Theoretically,P.bursaria can obtain zoochlorella either vertically (via the asexual reproduction of its mother cell)or horizontally (by ingesting free-living Chlorella from its habitat).Consider a P.bursaria cell containing zoochlorellae but whose habitat lacks free-living Chlorella.If this cell subsequently undergoes many generations of asexual reproduction,if all of its daughter cells contain roughly the same number of zoochlorellae as it had originally contained,and if the zoochlorellae are all haploid and identical in appearance,then what is true?
A)The zoochlorellae also reproduced asexually,at an increasing rate over time.
B)The zoochlorellae also reproduced asexually,at a decreasing rate over time.
C)The zoochlorellae also reproduced asexually,at a fairly constant rate over time.
D)The zoochlorellae reproduced sexually,undergoing mitosis and meiosis.

Question

Quizplus · Accepted Answer

Since the P. bursaria cell is not ingesting any free-living Chlorella, the only way for its daughter cells to obtain zoochlorellae is through vertical transmission (i.e. asexual reproduction). If all daughter cells contain the same number of zoochlorellae as the original cell, then it suggests that the zoochlorellae are reproducing at a fairly constant rate over time. This is because if the zoochlorellae were reproducing at an increasing rate over time, then each daughter cell would contain more zoochlorellae than the previous cell. Conversely, if the zoochlorellae were reproducing at a decreasing rate over time, then each daughter cell would contain fewer zoochlorellae than the previous cell. Therefore, option C is the best choice.