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.
B
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Two organisms containing identical GC ratios are not necessarily related
Indicate whether the statement is true or false.
Protists and some other animals use ____ digestion
Fill in the blank with the appropriate word.
Isolates from an ear swab that are gram-negative coccobacilli grow on chocolate agar in CO2 but not blood agar, require both X and V factors for growth, and are nonhemolytic on rabbit or horse blood may be identified as:
a. H. parainfluenzae. b. H. ducreyi. c. H. aphrophilus. d. H. influenzae.
Answer the following statements true (T) or false (F)
1. Translation is a relatively slow process. 2. tRNA contains the genetic code for producing a polypeptide. 3. More than one codon can specify the same amino acid. 4. The termination of translation occurs when a release factor recognizes the stop codon.