The structure of DNA is often described as a twisted ladder. The rungs of the ladder represent the sugar phosphate chains. Is this an accurate description? Why or why not?
What will be an ideal response?
No, it is not accurate--the rungs represent the paired nitrogenous bases.
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It is believed that the coelacanths and lungfish represent a crucial link between other fishes and tetrapods. What is the major feature in these fish in support of this hypothesis?
A) Like amphibians, they are tied to the water for reproduction. B) Their fins have skeletal and muscular structures similar to amphibian limbs. C) They have highly evolved nervous and circulatory systems. D) They have lungs and are able to breathe air when water is scarce. E) They enter a hibernative stage when food is scarce, as many tetrapods do.
Holoprosencephaly is a highly variable condition in mammals, including humans. Its effects range from an absence of brain areas, mid-face disorders, and cyclopia to slight dental abnormalities. One form, HPE3, is caused by Shh mutations
Familial cases are inherited as dominants. Which of the following do you expect? A) HPE3 is actually a multigene complex. B) Each type of malformation is due to a different HPE3 allele. C) HPE3 expression is modified by genetic background. D) HPE3 individuals also share a common environmental exposure. E) All mutations in Shh that result in HPE3 are due to frameshifts.
Cells use exocytosis to
A) ingest nutrients. B) pump hydrogen molecules across the membrane. C) create new cells. D) release substances from the cell. E) move away from danger.
Most cases of toxoplasmosis in patients that are not immunocompromised have the following symptoms:
A. bloody, mucus-filled stools, fever, diarrhea, and weight loss B. fever, swollen lymph nodes, and joint pain C. urinary frequency and pain, and vaginal discharge D. chills, fever, and sweating E. sore throat, low grade fever, and swollen lymph nodes