Use the following description and table to answer the question.
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. The following are data concerning the density (specific gravity)of various components of diatoms, and of their environment.
Specific Gravities of Materials Relevant to Diatoms
$\begin{array}{|c|c|}
\hline \text { Material } & \begin{array}{c}
\text { Specific Gravity } \
\left(\mathrm{kg} / \mathrm{m}^{3}\right)
\end{array} \
\hline \text { Pure water } & 1000 \
\hline \text { Seawater } & 1026 \
\hline \text { Hydrated silica } & 2250 \
\hline \text { Diquid laminarin } & 1500 \
\hline \text { Diatom oil } & 910\
\hline
\end{array}$

Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration, and using data from the table above, at which time of year should one expect diatoms to be storing excess calories mostly as oil?
A) mid-winter
B) early spring
C) late summer
D) late fall

Question

Use the following description and table to answer the question.
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. The following are data concerning the density (specific gravity)of various components of diatoms, and of their environment.
Specific Gravities of Materials Relevant to Diatoms
$\begin{array}{|c|c|}
\hline \text { Material } & \begin{array}{c}
\text { Specific Gravity } \
\left(\mathrm{kg} / \mathrm{m}^{3}\right)
\end{array} \
\hline \text { Pure water } & 1000 \
\hline \text { Seawater } & 1026 \
\hline \text { Hydrated silica } & 2250 \
\hline \text { Diquid laminarin } & 1500 \
\hline \text { Diatom oil } & 910\
\hline 
\end{array}$

Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration, and using data from the table above, at which time of year should one expect diatoms to be storing excess calories mostly as oil?
A) mid-winter
B) early spring
C) late summer
D) late fall

Quizplus · Accepted Answer

As water temperature increases, its density decreases, which makes it less buoyant. Diatom oil has a specific gravity of 910 kg/m³, while laminarin has a specific gravity of 1500 kg/m³. Since diatoms want to float to the top to get access to light for photosynthesis, they are better off storing excess calories in oil during times when the water is less buoyant. Late summer is the time of year when water temperature is the warmest and water density is the least, so diatoms should be storing excess calories mostly as oil during this time.

Use the Following Description and Table to Answer the Question