What is the effect of stress on a population?
a. Plants compete less with each other in stressful environments.
b. Plants compete more with each other in a stressful environments.
c. Only abiotic factors contribute to environmental stress.
d. Stressful environments brought about by humans do not affect populations.
e. Stressful environments brought about by nature do not affect populations.
ANSWER: a
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The force driving simple diffusion is _____, while the energy source for active transport is _____
A) the concentration gradient; ADP B) the concentration gradient; ATP C) transmembrane pumps; electron transport D) phosphorylated protein carriers; ATP
While innate immunity is ancient and universal amongst animals, the adaptive immune system is generally considered to be unique to the vertebrates. However, some researchers have suggested, with much controversy, that invertebrates may have a form of adaptive immunity as well. What sort of evidence would be required to fully demonstrate such a claim? (Check all that apply.)
_____ B and T cells _____ CD4 receptors _____ efficacy of vaccination _____ highly variable molecules that can bind various antigens _____ identified cells that are necessary to provide acquired immunity _____ immunoglobulin molecules _____ resistance upon second exposure to a pathogen _____ specific resistance to one strain but not another after exposure _____ thymus gland _____ Toll-like receptors
Proteins can be regulated by the removal of phosphates by
a. protein phosphatases. b. phosphoproteases. c. protein phosphorylases. d. protein kinases.
Which kind of T cells regulate the immune response by producing stimulatory lymphokines?
A. cytotoxic T cells (TC) B. suppressor T cells (TS) C. helper T cells (TH) D. memory T cells (TM)