Biology Study Guide
What additional sequence data would best support your hypothesis?
sequence data from other polypeptides involved in carotenoid biosynthesis Why: Sequence data from the remainder of this polypeptide and others involved in carotenoid biosynthesis could support the close similarity between aphid and fungal genes for this group of proteins.
A human is classified in domain _____ and kingdom _____.
Eukarya ... Animalia Why: Humans are animals, and animals are eukaryotes.
A rose bush is classified in domain _____ and kingdom _____.
Eukarya ... Plantae Why: Rose bushes are plants.
In the five-kingdom system, which kingdom consists primarily of unicellular eukaryotes?
protista Why: Protists are mostly unicellular eukaryotes, though they also include multicellular algae.
A phylogenetic tree is a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms and the relationships between them. This is one possible phylogenetic tree representing the relationships between some members of phylum Arthropoda. Use this phylogenetic tree and your knowledge of cladistics to determine the relationships between these species. Rank the species from most closely related to horseflies to most distantly related to horseflies. If two species are equally close in their relatedness to horseflies, overlap them.
MOST CLOSELY RELATED TO HORSEFLIES flea katydid/ human body louse mayfly/dragonfly silverfish MOST DISTANTLY RELATED TO HORSEFLIES Why: Phylogenetic trees show the evolutionary relationships between organisms. Closely related organisms have more common ancestors than distantly related organisms. In this case, fleas are more closely related to horseflies than are any other species on the tree, even though some of the other species look more like horseflies than fleas do. For pictured answer: https://quizlet.com/94497303/chapter-26-biology-homework-flash-cards/
In the five-kingdom system, prokaryotes are placed in the kingdom _____.
Monera Why: All monerans are prokaryotes.
The tree includes the most recent common ancestor of all living species of bears (branch point 1). What does this tell you about this phylogenetic tree?
This phylogenetic tree is rooted Why: In a rooted phylogenetic tree, the branch point drawn farthest to the left represents the most recent common ancestor of all taxa in the tree.
Part E of Video Tutor Session Quiz: Phylogenetic Trees
lizards and snakes Why: Because lizards and snakes have the most ancient common ancestor with the rest of the organisms shown here, we would expect their DNA sequences to be most different.
There is(are) _____ eukaryotic domain(s).
one Why: The only eukaryotic domain is the domain Eukarya
According to this tree, is the sun bear more closely related to the sloth bear or the polar bear?
the polar bear
How would you account for the similarities between the aphid sequence and the sequences for the bacteria and plant? Select all reasonable explanations.
- The sequence for this carotenoid-biosynthesis gene may have originally arisen in a bacterium, which passed it by horizontal gene transfer to a fungus, which then passed on a mutated version to the aphid. - An ancestor of the plant Arabidopsis may have acquired an earlier version of the carotenoid-biosynthesis gene from a bacterium or other unicellular organism via horizontal gene transfer.
A study published in 2000 sequenced part of the mitochondrial cytochrome b gene from 61 brown bears from two sites in Alaska. One population of brown bears lives on the coastal mainland of Alaska, while a separate population lives on the ABC islands in southeastern Alaska. Mainland and ABC brown bears differ by 11 fixed nucleotide substitutions in the cytochrome b gene. This suggests that the two brown bear populations represent genetically unique clades. The researchers compared the cytochrome b sequences of the two clades of Alaskan brown bears to those of 55 polar bears. The analysis showed that polar bears and ABC brown bears differ at only three nucleotides in this gene, whereas polar bears and mainland brown bears had more differences. Based on the results of the 2000 study, how should the portion of the tree extending from branch point 7 be altered?
---- Mainland Bear --ABC Brown Bear --Polar Bear
Part B of Video Tutor Session Quiz: Phylogenetic Trees
2 Why: A branch point represents a species that is the ancestor of all species that fall on lines to the right. So point #2 is the only branch point that includes those 3 groups of organisms but not lizards and snakes. Click here to review the figure.
Prokaryotic cells are found in the domain(s) _____.
Bacteria and Archaea Why: Both of these domains are composed of prokaryotic cells.
