Tadpoles must undergo a major metamorphosis to become frogs
This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine?
A) There are many different forms of thyroxine, each specific to a different tissue.
B) Different tissues have thyroxine receptors that activate different signal transduction pathways.
C) Some tissues have membrane receptors for thyroxine, while other tissues have thyroxine receptors within the nucleus.
D) Different releasing hormones release thyroxine to different tissues.
Answer: B
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What axonal characteristic facilitates the propagation of an action potential along a myelinated axon?
a. Voltage-gated Na+ and K+ channels are concentrated in the myelinated axonal segments. b. Voltage-gated Na+ and K+ channels are concentrated in the unmyelinated axonal segments. c. Voltage-gated Na+ channels are concentrated in the myelinated axonal segments; voltage-gated K+ channels are concentrated in the unmyelinated axonal segments. d. Voltage-gated K+ channels are concentrated in the myelinated axonal segments; voltage-gated Na+channels are concentrated in the unmyelinated axonal segments. e. Voltage-gated Na+ K+ channels are spread evenly throughout both myelinated and unmyelinated segments
Homologous Chromosomes synapse and crossing over occurs
A. The statement is true for mitosis only. B. The statement is true for meiosis I only. C. The statement is true for meiosis II only . D. The statement is true for mitosis and meiosis I. E. The statement is true for mitosis and meiosis II
In contrast to alpha radiation, beta radiation:
A) is easily stopped by a piece of paper. B) travels slowly and is less penetrating. C) can easily penetrate the human body. D) requires a layer of clothing to stop it.
Which of the following is thought to be the major promoter of fatty plaque buildup in the coronary arteries?
What will be an ideal response?