Which letter indicates the direction of incoming light in a typical vertebrate?
Vision differs from the other senses in two interesting ways. Although most sensory receptor neurons are depolarized when the receive a stimulus, rod and cone cells become hyperpolarized when they receive light. When hyperpolarized, they stop releasing inhibitory neurotransmitter and allow the bipolar cells to fire. A second unusual aspect is that the vision circuit seems to be organized "backwards" -- the light must pass through the layers of ganglion and bipolar cells to reach the rods and cones.
A. A
B. B
C. C
D. D
E. All of the directions are possible.
A. A
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Nosocomial infections are those acquired at a hospital
Indicate whether this statement is true or false.
How have classification systems for living things changed over the years?
A) Scientists have always recognized five kingdoms of living things, but the placement of species within those kingdoms has changed. B) Until the last 20 years, organisms had been classified first as animal or plant. Recently, a five-kingdom system became the preferred classification system. C) The three-domain system has been introduced within the last 30 years, to supplement the five-kingdom system. D) The exact organization proposed in the eighteenth century by Carl Linnaeus has recently been reinstituted by scientists.
You have two true-breeding rose bushes, one with red flowers and one with white flowers. A cross between these two roses yields a bush with white flowers that have red splotches. What condition does this demonstrate?
a) environmental effects b) incomplete dominance c) codominance d) monohybrid inheritance e) polygenetic inheritance
The process that converts nitrate into nitrogen gas is known as ____
a. denitrification b. nitrification c. nitrogen fixation d. assimilation e. assimilation and nitrification