Imagine that you are studying alien life-forms discovered on a distant planet. While geneticists are working out the genetic code of these organisms, you are asked to construct a phylogenetic tree based on four morphological features, or characters: presence or absence of a spring tail, presence or absence of a grasping hand, presence or absence of a second tail, and number of eyes. The organisms have been divided into five groups based on these characters. If we assume the alien with a tail stalk is an outgroup, what is the most likely phylogenetic tree based on these shared derived characters? When did these characters appear during the aliens' evolutionary history? Drag the aliens and shared derived characters to their appropriate locations on this phylogenetic tree. Use only the blue labels for the blue targets and the white labels for the white targets.
For pictured answer: https://quizlet.com/94497303/chapter-26-biology-homework-flash-cards/ Why: The presence or absence of characters can be used to build a phylogenetic tree based on morphology. In this example, all aliens other than the outgroup have a spring tail, all but two of the groups have a fourth eye, two of the aliens have two tails, and one of the aliens has a grasping hand. These characters can be used to create a hypothesis about the evolutionary relationships between these organisms.
Acyrthosiphon (aphid) IKIIIIGSGV GGTAAAARLS KKGFQVEVYE KNSYNGGRCS IIR_HNGHRF DQHPSL__YL Pantoea (bacterium) KRTFVIGAGF GGLALAIRLQ AAGIATTVLE QHDKPGGRAY VWQ_DQGFTF DAGPTV__IT Staphylococcus (bacterium) MKIAVIGAGV TGLAAAARIA SQGHEVTIFE KNNNVGGRMN QLK_KDGFTF DMGPTI__VM Ustilago (fungus) KKVVIIGAGA GGTALAARLG RRGYSVTVLE KNSFGGGRCS LIH_HDGHRW DQGPSL__YL Gibberella (fungus) KSVIVIGAGV GGVSTAARLA KAGFKVTILE KNDFTGGRCS LIH_NDGHRF DQGPSL__LL Arabidopsis (plant) WDAVVIGGGH NGLTAAAYLA RGGLSVAVLE RRHVIGGAAV TEEIVPGFKF SRCSYLQGLL Rank the five species in terms of how similar their amino acid sequences are to the aphid's sequence.
Least -> Most: Arabidopsis < Pantoea < Staphyloccocus < Gibberella < Ustilago - The amino acid sequences are conserved among the related species. This is the basis for sequence-based homology(similar function) prediction and to also estimate how closely two species are related. - The above sequences have identical amino acids at various positions and the percentage of identity tell us about their relatedness. - When compared to Aphid's DNA Arabidopsis has the lowest number and UStilago has the highest number of common amino acids in the sequence. - The order of the organisms from the least to most in terms of similarity to aphid is Why: In the partial polypeptides shown, the sequence from Ustilago has the most amino acids (38) in common with the aphid sequence. In decreasing order of similarity to the aphid sequence, Gibberella has 35 similar amino acids, Staphylococcus has 25, Pantoea has 20, and Arabidopsis has 18.
Video Tutor Session Quiz: Phylogenetic Trees Watch the Video Tutor Session to your right. You can also download the video or view the text of the tutor session to read while you are watching. After you have watched the tutor session, answer the questions. Estimated time: 10 minutes What does the leftmost point of this figure represent?
The species that is a common ancestor to all species shown on the tree Why: Any point along a line in a phylogenetic tree represents a species that is ancestral to all species to the right of that point. Thus, the far left point on this figure represents a species that is an ancestor of every species shown on the tree.
In this exercise, you will compare the amino acid sequence from the aphid to the amino acid sequences of the other species to identify how similar they are. As a first step, you will compare the aphid sequence (Acyrthosiphon) to a bacterial sequence (Pantoea). The sequences below show the first 60 amino acids of one polypeptide, using the one-letter abbreviations for the amino acids. An underscore (_) indicates a gap inserted in a sequence to optimize its alignment with the corresponding sequence in Arabidopsis. Acyrthosiphon (aphid) IKIIIIGSGV GGTAAAARLS KKGFQVEVYE KNSYNGGRCS IIR_HNGHRF DQGPSL__YL Pantoea (bacterium) KRTFVIGAGF GGLALAIRLQ AAGIATTVLE QHDKPGGRAY VWQ_DQGFTF DAGPTV__IT At how many positions are the amino acids the same between the two species?
