ASU BIO 182 EXAM 2 QUESTIONS WITH
COMPLETE SOLUTIONS
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. - ANSWER False
Over many generations, the average length of necks in a giraffe population will
increase indefinitely. - ANSWER False
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). - ANSWER True
Natural selection would reduce the variation in neck length in a population of giraffes.
- ANSWER True
In the absence of mutation, the heritability of neck length in a population of giraffes
would remain the same. - ANSWER False
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. - ANSWER False
, While in separate puddles, genetic drift could cause the evolution of reproductive
isolation in rotifers. - ANSWER True
When the pond reforms, the rotifers from each puddle could be considered different
evolutionary species. - ANSWER True
When the pond reforms, the bacteria from each puddle would be considered different
biological species. - ANSWER False
When the pond reforms, natural selection would favor prezygotic isolating
mechanisms that reinforce any postzygotic isolating mechanisms. - ANSWER True
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. - ANSWER True
During asexual reproduction, genetic drift cannot affect the population's evolution. -
ANSWER False
Water fleas switch from asexual reproduction to sexual reproduction to increase the
genetic variation among offspring. - ANSWER True
A population of water fleas would adapt to environmental change faster if all
reproduction were asexual. - ANSWER False
Asexual reproduction in the summer reduces the variation in fitness among offspring.
- ANSWER True
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.
COMPLETE SOLUTIONS
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. - ANSWER False
Over many generations, the average length of necks in a giraffe population will
increase indefinitely. - ANSWER False
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). - ANSWER True
Natural selection would reduce the variation in neck length in a population of giraffes.
- ANSWER True
In the absence of mutation, the heritability of neck length in a population of giraffes
would remain the same. - ANSWER False
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. - ANSWER False
, While in separate puddles, genetic drift could cause the evolution of reproductive
isolation in rotifers. - ANSWER True
When the pond reforms, the rotifers from each puddle could be considered different
evolutionary species. - ANSWER True
When the pond reforms, the bacteria from each puddle would be considered different
biological species. - ANSWER False
When the pond reforms, natural selection would favor prezygotic isolating
mechanisms that reinforce any postzygotic isolating mechanisms. - ANSWER True
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. - ANSWER True
During asexual reproduction, genetic drift cannot affect the population's evolution. -
ANSWER False
Water fleas switch from asexual reproduction to sexual reproduction to increase the
genetic variation among offspring. - ANSWER True
A population of water fleas would adapt to environmental change faster if all
reproduction were asexual. - ANSWER False
Asexual reproduction in the summer reduces the variation in fitness among offspring.
- ANSWER True
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.
