Deck 4: Evolution, Genetics, and Human Variation 

Question 1

Which of the following statements about individuals with the Hb^S allele in the homozygous form is TRUE?

A) They always develop fatal cases of sickle-cell anemia late in life.
B) They lack the capacity to digest lactose.
C) They are usually found in temperate regions of the world.
D) They rarely develop any form of sickle-cell anemia before reaching reproductive age.
E) They usually develop fatal cases of sickle-cell anemia.

Answer 1

E

Question 2

Although Darwin became the best-known evolutionist, the idea of evolution had been around well before him. Darwin's key contribution was to propose a mechanism that drives evolution, which is known as

A) lamarckianism.
B) natural selection.
C) creationism.
D) catastrophism.
E) mutation.

Answer 2

B

Question 3

The example of the sickle-cell allele demonstrates a key aspect of evolution through natural selection, in that

A) human populations in the tropics are the most susceptible to random changes caused by natural selection.
B) adaptation and fitness are in relation to specific environments; traits are not universally adaptive or maladaptive.
C) adaptation and fitness are in relation to the individual organism, not the general population.
D) although natural selection usually acts upon the phenotype, it can sometimes act upon the genotype.
E) natural selection increases the variety in a population upon which subsequent natural selective processes can act.

Answer 3

B

Question 4

We have learned that reliance on culture has increased in the course of human history. Yet the fact and mechanisms of evolution remain a key part of our human present and future because

A) they provide the clues to building a better human race by promoting directed speciation.
B) they determine, at the genetic level, our phenotype.
C) the pace of evolution has been continuously increasing, as human cultural solutions have not been able to keep up with environmental changes such as global warming.
D) they continue to justify anthropology's biocultural perspective.
E) people haven't stopped adapting biologically.

Question 5

Gregor Mendel's work with hereditary traits of pea plants

A) confirmed the paint-pot theory of inheritance.
B) led to the formulation of the law of independent assortment.
C) proved that natural selection operates on genotypes.
D) was the basis for Darwin's theory of evolution.
E) discredited the phenomenon of balanced polymorphism.

Question 6

Which of the following statements about natural selection is FALSE?

A) Natural selection operates with respect to specific environments.
B) Natural selection was first scientifically described by Darwin and Wallace.
C) Natural selection is the sum of environmental forces that conditions the survival of particular phenotypes.
D) Natural selection operates directly on genetic variety.
E) Natural selection is most obvious when there is competition among a population for strategic resources.

Question 7

Mendelian genetics studies

A) how nuclear DNA transmits information to other parts of the cell.
B) changes in gene frequencies in breeding populations.
C) the ways in which chromosomes transmit genes across generations.
D) phenotypic mutations.
E) evolution in pea plants.

Question 8

During the 18th century, many scholars became interested in biological diversity, human origins, and our position within the classification of plants and animals. At that time, the most commonly accepted explanation of the origin of species was

A) creationism, the belief that biological similarities and differences originated at the Creation and that these characteristics, once set, could not change.
B) biblical punctuated equilibrium.
C) catastrophism, the belief that species arise from one another through a long and gradual process of transformation.
D) Mendelianism.
E) uniformitarianism, the belief that natural forces at work today also explain past events.

Question 9

Any factor that contributes to the change in allele frequency in a breeding population from generation to generation is considered a mechanism of genetic evolution. Those mechanisms are

A) natural selection, mutation, random genetic drift, and gene flow.
B) random genetic drift and random gene flow.
C) independent assortment, recombination, and mutation.
D) sexual selection, mutation, and human biological plasticity.
E) phenotypic straining through the organism's development and mutations across the generations.

Question 10

Which of the following does NOT seek to explain the origin of species by referring to an outside agent?

A) extraterrestrial seeding
B) evolution
C) catastrophism
D) intelligent design
E) creationism

Question 11

What role do recombination and independent assortment play in evolution?

A) They act to reduce the overall fitness of a breeding population.
B) They act to create genetic variability in a breeding population.
C) They work to limit the amount of variation in a population.
D) They increase the frequencies of deleterious genes.
E) They work to limit the number of potential phenotypes.

Question 12

Natural selection is the process by which the forms most fit to survive and reproduce in a given environment do so in greater numbers than others in the same population. But more than survival of the fittest, natural selection is the natural process that leads to

A) the most fit members collecting the most resources from the environment.
B) survival success in any environment.
C) the toughest members of their population having the longest life span.
D) the survival of those members of their population that practice true altruism.
E) differential reproductive success.

