quiz 1-3 answers

Human beings have _____ pairs of chromosomes

23

Humans have 23 pairs of chromosomes. The process of sex-cell formation provides _____ chromosomes to an offspring from each parent

23

The DNA molecule is made up of _____ chemical bases

4

Which genotype has the highest fitness in a malarial environment?

AS

_____ first demonstrated the principles of genetic inheritance

Gregor Mendel

_____ developed the concept of the Inheritance of Acquired Characteristics

Jean Baptiste Lamarck

In DNA, the base A pairs with the base

T

There are two alleles for the PTC-tasting locus in humans: T, which codes for tasting, and t, which codes for non-tasting. T is dominant and t is recessive. Imagine two parents that are tasters have a child that is a non-taster. Given this information, you know that the genotypes of the parents had to have been

Tt and Tt

One difference between DNA and RNA is that RNA has the base _____ instead of the base T

U

Prior to the development of evolutionary thinking, the dominant view of biological variation focused on

an unchanging natural world

A polymorphism is defined as a genetic trait where there

are at least two alleles having frequencies greater than 0.01

You often hear arguments about whether evolution is a fact or theory. Which is it?

both

DNA sequences are found in long chains known as

chromosomes

Alleles are _____ if both of their effects are shown in the phenotype

codominant

The subfields of anthropology are

cultural, linguistic, archaeologic, and physical

As the frequency of the S allele increases in a malarial environment, the incidence of malaria in the population will _____ and the frequency of sickle cell anemia will _____.

decrease / increase

Mendel's experiments with pea plants showed that crossing plants with yellow seeds with plants with green seeds produced offspring with yellow seeds. This finding illustrates the principle of

dominance

An allele is _____ if it masks the effect of another allele

dominant

You visit a random mating population and find that the observed genotype frequencies are not what would be expected under Hardy-Weinberg equilibrium. What does this suggest?

evolution has occurred

(T/F) Species are always defined by reproductive isolation

false

(T/F) The fact that humans have five digits is not an example of a primitive trait

false

(T/F) The following are correct DNA and messenger RNA sequences: ACG TAA CTG GCC (DNA) UGC AUU GUG CGG (mRNA)

false

The probability of survival and reproduction of an organism is known as its

fitness

The relationship between sickle cell allele frequencies and malaria provides an excellent example of selection

for the heterozygote

You observe a change in allele frequency in a population from 0.1 to 0.4 in a single generation. The population is small (25 people) and exchanges many mates with surrounding population. This change could be due to

gene flow and/or genetic drift

Imagine you see the frequency of a harmful allele increase slightly over time in an isolated population. What could be responsible for this contradictory observation?

genetic drift

The total DNA sequence of an organism is known as its

genome

Selection against a recessive homozygote will

gradually decrease the frequency of the recessive allele

Genetic variation in Ireland shows an effect on longitude, where there is some basic separation of populations in the western and eastern parts of the islands, reflecting

greater settlement from England and Wales in the eastern part of the island

The shape of a DNA molecule is a

helix

_____ genes encode a sequence of 60 amino acids that regulate embryonic development

homeobox

Natural selection can act to _____ variation between populations

increase or decrease

Assume a locus where there is an occasional mutation from the A allele to the B allele. Under these circumstances, the frequency of the B allele will

increase over time

Sometimes alleles for different genes are inherited together, which is due to

linkage

_____ is responsible for transporting genetic information to the site of protein synthesis

mRNA

Darwin's development of natural selection was influences by the writing of the economist Thomas Malthus, who noted that

many organisms will not survive into adulthood

Hemophilia is caused by a recessive allele found on the X chromosome. As such, hemophilia will be

more common in men than women

Since most parents of achondroplastic dwarfs are normal, and since the achondroplastic allele is dominant, this means that

most dwarfs are the result of a mutation

Imagine a locus with two alleles, A and Z where individuals with the genotype AZ generally have more offspring than those with genotypes AA or ZZ. This is an example of

natural selection

The study of evolution of the peppered moth provides an excellent example of

natural selection

Given that humans and apes share over 90% of their genetic material, it seems likely that their anatomical differences involve differences in _____ genes

regulatory

Each parent contributes on allele at each locus to his or her offspring. This is known as Mendel's Law of

segregation

Babies born too small or too large are less likely to survive than those born closer to an average weight. This is an example of _____ selection

stabilizing

Imagine an allele frequency of 0.7 in a given population. If this population meets the assumption of Hardy-Weinberg equilibrium, the allele frequency will _____ in the next generation

stay the same

Complete selection against a recessive homozygote will not remove the recessive allele in a single generation. Why?

the heterozygotes in the population will continue to carry the allele

Mendel's Law of Independent Assortment states that

the set of chromosomes that is passed on from a parent to a child is not always the same

The ABO blood group has three alleles (A,B,O) where A and B are codominant and O is recessive. How can a woman with type A blood and a man with type B blood have a child with type O blood?

the woman must have genotype AO and the man must have genotype BO

To date, the results of the Human Genome Project have indicated that

there are far fewer genes in humans than expected

(T/F) A major discovery with the true human genome and decoding other genomes is that life shares a lot of genes and that relatively few are needed for humans

true

(T/F) Convergent evolution is when two species have the independent evolution of similar traits in distantly related species, such as fins on sharks and whales

true

(T/F) Darwin and Alfred Russel Wallace Share credit for independent invention of the mechanism of natural selection, although Darwin had developed it first

true

(T/F) Genetic drift will probably be involved in speciation once gene flow is stopped

true

(T/F) Natural selection is a force of evolution that often ultimately creates a new species

true

(T/F) The frequency of the sickle cell allele is higher in malarial regions than in non-malarial regions

true

Hardy-Weinberg equilibrium states

under certain conditions, allele frequencies will remain constant over time