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BIOL 210 Problem Set 1 KEY

Fall 2024

ps1key.Rmd

This is the key for PS 1. Before reading this document, you should have completed the problems. Use this key to check and correct your work BEFORE submitting the corrected version via the google form.

You should compare your responses with this key and make any changes in another font color. Be sure to explain why you got things wrong (showing that now you understand) as well as providing corrected responses.

Question Key

  1. Let’s practice using classification and scientific nomenclature. For each of the organisms named below (common names provided), find the scientific name (the binomial nomenclature). Be sure to use the proper formatting!
    1. common fruit fly,
      Drosophila melanogaster
    2. whale shark,
      Rhincodon typus
    3. Venus flytrap,
      Dionaea muscipula
    4. magic mushrooms,
      Psilocybe semilanceata or other species (many species in different genera are known by the name magic mushrooms)

  2. As a reminder about the proper formatting, for each of the examples below, describe what is incorrect about the binomial nomenclature.
    1. Homo sapiens
      should be italicized but is not
    2. homo sapiens
      The genus name, Homo should be capitalized
    3. Homo Sapiens
      The specific epithet, sapiens should not be capitalized
    4. Sapiens
      The genus name is missing AND the specific epithet should not be capitalized

  3. Use the Oak Phylogeny Sheet for questions 3-9. List the terminal taxon or taxa (in this case, species) identified by their most recent common ancestor, that are sister to each oak below.
    1. northern red oak is sister to…
      shumard oak
    2. post oak is sister to…
      overcup oak
    3. black oak is sister to…
      the clade defined by node H, taxa northern red, shumard, pin, and southern red
    4. swamp white oak is sister to…
      the clade defined by node C, taxa white oak and bur oak

  4. TRUE / FALSE Swamp white oak is most closely related to bur oak. Briefly explain your answer.
    No, swamp white oak is as closely related to bur oak as it is to white oak – it is equally related to those two species. Those two taxa form the sister group to swamp white oak.

  5. What is the most recent common ancestor of each of the pairs of species listed below? In other words, which node unites the following pairs of species? Write the correct letter for each node next to each pair of species.
    1. pin oak & shumard oak
      node I
    2. post oak & southern red oak
      node D
    3. bur oak & chestnut oak
      node A

  6. Rank the following nodes in Tree 1 in order of increasing age (i.e. youngest to oldest): A, D, K
    (youngest) K, D , A (oldest)


  7. Which terminal taxa are in the clade that is defined by node E?
    chestnut, blackjack, black, northern red, shumard, pin, southern red

  8. Now find all of the clades in Tree 1. How many are there? List them, using the node to define the clade (so clade defined by node A would be everything on the tree). (Remember that the clade is defined by an ancestor and all of its descendants, so all should be contained in the grouping.) One clade for each node (11) plus one clade for each terminal taxon (12) so 23 total.

  9. Below are several groups of taxa, some of which form clades in Tree 1 and others of which do not. Place an X next to each group of taxa below that collectively form a clade in Tree 1.
    1. white oak, bur oak, swamp white oak, Node B, and all of its descendants
      This is a clade.
    2. southern red oak, post oak, overcup oak, Node K, and all of its descendants
      Not a clade because not all ancestors are included nor all terminal taxa. If you took out southern red, it would be a clade. But to include southern red you must also have everything descended from node D to make a clade.
    3. black oak, northern red oak, shumard oak and all of Node I’s descendants
      Not a clade since the most recent common ancestor of all these taxa is Node G and node G (plus all descendants) is not included.
    4. northern red oak, pin oak, southern red oak, and Node H
      Not a clade. Missing shumard oak plus node H’s descendants.
    5. post oak, overcup oak
      Not a clade because you are not including the common ancestor. Must include node K and all its descendants.

  10. Referring to the Tree of Life sheet (before filled out):
    1. How many taxa on this tree possess vertebrae?
      4 (numbers 2-5, Lepidosaur, Aves, Mammalia, Actinopterygii)
    2. Find the branch where “segmentation” evolved. Is this trait present in all of the descendants of this ancestor?
      No, Nematoda have lost segmentation
    3. Which taxa have alternation of generations but lack vascular tissue?
      Moss, taxon number 16
    4. Which taxa on the tree are segmented but lack a collagen cuticle?
      Arthropoda and Annelida

  11. Finally, complete the table below, using the Tree of Life sheet and other resources (texts, internet, etc) to figure out which number corresponds to which of the following taxa, giving an example species, and listing defining features of the taxon (not the specific species but the larger taxonomic group).


    12. Note that in the table below, defining traits are given as traits mapped on the actual tree where available for the group. The below are examples of defining traits, other traits may also be used to define these groups. You may also wish to see the tree version of the key, available here.

    Taxon_Name Taxon_Number Example_Species Defining_Traits
    Actinopterygii 5 many possible responses fins with thin webbing between bony spines (ray-finned)
    Amoebozoa 1 many possible responses great flexibility in shape
    Angiosperms 19 many possible responses flowers and fruit
    Annelida 8 many possible responses segmented with collagen cuticle
    Arthropoda 10 many possible responses jointed appendages
    Aves 3 many possible responses feathers
    Bacteria 22 many possible responses peptidoglycan cell walls
    Cnidaria 11 many possible responses gelatinous body, possess venomed flagella
    Echinodermata 6 many possible responses pentaradial symmetry
    Euglena 21 many possible responses flagella
    Fern 17 many possible responses vascular tissue, spore (no flowers/seeds)
    Fungi 13 many possible responses chitinous cell wall
    Green algae 15 many possible responses chlorophyll, unicellular or colonial
    Gymnosperms 18 many possible responses vascular tissue, naked seeds
    Lepidosaur 2 many possible responses kinetic skull
    Lichen 14 many possible responses symbiosis of algae/cyanobacteria and fungi
    Mammalia 4 humans mammary glands
    Mollusca 7 many possible responses calcareous shell
    Moss 16 many possible responses multicellular, no vascular tissue, haploid dominant
    Nematoda 9 many possible responses collagen cuticle
    Paramecium 20 many possible responses cilia
    Porifera 12 many possible responses spicules