Life on Earth Exam 1

  • Define Science.

    • The use of objective problem solving methods to observe the natural world and arrive at reasonable explanations of how the world works

  • Explain what science can and cannot be used for.

    • Science CAN be used to study phenomena that can be observed and measured

      • Art teacher asking to use scientific process to determine which art piece is older

    • Science CANNOT study things that can’t be objectively measured or observed

      • Art teacher asking to use scientific process to determine which art piece is better

    • Science CANNOT be used to test beliefs

  • List the various activities involved in the scientific process.

    • Make observations

    • Come up with possible explanations (hypothesis)

    • Make predictions based on hypothesis

    • Test predictions of the hypothesis in an experiment

    • Decide if results of the test allow you to eliminate (reject) the hypothesis or  accept the hypothesis or revise the hypothesis

    • Let other scientists know about your results

  • Explain why science can be called a process of elimination.

    • Scientists eliminate any explanations that are not valid and keep the others for “further consideration”

    • Even if that means getting rid of all hypotheses

    • Scientists keep going until they are eventually right

  • What would cause a scientist to reject a hypothesis?

    • In order to be rejected it has to be tested or experimented

  • Explain how predictions are formulated from hypotheses using the “if…then…” process.

    • If _____ is correct, then when we do this test we should see these results

    • “If the battery is dead, then the car lights won’t work”

  • Describe the requirements for a controlled experiment.

    • Tests that can be accurately repeated

    • Looks at the effect of one variable (independent)

    • The event or condition affected by the independent variable (dependent)

    • Every variable is being kept the same other than the one independent variable being changed

  • In a controlled experiment, what is assumed to cause changes in the dependent variable?

    • The independent variable

  • Explain why controls are necessary.

    • To see if the independent variable changes anything in the experimental and control group

  • When science is done properly, experimental data are published and read by other scientists. How does that help scientists arrive at better solutions to problems?

  • How do scientists decide if the results of their experiments are valid?

    • By looking at the significant difference

      • Significant Difference - how likely it is that something happened due to the effects of the independent variable

      • 5% or less that the experiment occurred by chance then the results of experiment support the hypothesis

  • How does a hypothesis differ from a scientific theory?

    • Hypotheses can be rejected

    • A scientific theory is a hypothesis that has been tested over and over without being rejected

  • What is the value of a scientific theory?

    • They can be used to tie together facts in a coherent pattern or to identify the principles underlying complex natural patterns

  • Three experiments are described in this video. In one experiment, Marion Petrie cut off the eyespots of some peacocks with “otherwise well-endowed tails”. She then compared their mating success with males with unclipped tails.

    • Which group was the experimental group?

      • Male peacocks with the clipped tails

    • Which group was the control group?

      • Male peacocks with unclipped tails

    • What was the independent variable?

      • Male peacocks with clipped or unclipped tails

    • What was the dependent variable?

      • Female peacock choosing which male she prefers

  • Define Phylogeny

    • The study of the evolutionary history of organisms

  • What is shown on phylogenetic trees?

    • The relationship between different species or other groups of organisms

  • On a phylogenetic tree, what is represented by: 

    • Location of the branch points

      • Relative time of origin of different groups

    • Positions of the species on the tree

      • Indicate closeness of relationship

  • The phylogenetic tree below shows evolution of the major groups from the earliest cell ancestor. Answer the following questions, based on this tree.

    • Which group is most closely related to animals?

      • Fungi

    • Which group is most closely related to plants?

      • Green Algae

    • Which group is most closely related to brown algae?

      • Ciliates

  • How is the process of science applied to a group of phylogenetic trees showing different possible relationships among groups of organisms?

    • Phylogenetic trees are constantly being tested, once it contains a contradiction it will be eliminated or revised

  • Explain why humans use classification systems and the limitations of the systems we use.

    • There’s a lot of organisms and grouping helps simplify the systems into less complex systems

  • Explain how the process of classification works.

    • Works by looking for similarities between organisms and putting the most similar things together in the same group

  • What kinds of structures have been used in classification?

