Which of the following is not true of mycoplasmas?
a. They are the smallest truly living organisms.
b. They are members of the domain Bacteria.
c. They only inhabit multicelled organisms.
d. Although classified as gram-positive, they lack cell wall.
e. They can be pathogenic, causing pneumonia and urinary tract infections.
C; Mycoplasmas, while small and simple (choice a), apparently have their simplicity derived as an adaptation to parasitic life (choice e), including the loss of the (formerly gram-positive) cell wall (choice d). They are clearly true bacteria (choice b) and not an intermediate between the two domains.
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The stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in
A) potassium levels. B) chloride levels. C) sodium levels. D) calcium levels. E) neurotransmitter levels.
The karyotypes of several primate species, such as chimpanzee and gorilla, show two nearly telocentric chromosomes as opposed to the single large metacentric chromosome 2 in humans
Does this demonstrate chromosome breakage or fusion at the time of lineage divergence?
Which of the following enzymes is known to be expressed at a high level in the cancer cells of patients suffering from acute myeloid leukemia and at low levels in the cancer cells of patients suffering from acute lymphoblastic leukemia?
a) catalase b) cholesterase c) phosphodiesterase d) adenylyl cyclase e) protein kinase A
Vertebrates that practice internal fertilization employ three strategies for embryonic and fetal development. In one strategy, the female retains the young which develop and obtain nourishment from the female's blood. What is this called?
A. ovoviviparity B. oviparity C. protogyny D. protandry E. viviparity