BIOL 1503: EXAM 1 QUESTIONS AND ANSWERS A+ GRADED. Buy Quality Materials!
Evolution
change over time of the genetic composition of a population; descent of modern organisms with modification from preexisting organisms evolutionary adaptation
Evolution states that organisms descended from ___...
Evolution
change over time of the genetic composition of a population; descent of modern
organisms with modification from preexisting organisms evolutionary adaptation
Evolution states that organisms descended from ____________ organisms.
ancestral
Adaptation
accumulation of inherited characteristics that enhance organisms ability to survive in
specific environment
Favorable Adaptation
adaptations that help the organism survive and reproduce
Catastrophism
the principle that events in the past occurred suddenly and were caused by different
mechanisms than those operating today
Describe the evidence that supports catastrophism.
Each strata (layer of rock) represents some sort of catastrophe that destroyed many of
the species living at the time. Catastrophism is confined to local regions which were
later repopulated by new species.
Uniformtarianism
the principle that mechanisms of change are constant over time
What do scientists who support uniformtarianism believe?
The scientists believe that the same geological processes are operating today as in the
past and at the same rate.
Explain the mechanism for evolutionary change proposed by Jean Baptiste de
Lamarck.
1. Use and Disuse: bodies of living organisms are modified through the use or disuse of
parts
i.e. Giraffes:
Back in the day, scientists figured out that giraffes had shorter necks and legs. The
giraffes would stretch their legs and necks. The giraffes became longer and taller, and
passed the trait to the next generation
Inheritance of acquired characteristics: these modifications are inherited by offspring;
organisms have the innate desire to become more complex
Natural Selection
the unequal survival and reproduction of organism due to environmental forces,
resulting in the preservation of favorable adaptations
What are the requirements for natural selection to occur?
1. Variability: variation in traits in a population
2. Heritability: traits have to be inheritable - passed from one generation to the next
3. Differential reproductive success: traits must allow the population to survive and
reproduce better - favorable traits
,True or False: Natural selection "selects" from what is available in the gene pool.
True
Explain why new characteristics are not created on demand.
Natural selection only works on the variability already in the population. The favorable
traits are the ones that survive more and reproduce more and have a disproportionate
effect on the next generation.
Explain the mechanisms behind natural selection.
Individuals with heritable characteristics experience competition among each other for
finite resources. These facts result in those individuals who are more suited for their
environment produce more offspring than those who are not well-suited, and, over time,
these favorable traits increase in frequency within the population.
How does natural selection explain the unity of life?
Organisms share many characteristics, indicating that a common ancestor lived in the
remote past.
How does natural selection explain the diversity of life?
It is hypothesized that the ancestral organisms lived in various habitats, so they
accumulated adaptations that fit them to certain ways of life.
Describe the two inferences Darwin made from his observations that led him to
propose natural selection as a mechanism for evolutionary change.
1. Individuals whose inherited traits give them a higher probability of surviving and
reproducing in a given environment tend to leave more offspring than other individuals.
2. This unequal ability of individuals to survive and reproduce will lead to the
accumulation of favorable traits in the population over generations.
The widespread use of DDT in the mid-1900's put pressure on insect populations
to evolve resistance to the insecticide. As a result, large populations of insects
today are resistant to DDT.
A. Darwinian
B. Lamarckian
B. Lamarckian
Many bacterial strains that infect humans today are resistant to a wide range of
antibiotics. These resistant strains were not so numerous or common prior to the
use of antibiotics. These strains must have appeared or evolved in response to
the use of antibiotics.
A. Lamarckian
B. Darwinian
A. Lamarckian
Distinguish between artificial selection and natural selection.
artificial selection: the selective breeding of domesticated plaints and animals to
encourage the occurrence of desirable traits -- purposefully done by human intervention
natural selection: a process in which individuals that have certain inherited traits tend to
survive and reproduce at higher rates than other individuals because of those traits --
occurs naturally in nature
Explain why an individual organism cannot evolve.
, Evolutionary processes acts on individuals, but populations evolve. The effect of
evolution is seen and measured in populations - it is a change in gene frequency over
time through the generations.
Describe the observations of soapberry bugs that supported Carroll and Boyd's
hypothesis that changes in a population's food source can result in evolution by
natural selection.
The soapberry bugs in Florida's natural food source were bloom vine plants (puffy
plants). The soapberry bugs would use their beaks to suck the nutrients out of the
seeds. Another species of plant was introduced, and it was much more compact (the
seeds were closer to the surface). Since it doesn't require as long as a beak length to
feed on the plant, we see a decrease in the length of the beak. Those who fed more
effectively tended to reproduce more.
Explain how drug resistance develops in bacteria and viruses.
i.e. HIV Virus
Patients at time zero have a low percentage of resistance to the 3TC. After the drug is
administered, we change the selective pressure, and those who were not resistant to
the drug die off and those who were resistant reproduce and become more plentiful.
Over time, resistance goes up to nearly 100% resistance to 3TC, making the drug
ineffective.
How do we get around this problem?
Drug cocktails: we take three to four different drugs, affecting the bacteria in different
ways.
Within a few weeks of treatment with the drug 3TC, a patient's HIV population
almost entirely consists of 3TC-resistant viruses. How can this best be
explained?
A. HIV has the ability to change its surface proteins to resist drugs.
B. A few drug resistant viruses were present at the start of treatment and natural
selection increased their frequency.
B. A few drug resistant viruses were present at the start of treatment and natural
selection increased their frequency.
Homologous Structures
structures or other attributes in different species that resemble each other because of
common ancestry
How are homologous structures evidence of the theory of evolution?
An organism has that feature because a common ancestor had that feature and was
passed along.
Explain the homologous structures found in mammalian forelimbs.
Although our forelimbs are used for different functions, the skeletal structure has the
same structure of bones. Why? Vertebrates share a common ancestor with the same or
similar plan or format.
Explain the similarities found in vertebrate embryos.
All vertebrates share similar developmental genes. Differences arise by some genes
switched on or off at varying times during development.
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