Biology 101 Exam 2

Anatomical and molecular evidence suggests that animals may have evolved from a protist similar to a ___________.


Which of the following would be the most unexpected feature in a swiftly moving, actively searching predator?

radial symmetry

Within which sequence of clades, from most to least inclusive, are humans correctly classified?

Deuterostomia - Chordata - Gnathostome - Eutherian

sponges differ from other animals in that _______________.

their simple body structure has no true tissues and they have no symmetry

Which of the following characters was not an ancestral trait that facilitated the colonization of land by an animal group?

amniotic egg

which tissue type or organ is not correctly matched with its germ layer tissue?

nervous - mesoderm

which of the following phenomena is not considered a factor contributing to the amazing diversity of insect groups?

evolution of new Hox genes

which of the following contains the most species?


which of the following groups represents the basal lineage(s) of vertebrates?

hagfish and lampreys

which of the following lists provides the best description of cnidarians?

radial symmetry, two germ layers, and gastrovascular cavity

The basal group in clade Eumetazoa is __________.


Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

hard parts

Which of the following is not a clade, a group including an ancestral species and all of its descendants?


The first animals that biologists now classify as tetrapods appear in the fossil record __________ million years ago.


Major changes in ocean conditions during the early Cambrian period were probably linked most closely to the evolution of __________.

suspension-feeding animals

About __________ of documented animal extinctions have been of invertebrates.


Invertebrates include

all animals without backbones

Mollusks possess all of the following except which anatomical feature?


A coelem is a fluid-filled or air-filled space located

between the digestive tract and outer body wall

which of the following is not an osteichthyan?


brachiopods possess ________________ germ layers.


the ____________ is the outermost extraembryonic membrane of the amniotic egg.


Which mammal group if characterized by offspring that are born early in development and then finish embryonic development while nursing in their mother's abdominal pouch?


Sponges are most accurately described as

filter feeders

Which germ layer gives rise to muscles?


The most ancient branch point in animal phylogeny is that between having

true tissues or no tissues

What is the probable sequence in which the following clades of animals originated, from earliest to most recent?
1. tetrapods2. vertebrates3. deuterostomes4. amniotes5. bilaterians

5, 3, 2, 1, 4

Which of the following is unique to animals?

nervous system signal conduction and muscular

Which of the following functions as both a mouth and an anus in members of the phylum Cnidaria?

a gastrovascular cavity

The last common ancestor of all animals was probably a(n)


In terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?


Both animals and fungi are heterotrophic. The fact below that distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition from

ingesting it

When did the Cambrian explosion occur?

535 millions years ago

According to the evidence collected so far, the animal kingdom is


A student catches a ray-finned fish from the ocean and notices that attached to its flank is an equally long, snakelike organism. The attached organism has no external segmentation, no scales, a slimy substance on its surface, a round mouth surrounded by

slimy substance on its surface

Which extant chordates are postulated to be most like the earliest chordates in physical appearance?


If a multicellular animal lacks true tissues, then it can properly be included among the


Jaws first occurred in which extant group of fishes?


Chordate pharyngeal slits appear to have functioned first as

suspension-feeding devices

Which of the following belong to the lobe-fin clade?


Whatever is ultimate causes(s), the Cambrian explosion is a prime example of

adaptive radiation

Which of these are amniotes?
A) amphibians
B) fishes
C) mammals
D) placental mammals only
E) egg-laying mammals only

C) mammals

Arrange these taxonomic terms from most inclusive (most general) to least inclusive (most specific).
1. lobe-fins
2. amphibians
3. gnathostomes
4. osteichthyans
5. tetrapods


Which of the following statements concerning animal taxonomy is (are) true?
1. Animals are more closely related to plants than to fungi.
2. All animal clades based on body plan have been found to be incorrect.
3. Kingdom Animalia is monophyletic.
4. Only

C) 3 and 5

Which of the following are the only extant animals that descended directly from dinosaurs?
A) lizards
B) crocodiles
C) snakes
D) birds
E) tuataras

D) Birds

Which of the following animal groups is entirely aquatic?
A) Mollusca
B) Crustacea
C) Echinodermata
D) Nematoda
E) Platyhelminthes

C) Echinodermata

What do all craniates have that earlier chordates did not have?

partial or complete skulls

Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. The brothers' parents do not have PKU. What is the chance that Tom, who is normal for this trait, is a carrier of PKU?


Tail length in a certain species of armadillo falls along a continuum, following a normal distribution. Assuming that environmental factors do not play an important role in determining tail length, this type of variation probably reflects __________.

polygenic inheritance

According to Mendel's law of segregation, __________.

allele pairs separate in gamete formation

When two average-height parents give birth to a child exhibiting achondroplasia, it is most likely due to a new mutation. This is because __________.

achondroplasia is caused by an allele that is always expressed; therefore, the parents must not have the allele

Which of the following is a basic difference between Mendel's particulate hypothesis and the hypothesis of blending inheritance?

