ASU BIO 182 EXAM 2 QUESTIONS &
ANSWERS (RATED 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
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
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
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
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.
ANSWERS (RATED 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
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
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
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
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.
