162 terms


ch 1, 9,10,14,15
the process by which the characteristics of individuals are passed to their offspring.
segments of DNA ranging from a few hundred to many thousands of nucleotides in length are the units of inheritance
a gene's physical location on a chromosome is called its
different versions of a gene at a locus
when both homologues have the same allele at a given locus
when homologues chromosomes have different alleles at a given locus
organisms that are heterozygous at a specific locus are called
when an organism's sperm fertilize its own eggs
when sperm from one organism fertilize eggs from a different organism
when an organism possesses a trait, such as purple flowers, that is always inherited unchanged by all of its offspring that are produced by self-fertilization
law of segregation
ex; the pairs of alleles on homologous chromosomes separate, or segregate, from each other during meiosis
the actual combination of alleles carried by an organism
the organisms traits (outward appearance,behavior, digestive enzymes, blood types, or any observable/ measurable feature) make up its ______
Punnett square method
a convenient way to predict the genotypes and phenotypes of offspring
test cross
this tests whether the organism with the dominant phenotype is homozygous or heterozygous
law of independent assortment
the independent inheritance of two or more traits
genes on the same chromosome tend to be inherited together (gene)
genetic recombination
the appearance of new combinations of alleles that were previously linked (explained by crossing over during meiosis )
sex chromosomes
in mammals, an individual's sex is determined by a special pair of chromosomes known as the,
X chromosomes
females have two identical sex chromosomes, called
Y chromosome
males have one X chromosome and one
the other chromosomes that occur in pairs that have identical appearance in both males and females
genes that are on one sex chromosome but not on the other are said to be
incomplete dominance
when the heterozygous phenotype is intermediate between the two homozygous phenotypes (hair texture)
multiple alleles
an individual can have at most two different alleles, a species may have _____ of many of its genes (human blood type, human diseases)
when heterozygotes express phenotypes of both of the homozygotes
polygenic inheritance
a form of inheritance in which the interaction of to or more genes contributes to a single phenotype (human height, weight, eye color, skin color... not split up into convenient easily defined categories)
single genes commonly have multiple phenotypic effects (SRY gene on the Y chromosome)
diagrams that show the genetic relationships among a set of related individuals
a person who is heterozygous for a recessive genetic trait (phenotypically healthy but can pass on the trait)
sickle-cell anemia
results from a mutation in the hemoglobin gene. A change in a single nucleotide results in a n incorrect amino acid at a crucial position in the hemoglobin molecule
huntington disease
a dominant disorder that causes a slow, progressive deterioration of parts of the brain, resulting in a loss of coordination, flailing movements, personality disturbances, and eventual death
caused by a recessive allele on the X chromosome that results in a deficiency in one of the proteins needed for blood clotting
during meiotic cell division, when a step is missed it results in gametes that have too many or too few chromosomes (effects number of sex chromosomes or autosomes)
Turner sydrome
When a female only has 1 X chromosome
trisomy X
triple x, 3 x chromosomes
Klinefelter syndrome
Jacob syndrome
trisomy 21/ down syndrome
an extra copy of chromosome 21
change over time in the characteristics of populations
the preserved remains or traces of organisms that died long ago
all the individuals of one species in a particular area
natural selection
individuals with advantageous traits survive the longest and leave the most offspring
homologous structures
when internal structures have the same evolutionary origin despite any differences in current function or appearance
vestigial structures
i.e molar teeth in bats that don't chew their food... traits that show up in animals that have no use for it
convergent evolution
natural selection causes non-homolgous structures that serve similar functions to resemble one another (birds and insects' wings)
analogous structures
these structures are typically very different in internal anatomy , because the parts are not derived from common ancestral structures (outwardly similar but non-homologous structures)
artificial selection
the breeding of domestic plants and animals to produce specific desirable features.
gene pool
the sum of all the genes in a population (in other words it consists of all the alleles of all the genes in all the individuals of a population)
allele frequency
the relative proportion of each allele
Hardy-Weinberg principle
under certain conditions, allele frequencies and genotype frequencies in a population will remain constant no matter how many generations pass (this population will not evolve)
equilibrium population
the term for the hypothetical non evolving population in which allele frequencies do not change so long as certain conditions are met
gene flow
there must be no movement of alleles into or out of the population
a population remains in evolutionary equilibrium only if there are no _____
genetic drift
the process by which chance events change allele frequencies
population bottleneck
a population is drastically reduced as a result of a natural catastrophe or over hunting
founder effect
occurs when isolated colonies are founded by a small number of organisms
