Which human extraembryonic membrane forms the blood vessels of the umbilical cord?
a. amnion
b. yolk sac
c. chorion
d. allantois
e. protein coat
ANSWER: d
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The explanation for the differences between a
human liver cell and a cell from the skin is the a. maternal and paternal origins of the genes. b. gene content of the two cells. c. expression of the genes in the two cells. d. fact that they originated from different primary tissue layers. e. different functions of the cells.
You may have observed plants rotate towards a light source, thereby increasing the plant's ability to intercept light energy and increase photosynthesis. You, however, are given the task of preventing grass seedlings from rotating toward the light. Using your knowledge of phototropism, which of the following experimental procedures would you use to complete your task?
A) Cover the growing tip of the grass seedling with black paper. B) Supply the seedlings with very dim light. (red light does not induce a bend) C) Cover the portion of the seedling below the tip with a black shield. D) Supply the seedling with nutrient-rich fertilizer solution.
Which of the following structure of a eukaryotic cell is not likely derived from endosymbiotic bacterium?
A. mitochondria DNA B. mitochondria ribosomes C. inner membrane D. outer membrane
Which of the following cells is living but their nuclei are lost during maturation?
A. guard cells B. companion cells C. meristem cells D. collenchyma E. sieve cells