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Chromosome number is reduced during meiosis because the process consists of
A) two cell divisions and a single round of chromosome replication
B) a single cell division without any chromosome replication
C) two cell divisions without any chromosome replication
D) four cell divisions with no chromosome replication
Which statement best describes Mendel's law of independent assortment?
A) Distribution of alleles for one pair of chromosomes is not affected by distribution of other chromosomes
B) During fertilization, which sperm combines with which egg is random
C) Diploid organisms contain two copies of each chromosome that are homologous to each other.
D) homologous chromosomes pair up during meiosis I
E) Mutations are random events, which affect each chromosome independently
When setting up an genetic cross, to ensure that you start with homozygous genotypes you should:
A) Start with individuals which look very different from other individuals
B) Mate close relatives for many generations
C) Examine each individual very closely for signs of variation
D) Start with individuals who always produce offspring with the same phenotype as themselves
A) the ability of a single gene to affect multiple phenotypic traits
B) when a heterozygote exhibits phenotypes for both its alleles
C) when one gene affects the expression of another gene
D) more than one gene affects a single phenotypic character
A characteristic of K- selected populations is
A) a high intrinsic rate of increase (r)
B) small offspring
C) many offspring per reproductive episode
D) offspring with good chances of survival
E) early parental reproduction
Formation of thick or thin hair shafts in an animal is controlled by a single gene with two alleles. Thick hair is needed for survival in cold climates but not in warm climates. Most animals in a population have thick hair. Which allele for this trait is dominant?
A) Thin hair
B) It depends on the climate
C) Thick hair
D) They are co- dominant
E) It can't be determined with the information provided.
Which of the following is NOT needed for the Hardy- Weinberg equation to successfully predict the genetic make- up of a population?
A) random mating among the population
B) equal reproduction rates among all individuals in the population
C) the population is large
D) there is no immigration or emigration
E) all individuals in the population are long lived
Which statement best describes the effect of genetic drift on the gene frequencies of a population?
A) Chance alone can cause significant changes in gene frequencies of small populations
B) Genes enter a population through immigration, thus changing gene frequencies
C) Exposure to mutagens increases the frequency of a particular trait in the population.
D) Individuals with one allele reproduce more successfully than individuals with other alleles.
Which is/are necessary for evolution of a trait by natural selection to take place?
i. The trait is heritable (controlled by genes)
ii. Differences among individuals lead to different numbers of successful offspring being produced.
iii. Individuals change their behavior depending on the environment.
iv. Every individual produces large numbers of offspring.
A) ii only D) ii, iii, and iv
B) i and ii E) All of the above
C) iii and iv
Which is necessary for two populations to be considered separate species according to the biological species concept?
A) They must be reproductively isolated from each other.
B) They must accumulate a large number of different mutations
C) They must differ significantly in the sizes of their populations.
D) Only a few of the offspring produced through matings between two populations survive.
E) The two populations must be geographically separated from one another
Crossing over can be observed between which structures during prophase I?
A) sister chromatids only
B) sister chromatids and non- homologous chromosomes
C) non- homologous (different) chromosomes
D) homologous and non- homologous chromosomes
E) homologous chromosomes only
E) The alleles for body colour and wing shape assort independently
In the pedigree shown above, individuals with the solid symbols display a rare genetic trait caused by a recessive allele at an autosomal locus. The probability that a child indicated by the question mark will have the disease is:
A man is brought to court in a paternity case. He has blood type B. The mother has blood group AB. The child's blood type is A. Which statement about the man is CORRECT ?
A) He might be the father
B) He is the father
C) He is not the father
D) there is not enough information to
make a decision.
What is the probability of having an offspring showing dominant traits for all five genes produced from the following cross?
AaBbccddEe X AabbCcddEe
According to the logistic growth equation
dN/ dt = rmaxN [(K - N) / K]
A) population growth is zero when N equals K .
B) the population grows exponentially when K is small.
C) the number of individuals added per unit time is greatest when N is close to zero.
D) the per capita growth rate (r ) increases as N approaches K.
E) the birth rate (b ) approaches zero as N approaches K.
In a population, one of every five gametes carries a recessive allele. Assuming Hardy- Weinberg equilibrium, what is the frequency of the homozygous recessive genotype in a population?
Which BEST explains why it is unlikely that humans will undergo speciation in the future?