when other organisms compete for scarce resources, most intense amongst organisms of the same species
when one species evolves a new feature or modifies an old one, the other typically evolves new adaptations in response
includes any situation in which one organism eats another
sexual selection
the special kind of selection that acts on traits that help an animal acquire a mate
directional selection
favors individuals with an extreme value of a trait and selects against both average individuals and individuals at the opposite extreme
stabilizing selection
favors individuals with the average value of a trait and selects against individuals with extreme values
disruptive selection
favors individuals at both extremes of a trait and selects against individuals with intermediate values
all matter on Earth consists of atoms of substances called _______
the smallest particle of an element that retains all the properties of that element
atoms may combine in specific ways to form assemblies called ______
the bodies of living things
organic molecules
contain a framework of carbon to which at least some hydrogen is bound
the smallest unit of life
cells of similar type combine to form structures known as
different tissues may combine to form
organ systems
a group of organs united by a common overall function are called
a collection of populations of different species that interact with one another makes up a
a community and the nonliving environment that surrounds it constitute an ____
the entire surface of Earth and the living things that dwell in and on it is called the
in a typical human body cell, how many chromosomes are there?
the chromosomes must be duplicated
what must happen before a cell can begin mitosis?
the centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
the chromosomes line up in the center of the cell during which phase of mitosis?
the sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
the chromosomes arrive at the poles and the nuclear envelopes form during which phase of mitosis?
at the end of the mitotic (M) phase, the cytoplasm divides in a process called
when a cell divides via asexual reproduction
each daughter cell receives a nearly perfect copy of the parent cell's genetic information
4 haploid cells
meiosis starts with a single diploid cell and produces
a cell preparing to undergo meiosis duplicates its chromosomes during
during prophase I of meiosis,
homologous chromosomes stick together in pairs
the correct order of events during meiosis is
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II
prophase I
during meiosis, segments of insister chromatids can trade places. this recombination of maternal and paternal genetic material is a key feature of meiosis. during what phase of meiosis does recombination occur?
the S phase of interphase
during which phase of the eukaryotic cell cycle does DNA and chromosome replication occur?
reproductive tissues, gametes
Meiotic cell division occurs in the ________ and results in the production of __________
in a typical human body cell, how many sex chromosomes are there?
AA is a ___________ genotype
gene pool
all the genes in a population are that population's _______
the role of chance
genetic drift is a process base on ____
there is a change in the DNA sequence of a gene
a mutation occurs when
alleles that promote "tallness" will decrease in frequency
every few years a giant axe chops off the head of every person who is over 6 feet tall. how will this affect the human population?
genetic drift
modern travel along with migration reduces the probability of ________ having an effect on the evolution of humans
gene flow
the ease with which humans travel across the globe is likely to increase
metaphase I
homologous pairs of chromosomes are lined up independently of other such pairs during
nonsister chromatids of homologous chromosomes
crossing over, resulting in an increase in genetic variation, occurs between
in human gamete production there is an average of ______ crossover events per chromosome pair
prophase I
when does crossing over occur
ability to fuse haploid gametes to for a new individual
what is the most important for generating the most genetic variability in a species?
which phase of the cell cycle is most similar between a cell that will divide by mitosis and one that will divide my meiosis?
homologous chromosomes contain the same genes, but may contain different alleles
how are homologous chromosomes defined?
markers in your cells
research indicates that the best estimate of your age is from
the cells examined from the 2,400 people in this study were from
what damages cells and causes call aging
longer telomeres indicate younger cells
the researchers used strands of DNA located at the ends of chromosomes called telomeres to classify the cells they studied. what assumption did they make about telomeres?
longer in individuals who exercised regularly
the researchers found that telomeres were
exercised for an average of 30 minutes per day
the researcher showed that individuals who ______ had younger looking cells based on telomere measurements
fat, cigarette smoke, testosterone, UV light are all examples of
______ is a carcinogen that promotes colon cancer
genetic drift
the evolution of populations due to chance is
the frequency of the green allele will increase
if color is an inherited trait in beetles , and birds are more likely to eat brown beetles than green beetles,
has more effect on the evolution of a small population
in a population with brown and green alleles for color, genetic drift
gene flow causes the frequency of the green allele to increase
color is an inherited trait in beetles. if brown beetles move into a population from a nearby island, which statement is correct :