Question 13

For natural selection to work on a particular population,

A) the environment must remain constant.
B) there must be genotypic diversity but phenotypic homogeneity.
C) the members must have a sufficiently long life span.
D) there must be variety within that population.
E) the members must have a strong will to survive.

Question 14

Darwin and Wallace simultaneously proposed which of the following theoretical models?

A) transformism
B) natural selection
C) evolution
D) creationism
E) uniformitarianism

Question 15

What is the process by which sex cells are produced?

A) directional selection
B) recombination
C) mitosis
D) independent assortment
E) meiosis

Question 16

What is the term for the belief that explanations for past events should be sought in ordinary forces that are at work today?

A) uniformitarianism
B) creationism
C) recombination
D) catastrophism
E) speciation

Question 17

The term gene pool refers to all the

A) alleles, genes, chromosomes, and genotypes within a breeding population.
B) alleles, genes, chromosomes, and genotypes of the animal kingdom.
C) mechanisms of competition over strategic resources.
D) processes of achieving a perfect fit to the environment.
E) mutations in a breeding population.

Question 18

This chapter describes the case of giraffes' long necks to illustrate how natural selection works on variety within a population. This explanation contrasts with the incorrect alternative of the inheritance of acquired characteristics, which suggests that

A) in each generation, individual giraffes mate with giraffes having longer necks because they are better at getting food, and their offspring's neck size results in an average of the parents' neck sizes.
B) the presence of variety among a population works against the advantages of natural selection.
C) a need for a longer neck activates the long-neck gene throughout development.
D) in each generation, individual giraffes strain their necks to reach food just a bit higher, and that this straining somehow modifies their genetic material.
E) natural selection works on the genotype, not the phenotype.

Question 19

Human biology

A) is 75 percent genotype and 25 percent phenotype.
B) is all in the genes.
C) is no longer affected by evolutionary processes.
D) remains the best explanation for genetic evolution.
E) is not set at birth; it has considerable plasticity.

Question 20

Why are genetics and evolution so important to anthropology?

A) They determine the clear distinction between biological and cultural forces acting through human history.
B) They help anthropologists document and explain human biological diversity.
C) They provide the key to understanding the rate of environmental change throughout human history.
D) They define humans' position at the top of the hierarchy of biological diversity.
E) They give anthropology some credibility as a scientific field.

Question 21

Directional selection works to reduce genetic variation by removing maladaptive traits from the gene pool.

Question 22

Which of the following statements about the Hb^S allele is FALSE?

A) It is found in higher gene frequencies in regions where malaria is endemic.
B) In areas where malaria has been reduced through drainage and insecticides, its frequency declines.
C) It causes sickle-cell anemia in homozygous individuals.
D) Heterozygous individuals have an increased immunity to malaria.
E) Homozygous individuals usually develop fatal cases of dysentery.

Question 23

One of Gregor Mendel's contributions to genetics was his discovery that traits are inherited as discrete units.

Question 24

Mitosis is the special process by which sex cells are produced.

Question 25

The study of sickle-cell anemia and its relation to malarial environments demonstrates that

A) homozygotes lack the capacity to digest lactose.
B) a maladaptive allele may be preserved if it provides an advantage.
C) natural selection improves a gene pool by wiping out deleterious alleles.
D) selection removes recessive alleles from the gene pool faster than it does dominant alleles.
E) heterozygotes are not as selectively fit as are dominant homozygotes.

Question 26

The theory of creationism argues that all the species present today were created as natural selection selected the fittest individuals.

Question 27

Fixation due to random genetic drift is more rapid in

A) tropical environments.
B) small populations.
C) blue-eyed persons.
D) the formation of a new species.
E) the punctuated equilibrium model of evolution.

Question 28

To what does the term gene flow refer?

A) the genetic mutations that occur during meiosis
B) the movement of alleles from one chromosome to another
C) the exchange of genetic material between populations of the same species
D) the random loss of genes through sampling error
E) a random pattern of chromosome mutations

Question 29

Natural selection is the only mechanism driving genetic evolution.

Question 30

Recessive traits are expressed only in homozygous individuals.

Question 31

Darwin proposed the theory of evolution, although the fact of evolution was known well before his work.

Question 32

Genetic evolution involves changes in gene frequencies between generations within a given breeding population.

Question 33

Mendelian genetics studies the ways in which gene frequencies vary in communities from generation to generation.

Question 34

Uniformitarianism states that the natural forces at work today have more or less been the same as those at work in the past.

Question 35

Balanced polymorphism refers to two or more alleles of the same gene that maintain constant frequencies in a population from generation to generation.

Question 36

Against what does gene flow act?