A) Random effects have become more important in large populations
B) Natural selection is no longer operating on humans
C) Migration among populations is high
D) The environment on Earth is being controlled and stabilized
E) There is not enough variation present in human populations.
Which conditions are necessary for evolution by natural selection?
i. Heritable variation
ii. Competition for resources
iii. Differences in fitness between individuals
iv. Major environmental changes
A) i only
B) ii and iv
C) i, iii, and iv
D) ii only
E) i, ii, and iii
Which would NOT be evidence to support the view that genes are on chromosomes?
A) That chromosomes consist of a polymer of nucleotides linked together by alternating phosphates and sugars
B) That both genes and chromosomes sort independently into gametes
C) That both alleles and homologous chromosomes segregate into different gametes
D) That Down syndrome correlates with an extra chromosome 21
E) Inheritance of a form of color blindness correlates with the inheritance of one X chromosome in males.
After telophase I of meiosis, the chromosomal makeup of each daughter cell is
A) haploid, and the chromosomes are each composed of two chromatids.
B) diploid, and the chromosomes are each composed of a single chromatid.
C) haploid, and the chromosomes are each composed of a single chromatid.
D) tetraploid, and the chromosomes are each composed of two chromatids.
E) diploid, and the chromosomes are each composed of two chromatids.
Which statement about inheritance of genes is incorrect?
A) Genotype refers to the alleles for a gene present in an individual.
B) Alternate forms of genes are called alleles.
C) Individuals with the same phenotype can have different genotypes.
D) Only two alleles can exist for a given gene in a population.
E) A single gene can influence multiple phenotypes.
In the Hardy- Weinberg equation, the 2 in the term 2pq is necessary because
A) the population is doubling in number.
B) heterozygotes can form in two ways.
C) heterozygotes have two alleles.
D) the population is diploid.
A) when one gene affects the expression of another gene
B) the ability of a single gene to affect multiple phenotypic traits
C) when a heterozygote individual has a phenotype intermediate between those of the two types of homozygotes
D) when a heterozygote exhibits phenotypes for both its alleles
Which information can be used to determine which of two alleles for a gene is dominant?
i. which phenotype promoted by these alleles is most common in the population.
ii. which phenotype promoted by these alleles is expressed in heterozygotes.
iii. which phenotype promoted by these alleles is more critical for survival in a given environment
A) i only D) i and ii
B) ii only E) i, ii, and iii
C) iii only
An individual’s fitness is BEST measured by:
A) its relative contribution to the gene pool of the next generation
B) its ability to compete with other individuals for key resources
C) its resistance to disease and parasites
D) its ability to survive relative to other individuals
E) how early it can begin to reproduce
Which was NOT part of Darwin's explanation of natural selection?
A) Organisms commonly produce more offspring than can possibly survive.
B) Mutations can create new versions of genes.
C) Variation exists within each species.
D) Members of a species compete with each other for food and space.
E) Offspring that are most fit have traits best suited to the environment.
Which is likely to have the smallest impact on allele frequencies of a population in two generations?
B) natural selection
C) genetic drift
Which would generally REDUCE the likelihood of speciation?
A) immigration and emigration
B) genetic drift
C) geographic isolation
D) natural selection
E) genetic variation in populations
Which of the following does NOT contribute to genetic variation among offspring?
A) Independent assortment of sister chromatids during metaphase II
B) Independent assortment of homologous chromosomes during metaphase I
C) Crossing over during prophase I
D) Random fertilization
In corn, the trait for tall plants (T ) is dominant to the trait for dwarf plants (t ) and the trait for colored kernels (C ) is dominant to the trait for white kernels (c ). In a particular cross of corn plants, the probability of an offspring being tall is 0.5 and the probability of a kernel being colored is 0.75. Which of the following most probably represents the parental genotypes?
A) TtCc x ttCc D) TTCc x ttCc
B) TtCc x TtCc E) TTCc x TtCC
C) TtCc x ttcc
A man with blood type A, whose father was blood type O, married a woman of blood type B whose mother was blood type O. What are the possible blood types of their offspring?
A) A, B, AB, or O
B) Only AB
C) Only AB or O
D) Only A or B
E) Only A, B, or AB
Feather colour in budgies is determined by two different genes that affect the pigmentation of the feathers: Y_B_ is green; yyB_ is blue; and yybb is white. Two blue budgies were paired for life. Over many years, they produced 22 offspring, five of which were white. What are the most likely genotypes for the parents?