natural selection causes the frequency of the brown allele to increase

this is an example of genetic drift

gene flow causes the frequency of the brown allele to increase

gene flow causes the frequency of the green allele to increase

natural selection causes the frequency of the green allele to increase
Green beetles leave more offspring that brown beetles because they are better at finding food.
remember that color is an inherited trait in beetles. WOF is an example of natural selection?

Green beetles migrate out of the population, and brown beetles migrate into the population

A storm kills more green beetles than brown beetles by chance,

Green beetles and brown beetles always leave the same number of offspring.

Green beetles leave more offspring than brown beetles because are better at finding food.

Green beetles migrate out of the population.
natural selection
1. pesticide is applied to a population of insects. 2. some insects have a gene that makes them resistant to the pesticide. these insects survive. insects without the gene die. 3. the surviving insects reproduce. the frequency of resistant insects in the population increases.
mutations must occur to create new variety in the population
consider a population of bacteria that came from a single ancestor. because bacteria reproduce asexually, there should be no variation in this population, but that violates the first postulate of natural selection. how is it then that this population of bacteria can still evolve?
lamarck focused on genetic changes in an individual. darwin focused on genetic changes in a population
both lamarck and darwin proposed mechanisms to explain how evolution occurs. what was different about these mechanisms?
natural selection can at on a certain trait only if the trait is
the fish with green scales will become more common
fish in a local lake have a mixture of brown and green scales are are found throughout the lake. over a five-year period, the lake develops more plant growth and an exotic predatory frog is introduced. what change would you expect to see in the original fish population?
natural selection acts on individuals
which of the following is true about natural selection?
gene flow
from an evolutionary point of view, what important process occurs when a young male baboon leaves the troop that he was born in to join another troop?
if more offspring caring an allele are created, the frequency of the allele increases.
why is natural selection based entirely on reproductive success?
a mutation resulting in a heat-resistant enzyme in a bacterium living in a hot spring
Which trait is the BEST example of an adaptation?

a shorter neck in a giraffe that lives in an area with many rival males and tall trees
a new mutation that confers Tay-Sachs disease in humans
a mutation resulting in weak branches in a species of tree that lives in windy regions
a mutation resulting in a heat-resistant enzyme in a bacterium living in a hot spring
a longer tongue in an insect-eating mammal that feeds on insects that live in shallow burrows
natural selection
a patient has an infection of Streptococcus bacteria. she takes azithromycin, which kills 99 percent of a bacteria population. all surviving bacteria are resistant to azithromycin. what has occurred in this bacterial population ?
reproductive success
in the common phrase, "survival of the fittest," what determines how fit an individual is?
inbreeding (if the member of the population mater only with the closest individual, the population can quickly become inbred. this can happen in a predator pack or in pockets of plants in a larger population)
WOF is a result of nonrandom mating within a population?

gene flow
genetic drift
the population needs to be small
what condition is necessary for genetic drift to have a significant effect on a population?
one that increases the frequency of successful reproduction
WOF mutations would increase evolutionary fitness?

one that removes other alleles from the population
one that increases the life span of the organism
one that increases the frequency of successful reproduction
one that attracts more potential mates without increasing the frequency of reproduction
one that increases the birth weight of offspring while decreasing their number
you wish to research how genetics determine color of deer mice. how many genes should you focus on?
to allow for faster growth
the three-spine stickleback typically lacks armor in fresh water. why?
genotype determines phenotype
WOF is true?

