Dencology

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If you can please explain your answers:


35. in mammals, which of the following are produced after rearrangement of DNA swequences in specific cells?

a. Hemoglobins
b. actins
c. Antigens
d. Antibodies
E. Trypsins

51. of the following, which appears first in the fossil record?

a. Insects
b. corals
c. octopi
d. Amphioxi
e. lamprey eels

84. All of the following maybe true of a population with a stable age distribution EXCEPT:

A. The # of organism is changing at a constant rate.
b. Age-specific birth and death rates are not changing over time.
c. Population size is increasing.
d. The proportions of organisms in each age class are changing.
e. population size is decreasing.

D is the answer.

105. Which of the following is a postzygotic isolating mechanism in speciation?

a. isolation by hybide sterility
b. Geographic isolation
c. behavioral isolation
 
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Dentista08

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If you can please explain your answers:


35. in mammals, which of the following are produced after rearrangement of DNA swequences in specific cells?

a. Hemoglobins
b. actins
c. Antigens
d. Antibodies
E. Trypsins



51. of the following, which appears first in the fossil record?

a. Insects
b. corals
c. octopi
d. Amphioxi
e. lamprey eels

84. All of the following maybe true of a population with a stable age distribution EXCEPT:

A. The # of organism is changing at a constant rate.
b. Age-specific birth and death rates are not changing over time.
c. Population size is increasing.
d. The proportions of organisms in each age class are changing.
e. population size is decreasing.

D is the answer.

105. Which of the following is a postzygotic isolating mechanism in speciation?

a. isolation by hybide sterility
b. Geographic isolation
c. behavioral isolation

#35 Antiodies quoted from http://www.ncbi.nlm.nih.gov/books/bv.fcgi?indexed=google&rid=cooper.section.828

Site-specific recombination is important not only in the interaction of viruses such as λ with their host cells, but also in programmed gene rearrangements within cell genomes. In vertebrates, site-specific recombination is critical to the development of the immune system, which recognizes foreign substances (antigens) and provides protection against infectious agents. There are two major classes of immune responses, which are mediated by B and T lymphocytes. B lymphocytes secrete antibodies (immunoglobulins) that react with soluble antigens; T lymphocytes express cell surface proteins (called T cell receptors) that react with antigens expressed on the surfaces of other cells. The key feature of both immunoglobulins and T cell receptors is their enormous diversity, which enables different antibody or T cell receptor molecules to recognize a vast array of foreign antigens. For example, each individual is capable of producing more than 1011 different antibody molecules, which is far in excess of the total number of genes in the human genome (approximately 105). Rather than being encoded in germ-line DNA, these diverse antibodies (and T cell receptors) are encoded by unique lymphocyte genes that are formed during development of the immune system as a result of sitespecific recombination between distinct segments of immunoglobulin and T cell receptor genes.

#51- corals are a part of Cnidaria which appears to be the oldest on this chart http://www.ucmp.berkeley.edu/phyla/metazoafr.html

#84 If the distribution is stable, how is it changing? D is the only one thats false

#105.- Definition of species: A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.

where r u getting these from?
 
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