    • Tissues

    • Cells

    • DNA

  • What is the key evidence that all living things descended from the same common ancestors?

    • All living things are made of the same chemical elements (carbon, hydrogen, oxygen, nitrogen)

    • All living things are made of basic molecules (amino acids, sugars, fats, and nucleic acids)

  • What  assumption can be made about two different organisms that have the same type of cell or tissue in their bodies?

    • It’s safe to assume that they have descended from a common ancestor

  • What is taxonomy?

    • The process of identifying and classifying species

  • List the levels of taxonomic classification, from largest to smallest.

    • Domain

    • Kingdom

    • Phylum

    • Class

    • Order

    • Family

    • Genus

    • Species

  • What are the parts of a scientific name?

    • Made up of two latin words

    • Genus and Species/Epithet

  • What are the rules for writing out a scientific name by hand? In print?

    • When writing a scientific name out by hand you have to capitalize the first word (but not the second) and underline the whole name

    • When typing a scientific name out in print then you have to capitalize the first word (but not the second) and italicize the whole name

  • Define a species, using the biological species concept.

    • The concept refers to organisms that reproduce sexually

    • Species - a collection of similar organisms that are capable of interbreeding under natural conditions and producing live, fertile offspring

  • What two conditions are necessary for individuals to belong to the same species?

    • Interbreeding, but naturally, like out in the wild

    • Live and healthy offspring can be produce, which are capable of having offspring

  • Describe the Three Domain classification system. Describe the characteristics of the organism in each Kingdom.

    • Bacteria

      • Unicellular

      • Prokaryotic cell

      • DNA arranged in one circular ring

      • Bacteria, cyanobacteria

      • E Coli, Salmonella, Staphylococcus aureus

    • Archaea

      • Unicellular

      • Prokaryotes

      • Hostile environments (extremophiles)

      • Thermoacidophiles, methanogens, halophiles

    • Eukarya

      • Complex multicellular organisms

      • Eukaryotes

      • Protists, plants, animals fungi

  • Which two Domains contain prokaryotes?

    • Bacteria & Archaea

  • Which Domain is most closely related to Domain Eukarya?

    • Archaea

  • The study of the history of evolution focuses on biodiversity

  • The study of the process of evolution focuses on all of the mechanisms that affect how living things have changed over time (genetic variation, natural selection)

  • Define biodiversity.

    • All organisms alive today or in the past is the result of more than 3.5 billion years of evolution on this planet, including extinctions and speciation events

  • The earliest cells to evolve were Cyanobacteria (prokaryotes) (choose between eukaryotes and prokaryotes).

  • Why are cyanobacteria important in the history of the Earth?

    • They were the first cells to evolve the ability to generate oxygen as a byproduct

  • Describe the origin of eukaryotic cells, including the origin of the nucleus, mitochondria, and chloroplasts.

    • The eukaryotic cells developed as different organelles developed

    • Nucleus

      • Probably evolved from infolding of the plasma membrane which divided the interior of the cell into many compartments

    • Mitochondria

      • Endosymbiosis

    • Chloroplasts

      • Endosymbiosis

    • Endosymbiosis

      • Involves an intimate relationship between two species in which one species lives inside the other species

  • What are protists?

    • Eukaryotes that aren’t plants, animals, or fungi that are usually tiny aquatic organisms

    • (kelp, seaweed)

  • Briefly describe the characteristics of:

    • Plants

      • Multicellular eukaryotes that make their own food (autotrophs)

      • Moss, ferns, horsetails, conifers, flowering plants

    • Fungi

      • Multicellular eukaryotes that are absorptive heterotrophs, digest food by secreting chemicals outside of their bodies onto food particles

      • Mushrooms, molds, yeasts

    • Animals

      • Multicellular eukaryotes that are ingestive heterotrophs, bring food into their bodies, secrete chemicals internally to break down food substances

      • Sponges, worms, crustaceans, insects, fishes, reptiles, birds, mammals

  • Three billion years ago, what type of organisms were present on Earth?

    • Single celled microbes

  • Give an example of how evolution today affects all of us, not just biologists.