Phenotype determines genotype.
Genotype and phenotype are the same thing.
Genotype determines phenotype.
Genotype and phenotype are not related.
in a monastery
Mendel worked
all of the above
how do mutations affect an organism?

they may cause the development of a disease-causing allele
they may cause the development of a more beneficial allele
they, in some cases, may have no noticeable affect
all of the above
DNA replication occurs at an unbelievably fast rate. once replication is complete, we can expect to find a _____ number of mistakes.
her egg cells
a female that is planning to become pregnant is concerned about her exposure to environmental mutagens which may have caused DNA mutations. In order for these mutations to become heritable, they must affect:
both parents are heterozygous for both genes
a phenotypic ratio of 9:3:3:1 in the offspring of a cross indicates that
a G paired with a T
WOF would indicate a base pairing mutation in DNA?

an A paired with a T
a C paired with a G
a G paired with a T
all of the above are improper base pairs
In people, a dimpled chin is an autosomal dominant trait. Many famous celebrities, such as John Travolta and Michael and Kirk Douglas, have this condition. Assume that the wrestler and actor Hulk Hogan is homozygous for the dimpled chin, and he married a woman with a round chin. They had two children, Brooke and Nick. What proportion of their female progeny (such as Brooke Hogan) will show the trait?
75% dominant: 25% recessive
What is the ratio of phenotypes in the offspring produced by the cross Aa x Aa? Assume complete dominance for the trait.
In crossing a homozygous recessive with a heterozygote, what is the chance of getting a homozygous recessive phenotype in the F1 generation?
anaphase I
During which phase of the cell cycle does the Law of Segregation of Alleles occur?
linkage (linked genes do not assort independently)
Which of the following represents an exception to the law of independent assortment?
crossing over
when genes are linked, a few of the recombinant genotypes still occur in the offspring because of:
both parents are heterozygous for the disease allele
two healthy parents give birth to a child with cystic fibrosis, a recessive disorder. what can we say about both parents?
they have only one gene for that trait
traits controlled by sex-linked recessive genes are expressed more often in males because;
a color-blind boy has a mother with normal vision and a color-blind father. from which parent did he get the color-blind gene?
males can express single recessive alleles from their single X chromosome
why do males suffer from sex-linked disorders more often than females?

Fathers are more likely to pass disease alleles on to sons than to daughters.
The diseases that are sex-linked require the expression of testosterone.
Males can express single recessive alleles from their single Y chromosome.
Males can express single recessive alleles from their single X chromosome.
The disease genes are only located on the Y chromosome of males.
the father only gives his Y chromosome to his sons
why can't a color blind father pass this condition on to his sons?

Fathers only pass on dominant alleles for color vision to their sons.
Children can only receive the color-blind allele from their mother.
The father only gives his X chromosome to his sons.
The father only gives his Y chromosome to his sons.
both of the alleles in a heterozygote are expressed phenotypically in an individual
codominance occurs when:

expression of two different alleles alternates from one generation to the next.
a heterozygote expresses an intermediate phenotype.
both of the alleles in a heterozygote are expressed phenotypically in an individual.
offspring exhibit several different phenotypic expressions of a single trait.
It has been discovered that some men are missing copies of a gene that converts testosterone into a form that dissolves in what?
The gene that some men are missing adds which of the following chemicals to testosterone?
Where does the testosterone used in doping usually come from?
Which ethnic group had the highest percentage of men missing copies of the gene in question?
When discarding bad genes, what does the Y chromosome recombine with?
What holds a pair of copied chromosomes together?
a single x chromosome
A person with Turner's syndrome has which of the following?

a single X chromosome
a single Y chromosome
two X chromosomes
two Y chromosomes
close to the end of the left arm
Where is the male-determining gene on the Y chromosome?