LS7B LaunchPad Week 6

What is the main difference between the two hypotheses for the origin of the eukaryotic cell?

One hypothesizes that engulfment of a proteobacterium occurred after formation of the nuclear envelope rather than before.

Which of the following statements is TRUE regarding a phylogenetic tree?

Phylogenetic trees could be considered physical representations of hypotheses that seek to establish the evolutionary relationships between different organisms.

Of the taxa listed on the phylogeny, which is more closely related to the frog?

caecilians

Of the taxa listed on the phylogeny, which is more distantly related (least related) to the lungfish?

ceolacanths

Of the following taxonomic categories, which is the MOST inclusive?

class

The nodes on a phylogenetic tree represent:

common ancestors

Why might a phylogeny based only on molecular data show a different pattern of relationships than a phylogeny of the same taxa that is based only on morphological traits? (Select all that apply.)

-Gene sequence changes may not result in morphological changes. -Some highly conserved genetic sequences can result in unrelated species appearing closely related in a molecular phylogeny, and not reflect the same pattern as the morphologic phylogeny.

Chloroplasts are thought to have evolved from cyanobacteria. Which of the following observations support this hypothesis? (Select all that apply.)

-They both have small circular DNA genomes. -They both have similar internal membranes that organize the light reactions of photosynthesis.

If ctenophores are sister to all animal taxa, excluding cnidarians and placazoans, then: (Select all that apply.)

-ancestral sponges exhibited morphologic complexity seen in other Eumetazoans. -radial symmetry was lost in placazoans. -the anatomical complexity of ctenophores arose independently of what is found in other Eumetazoan groups.

The amniotes include: (Select all that apply.)

-mammals -reptiles -birds

Practice Exam Questions Week 6

11/11

Pre-lab review questions pt. II

3/3

Animation: Evolutionary groups

4/4

Pre-lab Review Questions pt. III

4/4

Pre-lab review questions pt. I

4/4

Pre-lab review questions pt. VI

4/4

Animation: Vertebrate tree

5/5

Pre-class Review Questions pt. I

5/5

Pre-class Review Questions pt. II

5/5

Pre-lab review questions pt. V

5/5

Animation: Reading Phylogenies

6/6

Pre-lab review questions pt. IV

6/6

What is the predominant hypothesis to explain why animals only appeared in the fossil record about 3 billion years after life originated?

Animals large enough to be recorded in the fossil record could not evolve until oxygen reached levels sufficient to support aerobic respiration.

In the phylogenetic tree above, which of the following could be considered a sister group?

B

The period of time during which an "explosion" of fossilized animals with bilateral symmetry are first found is the:

Cambrian

_____, which include lobsters and crabs, have _____ legs and, in the ocean, fill many of the ecological roles filled by insects on land.

Crustaceans; branched

Which of the following statements is TRUE of the gastric cavity of cnidarians?

Digestive enzymes allow the consumption of prey such as fish whole.

You discover a new species of ape that is more closely related to gorillas than to any other species of ape, but walks upright. How would you change the phylogeny below?

I would branch the gorilla lineage and add the new species sister to gorillas.

Imagine that a scientist discovers a new, flying species of mammal that resembles a winged rabbit. What can the scientist say about this organism?

If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered homologous.

Synapomorphies are used in determining relationships among animal groups. Synapomorphies are:

both evolutionary innovations and shared, derived traits.

Which of the following statements is always TRUE about sister taxa on a phylogenetic tree?

Sister taxa always share a most recent common ancestor that is not shared with any other taxon on the phylogeny.

Early scientists used morphological characteristics to create a phylogeny of animals, but recently, DNA sequence data have helped in the revision of phylogenies of taxa within the larger groups (i.e., bilaterians, sponges, cnidarians). Why are morphological characteristics like "fate of the blastopore" or "body symmetry" relatively good at predicting larger-scale branching patterns on phylogenies?

The development of these characteristics is controlled genetically, therefore similarities in DNA sequence would be expected in more closely related taxa.

Most eukaryotic cells contain mitochondria, but a few single-celled eukaryotic organisms found in oxygen-free environments do not. Which of the following observations led biologists to reject the hypothesis that these mitochondria-free eukaryotes evolved BEFORE the endosymbiotic event that established mitochondria in other eukaryotes?

The nuclear genome of these mitochondria-free eukaryotes contains relics of mitochondrial genes.

Excluding the outgroup, taxon A, how many equivalent sister-group relationships are depicted between the two phylogenies given below?

There are no equivalent sister-taxa shown between the two phylogenies.

The diagram below depicts three phylogenetic trees. Which of the three show the same sister group relationships among groups A, B, and C?

Trees 1 and 2 are equivalent

Of the taxa listed on the phylogeny, which is more closely related to bats?

