Otto Loewi performed an experiment in which he electrically stimulated the vagus nerve connected to one frog heart and let the fluid bathing this first heart pass to a second chamber containing a second frog heart not connected to a nerve. What did Loewi observe?
A. There was no effect on the beating of either heart.
B. The first heart showed an increase in beat rate, but there was no change in the second heart.
C. The first heart showed an increase in beat rate and so did the second heart.
D. The first heart showed a decrease in beat rate, but there was no change in the second heart.
E. The first heart showed a decrease in beat rate and so did the second heart.
E. The first heart showed a decrease in beat rate and so did the second heart.
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Cultural traits are transmitted horizontally and vertically through learning. Which of the examples below shows the horizontal transmission of culture?
A. A mother teaches her son how to ride a bike. B. A female chimpanzee teaches her offspring to capture termites using a stick. C. A son inherits the recessive form of a gene from his father. D. A teenager teaches her brother how to text. E. None of a-d are examples of horizontal transmission of culture.
Ultraviolet light can cause permanent changes in genes. These changes are called
a. mutations. b. enzymes. c. fibrin. d. promoters. e. polypeptides.
In humans, X-linked genetic diseases
a. are associated with autosomes. b. tend to be expressed more in females than males. c. only affect males. d. tend to be expressed more in males than in females.
A signal sequence in the polypeptide chain targets all but _______ proteins to the rough ER surface.
a. secreted b. plasma membrane c. mitochondrial d. lysosomal