A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light
, whereas organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively, _____.
A) mitochondria and chloroplasts
B) chloroplasts and peroxisomes
C) peroxisomes and chloroplasts
D) chloroplasts and mitochondria
E) mitochondria and peroxisomes
Answer: D
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A friend asks you how exocrine glands differ from endocrine glands. She knows that both form from invaginated epithelium. How do you respond?
A. Exocrine and endocrine glands are essentially the same, both produce products that are secreted to the skin's surface. B. Exocrine glands produce hormones which enter the blood stream, while endocrine glands secrete sweat and oil directly to the surface of the skin. C. Endocrine glands produce hormones which enter the blood stream, while exocrine glands secrete sweat and oil directly to the surface of the skin. D. Exocrine glands are found in the thoracic cavity while endocrine glands are located in the pleural cavity. E. The liver is an endocrine gland that secretes directly into epithelial tissues. The pituitary gland is an exocrine gland that secretes into the blood stream.
"A bands" in skeletal muscle are composed of
a. discs to which thin filaments are anchored. b. stacked thick filaments along with parts of thin filaments that overlap both ends. c. thin filaments but no thick filaments. d. thick filaments but no thin filaments. e. discs to which thick filaments are anchored.
Answer questions 72-76 using the five groups listed below:a
halophiles b. cyanobacteria c. thermophiles d. proteobacteria e. methanogens D 72. These bacteria live in temperatures that are not usually conducive to life. M 73. These produce CH4. D 74. These bacteria can live in water of very high salt concentration. M 75. These can form heterocysts, valuable in nitrogen fixation. M 76. These are the most diverse monophyletic group of bacteria.
Explain why epithelial cells are the source of 80% to 90% of all cancers. Then list at least two types of epithelial cells,
and at least four types of cancer for which they are the source. What will be an ideal response?