Toward the end of the Proterozoic eon, multicellular animals emerged. The first animals were
A. Fish.
B. Reptiles.
C. Invertebrates.
D. Chordates.
E. Tetrapods.
C. Invertebrates.
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Chemical reactions are classified as exergonic if ________
a. they involve gain or loss of atoms b. they need a boost of energy to begin c. they end with a net release of energy d. the bonds in the reactants have more energy than the bonds in the products
The movement of some molecules and ions out of excretory system tubules and back into body fluids
is
a. reabsorption. b. release. c. filtration. d. secretion. e. diffusion.
In an antibody- mediated immune response,
what causes effector helper T cells to release cyokines?
a. binding to antigen presenting dendritic cells b. binding to a bacterial complement c. binding to a naive helper T cell d. binding to a B cell e. engulfing a bacterium
According to the theory of common descent, how should each species on Earth today compare?
A) They should look very similar to all other species. B) They should not have ancestors in common with members of other species. C) They should have a single ancestor in common. D) They should have DNA that is mostly unique from other species.