73. Many small creatures that live in temporary puddles can reproduce asexually at least occasionally. Why might this be a useful strategy for a puddle-dweller? (A) Puddles are very stable environments, so well adapted creatures should maintain their genes without mixing. (B) A single individual can quickly populate a transient environment. (C) Using asexual reproduction increases genetic variety and thus adaptability. (D) In asexual reproduction, the mother can choose the best of each chromosome to make the ideal haploid individual.

76. Most bird species that form flocks show a negative relationship between flock size and individual vigilance (i.e., the larger the flock, the less often an individual lifts its head to scan the surrounding environment). However, some bird species have shown a positive relationship between flock size and individual vigilance. The positive relationship is particularly strong when flocks are space-constrained, such as in small ponds or fields. What is the most likely explanation for this? (A) As flock size increases, the number of "cheaters" increases, so individuals must spend more time scanning for predators. (B) As flock size increases, the risk for interference and aggression between members increases, so individuals must scan for both conspecifics and predators. (C) As flock size increases, the risk of predation for any given member increases, so individuals must spend more time scanning for predators. (D) As flock size increases, mating opportunities decrease, so individuals must spend more time scanning for potential mates.

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