Turtles and birds are equally related to bats.

Examine the following table of characters in four different species of flower. Based on the matrix, Derek concludes that species A is sister to the remaining three species. Wilma, in contrast, argues that species D is sister to all other species. Who is CORRECT?

We can't decide from the information given as trees with species A, B, or D as sister to all other species are equally parsimonious.

A node on the phylogenetic tree indicates:

a branch point and common ancestor.

All echinoderms (sea stars and sea urchins) have:

a water vascular system and five-fold symmetry.

Given the tree above, which key developmental trait is shared by birds, crocodiles, and mammals but not by other groups?

amniotic egg

Given the tree above, which of the following characteristics is not shared by both coelocanths and salamanders?

bony limbs

Seals and penguins both have streamlined body forms that allow them to move through water efficiently. This similarity in body shape is MOST likely the result of:

convergent evolution.

A population of rodents, called population A, lived together in harmony on a large landmass until one group of the population dispersed to a nearby island. Two million years later, the island population is split into two smaller, equal-sized populations when a river formed across the middle of the island. Now two new species have evolved on the island, A1 and A2. They have replaced the population from which they were derived. Which represents the phylogeny of the three extant species discussed in this scenario?

diagram K

Modern-day birds are MOST closely related to which of the following?

dinosaurs

Compared with more distantly related taxa, the DNA sequences of two closely related taxa are expected to show:

fewer differences because mutation rates are usually relatively constant and recently diverging species have had less time to accumulate differences.

The group mollusks includes:

gastropods and cephalopods.

Most amphibians have an aquatic larval form with _____ and a terrestrial adult form with _____.

gills; lungs

Cartilaginous fish (chondrichthyes):

have teeth mineralized by calcium phosphate.

Frogs, birds, rabbits, and lizards all have different forelimbs, which makes sense when you consider their different lifestyles. Interestingly, all of their forelimbs share the same set of bones the ulna, the radius, and the humerus. These same bones are also seen in fossils of the extinct animal Eusthenopteron, which demonstrates common ancestry among these four groups of animals. Hence, these forelimbs are an example of:

homologies.

Traits that are similar in two species as a result of common ancestry are referred to as:

homologous.

The phylogeny below shows:

humans and gorillas are more closely related than orangutans and gorillas.

The majority of all known animal species are:

insects.

What structure would you expect to find in every type of mollusk (i.e., gastropods, cephalopods, and bivalves)?

mantle

The colonization of land by animals:

may have taken place independently by a variety of species descended from aquatic ancestors.

A taxon that includes a single common ancestor and all its descendants is a _____ group.

monophyletic

efer to the phylogenetic tree above. The grouping that includes Turtles, Lizards and snakes, Crocodiles and alligators, Birds, and Bats is:

monophyletic.

Cnidarians are able to capture prey with the aid of _____, harpoon-like organelles that are often tipped with neurotoxins.

nematocysts

Marsupials:

nurse their young.

Based on the diagram below, you predict that the earliest fossil gorilla (which may not resemble modern-day gorillas) would be _____ than the earliest fossil _____.

older; bonobo

What feature of animals enabled them to diversify in ways that plants, fungi, algae, and protozoans have not?

organ systems

Refer to the phylogenetic tree above. The grouping that includes Salamanders and Caecilians is:

paraphyletic.

Refer to the phylogenetic tree provided. The grouping that includes Hagfish, Lampreys, Sharks and Rays is:

paraphyletic.

Examine the following table of characters in four different species of flower. Based on the matrix, which tree represents the MOST parsimonious explanation of relatedness among these species?

phylogeny 2

Cnidarians have _____ symmetry.

radial

Organelles have their own genomes. When chloroplast DNA is sequenced and compared to genomes from members of the cyanobacteria, the sequence is nested within cyanobacteria. This is strong evidence for the hypothesis that:

the chloroplast originated as a symbiotic cyanobacterium that became permanently incorporated into its host.

In the phylogenetic tree above, A indicates:

the root

A phylogenetic tree is a hypothesis about the evolutionary relationships among organisms based on available anatomical and/or molecular data.

true

In at least one group of bony fish (Osteichthyes) a structure known as a swim bladder was modified to become a primitive lung.

true

Traditional levels of taxonomy are nested in categories from least to most inclusive. This same relationship is also represented on a phylogenetic tree by moving from the terminal (most recent) nodes to the earliest nodes.

true

Chordates include:

tunicates and vertebrates.

Which of the following are traits shared by all vertebrate animals except hagfish?

vertebrae and a cranium

Given the tree above, which of the following traits is not shared by all animals with bony limbs?

walking legs

Based on Figure 23.7, which of the following are examples of convergent evolution?

wings in birds and bats