    • It underlies many of the most important issues society faces: ways of extinction, evolving bacteria and viruses

  • The study of the process of evolution focuses on:

    • All of the mechanisms that affect how living things have changed over time (genetic variation, natural selection)

  • Define fossils.

    • Any evidence of past life

    • Includes chemical evidence, body parts, traces or impressions of an animal or plant that has been preserves

  • Why do evolutionary biologists use fossils?

    • It helps better understand the process of evolution

  • What is the relationship between the difference in the DNA of two species and the time of divergence of their evolutionary history (split from a common ancestor)?

    • It is assumed that the longer the two species diverged, the more differences accumulated in their DNA

  • What assumption can be made about plants or animals that have similar body structures? Why is this assumption valid?

    • They are assumed to be closely related

    • This assumption is valid because they were inherited from a common ancestor

  • What assumption can be made about plants or animals that have similar embryos? Why is this assumption valid?

    • We can assume that the two species are closely related and have a common ancestor

    • This assumption is valid because if the embryos are similar then there wasn’t much time for evolution to make a big change, therefore they have to be closely related

  • Define biogeography.

    • Branch of science that attempts to explain the distribution of species on Earth

  • What did the distribution of plants and animals he observed suggest to Darwin?

    • He suggested that in different parts of the world there were different ways that each organism evolved

  • What did Phil Gingerich discover in Pakistan? What was unusual about this fossil?

    • The back of a skull

    • It could not be identified

    • Similar in size and shape to a wolf skull but there was a bump on the underside (inner ear)

  • What unexpected evidence of whale evolution did Gingerich discover when he found Basilosaurus fossils in the Valley of the Whales?

    • Basilosaurus had legs

  • What has comparing whales to land mammals revealed about the method of swimming used by whales?

    • They don’t swim like fish

    • Instead they move their spines up and down

  • Identify and discuss four differences between whales and fish.

    • Whales must rise to the surface of the ocean to breathe

    • Whales have bones where hips would be on a land animal

    • Whales have long muscles horizontally down their bodies

    • Whales give birth to young to live young that cannot give their own food (they get milk produced by their mothers)

  • Based on DNA evidence, the ancestor of whales belonged to a group of land mammals called the artiodactyls, which includes hippos and camels.

  • Based on fossil evidence what evolutionary changes evolved in whales with respect to:

    • Front Legs

      • Flat flippers

    • Rear Legs

      • Completely lost

    • Nostrils

      • Shifted up their skulls to where the blow hole is

  • When Thewissen and his team measured the ratio of light and heavy oxygen in fossil whale teeth, what did they discover about the lifestyles of Pakicetus and Ambulocetus?

    • The Pakicetus drank fresh water

    • The Ambulocetus drank brackish water (mix of fresh and sea water)

  • There are lineages of modern whales, both descended from a common ancestor that lived about 35 million years ago. Name the two lineages and briefly discuss the differences between them.

    • Toothed whales

    • Baleen whales

    • Toothed whales: evolved special organs to produce high pitched sounds with their blowholes and to hear echoes that bounce of animals and other objects

    • Baleen whales: lost teeth and evolved huge stiff pleats in their mouths that allowed them to swallow and push out water, straining shrimp and fish

  • Disabled genes have been found in dolphins (see page 10) and baleen whales. If these genes still worked, what structures would be formed?

    • Baleen Whales would form teeth

  • Explain the statement “Natural selection does not have foresight”

    • Evolution is imperfect because it does not invent things from scratch, it only modifies what already exists and shows progress towards some particular goal

  • Define teleology.

    • The philosophical view that attributes a purpose to living and nonliving things

  • What phrase is commonly found in teleological statements?

    • “In order to”

  • What is the problem with this statement? Dolphins developed echolocation in order to find their prey more easily.

    • It uses the phrase “in order to” which assumes that animals developed and evolved because they knew future events were going to happen

  • Reword the following so that it is not teleological (does not imply purpose). Bacteria become resistant to antibiotics in order to survive.

    • Random mutations in bacteria led to resistance to antibiotics in some bacteria and those specific bacteria were better adapt to survive