Primary productivity is limited in surface waters of the open ocean by:
a. sunlight.
b. nutrients.
c. carbon dioxide.
d. oxygen.
e. temperature.
B
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Which proteins recognize and bind molecules from other cells that act as chemical signals?
a. transport proteins b. recognition proteins c. receptor proteins d. cell adhesion proteins e. nuclear proteins
The brains of female zebra finches lack the hormonal influences that occur in the brains of males. As a result, what
changes are seen in the female brains?
a. auditory processing centers are especially well-developed in females b. more neurons are produced in the higher vocal center c. increased transcription of genes whose products are involved in memory retention d. the number of neurons in the higher vocal center declines e. octopamine levels increase, stimulating neural transmissions
Secondary succession is likely to occur in a(n) ____
a. burned forest only b. shallow lake only c. abandoned field only d. burned forest and an abandoned field e. burned forest, a shallow lake, and an abandoned field
Identify the point in time during an action potential when a positive feedback process is occurring in a neuron.
A. when the neuron is at rest B. after the peak depolarization of the action potential when it is rapidly repolarizing C. as the neuron is being depolarized and passes the threshold potential D. during the undershoot phase when the neuron is slightly hyperpolarized relative to the resting potential E. A positive feedback process is occurring at all the time points given.