Many cells of the immune system have receptors that detect peptidoglycans and lipopolysaccharides. How do pathogenic bacteria avoid detection?
A. Pathogens often encase themselves in a gelatinous capsule.
B. Peptidoglycans are absent from pathogenic bacteria.
C. Disease is only possible if the immune system has been compromised by some other event.
D. Pathogenic bacteria lack cell walls.
Answer: A
You might also like to view...
What type of inheritance is observed with extranuclear DNA?
A. Mendelian inheritance B. Sex-linked inheritance C. Paternal inheritance D. Maternal inheritance E. Maternal effect
At one point in human development, tissue connects the fingers and the hand, giving the hand a
“webbed” appearance. Enzymes eventually destroy the cells of the webbing and the fingers separate. These enzymes are probably liberated from the
a. chormosomes. b. smooth endoplasmic reticulum. c. lysosomes. d. nucleus. e. vacuoles.
When homologous chromosomes cross over, what occurs?
A) Two chromatids get tangled, resulting in one re-sequencing its DNA. B) Two sister chromatids exchange identical pieces of DNA. C) Corresponding segments of non-sister chromatids are exchanged. D) Maternal alleles are "corrected" to be like paternal alleles and vice versa.
The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information above, which explanation is most likely?
A) Pax-6 in all of these animals is not homologous; it arose independently in many different animal phyla due to intense selective pressure favoring vision. B) The Pax-6 gene is really not one gene. It is many different genes that, over evolutionary time and due to convergence, have come to have a similar nucleotide sequence and function. C) The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor. D) The need for eyes has resulted in the separate evolution of Pax-6 genes.