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