Earth and Early Life Forms Quiz

Earth and Early Life Forms

• Stromatolites: Layered sedimentary rocks formed by ancient cyanobacteria. They are the first fossil evidence of life.

• Endosymbiotic Theory: Explains that eukaryotes originated from prokaryotes in a symbiotic relationship.

• Evidence Supporting Endosymbiotic Theory:

  • Prokaryotes have enzyme and transport systems similar to those in mitochondria and plastids.
  • Binary fission, a method of prokaryotic reproduction, is similar to how endosymbionts divide.
  • Circular DNA and protein types are present in both prokaryotes and endosymbionts (with a few, or no, histones).
  • Endosymbionts have machinery to transcribe and translate DNA into proteins, similar to prokaryotes.
  • Prokaryotes and endosymbionts have similar ribosome structures.

Divisions of Geologic Time

• Geology time scale: Records Earth's history and the order of life from 2.5 billion years ago to the present.

• Eons: Major divisions of time (hundreds of millions of years).

  • Hadean Eon
  • Archaean Eon
  • Proterozoic Eon
  • Phanerozoic Eon

Mechanisms of Evolution

• Evolution: The process by which changes in plants and animals occur over time, driven by mechanisms like natural selection and mutations.

• Mechanisms of Evolution:

  • Natural Selection
  • Mutations
  • Genetic Drift

Principles of Natural Selection

• Natural populations: Have a capacity to increase in size.
• Limited resources: As populations grow resources like food and space become limited leading to competition.
• Variation: Individuals within species share many traits but vary in details of these traits. Variations in traits are heritable.
• Inference: The form of a trait that allows an organism better survival will allow it to produce more offspring, therefore individuals with advantageous variations will have more offspring and those variations therefore become more common within a population over time.

Mutation

• Mutation: A change in the DNA sequence of a gene, potentially leading to a phenotypic change in an organism.
  • Mutations can be harmful, beneficial, or neutral.
  • Harmful mutations are often removed from a population.
  • Beneficial mutations can spread through a population.
  • Neutral mutations may have no effect on fitness.
• Genetic Drift: Random fluctuations in allele frequencies (the presence of different forms of a gene) within populations. This occurs when some individuals of a population have more offspring than others, altering the genetic makeup of subsequent generations. This is a random effect as opposed to selection effects driven by natural selection.

Test your knowledge on stromatolites and the endosymbiotic theory, which discusses the origins of eukaryotes. Explore key evidence supporting these concepts and learn about the divisions of geologic time. Perfect for biology enthusiasts and students alike!