The Following Questions Refer to the Description and Table 28

question 16

Multiple Choice

The following questions refer to the description and Table 28.1 below.
Diatoms are encased in Petri-plate-like cases (valves) made of translucent hydrated silica whose thickness can be varied. The material used to store excess calories can also be varied. At certain times, diatoms store excess calories in the form of the liquid polysaccharide, laminarin, and at other times, as oil. Below are data concerning the density (specific gravity) of various components of diatoms, and of their environment.
Table 28.1: Specific Gravities of Materials Relevant to Diatoms
$$\begin{array} { l l } \text { Material } & \text { Specific Gravity } ( \mathrm { kg } / / \mathrm { m }^{3} ) \\\text { Pure water } & 1000 \\\text { Seawater } & 1026 \\\text { Hydrated silica } & 2250 \\\text { Liquid laminarin } & 1500 \\\text { Diatom oil } & 910\end{array}$$
-The chloroplasts of all of the following are derived from ancestral red algae, except those of

• A)golden algae.
• B)diatoms.
• C)dinoflagellates.
• D)green algae.
• E)brown algae.

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Definitions:

Cell Body

The part of the neuron that keeps it alive and determines whether or not it will fire.

Neurons

Cells within the nervous system that transmit information to other nerve cells, muscle, or gland cells.

Muscle Action

The contraction or relaxation of muscles which results in movement of body parts.

Acetylcholine

A neurotransmitter in the nervous system that plays a key role in muscle activation and also influences many functions in the brain.