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ACT: Science Question #7 |
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Passage 2
During incubation, a bird embryo, like a mammal embryo, uses oxygen to satisfy its energy needs. However, unlike a mammal embryo, a bird embryo cannot rely on its mother to supply the necessary oxygen. The oxygen must be supplied directly from the outside environment by diffusion through pores in the egg's shell. Diffusion is the movement of substances through a membrane from a region of higher concentration to a region of lower concentration.
Based on this fact, a group of scientists suspected that there might be a relationship between the mass of an egg and its total pore area. A pore is a channel through which substances can diffuse from one side of the membrane to the other.
To investigate this concept, the scientists collected the data shown in the table in Table 1.
Question:
Which type of bird egg has the greatest ratio of average egg mass to average pore area?
Choices:
The correct answer is C.
To find the answer you must compare the average
egg mass to the average pore area. For the rhea, the ratio is 820/5.0,
or 164. Choices (A), (B), and (D) are 15, 70, and 7.5 respectively.
These ratios are all less than that of the rhea.
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