Immune cells that secrete cytokines and activate other immune cells are:
a. Virally infected cells
b. Helper T-cells
c. Invading pathogenic bacteria
d. Cytotoxic T-cells
e. Abnormal body cells
Ans: b. Helper T-cells
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Nitrogen is made available to plants for their use by the process(es) of ____
a. ammonification only b. nitrification only c. nitrogen fixation only d. ammonification and nitrification only e. ammonification, nitrification, and nitrogen fixation
Which type of plant hormone governs senescence in plants, such as the loss of leaves in autumn by
some plants?
a. cytokinins b. abscisic acid c. gibberellins d. brassinosteroids e. ethylene
pH is a measure of the number of _____ in a fluid
1.covalent bonds 2.hydrogen ions 3.calcium ions 4.water molecules
How much rainfall is received in a desert?
A) a negligible amount (essentially 0 inches per year) B) less than 1 inch per year C) less than 20 inches per year D) more than 20 inches per year