What are the two most likely reasons for cellular senescence (the loss of proliferative ability)?
a. DNA damage and telomere lengthening
b. DNA damage and telomere shortening
c. DNA intactness and telomere shortening
d. DNA intactness and telomere lengthening
Answer: b. DNA damage and telomere shortening
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How might absorption of organic compounds into clays assist in their aggregation and organization
into membrane-bound protocells?
a. Clays contain many minerals in extremely thin layers and readily repel ions, forcing multiple chemical interactions. b. Clays are highly structured, contain water, and store potential energy that could drive the chemical reactions forward. c. Clays lack water, forcing the concentration of the organic molecules and thus driving multiple interactions. d. Clays are extremely resistant to temperature changes and thus would insulate the organic compounds from temperature changes in the atmosphere. e. None of the above statements accurately explain clays’ possible roles in the formation of protocells.
In order for DNA molecules to undergo
recombination, a. they must be from the same species. b. their strands must separate as in replication. c. they must be cut and spliced at specific nucleotide sequences. d. one of the two DNA strands must be degraded. e. they must first be transcribed
What is the name of the meristematic tissue that gives rise to future vascular tissue?
A. Procambium B. Dermal tissue C. Ground meristem D. Cork cambium E. Protoderm
Please choose the statement that best describes the immunologic basis of organ or tissue rejection after transplantation.
A) Specific T cell populations recognize non-self MHC molecules on transplanted tissue and mount a cell-mediated immune response damaging the transplant. B) Transplanted tissue is normally rejected only if it becomes infected. C) Organ/tissue transplant rejection is mostly due to Type 2 cytotoxic reactions mediated by IgG and IgM. D) IgE antibodies as well as basophils and mast cells attack the transplanted tissue if they recognize it as "non-self."