr² and volume = 4/3πr³.). Remember that the value of π is 3.14.)
What is the ratio of surface area to volume for this cell? Now do the same calculations for a second cell, this one with a radius of 20 μm. Compare the surface-to-volume ratios of the two cells.
How is this comparison significant to the functioning of cells?
- Describe the pathway of the protein hormone insulin from its gene to its export from a cell of your pancreas.
Problem 16
- How might the phrase 'ingested but not digested' be used in a description of the endosymbiotic theory?
Problem 17
- Cilia are found on cells in almost every organ of the human body, and the malfunction of cilia is involved in several human disorders. During embryological development, for example, cilia generate a leftward flow of fluid that initiates the left-right organization of the body organs. Some individuals with primary ciliary dyskinesia exhibit a condition (situs inversus) in which internal organs such as the heart are on the wrong side of the body. Explain why this reversed arrangement may be a symptom of PCD.
Problem 18
Problem 19a
Microtubules often produce movement through their interaction with motor proteins. But in some cases, microtubules move cell components when the length of the microtubule changes. Through a series of experiments, researchers determined that microtubules grow and shorten as tubulin proteins are added or removed from their ends. Other experiments showed that microtubules make up the spindle apparatus that 'pulls' chromosomes toward opposite ends (poles) of a dividing cell. The figures below describe a clever experiment done in 1987 to determine whether a spindle microtubule shortens (depolymerizes) at the end holding a chromosome or at the pole end of a dividing cell. Experimenters labeled the microtubules of a dividing cell from a pig kidney with a yellow fluorescent dye. As shown on the left half of the diagram below, they then marked a region halfway along the microtubules by using a laser to eliminate the fluorescence from that region. They did not mark the other side of the spindle (right side of the figure).
Problem 19b
The figure below illustrates the results they observed as the chromosomes moved toward the opposite poles of the cell. Describe these results.
What would you conclude about where the microtubules depolymerize from comparing the length of the microtubules on either side of the mark?
How could the experimenters determine whether this is the mechanism of chromosome movement in all cells?
