Mastery Biology #2

Evolution works by __________.

"tinkering" with existing structures

What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

0.4

The Precambrian time began at least _____ million years ago.

4600

If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be

54%

The Cenozoic era began approximately _____ million years ago.

65

In Europe, there is a long narrow hybrid zone, shown in red on the map, between the high-altitude habitat of the yellow-bellied toad and the lowland habitat of the fire-bellied toad. Despite this, there is little gene flow between the two species. Select the correct explanation.

Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species.

Which of the following are basic components of the Hardy-Weinberg model?

Frequencies of two alleles in a gene pool before and after many random matings

What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?

Specific ecological niches

Select the correct statement describing sympatric speciation.

Sympatric speciation can occur in a single generation.

What was the "oxygen revolution," which took place 2.3 billion years ago?

The "oxygen revolution" was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, dooming many prokaryotic groups.

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to

cross your flies with flies from another lab.

_____ were the dominant vertebrate life form during the Mesozoic era.

dinosaurs

True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.

false

What is the result of adaptive evolution?

increase in frequency of alleles that provide reproductive advantage

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies?

selection

Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

species selection

True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics.

true

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating.

true

Which Anolis lizard ecomorph has long legs?

trunk ground

Which of the following reproductive types of isolation illustrates postzygotic barriers?

hybrid breakdown

The first prokaryotic cells appeared during the ____

precambrian

You have discovered a mammoth tusk buried in the Arctic tundra. If only one quarter of the carbon-14 in this fossil remains, then when was this animal alive?

11,460 years ago

The Mesozoic era began approximately _____ million years ago.

251

Which of the following statements about adaptive radiation is correct?

Adaptive radiation occurs within a single lineage.

We are living during the _____era.

Cenozoic

Which of the following is correct about genetic variation?

It must be present in a population before natural selection can act upon the population.

Which organisms are not examples of an adaptive radiation?

Mammals and reptiles in the post-dinosaur age

Dinosaurs went extinct during the ____

Mesozoic

Flowering plants first appeared during the _____

Mesozoic

Bony fish first evolved during the _____ .

Paleozoic

Most modern animal phyla evolved during the _____ era.

Paleozoic

Reptiles first appeared during the _____ era.

Paleozoic

Seed plants first appeared during the ____

Paleozoic

Adaptive radiations on archipelagos (island chains) represent some of the best-understood speciation events. Why is an ancestral species more likely to give rise to multiple descendent species on an archipelago than on an equal-sized area of mainland?

Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland.

Animals first appeared during the _____.

Precambrian

Life arose during the _____.

Precambrian

What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene?

The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.

What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

The frequency of the A1 allele is 0.3.

Which of the following statements is not a part of the Hardy-Weinberg principle?

The genotype frequencies in the offspring generation must add up to two.

Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true?

The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place.

How long does it take new species to form on Earth?

The time required varies considerably.

Which statement correctly describes the role of chance in evolution?

The ultimate source of new alleles is mutation, random changes in the nucleotide sequences of an organism's DNA.

_____ were the dominant vertebrate life form during the Paleozoic era.

amphibians

How can genetic variation at the whole gene level (gene variability) be quantified?

by the average percentage of loci that are heterozygous

What is the most important factor that holds the gene pool of a species together and prevents speciation?

gene flow

Allele frequencies in a gene pool may shift randomly and by chance. What is this random shift called?

genetic drift

The Hardy-Weinberg equation p2 + 2pq + q2 = 1 allows you to calculate

genotype frequencies

Which of the following is the first step in allopatric speciation?

geographic isolation

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

According to the punctuated equilibria model, __________.

most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species

Which of the following evolutionary forces could create new genetic information in a population?

mutation

Which of the following are causes of evolutionary change?

mutation, gene flow, genetic drift, natural selection

Which of the following is a biological cause of extinctions?

origin of species