In bottom sediments of lakes and streams, organic matter is broken down by heterotrophic microorganisms and ammonia is released. Under aerobic conditions, specialized bacteria convert ammonia to nitrate (nitrification). This nitrate, together with nitrate from other sources, diffuses into the deeper sediments, where it may undergo anaerobic conversion to nitrogen gas (denitrification). These sediments typically contain oligochaete worms that live with their heads buried and their tails waving back and forth in the overlying water. Plastic columns were packed with freshly collected  stream  sediments  and  then  covered  with  layers  of  nitrate enriched  water.  A  similar  set  of  columns  was packed with sediment that had been sterilized and then covered with either nitrate-enriched water or distilled water. Oligochaete  worms  were  collected  and  acclimated  to  20°(C)Following  acclimation,  worms  were  rinsed  in  distilled water and then added to three sediment columns. The columns were incubated in the dark at 20°C and monitored every three days for changes in the concentration of nitrate in the overlying water. Nitrate concentrations in each of the experimental treatments were plotted against time, as shown in the graph below.

Which of the following explains why the columns were incubated in the dark?

#Question id: 3482

#Unit 11. Evolution and Behavior

Which statement below about mating behavior is correct?

A) Some aspects of courtship behavior may have evolved from agonistic interactions.

B) The degree to which evolution affects mating relationships depends on the degree of prenatal and postnatal input the parents are required to make.

C) The mating relationship in most mammals is monogamous, to ensure the reproductive success of the pair.

D) Polygamous relationships most often involve a single male and many females, but in some species this is reversed

#Question id: 3483

#Unit 11. Evolution and Behavior

Which of the following statements about evolution of behavior is correct?

A) Natural selection will favor behavior that enhances survival and reproduction.

B) An animal may show behavior that maximizes reproductive fitness.

C) If a behavior is less than optimal, it is not completely evolved but will eventually,become optimal.

#Question id: 3484

#Unit 11. Evolution and Behavior

Modern behavioral concepts relate the cost of a behavior to its benefit. Under which relationship might a behavior be performed?

A) cost is greater than the benefit

B) cost is less than the benefit

C) cost is equal to the benefit

#Question id: 3485

#Unit 11. Evolution and Behavior

Optimal foraging involves all of the following except

A) maximizing energy gained by the forager.

B) minimizing energy expended by the forager.

C) securing essential nutrients for the forager.

D) minimizing the risk of predation on the forager.

E) maximizing the population size of the forager

#Question id: 3486

#Unit 11. Evolution and Behavior

Which of the following might affect the foraging behavior of an animal in the context of optimal foraging?

A) risk of predation

B) prey size

C) prey defenses

#Question id: 3487

#Unit 11. Evolution and Behavior

Which of the following is true of innate behaviors?

A) Genes have very little influence on the expression of innate behaviors.

B) Innate behaviors tend to vary considerably among members of a population.

C) Innate behaviors are limited to invertebrate animals.

D) Innate behaviors are expressed in most individuals in a population across a wide range of environmental conditions.

E) Innate behaviors occur in invertebrates and some vertebrates but not in mammals.