A) balanced polymorphisms
B) migration
C) mutations
D) natural selection
E) speciation

Question 37

Genotype refers to expressed physical traits based on genetic makeup.

Question 38

The inheritance of acquired characteristics is central to Darwin's theory of evolution.

Question 39

Natural selection operates directly on the genotype of an organism.

Question 40

Mendel's concept of independent assortment is based on the fact that individual traits are inherited independently of one another.

Question 41

Directional selection has eliminated sickle-cell anemia from all human populations, except those in regions where diabetes is endemic.

Question 42

Which of the following is the best example of how diseases have been powerful selective agents for humans, particularly before the arrival of modern medicine?

A) Blood type A individuals are more prone to stomach and cervical cancer. Since these diseases usually occur after reproduction has ended, they are particularly powerful agents in adaptation and evolution through natural selection.
B) Smallpox, which appeared after people and animals started living together, has worked as a selective agent for people with blood types B and O who have an ability to produce antibodies against smallpox.
C) Diseases no longer work as powerful selective agents for humans, thanks to the widespread availability of modern medicine.
D) Blood type O will soon become something of the past, since it does not confer an advantage to any disease.
E) Smallpox, which appeared after people and animals started living together, has worked as a selective agent against people with sickle-cell anemia.

Question 43

In understanding the problems with attempts at human racial classification, why is it important to know the difference between genotype and phenotype?

A) Although phenotypic characteristics may change, the genetic material of populations stays the same for a long time.
B) The phenotypic traits typically used to classify humans into races go together as genetic units.
C) Phenotypic similarities and differences always have a genetic basis.
D) Attempts at human racial classification have typically used phenotypic traits like skin color as markers of common ancestry, but many such traits do not reflect shared genetic material. Instead, they are often the result of different populations biologically adapting to similar environmental stressors in similar ways.
E) Attempts at human racial classification have typically used genotypic traits like blood type as markers of common ancestry, and these traits are passed on from generation to generation in discrete bundles.

Question 44

Mutations introduce genetic variation into a gene pool.

Question 45

The explanations given in this chapter for the differences in and distribution of skin color in populations around the world are examples of

A) explanatory approaches to human biological diversity.
B) how having a political interest in justifying racial policies interferes with objective science.
C) the social construction of so-called scientific categories.
D) attempts at classifying human groups into clines.
E) punctuated equilibrium.

Question 46

Which of the following is the best plan of action for a light-skinned woman of childbearing age living in the tropics and concerned about giving birth to a child with neural tube defects (NTDs)?

A) taking folic acid/folate supplements and protecting herself against the sun with sunscreen, clothing, and shelter
B) doing nothing, since a woman's chance of giving birth to a child with NTDs is genetically determined
C) taking vitamin D supplements
D) drinking plenty of fluids to boost her body's ability to regulate its own temperature
E) using a tanning booth to give her skin accelerated protection against the sun

Question 47

Traditional racial classification assumed that biological characteristics such as skin color were determined by heredity and remained stable over many generations. We now know that

A) skin color is determined by a single gene that is prone to mutations over many generations.
B) skin color is determined by sun exposure and the amount of melanin in our diets.
C) a biological similarity such as skin color is always the result of both common ancestry and natural selection.
D) skin color is actually determined throughout child development.
E) a biological similarity such as skin color is also the result of natural selection working among different populations that face similar environmental challenges.

Question 48

Historically, scientists have approached the study of human biological diversity in two main ways: racial classification (now largely abandoned), and the current explanatory approach, which focuses on understanding specific differences.

Question 49

The Hb^S allele has been maintained in certain populations in Africa, India, and the Mediterranean because heterozygous individuals with this allele are less susceptible to malaria.

Question 50

In the early 20th century, anthropologist Franz Boas described changes in skull form among the children of Europeans who had migrated to North America. He found that the reason for these changes could not be explained by genetics. His findings underscore the fact that

A) observing changes over one generation is not enough to make conclusions about changes in genotype and phenotype.
B) phenotypic similarities and differences don't necessarily have a genetic basis.
C) describing changes in skull form is the most accurate way to study the impact of migration on traveling populations.
D) though the environment influences phenotype, genetics is a more powerful determinant of racial differences.
E) diet affects which genes get turned off and which on, resulting in a particular phenotypic characteristic.

Question 51

In theory, a biological race is a geographically isolated subdivision of a species. Humanity (Homo sapiens) lacks such races because

A) although humans exhibit biological differences, these are only skin deep.
B) humans are less genetically predictable than animals and plants susceptible to domestication.
C) human populations have not been isolated enough from one another to develop such discrete groups.
D) human populations have experienced a type of controlled breeding distinct from that of dogs and roses.
E) they are politically incorrect.