The blending inheritance hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring and that these contributions cannot then be separated.

How does codominance at the molecular level help to explain why evolutionary processes haven't resulted in the elimination of the sickle-cell allele among people of African descent?

Heterozygous individuals have both normal and sickle-cell hemoglobin in their red blood cells and reduced vulnerability to malaria.

In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation had the __________ phenotype because their genotype was __________ at the flower-color locus.

purple-flowered; heterozygous

A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood?


A single genetic locus that controls more than one trait is said to be __________.


Huntington's disease is an example of a genetic disorder caused by __________.

a lethal dominant allele that afflicts an individual later in life

Which of the following human diseases is inherited as a simple recessive trait?

cystic fibrosis

If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous?


How does codominance at the molecular level help to explain why evolutionary processes haven't resulted in the elimination of the sickle-cell allele among people of African descent?

Heterozygous individuals have both normal and sickle-cell hemoglobin in their red blood cells and reduced vulnerability to malaria.

In the F2 of a dihybrid cross involving two independently assorting genes, what proportion of the offspring will be true-breeding?


Heart disease, diabetes, cancer, alcoholism, and many mental illnesses can best be described as __________.

multifactorial disorders with a possible polygenic component

Assume that in guinea pigs, the brown coat color allele (B) is dominant over red (b), and the solid color allele (S) is dominant over spotted (s). The F1 offspring of a cross between true-breeding brown, solid-colored guinea pigs and red, spotted guinea p


In carrying out his breeding studies, Mendel determined patterns of inheritance by examining characters that had which of the following properties?

all of the listed responses are correct

Mendel's theory of particulate inheritance __________.

can explain inheritance patterns for virtually every sexually reproducing organism but does not explain multifactorial characters

In the F2 of a dihybrid cross involving two independently assorting genes, what proportion of the offspring will be true-breeding?


Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plan

25% red, 50% pink, and 25% white

Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous?

A 1:1 ratio of tall offspring to short offspring

Which of the following describes the expression of the Tay-Sachs allele in humans at the biochemical level?

incompletely dominant

Which of the following statements concerning the direct observation of evolution is most correct?

There are extremely numerous examples where evolution can be directly observed, and these observations provide strong support for the idea of natural selection.

To Cuvier, the differences in fossils from different strata were evidence for __________.

local catastrophic events such as droughts or floods

What insight did Darwin gain from reading Thomas Malthus's essay on human suffering?

Organisms have the capacity to overreproduce.

A population of zooplankton is exposed to a small number of predatory fish that feed on the larger-sized (adult) zooplankton. Based on the principles of evolution by natural selection, which of the following would be most likely?

Adult zooplankton will start to reach sexual maturity when they are still relatively small.

The hypothesis that whales evolved from land-dwelling ancestors is supported by __________.

fossils of extinct whales that had increasingly reduced hind limbs

The smallest unit that can evolve is a(n) __________.


All of the following influenced Darwin as he synthesized the theory of evolution by natural selection except _________.

Mendel's paper in which he described his "laws of inheritance

What did Darwin observe about species on islands?

They are often closely related to species from the nearest mainland or neighboring islands.

To describe evolution as a "scientific theory" means that __________.

it is a broad model that is supported by many observations and much experimental evidence

Which of the following is an example of convergent evolution?

Similarities between the marsupial Tasmanian wolf and the eutherian North American wolf

Lyell's principle of uniformitarianism __________.

strongly influenced Darwin's view of how living organisms could change over time

At the time Charles Darwin sailed on the HMS Beagle, __________.

several biologists had proposed that species might change over time, but none had suggested a convincing mechanism that might cause the change

All known organisms appear to translate genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that __________.

all organisms are descended from a single common ancestor

Carolus Linnaeus is considered to be the founder of __________, and he __________.

the binomial classification system; thought that resemblances among different species reflected the pattern of their creation

The remnants of pelvic and leg bones in a snake __________.

are vestigial structures

When cytochrome c molecules are compared, yeasts and molds are found to differ by approximately 46 amino acids per 100 residues (amino acids in the protein); insects and vertebrates are found to differ by 29 amino acids per 100 residues. What can one conc

Insects and vertebrates diverged from a common ancestor more recently than did yeasts and molds.

At the time Darwin voyaged on the HMS Beagle, the popularly accepted theory in Western culture that explained the origin of Earth's plants and animals held that the various species __________.

had been created by divine intervention a few thousand years before

When they were first sold, aerosol insecticides were highly effective in killing mosquitoes. Now, several decades later, a much smaller proportion of these insects die when sprayed. The reason fewer insects die when they are sprayed is that __________.

larger portions of the mosquito populations today are descendants of individuals that were insecticide-resistant

Which of the following points is not considered part of the process of natural selection?

Many adaptive traits may be acquired during an individual's lifetime and passed on to that individual's offspring.

