Wednesday
July 23, 2014

Homework Help: chemistry

Posted by jen on Wednesday, February 10, 2010 at 10:23am.

1. Which of the following statements about the cell theory is correct?
a) All living organisms are made up of one or more cells.
b) All cells arise from other, pre-existing cells
c) All eukaryotic cells contain symbiotic prokaryotes.
d) All prokaryotic cells contain symbiotic eukaryotes.
e) Both a) and b) are correct.



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2. Which of the following statements about prokaryotes is incorrect?
a) Prokaryotes appeared on earth before eukaryotes.
b) Prokaryotes have circular pieces of DNA within their nuclei.
c) Prokaryotes contain cytoplasm.
d) Prokaryotes contain ribosomes.
e) Some prokaryotes can conduct photosynthesis.



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3. Which of the following facts supports the claim that mitochondria developed from bacteria that, long ago, were incorporated into eukaryotic cells by the process of phagocytosis?
a) Mitochondria have flagella for motion.
b) Mitochondria have proteins for the synthesis of ATP.
c) Mitochondria are the "powerhouses" of the cell.
d) Mitochondria are small and easily transported across cell membranes.
e) Mitochondria have their own DNA.



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4. Hydrophobic molecules can pass freely through the plasma membrane, but molecules with electrical charges (such as ions and polar molecules) are impeded by the hydrophobic core. For this reason, plasma membranes can be considered:
a) partially permeable.
b) impermeable.
c) hydrophobic.
d) hydrophilic.
e) None of these terms properly describe plasma membranes.



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5. Drugs called beta-blockers do all of the following except:
a) reduce high blood pressure.
b) block signaling through adrenaline receptors.
c) reduce outward symptoms of anxiety.
d) bind to the cytoplasmic side of a receptor protein.
e) reduce the effects of adrenaline on the heart.



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6. Cellular fingerprints:
a) are exposed on the cytoplasmic side of the membrane.
b) are made from cholesterol.
c) are "erased" by the HIV virus.
d) can help the immune system distinguish "self" from "non-self".
e) All of the above are correct.



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7. The movement of molecules across a membrane from an area of high concentration to one of low concentration is best described as:
a) active transport.
b) inactivated transport.
c) passive transport.
d) channel-mediated diffusion.
e) electron transport.



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8. The transport of water across a membrane from a solution of lower solute concentration to a solution of higher solute concentration is best described as:
a) osmosis.
b) facilitated diffusion.
c) receptor-mediated transport.
d) active transport.
e) general diffusion.



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9. In an experiment, you measure the concentration of a polar molecule inside and outside a cell. You find that the concentration is high and gradually increasing inside the cell. You also measure the ATP concentration inside the cell and find that it is dropping. What is your best hypothesis for the process you are observing?
a) facilitated diffusion
b) passive transport
c) simple diffusion
d) active transport
e) endocytosis



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10. Which of the following allows the passage of small molecules between animal cells?
a) nucleoli
b) tight junctions
c) desmosomes
d) gap junctions
e) black holes



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11. The largest structure in a eukaryotic cell is the ______ and it is surrounded by ______ membrane(s).
a) nucleus; one
b) nucleus; two
c) Golgi apparatus; one
d) mitochondrion; two
e) mitochondrion; one



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12. The cytoskeleton:
a) is a viscous fluid found in all cells.
b) fills a cell's nucleus but not the other organelles.
c) gives an animal cell shape and support, but cannot control movement.
d) helps to coordinate intracellular movement of organelles and molecules.
e) All of the above are correct.



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13. Which of the following statements about mitochondria is correct?
a) Mitochondria are found in both eukaryotes and prokaryotes.
b) There tend to be more mitochondria in fat cells than in liver cells.
c) Most plant cells contain mitochondria.
d) Mitochondria may have originated evolutionarily as photosynthetic bacteria.
e) All of the above are correct.



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14. Which of the following organelles is not present in animal cells?
a) lysosome
b) Golgi apparatus
c) rough endoplasmic reticulum
d) mitochondrion
e) chloroplast



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15. Given that a cell's structure reflects its function, what function would you predict for a cell with a large Golgi apparatus?
a) movement
b) secretion of digestive enzymes
c) transport of chemical signals
d) rapid replication of genetic material and coordination of cell division
e) attachment to bone tissue.



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16. Cell walls:
a) only occur in plant cells.
b) are not completely solid, having many small pores.
c) confer less structural support than the plasma membrane.
d) dissolve when a plant dies.
e) are made primarily from phospholipids.



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17. Which one of the following organelles is not found in both plant and animal cells?
a) nucleus
b) rough endoplasmic reticulum
c) mitochondrion
d) smooth endoplasmic reticulum
e) central vacuole



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18. In plant cells, chloroplasts:
a) serve the same purpose that mitochondria serve in animal cells.
b) are the site of conversion of light energy into chemical energy.
c) play an important role in the breakdown of plant toxins.
d) have their own linear strands of DNA.
e) Both a) and b) are correct.

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