There are 20 positions with the same amino acid. The positions are 6, 7, 9, 11, 12, 14, 16, 18, 19, 23, 28, 30, 36, 37, 38, 47, 50, 51, 53, and 54. Why: There are 20 positions along the 60-amino-acid sequence that are identical between the aphid and the bacterium Pantoea. A computer can be used to compare the sequences from the rest of the species to the aphid sequence.
In the two-kingdom system, why were fungi classified in the kingdom Plantae?
They are sedentary. Why: This is why fungi were placed in the same kingdom as plants.
Do these data support the hypothesis that aphids acquired the gene for this polypeptide by horizontal gene transfer? Why or why not?
Yes; the aphid's sequence is similar to the sequences of distantly related organisms. Why: These data—in particular, the similarity in amino acid sequence between the aphid polypeptide and the polypeptides from the other, only distantly related organisms—do support the hypothesis that aphids acquired the gene for the polypeptide by horizontal gene transfer. Finding an extremely similar gene or polypeptide in two organisms known to be only very distantly related—such as an animal and a fungus—suggests that the gene may have been transferred horizontally long after the divergence of the two organisms in the evolutionary past.
If horizontal gene transfer did occur, what type of organism is likely to have been the source?
a fungus Why: From the fact that the fungal polypeptides are the most similar to the aphid polypeptide, we can infer that a fungus is most likely to have been the source of the transferred gene.
Based on the revised branch of the tree, what kind of group do brown bears plus ancestral species 7 represent?
a paraphyletic group Why: The mainland brown bears and the ABC brown bears both share common ancestor 7. But the polar bears also descended from ancestral species 7. Because not all descendants of ancestral species 7 are included in the brown bear group, that group is considered paraphyletic.
Part C of Video Tutor Session Quiz: Phylogenetic Trees
birds Why: In the bottom right, you can see that birds and Saurichian dinosaurs share the most recent common ancestor.
Which branch point represents the most recent common ancestor of all bears?
branch point 1
Which branch point represents the most recent common ancestor of the sloth bear and the spectacled bear?
branch point 2
Which branch point represents the most recent common ancestor of the Asian black bear and the brown bear?
branch point 4
The geneticists studying the alien organisms have deciphered their genetic code. For familiarity, they have used A, C, G, and T to indicate the bases in this code. A comparable genetic sequence in each alien has been identified in the genes that code for eye growth. This genetic sequence has allowed the aliens to be divided into six groups, with the single-tail, three-eye group split in half. The geneticists also studied several outgroup species (not shown) to compile a likely ancestral DNA sequence. From this information, they have constructed four possible phylogenetic trees. Based on this genetic information, which phylogenetic tree is most parsimonious? Select the most parsimonious tree. If there is a tie, select both trees. (For help approaching this problem, open Hint 2.)
phylogenetic tree III Why: Tree III requires the fewest base-change events, so it is the most parsimonious phylogenetic tree. Based on this genetic evidence, we can hypothesize that group 2b diverged from group 2a at the same time that groups 3, 4, and 5 diverged from group 2a. Either the addition of a fourth eye came after this divergence, or group 2b lost its fourth eye sometime in this group's evolutionary history.
Which of the following groups of species is a monophyletic group, or clade?
sun bear, Asian black bear, American black bear, ancestral species 5, ancestral species 6 Why: This is a monophyletic group, or clade, because it includes ancestral species 5, the common ancestor of all taxa in the clade, and all of its descendents.
Identify the sister taxon to the polar bear.
the brown bear
Which species is the basal taxon in this tree?
the giant panda
Part D of Video Tutor Session Quiz: Phylogenetic Trees
time Why: Time is shown along the X axis of a phylogenetic tree, with the most ancient time on the left, and the present day on the right.
