ASU BIO 182 EXAM 2 AND PRACTICE EXAM
NEWEST ACTUAL EXAM COMPLETE 250
QUESTIONS AND CORRECT DETAILED ANSWERS
(VERIFIED ANSWERS) |ALREADY GRADED A+
Head in the Clouds
Giraffes are the tallest animals on land. An adult giraffe has a neck that exceeds 2 m in
length. This neck enables a giraffe to access food that other animals cannot reach and
detect predators from a long distance. Studies have shown that
giraffes will browse trees at heights that other herbivores cannot reach. The water and
nutrients gained from leaves enhance a giraffe's fitness by increasing survival and
reproduction. However, a long neck comes with a cost: the heart must spend more
energy to pump blood to the brain. If a giraffe's neck were too long, the energy required
to circulate blood would exceed the energy gained from eating leaves.
1. In a population of giraffes, the average length of the neck is under directional
selection. - ANSWERFalse
Over many generations, the average length of necks in a giraffe population will increase
indefinitely. - ANSWERFalse
The relationship between a giraffe's neck length and its fitness would be better described
by a quadratic equation (y = ax^2 + bx + c) than a linear equation (y = ax + b). -
ANSWERTrue
Natural selection would reduce the variation in neck length in a population of giraffes. -
ANSWERTrue
In the absence of mutation, the heritability of neck length in a population of giraffes
would remain the same. - ANSWERFalse
Puddle Ponds
,During the summer, a small pond loses water to evaporation. Eventually, this pond
becomes a series of puddles separated from one another by at least several meters. Most
animals disperse or die as the pond dries, but some microbes still remain in the puddles.
Each of these species used to live in the pond as a much larger population, but are now
subpopulations that reside in the puddles.
Some of the microscopic species with short generations are bacteria, paramecia, and
rotifers. All of these species reproduce asexually, except for one species of rotifer that
reproduces sexually. The puddles remain separated until the following spring, when
abundant rain causes them to expand and form a pond like the one from last year.
6. During the time that subpopulation lived in puddles, they would have been considered
sympatric. - ANSWERFalse
While in separate puddles, genetic drift could cause the evolution of reproductive
isolation in rotifers. - ANSWERTrue
When the pond reforms, the rotifers from each puddle could be considered different
evolutionary species. - ANSWERTrue
When the pond reforms, the bacteria from each puddle would be considered different
biological species. - ANSWERFalse
When the pond reforms, natural selection would favor prezygotic isolating mechanisms
that reinforce any postzygotic isolating mechanisms. - ANSWERTrue
Fickle fleas
Daphnia magna is an aquatic species of crustaceans, commonly referred to as the water
flea. These animals have 10 pairs of chromosomes, all of which are autosomal. Most
water fleas are females that reproduce asexually. During asexual reproduction, a single
female produces as many as a hundred offspring at a time. Each offspring is genetically
identical to the mother (except for a few mutations). As winter approaches, however,
some offspring develop into males and the population reproduces sexually. After having
sex, a female lays a few large eggs, which must survive at the bottom of the lake until the
water warms in spring.
11. During sexual reproduction, the population is more likely to evolve by genetic drift. -
ANSWERTrue
During asexual reproduction, genetic drift cannot affect the population's evolution. -
ANSWERFalse
Water fleas switch from asexual reproduction to sexual reproduction to increase the
genetic variation among offspring. - ANSWERTrue
A population of water fleas would adapt to environmental change faster if all
reproduction were asexual. - ANSWERFalse
Asexual reproduction in the summer reduces the variation in fitness among offspring. -
ANSWERTrue
, Fishy proteins
Cod fish have two alleles for a protein that binds oxygen, called the Hb-1 and Hb-2
alleles. Fish expressing the Hb-1 allele are found in different environments than fish
expressing the Hb-2 allele. Upon bringing both groups of fish into a lab, scientists found
that the Hb-1 and Hb-2 proteins function differently when tested under two different
temperature treatments, cold and warm temperature. The groups of fish were similar in
size, age, and sex ratios. The figure below shows the findings from the scientist's
research.
16. In cold water, natural selection would favor heterozygotes that expressed Hb-1 and
Hb-2 at the same time. - ANSWERFalse
The Hb-2 proteins are likely more flexible than the Hb-1 proteins. - ANSWERTrue
In warm water, a fish with Hb-1 could not perform as many reactions requiring oxygen as
could a fish with Hb-2. - ANSWERFalse
Fish with Hb-2 likely occur in warmer waters than fish with Hb-1. - ANSWERFalse
A heterozygous fish that simultaneously expresses Hb1 and Hb2 alleles would pay an
energetic cost to bind oxygen well in cold and warm waters. - ANSWERTrue
Cell membranes balance the need to remain intact with the need to move during function.
Researchers studying fruit flies discovered that the cell membranes of these ectothermic
animals changed throughout the day. During the night, when the environment was cool,
the membranes were composed of mostly unsaturated phospholipids, leading to a very
flexible structure. During the day, when the environment was warm, the membranes were
composed of mostly saturated phospholipids, leading to a less flexible structure.
21. The change in the structure of the membrane is likely a case of adaptive plasticity. -
ANSWERTrue
On a cold night, less flexible cell membranes will function better than more flexible ones.
- ANSWERFalse
A fly alters the composition of phospholipids in its cell membranes as fast as or faster
than the air temperature changes during the day. - ANSWERTrue
If a fly acclimated more slowly than the change in air temperature, it would pay an
opportunity cost at some time of the day. - ANSWERTrue
If flies were collected and immediately tested at a high temperature, a fly collected during
the night would probably fly better than one collected during the day. - ANSWERFalse
Cooking camel
While walking in the desert, a well-hydrated camel was exposed to intense solar radiation
and hot surroundings. During the morning, its body temperature rose steadily by 6°C. In
