The next few questions refer to the following description and Table 25.1.
Diatoms are encased in Petri-platelike 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. Table 25.1 shows data concerning the density (specific gravity) of various components of diatoms, and of their environment.
Table 25.1 Specific Gravities of Materials Relevant to Diatoms
-Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration and using data from Table 25.1, 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

The next few questions refer to the following description and Table 25.1.
Diatoms are encased in Petri-platelike 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. Table 25.1 shows data concerning the density (specific gravity) of various components of diatoms, and of their environment.
  Table 25.1 Specific Gravities of Materials Relevant to Diatoms
-Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration and using data from Table 25.1, 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

According to Table 25.1, the density of oil is lower than that of water, so storing excess calories as oil would result in greater buoyancy for the diatoms. As water temperature increases (e.g. in late summer), water density and buoyancy decrease, making it advantageous for diatoms to store excess calories as oil to remain buoyant. Therefore, C) late summer is the best choice for when to expect diatoms to be storing excess calories mostly as oil.

The Next Few Questions Refer to the Following Description and Table