Germ-free animals are often more susceptible to infections and serious disease than are animals with a typical complement of normal microbiota. Based on this observation, which of the following would be an appropriate conclusion?

A. Normal microbiota are incapable of causing disease
B. Normal microbiota stimulate the development of the immune system
C. Normal microbiota are parasitic
D. Normal microbiota are opportunists
E. Normal microbiota provide supplemental nutrition to the host


Ans: B. Normal microbiota stimulate the development of the immune system

Biology & Microbiology

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All of the following tumor-suppressor genes inhibit cell division EXCEPT

A. BRCA1. B. Rb. C. NF1. D. p16. E. Rb and p16.

Biology & Microbiology

Bacteriophages were used by Hershey and Chase to further elucidate our understanding of heredity. Why were bacteriophages used?

What will be an ideal response?

Biology & Microbiology

The burning of fossil fuels by cars and factories has most affected the ______________ cycle.

Fill in the blank(s) with the appropriate word(s).

Biology & Microbiology

One parent carries a dominant allele (AL) that is lethal in early life in homozygotes. The other parent is homozygous for the wild type allele (A+) of the same gene. What is the expected dominant:wild type phenotype ratio for their offspring?

A) 100:0 B) 75:25 C) 50:50 D) 25:75 E) 0:100

Biology & Microbiology