Download Tommy Williams NC SCoS 3

Tommy Williams  NC SCoS 3.05
Evolution, the change of species over time, is the central unifying theme of biology.
Biological evolution occurs through natural selection. Natural selection is the result of
overproduction of offspring having variations, these variations struggling for survival, and the
subsequent survival and increased reproduction of those best adapted to a particular environment.
Natural selection is the evolutionary process which selects the variations of organisms best suited
for a particular environment. Natural selection and its evolutionary consequences provide a
scientific explanation for the fossil record of ancient life, as well as for the molecular and
structural similarities observed among the diverse species of living organisms.
The degree of kinship between organisms or species can be estimated from the similarity of their
DNA sequences; this similarity often closely matches organisms' or species' classification based
on anatomical similarities.
DNA Sequence Similarities in Some Primates
The graphic above shows that:
1. All of these primates had a common ancestor, the
ancestral primate.
2. The human and chimpanzee have the closest
evolutionary relationship as their DNA is the
most similar.
Characteristics of Natural Selection:
1. Overproduction: Within a population more offspring are born than can possibly survive.
2. Competition: Since the number of individuals in a population tends to remain
constant from generation to generation due to limited resources, a struggle for survival
occurs.
3. Survival of the Fittest: The individuals who survive are the ones best adapted to exist in
their environment due to the possession of variations that best suit them to their
environment. This genetic variability within a species is chiefly due to mutation
and genetic recombination. The variation of organisms within a species increases the
likelihood that at least some members of the species will survive under
changed environmental conditions.
4. Reproduction: Variations assist or hinder individuals in their struggle for survival. The
best adapted individuals survive and reproduce, passing on the favorable variations to
their offspring.
5. Speciation: As time and generations continue, adaptations are passed on and new species
may evolve from a common ancestor.
Relative Dating of Undisturbed Sedimentary Rock and
its Fossils
Upper strata generally contain fossils of younger, more
complex
organisms, whereas, the lower strata contain fossils of
simpler life forms. This means there is a tendency toward
increasing complexity in life forms over time.
When comparing fossils in undisturbed strata, fossils can be found in upper strata which, although
different from fossils in lower strata, resemble those fossils. This suggests links between modern
forms and older forms, as well as divergent pathways from common ancestors.
Evolution does not occur in individuals but in populations. Darwin's theory included the fact that
evolutionary changes take place slowly. In many cases, the fossil record shows that a species
changed gradually over time. The theory that evolution occurs gradually is known as gradualism.
In contrast to gradualism is the theory of punctuated equilibrium, which is a point of discussion
among scientists. According to the theory of punctuated equilibrium, some species have long,
stable periods of existence interrupted by relatively brief periods of rapid change.
Both groups of scientists agree that natural selection is the single most important factor in
evolutionary changes in species. Whether the change is slow and gradual, or punctuated and
rapid, one thing is certain: Organisms have evolved over time.
(E.X. The DNA base-pair sequences that serve as gene-regulatory sites have been selected
during evolution to provide an appropriate functional binding for a particular protein)
Multiple choice
1.) The spotted touch-me-not, a flowering plant, has seed pods that burst open when
touched and forcefully eject their seeds. Such an adaptation is favorable because it
A.
B.
C.
D.
aids in the dispersal of the species.
attracts insects that aid in pollination.
prevents germination within the seed pod.
can cause genetic changes to occur.
2.) The diagram below illustrates the change that occurred in the frequency of phenotypes
in an insect population over 10 generations. A probable explanation for this change
would be that over time there was
A.
B.
C.
D.
a decrease in the adaptive value of gene a
an increase in the adaptive value of gene a
an increase in the population of this insect
a decrease in the mutation rate of gene A
3.) According to Darwin's theory of evolution, differences between species may be the
result of
A.
B.
C.
D.
the disuse of body structures
the transmission of acquired characteristics
natural selection
mutagenic agents
4.) Two nucleotide sequences found in two different species are almost exactly the same.
This suggests that these species
A.
B.
C.
D.
are evolving into the same species
contain identical DNA
may have similar evolutionary histories
have the same number of mutations
5.) The diagram below shows undisturbed sedimentary strata at the bottom of an ocean.
The fossils found in layer B resemble the fossils found in layer A. This similarity
suggests that
A.
B.
C.
D.
the fossils in layer B were formed before the fossils in layer A
modern forms of life may have evolved from earlier forms of life
vertebrate fossils are only found in sediments
the fossils in layer A must be more complex than those in layer B
6.) The theory that evolutionary change is slow and continuous is known as
A.
B.
C.
D.
punctuated equilibrium
geographic isolation
speciation
gradualism
7.) The concept that species have changed over long periods of time is known as
A.
B.
C.
D.
ecology
embryology
spontaneous generation
organic evolution
8.) The study of homologous structures in mature organisms provides evidence for the
evolutionary relationships among certain groups of organisms. Which field of study
includes this evidence of evolution?
A.
B.
C.
D.
comparative cytology
biochemistry
geology
comparative anatomy
9.) The diagram below represents a section of undisturbed layers of sedimentary rock in
New York State and shows the location of fossils of several closely related species.
According to currently accepted evolutionary theory, which is the most probable
assumption about species A, B, and C?
A.
B.
C.
D.
Species B is more abundant than species C.
Species C existed before species B.
Species A and B are genetically identical.
Species B descended from species A.
10.) Which group of organisms is believed to be among the earliest to evolve on Earth?
A.
B.
C.
D.
arthropods
coelenterates
protozoans
reptiles
Multiple Choice Answers
1.A
2.B
3.C
4.C
5.B
6.D
7.D
8.D
9.B
10.C
Short Answer
1.) _______ are an important source of evolutionary evidence because they
provide a record of early life and evolutionary history.
2.) ______ the change of species over time, is the central unifying theme of
biology.
3.) ______ is the evolutionary process which selects the variations of organisms
best suited for a particular environment.
4.) Evolution does not occur in individuals but in_______.
5.) The individuals who survive are the ones best adapted to exist in their
6.)
7.)
8.)
environment due to the possession of variations that best suit them to their
environment is known as survival of ____ _______.
According to the theory of______ __________, some species have long, stable
periods of existence interrupted by relatively brief periods of rapid change.
Within a population more offspring are born than can possibly survive. This
process is known as _________.
. Darwin's theory included the fact that evolutionary changes take place
(Slow/Fast)?
The theory that evolution occurs gradually is known as ______?
9.)
10.)
A species is a group of similar organisms that ___________
11.)
A species that no longer is found on Earth is said to be _______
12.)
a/an _______ helps an organism to survive
13.)
A change in an organisms DNA is known as ___________
14.)
differences between members of the same species are called
_______
15.)
Structures that are no longer used in an organism are called ______
16.)
the process where desired characteristics are chosen for
reproductive purposes is __________
17.)
Breeding organisms with specific traits in order to produce
offspring with identical traits is called __________
18.)
_______ is a structural adaption that enables one species to
resemble another species.
19.)
According to the heterotroph hypothesis, the first life on Earth was
able to ___________.
20.)
Darwin's theory of evolution is based on the concept of _______.
SHORT ANSWER ANSWERS
1.) Fossils
2.) Evolution
3.) Natural Selection
4.) populations
5.) the fittest
6.) punctuated equilibrium
7.) overproduction
8.) Slow
9.) gradualism
10.) can mate with each other and produce offspring
11.) extinct
12.) adaption
13.) mutation
14.) variations
15.) vestigial structures
16.) selective breeding
17.) artificial selection
18.) mimicry
19.) feed upon available nutrients in the environment
20.) natural selection