Chapter 19 Biology

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?

All organisms use essentially the same genetic code

Of the following anatomical structures, which is homologous to the bones in the wing of a bird

Bones in the flipper of a whale

If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

C

Two plant species live in the same biome but in different continents although the two species are not closely related they may appear quite similar as a result of?

Convergent evolution

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta and a third species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?

E. Tree that goes z, x, y

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

Examples of convergent evolution Adaptations to a common environment

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because

Humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin

Evolutionary trees such as this are properly understood by scientists to be

Hypothesis

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

Island forms and mainland forms descended from common ancestors

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z.

About 13 different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the 13 species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). If the six ground finch species have evolved most recently, then which of these is the most logical prediction?

Their genomes should be more similar to each other than are the genomes of the five tree finch species.

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

These bacteria should be outcompeted and replaced by bacteria that have lost these genes.

Which of the following statements best describes theories?.

They are supported by, and make sense of, many observations.

If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?

Two strata

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.