Question 52

Which of the following statements about the concept of race as applied to humans is true?

A) It has been verified by recent fossil finds in the Neander Valley in Germany.
B) It is determined by the juxtaposition of alleles.
C) It is based on the Western science of genetics.
D) It does not include what used to be called subraces, because these are now known as ethnic groups.
E) It is a discredited concept in biology.

Question 53

Human biological differences are evident only to individuals who wrongfully sustain the validity of human races.

Question 54

According to contemporary scientists, racial distinctions are based on

A) shared blood.
B) biological classifications.
C) genetics.
D) culture.
E) human breeds.

Question 55

Which of the following statements about attempts to assign humans to discrete racial categories, purportedly based on common ancestry, is true?

A) They are based on global racial categories that vary little from one society to another.
B) They are culturally arbitrary, even though most people assume they are based in biology.
C) They are based on genotypic rather than phenotypic characteristics.
D) They are applied to endogamous breeding populations.
E) They are a recent phenomenon brought on by globalization.

Question 56

An examination of racial taxonomies from around the world would indicate that

A) classifying racial types can best be done by considering only genotype.
B) the best classification of racial types considers genotype as well as phenotype.
C) all cultures classify races similarly.
D) the classification of racial types is an arbitrary and culturally specific process.
E) classifying racial types can best be done by considering only phenotypic traits.

Question 57

What does the relationship between genetic traits and the prevalence of diseases such as malaria and smallpox illustrate?

A) the ways in which human biological diversity reflects adaptation to such environmental stresses as disease, diet, and climate
B) the shortcomings of research that focuses on environmental variability but ignores genetics
C) how despite some evidence to the contrary, some human races are better than others
D) how with technology, human biology is less important to human survival
E) the mechanisms of hominid evolution

Question 58

What term refers to an organism's evident traits, its "manifest biology"?

A) phenotype
B) hereditary inequality
C) biological circumscription
D) genotype
E) manifest destiny

Question 59

Gene flow between populations works to prevent speciation.

Question 60

East Asians who have migrated recently from India and Pakistan to northern areas of the United Kingdom have a higher incidence of rickets and osteoporosis than the general British population. This illustrates that

A) natural selection's role in determining skin color is a thing of the past, relevant only prior to the sixteenth century when massive migrations of populations altered the geographic distribution of dark-skinned people.
B) natural selection continues today.
C) because of global warming, the lack of sunlight that people are exposed to in these northern regions is made up for by the intensity of the sunlight.
D) genetic adaptation of environmental stressors can occur within one generation.
E) cultural adaptation provides effective shortcuts to the genetically disadvantaged in a foreign environment.

Question 61

The indigenous communities in the tropical regions of the Americas are not as dark skinned as populations living in other tropical regions, because the dense vegetation in this continent blocks out much of the sunlight.

Question 62

Biologists have rejected the idea of three great races (white, black, and yellow) largely because it fails to account for Native Americans.

Question 63

Phenotypic similarities and differences always have a genetic basis.

Question 64

The only chance for human racial classification schemes to work is to shift from using phenotypic to genotypic characteristics of human populations.

Question 65

One of the selective advantages of dark skin color in the tropics is that it reduces the susceptibility to folate destruction and therefore diminishes the likelihood of neural tube defects among human embryos. Folate is also necessary in men in order to maintain normal sperm production.

Question 66

Biological races have been scientifically discredited in their application not just to humans but to all living species.

Question 67

Physical features cluster into discrete genetic units.

Question 68

Higher amounts of melanin in the skin inhibit the body's ability to manufacture vitamin D. This confers an adaptive advantage in environments with excessive sun exposure.

Question 69

Thanks to medical advances, genetic resistance to diseases no longer confers any selective advantage.

Question 70

The role of natural selection in producing variation in human skin color illustrates the explanatory approach to explaining human biological diversity.

Question 71

Rickets is caused by an overabundance of vitamin D in the body.

Question 72

Humanity (Homo sapiens) lacks distinct races because human populations have not been isolated enough from one another to develop into discrete groups.

Question 73

In the case of skin color, natural selection is no longer active today, thanks to human cultural adaptations that confer an advantage no matter the skin color or environment one lives in.

Question 74

Skin color is a simple biological trait that is influenced by one gene and environmental exposure to sunlight.

Question 75

There is much greater variation within each of the traditional so-called races than between them.

Question 76

Native Australians are closer genetically to tropical Africans than they are to Asians.