Biology 1023 Final Exam Based With
Correct Answers
Lamarck's proposal of evolution - CORRECT ANSWER-1. Originally, giraffes had short
necks.
2. Giraffes stretched their necks in order to reach food.
3. With continual stretching, most giraffes now have long necks.
Darwin's proposal of evolution - CORRECT ANSWER-1. Originally, giraffe neck length
varied.
2. Struggle to exist causes long-necked giraffes to have the most offspring.
3. Due to natural selection, giraffes now have long necks.
Darwin completed a five-year journey around the world on what? And what did he do
during this time? - CORRECT ANSWER-The HMS Beagle. He made many geological
observations. He hypothesized that slow processes brought geological changes over
time. Based on this, the earth must be very old. He collected fossil specimens within the
area he traveled. He found that these specimens varied from the modern species
around the world. He hypothesized that there would be enough time for descent with
modification to occur and change species over time.
Steps involved in natural selection - CORRECT ANSWER-1. Organisms within a
population have heritable variations that are passed on from generation to generation.
2. The population produces more offspring than the resources of the environment can
support, therefore, only certain members survive and reproduce.
3. Individuals with favorable traits survive and reproduce to a greater extent than those
without them.
4. Over time, the proportion of the favorable traits increases in the population, and the
population becomes adapted to the environment.
Examples of artificial selection - CORRECT ANSWER-1. Brussels sprouts evolved as a
result of farmers selecting for abnormally large bud size.
2. Dogs are all the same species but breeds exist due to selective breeding by humans.
3. Chinese cabbage evolved as a result of farmers selecting for plants with decreased
internode length.
4. Kohlrabi evolved as a result of farmers selecting for plants with increased lateral
meristematic growth.
5. Intentional choice of specific characteristics.
The fossil record and how it supports the hypothesis of common descent. - CORRECT
ANSWER-1. The remains of once-living species called fossils are found in the strata
and provide a fossil record that tells us about the history of life.
,2. A striking pattern found in this is a succession of lifeforms from simple to more
complex.
3. Of great interest are the transitional links that show the relationship between different
groups of lifeforms.
4. For example, in 2004 paleontologists discovered Tiktaalik roseae, which is the
transitional form between fish and four-legged animals.
Describe homologous structures as evidence for evolution. - CORRECT ANSWER-1.
Structures that are anatomically similar because they were inherited from a common
ancestor are called homologous structures.
2. The forearms of a bat, bird, whale, and cat all contain the same arrangement of
bones, but each serves a different function.
3. Oppositely, analogous structures are those that serve the same function, but are
anatomically different.
4. The presence of homology, not analogy, is evidence that organisms are related.
Molecular evidence for common descent. - CORRECT ANSWER-1. All living organisms
use DNA, RNA, and ATP, which leads scientists to the conclusion that these molecules
were present in the first living organism.
2. Organisms also use the same DNA triplet code for amino acids in their protein
structure.
3. Thus, differences between species exist mainly due to small differences between the
proteins each one produces and uses.
4. Some organisms have very few differences in the amino acid sequences of their
proteins, yet are vastly different in structure and function.
5. These biochemical differences account for a vast majority of variation in life on Earth.
True or false: Based upon the identification of 12 species of Galapagos finches, and
other observations he made, Charles Darwin hypothesized that the finches were not
closely related. - CORRECT ANSWER-False
Directional Selection - CORRECT ANSWER-Form of natural selection in which the
entire curve moves; occurs when individuals at one end of a distribution curve have
higher fitness than individuals in the middle or at the other end of the curve
Stabilizing Selection - CORRECT ANSWER-form of natural selection by which the
center of the curve remains in its current position; occurs when individuals near the
center of a distribution curve have higher fitness than individuals at either end
Disruptive Selection - CORRECT ANSWER-form of natural selection in which a single
curve splits into two; occurs when individuals at the upper and lower ends of a
distribution curve have higher fitness than individuals near the middle
How heterozygotes maintain variation in populations. - CORRECT ANSWER-1. One of
the tenets of natural selection is that within populations, variation exists amongst the
individuals.
, 2. This variation is generated through mutations, recombination, independent
assortment, and gene flow.
3. Because only alleles that are phenotypically expressed are subject to the pressures
of natural selection, heterozygotes can be protectors of recessive alleles that could
possibly be lost otherwise.
4. As long as the heterozygote survives, so do recessive alleles and their corresponding
phenotypes, which could possibly have greater fitness in a changing environment.
5. When natural selection favors the ratio of two or more phenotypes over multiple
generations, it is called balanced polymorphism.
Microevolution - CORRECT ANSWER-1. Peppered moths can be light or dark in color,
and this coloration is controlled by a single set of alleles.
2. The dominant allele encodes for melanin production, which creates dark coloration in
the moths.
3. On the other hand, individuals with two recessive alleles will show light phenotypes.
4. Previous to the rise of industry in Britain, the frequency of the light phenotype was
predominant and enhanced the survival of moths.
5. With the advent of industry, however, pollution darkened the tree trunks, resulting in
an increased frequency of the dark phenotype.
6. This illustrates the process of microevolution and shows that natural selection can
occur even over a short period of time.
Hardy-Weinberg equilibrium - CORRECT ANSWER-1. The Hardy-Weinberg equation is
used to calculate the genotype and allele frequencies of a population.
2. According to this equation, the term p^2 represents the homozygous dominant
individuals within a population.
3. Secondly, the term q^2 represents the homozygous recessive individuals within a
population.
4. Finally, the term 2pq represents the heterozygous individuals within a population.
5. The relationship between the components of the Hardy-Weinberg equation will
remain constant throughout generations, providing five conditions are met.
6. Mutations cannot occur. Gene flow cannot allow alleles into or out of the population.
Individuals must pair randomly. Genetic drift does not occur. All genotypes have an
equal chance to survive.
Describe how nonrandom mating affects populations. - CORRECT ANSWER-1. When
individuals select their mates according to their genotypes or phenotypes, it is called
nonrandom mating; however, when individuals select their mate randomly without
attention to phenotype, it is called random mating.
2. An example of nonrandom mating is inbreeding, or mating between relatives.
3. While inbreeding does not change the allele frequency, it does change the proportion
of homozygous individuals.
4. When individuals mate with those that have the same phenotype with respect to a
certain characteristic, it is called assortative mating.
5. For example, in humans, tall individuals tend to mate with tall individuals.
