What are on the surface of most vertebrate cells, acting as markers of "self"?
A. T-cell receptors
B. Major histocompatibility complex proteins
C. Immunoglobulins
D. Antigens
Answer: B
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Which of the following species can be considered exotic in North America?
a. sea lamprey b. water hyacinth c. nutria d. all of the choices
Describe the major changes in the embryo during the first trimester
What will be an ideal response?
A disorder is inherited by all the daughters of affected males, but by none of his sons. Heterozygous females are affected, and will pass on the trait to half their children, with boys and girls equally affected. What is the mode of inheritance of the trait?
1.autosomal dominant 2.sex-linked recessive 3.autosomal recessive 4.X-linked dominant 5.X-linked recessive 6.mitochondrial inheritance 7.Y-linked inheritance
Which of the following statements about ecological pyramids is true?
A. A pyramid of organism numbers will always have a large base and a small top. B. The limited number of trophic levels in an ecological pyramid is due to increasing complexity and size of organisms at each greater trophic level. C. Pyramids built upon the biomass of organisms at each level eliminate size as a factor. D. Energy gains between trophic levels occur based upon biomass conversion. E. None of the choices are true.