widely known theory that all forms of life have been derived from a single ancestor is explained by Darwin’s Theory of Evolution. Darwin's general theory postulates the creation of living organisms from non-life by some wholly unknown process and touts a purely naturalistic and undirected "descent with modification” Arising from simpler beings, today’s organisms have evolved to become more complex. One of the major factors that have been attributed to such deviations is genetic variation. Genes are dynamic and undergo mutations. Those that are favorable to life and optimize survival help the particular genes to thrive and be passed on to subsequent generations.
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Prokaryotes were Earth’s original inhabitants, being derived from amino acid precursors 3-4 billion years ago. Over the next few billion years, the gene pool remained relatively static and no major deviations were seen. Single celled eukaryotes emerged between 1.6 – 2.7 billion years ago. Drastic changes began to occur when bacteria were enveloped by eukaryotic cells during a collective relationship called endosymbiosis.
The beginning of life on Earth was composed of three different categories that included unicellular eukaryotes, archaea, and prokaryotes until about 610 million years ago. During the Ediacaran period, multicellular organisms began to emerge in aquatic environments. Multicellular organisms evolved over time via a variety of independent events,
which was accompanied by the creation of organisms as diverse as brown algae, sponges, cyanobacteria, myxobacteria, and slime molds. The Cambrian explosion occurred soon after, leading to a surprising bloom of biological diversity over the course of the next 10 million years. This event was a milestone that eventually le a d to t he appearance of modern animals in the fossil record , as well as other extraordinary lineages that subsequently became extinct. There are many hypotheses regarding the cause of the dramatic Cambrian expansion, but the most popularly held belief is that it was due to the accumulation of oxygen in the atmosphere as a result of photosynthesis. About 500 million years ago, plants and fungi took root and were soon accompanied by arthropods and other animals. Insects were considerably more successful and to this day make up the vast majority of the animal kingdom. Amphibians first arose around 364 million years ago and were followed by primitive amniotes and birds about 155 million years ago. Both groups developed from reptile-like lineages. Mammals finally emerged around 129 million years ago, with homininae coming to existence around 10 million years ago and modern humans around 250,000 years ago. However, even though larger, more robust animals have evolved, smaller organisms analogous to those of primeval times remain immensely successful and continue to dominate. Prokaryotes comprise the largest biomass on the planet as well as species number.
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Consequently, even though structures have similar internal mechanics and organization, they may have different functions and purposes, even in related organisms.
This is the result of a single ancestral structure being adapted to function in varying ways that best suit the host. For example, the bones in bat wings share similarities with those in primate hands and mice feet . This is due to the fact that all of these structures descended from a common mammalian denominator. Therefore, since all living organisms are interconnected to some degree, even organs that seem to have little or no structural similarity can trace their lineage to a common set of homologous genes that control their function and assembly. This is called deep homology, and these features of biological organisms are known as homologous structures.
Adaptation may cause either the acquisition of new features, or the disappearance of
an ancestral feature. An example that shows both versions of change relates to the use of antibiotics and the development of resistant bacteria . Antigenic variation cause antibiotic intransigence that is effective due to the increase the activity of transporters that pump drugs out of the cell or by modifying the target of the drug . Other stunning examples include the and its ability to utilize citric acid as a form of nutrition . T he bacterium Sphingobium , which lives in soil, evolved a completely new metabolic process that degrades the synthetic pesticide pentachlorophenol. Flavobacterium evolved a unique enzyme that permits the bacteria to grow on the by-products of nylon manufacturing.
P1 - 1.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? <hl id=”reading-19”>Darwin's general theory postulates
the creation of living organisms from non-life by some wholly unknown process and touts a purely naturalistic and undirected "descent with modification .” </hl> Incorrect choices change the meaning in important ways or leave out essential information. <QT1.Sentence simplification>B
a. The development of organisms is directed mainly by the hand of man or another entity
in order to breed the best animals for consumption.
b. Combinations of inorganic material formed a living being by means unknown, and over time, further changes in structure and function that aided in survival remained.
c. The accidental combination of inorganic material created the first traces of life which led to the creation of more complicated organisms over time.
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d. Random organic compounds were coupled with DNA to help change their physiology and further enable them to adapt to their environments.
