11 Jun Broward BSC 2011 – Principles of Evolution
Question
Critical Thinking Questions
Principles of Evolution
Analyze each of the following questions and decide on the choice that best completes the question.
Defend your choice in the space provided.
A) Microevolution
1. Which of the following mechanisms would be necessary in order for Lamarck’s theory of evolution to be valid?
a)
The nervous system causes specific mutations of DNA.
b)
Mutations occur at random locations in DNA.
c)
All parts of the body contribute to the genetic information in the gamete.
d)
Proteins direct their own replication.
e)
One parent’s gametes are diploid.
Answer: ______: 2. It is often stated that most new mutations are recessive. Which of the following assumptions would be most
important in arguing for this statement?
a)
Most individuals are heterozygous for most of their genes.
b)
Most individuals are homozygous for most of their genes.
c)
Most existing alleles are recessive.
d)
Most existing alleles are dominant.
e)
Mutations are rare events.
Answer: ______: 3. A sample of butterflies contained 50% yellow-winged individuals and 50% black-winged individuals. In this
species, wing color is determined by a single gene with two alleles, and the allele for black is dominant. Which of
the following statements about the allele frequencies in the sample would most likely be true? Do not assume that
this sample was obtained from a population in genetic equilibrium.
a)
The frequency of the yellow allele is greater than that of the black allele.
b)
The allele frequency of yellow is 3 times the allele frequency of black.
c)
The allele frequency of yellow is twice the allele frequency of black.
d)
The allele frequencies of black and yellow are equal.
e)
The allele frequency of black is greater than the allele frequency of yellow.
Answer: ______: 4. Now assume that the population of butterflies sampled in question 3 is in Hardy-Weinberg equilibrium. Also assume
that the sample is random and large enough that the allele frequencies in the sample equal the allele frequencies in
the population. What is the frequency of the allele for yellow wings in the population?
Answer: ______: B) Speciation
5. Once concept of evolution has been based on the idea that a new kind of organism would emerge by a sudden, large
mutation in an individual. This new type of individual would then exploit a new way of life and proliferate as a new
species. Which of the following statements makes the strongest argument against this hypothesis?
a)
A single, sudden mutation cannot produce that much difference in an individual.
b)
Such a large mutation would most likely be lethal.
c)
Natural selection takes longer than one generation to produce a new species.
d)
There would be no mate for the first individual of the new species.
e)
The new species would begin with too little genetic variation and would rapidly become extinct.
Answer: ______: 6. Which of the following would best test the hypothesis that two populations of very similar squirrels, isolated from
contact with each other, are different species?
a)
Examine many individuals to determine whether there are any morphological differences between the two
populations.
b)
Examine DNA from many individuals to assess genetic differences between the two populations.
c)
Examine the environments in the two locations to determine whether the same selection pressures would be
operating.
d)
Capture live individuals from both populations and determine whether they can crossbreed and produce
viable, fertile offspring.
e)
Look for hybrids between the two populations in the wild.
Answer: ______: C) Macroevolution
7. Sequences of strata in sedimentary rocks are very useful in the working out of evolutionary sequences. Occasionally,
however, anomalous patterns are observed that seem to be due to later inversion of many strata. Which of the
following observations would be evidence of secondary inversion of strata?
a)
Unusual sequences of fossils in strata.
b)
Human and dinosaur fossils in the same strata.
c)
Strata tilted from the horizontal plane.
d)
Raindrop imprints and ripple marks on the bottoms of strata.
e)
Sudden changes from one type of rock to another in the horizontal plane within one layer.
Answer: ______: 8. Fossils found in rock suggest that
Life started on Earth
Plants live on land
Flowering plants (monocots) “develop”
Dinosaurs “vanish”
Humans “appear” 3,500 million years ago (mya)
400 mya
80 mya
65 mya
150,000 years ago Compare these time spans by changing the scale from years to seconds: let 1 yr = 1 sec.
Thus, in this scale the average biology student is 20 seconds old.
a) In this scale, how many days ago did humans appear? b) How many years ago did the dinosaurs vanish? c) How many years ago did flowering plants begin to dominate? d) How many years ago did plants start to live on land? e) How many years ago did cells first fossilize? 9. In studying evolution, a common characteristic can be compared to determine how much variability exists among
species. An example in vertebrate species is the number of differences in hemoglobin. Hemoglobin has 146 amino
acids.
The following chart compares hemoglobin from five other species to that of humans:
Species
Rhesus monkey
Mouse
Chicken
Frog
Lamprey Number of Different Amino Acids
8
25
45
70
125 Estimated Million of Years from
Common Ancestor
26
80
275
330
450 a) Find the average number of years per mutation in hemoglobin for each species listed. b) Find the mutation rate in mutations per million years for each species. c) Which animal show a mutation rate closest to the average? d) What percentage of the amino acids are different from humans in the monkey and the lamprey? 10. New species arise by several different mechanisms. Allopatric speciation is due to changing geographical barriers,
such as widening oceans in geological time. Sympatric speciation is due to a radical change in the genome.
Recombinant speciation can occur naturally or because of human selection of desirable traits, and results in the
many species of tulips and dogs that exist.
An example of allopatric speciation occurred with the sycamore. Sycamores in Eurasia and North America were
separated about 50 million years ago. During that time mutations caused two identifiable species, although when
Europeans brought the North American species to England in the 1600s the two species were crossed and produced
a fully fertile hybrid.
Sympatric speciation occurred in goat’s beard in less than 100 years (100 generations), by allopolyploidy.
In sunflowers, a “new species” can arise in 5 generations (5 years) by recombinant speciation.
a) If the length of a generation of sycamores is 25 years (time from seed to seed), how many generations elapsed
in the creation of the two morphological species? Of the examples listed above:
b)
How many times faster is recombinant speciation than the other two types, in terms of years? c) How many times faster is recombinant speciation than the other two types, in terms of generations?
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