Define the following terms

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Evolution Study Guide

  1. Define the following terms:

Spontaneous Generation

The belief that living things came from non-living things


All living things come from other living things


Differences among the same species


A trait that makes an organism successful in its environment


Two species evolve together, changing and impacting one another

Natural Selection

The environment selects for desirable traits. It is the mechanism for “descent of modification”

Big Bang Theory

Scientifically supported that the universe began from an explosion in space

  1. Explain the experiments and conclusions of the following scientists. Be sure you know how their experiments disproved spontaneous generation!

Redi: 1668

Conducted experiments to disprove spontaneous generation

Control group: jar with meat in it open to the air

Experimental Group: Jar with meat and covered so air can pass through but nothing else

Conclusion: maggots don’t come from rotting meat, rather they are the hatched eggs of flies

Spallanzani: 1768

Performed more experiments to disprove spontaneous generation

Control Group: boiled broth and left the broth open

Experimental Group: boiled broth and sealed the flask

Bacteria grew in the open flask and did not grow in the sealed flask.

Conclusion: bacteria comes from the air


Disproved spontaneous generation

Boiled broth and bent the neck of the flask to allow air to pass but not any particles.

Conclusion: The open curved neck flask with the boiled broth did not grow any bacteria.

  1. Explain the experiment of the Miller and Urey. Be sure you are familiar with their set- up apparatus and what their conclusions were.

Miller and Urey recreated the conditions of the primitive earth in a closed experiment. They used gases believed to have existed on the primitive earth and used an electrical spark to simulate the energy from lightening. The result was they organic compounds were produced.

  1. Who was Oparin? What did he do and conclude?

Oparin is credited with the heterotroph hypothesis. He, along with other scientists, thought that the early atmosphere contained ammonia, hydrogen gas, water vapor and methane. According to Oparin, at high temperatures, these gases might have formed simple organic compounds such as amino acids. When the earth cooled and water vapor condensed these simple organic compounds collected in the water. Over time these compounds could have entered complex chemical reactions, fueled by energy from lightning and ultraviolet radiation. These reactions ultimately would have resulted in the macromolecules essential to life such as proteins.

  1. Explain the endosymbiotic theory.

Early prokaryotic cells may have developed a mutually beneficial relationship early on. Evidence suggests that a small aerobic prokaryote was engulfed by and began to live and reproduce inside a larger anaerobic prokaryote. It is thought that these early symbiotic prokaryotes over time developed into mitochondria capable of aerobic respiration and chloroplasts capable of photosynthesis.

  1. Explain the first organisms on earth (were they prokaryotes or eukaryotes; anaerobic/aerobic; able to perform photosynthesis).

The first organisms were anaerobic heterotrophic prokaryotes as there was no oxygen in the early atmosphere. These prokaryotes had to rely on others for a source of food.

  1. Explain the different parts of Darwin’s theory of natural selection.

  1. Overproduction – more offspring are produced than can survive

  2. Competition – only some organisms survive long enough to reproduce

7a. Components of Darwin-Wallaces Theory:

  1. Descent with modification – states that evolution is the development of new organisms from pre-existing organisms over time.

  2. Natural Selection – the environment selects the desirable traits

  3. Variation – variations within a population are inherited and lead to differences in organisms

  4. Adapation- traits that are favorable and improve the organism’s ability to function and reproduce.

  5. Survival of the fittest – states that survivors pass on their variations, resulting in the next generation will have those variations

  6. Fitness – is the measure of an individual’s genetic contribution to the next generation

  7. Speciation – over time, small changes accumulate and populations change.

  8. Species – a group of organisms that can mate and produce fertile offspring.

  1. What was LaMarck’s theory? How did it compare/contrast to Darwins?

  1. Use and Disuse – body parts that are used more grow stronger and bigger while body parts that are not used deteriorate.

  2. Inheritance of Acquired Characteristics Theory – physical traits that were changed in an organism are inherited by their offspring. (these changes are not in the genes!)

  1. In the chart below there are evidence to prove evolution. Please define these pieces of evidence and give examples (if appropriate).

Geologic Evidence (Fossils)

Fossils are remains/traces of organisms that died long ago. They are often found in rock layers. Fossil record suggests that different species were present in the past than today.

Comparative Embryology

This is the study of embryos as they develop. Similarities of the development of embryos suggest that the species have a common ancestor

Comparative Biochemistry

Comparison of amino acids that shows a relationship between organisms for example the comparison of cytochrome C between different organisms.

Homologous Structures

Organisms with similar internal parts have different functions in different organisms. This suggests a common ancestor.

Ex. Bat wing, whale fin, cat leg, human arm

Analogous Structures

Structures of different organisms have similar external form and function and different internal forms and functions. It suggests that species came from different ancestral lines.

Ex. Bat wing, bird wing, insect wing

Vestigial Structures

These are structures that over time have been reduced in size and have no function.

This suggests that the structure was once used by an evolutionary ancestor.

Ex. Human appendix, tailbone

  1. What was the overall conclusion that could be made about all the pieces of evidence that you listed for question #9?

Overall the evidence demonstrates that different modern organisms once shared a common ancestor and that over time they have evolved, supporting the theory of evolution.

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