P1 - 2. The word <hl id=”reading-20”>”deviations”</hl> in the passage is closest in meaning to <QT3.vocab>A
creations c. genetics d. organisms
P2 - 3. According to paragraph 2, which of the following is true of early cellular evolution? <QT2.fact &negative fact> A
a. For the first 3 billion years of prokaryotic life, there were no drastic genetic changes
b. Prokaryotes quickly evolved into eukaryotes when they combined with bacteria
c. Eukaryotes gave rise to prokaryotes after a few billion years of evolution
d. Bacteria and eukaryotes underwent evolution at the same time and created prokaryotes
Paragraph 2 is marked with an arrow <ar id=”reading-21”></ar>
P2 - 4.The word <hl id=”reading-22”>“enveloped”</hl> in the passage is closest in meaning to <QT3.vocab>C
P3 - 5. According to paragraph 3, where did multicellular life on earth first occur? < QT2.fact & negative fact> D
c. on land
Paragraph 3 is marked with an arrow <ar id=”reading-23”></ar>
P3 - 6. Which of the following can be inferred from paragraph 3 about the timeline of evolutionary biology? <QT6.inference>C
became very prolific about 610 billion years ago
b. it occurred billions of years before prokaryotes
c. it has occurred fairly recently in the earth’s history
d. it did not begin until the Cambrian explosion
Paragraph 3 is marked with arrow <ar id=”reading-23”></ar>
P4 - 7. According to paragraph 4, which organisms were the first to move onto land? PICK TWO <QT2.Fact & Negative fact>A,D
Paragraph 4 is marked with an arrow <ar id=”reading-24”></ar>
P4 - 8.The word <hl id=”reading-25”>“primitive”</hl> in the passage is closest in meaning to <QT3. Vocab>B
P5 - 9. What is the purpose of paragraph 5? <QT5.Rhetorical purpose>C
a. to explain the process through which hands evolved into wings
b. to discuss the function and evolution of mammal appendages
c. to explain post single-cell and homologous evolution in detail
d. to discuss how different adaptations have the same purpose
Paragraph 5 is marked with an arrow <ar id=”reading-26”></ar>
P5 - 10. The word <hl id=”reading-27”>“lineage”</hl> in the passage is closest in meaning to <QT3. vocab>D
P5 - 11.Paragraph 5 suggests what about evolution and deep homology? <QT2.Fact and Negative fact>A
a. that all organisms can trace their adaptations back to a few sets of homologous genes
b. that many animals have internal adaptations independent in function from each other
c. deep homology generally only appears in mammals and other land dwelling animals
d. it applies to arthropods, fish, and some algae based on their processes of evolution
Paragraph 5 is marked with an arrow <ar id=”reading-26”></ar>
P6 - 12.According to paragraph 6, bacterial adaptation to antibiotics occurs in which way? <QT2. fact and Negative fact> C
a. they need certain interactions in a laboratory environment for this to occur
b. they have been almost completely eradicated except for the most resistant strains
c. they can gain or lose adaptations based on environmental circumstances
d. they can only evolve if they come into contact with chemicals that can kill them
Paragraph 6 is marked with an arrow <ar id=”reading-28”></ar>
P6 - 13. Look at the four squares <sq id=”reading-29”></sq> that indicate where the following sentence could be added to the passage. <QT7.insertion>2nd
This is a good example of how survival plays into the nature of evolutionary adaptations and how those organisms that don’t adapt die.
Where would the sentence best fit? Click on a square <sq id=”reading-29”></sq> to add the sentence to the passage.
14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.<br /><br />
Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. To review the passage, click VIEW TEXT.<Summary>A,C,D<br /><br />
Evolution is the process of organisms adapting to changes in their environment to survive and the death of those that do not.
a. Initially, prokaryotes and eukaryotes existed in the oceans and absorbed bacteria, and through mutual adaptation in both organisms, caused increased diversity.
b. Single-celled organisms gave rise to bacteria, which in turn gave rise to eukaryotes, and then to amphibians and crustaceans,
but they never moved out of the oceans.
c. After eukaryotes emerged, the Cambrian explosion
hosted an increased rate of evolution which led to land first being colonized by plants and fungi, followed by other animals.
d. Many animals and organisms develop homogeneously, meaning that they share a set of common, homogenous genes which evolved differently over time in different animals
e. Bacteria are the main cause of continued evolution in humans and other species because they force us to adapt to the different sicknesses that they cause.
f. Most organisms on earth are now multicellular because they have found it to be more evolutionarily advantageous to use multiple cells and utilize many different adaptations.