The scala naturae, or scale of nature is based on the ideas of


According to the theory of evolution by natural selection, anatomical and molecular homologies should ____________.

indicate similar patterns of evolutionary relatedness

How did some strains of Staphylococcus aureus become resistant to antibiotic drugs?

Some members of the bacteria population must have had genes that made them resistant to antibiotics, and these genes became more prevalent in subsequent generations.

Darwin originally defined evolution as __________.

descent with modification

The modern idea of extinction as a common occurrence in Earth's history was first proposed in the early 19th century writings of __________.


Which is a key observation that must be explained in a unifying theory about life?

many basic characteristics are shared by all living things

The scala naturae, or scale of nature, is based on the ideas of __________.


At the time Darwin voyaged on the survey ship HMS Beagle, the popularly accepted theory in Western culture that explained the origin of Earth's plants and animals held that the various species __________.

had been created by divine intervention a few thousand years before

Which is a true statement about Charles Darwin?

He proposed natural selection as the mechanism of evolution.

After invoking selective breeding of domesticated species as evidence that groups of organisms are capable of change, Darwin then proposed that natural populations can change as well. On which two lines of evidence did he base this proposal?

Organisms within a population vary, and all populations produce more offspring than can be supported by the environment, resulting in competition for survival within the population.

In Darwin's view of descent with modification __________.

natural selection can improve the match between an organism and its environment

The breeding of plants and animals for particular traits by humans is called __________.

artificial selection

An important challenge to traditional, pre-Darwinian ideas about species was the observation that seemingly dissimilar organisms such as hummingbirds, humans, and whales have similar skeletal structures. This most directly suggested to biologists that ___

dissimilar organisms might have evolved from a distant, common ancestor

Animals that possess homologous structures probably __________.

evolved from the same ancestor

Vestigial organs are __________.

remnants of structures that were useful to an organism's ancestors

Evidence from molecular biology supports the theory of evolution by demonstrating that __________.

closely related organisms have more similar DNA and proteins

Which is a basic difference between Mendel's particulate hypothesis and the hypothesis of blending inheritance?

The blending inheritance hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring, losing its individual identity.

If a plant variety is true-breeding for a dominant trait, then __________.

if the plant were allowed to self-pollinate over many generations, all of the progeny would have the dominant trait

Physically, what are different alleles?

Different alleles are different DNA sequences found at the same locus on homologous chromosomes.

What is indicated when a single-character testcross yields offspring that all have the dominant phenotype?

The parent with the dominant phenotype was homozygous.

The law of independent assortment __________.

-can account for a 9:3:3:1 ratio seen in the F2 generation
-states that the alleles at different loci segregate independently from one another during a dihybrid cross
-applies only to genes that are present on different chromosomes (or behave as if they w

Homologous pairs of chromosomes often __________.

contain different alleles

If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce?

10,000 (100x100)

An individual with the genotype AABbCcDD can make how many different kinds of gametes?

The individual varies only at loci B and C (not at A and D, which are homozygous), and there are two possible alleles at each loci (22 = 4).

A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are __________.


Unlike other animals, sponges __________.

lack true tissues

Sponges feed by ________________.

filtering small particles from water

Symmetry is one of the most basic characteristics of animals. The group that has a different symmetry from the other four groups listed here is the __________.


All animals with bilateral symmetry have __________ germ layer(s).


A __________ is a chordate but not a vertebrate.


A lamprey, a shark, a lizard, and a rabbit share all these characteristics except __________.

hinged jaws

Which set of animals contains only gnathostomes?

rays, turtles, pigeons, and tuna

In most insects, gas exchange is accomplished by __________.

a tracheal system

The majority of animal species are __________.


The adaptation that freed vertebrates from water for reproduction and allowed them to radiate into diverse terrestrial environments was the __________.

amniotic egg

All mammals ____________________.

nourish their offspring through mammary glands

The opossum is an example of a(n) __________ mammal.


Which of the following statements correctly describes a monohybrid cross?

Organisms that are heterozygous for one characterisitic

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

traits are inherited in discrete units and are not the results of "blending".

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?


In the cross AaBbCc � AaBbCc, what is the probability of producing the genotype AABBCC?


In humans, wavy hair occurs in heterozygotes (HSHC) offspring of people with straight hair (HSHS) and curly hair (HCHC). Which of the following crosses would produce offspring with the ratio of 1 straight:2 wavy:1 curly?

wavy x wavy

Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. These results indicate which of the following about the

Epistasis is involved.

Evolution is best defined as which of the following?

change in allele frequency in a population

Fossils are found in

sedimentary rock

Lamarck's contribution to evolutionary theory was the

physical changes in organisms

Natural selection is based on all of the following except

Individuals adapt to their environments and, thereby, evolve.

Which of the following must exist in a population before natural selection can act upon that population?

genetic variation among individuals