A) yyBb and yyBb D) yyBB and yybb
B) yyBB and yyBB E) yyBb and yybb
C) yyBB and yyBb
What is the probability of having an offspring
showing recessive traits for all five genes produced from the following cross?
AaBbccddEe X AabbCcddEe
Which statement regarding the logistic growth equation is correct?
dN/ dt = rmaxN [(K - N)/ K]
A) The intrinsic growth rate (r) of a population is considered to be constant but K can vary over time.
B) At K, dN/dt = 1.
C) For a given population, the value of K does not change over time
D) Populations experience the most rapid growth as they approach K
E) When K is reached, environmental resources are fully depleted
A population of butterflies has two alleles for wing- spot colour. The red allele is fully dominant to the white allele. In a population of 200 diploid butterflies known to be in Hardy- Weinberg equilibrium there are 18 white- spotted butterflies. What percentage of the population is heterozygous?
Which statement about genetic drift is FALSE ?
A) It is not influenced by the phenotype of an individual
B) It decreases the average variation in a population
C) It is more common on small islands than on large continents
D) It is dependent on the kind of genotype an individual possesses
E) It can produce changes that have positive or negative effects on the fitness of an individual
Which is NOT required for the size of a given trait to evolve by natural selection?
A) Individuals with larger traits live longer
B) The size of the trait varies among individuals in the population
C) There is a relationship between the size of the trait and the reproductive success of the bearer of the trait
D) The size of the trait has a genetic basis
An advantage of sexual over asexual reproduction is that sexual reproduction:
A) produces offspring with more variety
B) produces offspring with phenotypes
more similar to the parents
C) ensures the survival of the species
D) produces more offspring
Which statement about meiosis is FALSE ?
A) Crossing over occurs in prophase of the second meiotic division
B) There is no DNA replication between the first and second meiotic division
C) the behavior of chromosomes during mitosis is most similar to the second meiotic division
D) The two meiotic divisions reduce the DNA content per cell to one half of the initial content
In humans, the sex ratio is close to 50:50. Which mechanism best explains this?
A) non- homologous chromosomes sort into gametes independently of each other
B) genes on the same chromosome tend to be inherited together
C) homologous chromosomes sort into separate gametes during meiosis
D) linked genes can be separated by crossing over
Which statement concerning karyotypes is CORRECT
A) The sex chromosomes in a karyotype are also known as autosomes
B) All of the chromosomes in a karyotype have the same length and shape
C) Normal individuals from the same species have the same number of chromosomes in a karyotype
D) karyotypes involve examining chromosomes under a microscope to determine their nucleotide sequence
E) Karyotypes can be prepared from cells at any stage in the cell cycle
Co- dominance describes
A) when a heterozygote exhibits phenotypes for both its alleles
B) when a heterozygote individual has a phenotype intermediate between those of the two types of homozygotes
C) when one gene affects the expression of another gene
D) two or more genes affecting the same phenotype
E) the ability of a single gene to affect multiple phenotypic traits
Dominant mutations are easier to detect than recessive mutations because they
A) are always neutral in their effect
B) are expressed in both homozygotes and heterozygotes
C) occur more frequently than recessive mutations
D) are always favored by selection
E) are always lethal and so their appearance is unmistakable
As the number of individuals in a population approaches the carrying capacity of the environment, you expect to see that:
A) Population density will decrease exponentially
B) Population growth rate will decrease
C) Population growth rate will increase
D) Population biomass will remain the same
E) Population density will increase exponentially
Which statement best defines evolution?
A) Change in the phenotype of an individual through time
B) Change in genetic composition of a population
C) Individuals in two populations look different
D) The close resemblance between parents and their offspring
The main feature of the "biological species concept" is its emphasis on the
A) genetic variation within populations
B) recognition of different species based on their ecological separation
C) role of sexual reproduction in maintaining diversity within a species
D) absence of gene flow between different species
E) large morphological differences between different species
For evolution to occur, which must be true?
i. There is variation among individuals within a species.
ii. Some variation within species is passed on to the offspring (i.e., it is inherited).
iii. Some individuals survive and reproduce more successfully than others.
iv. Differences in reproductive success must be present for several generations.
A) i, ii and iv D) i, ii, and iii
B) i, ii, iii, and iv E) iii only
C) iv only
A cell containing 40 chromatids at G2 of mitosis would produce cells each with how many chromosomes at the end of meiosis?
Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. A man and a woman, both normal pigmented, have an albino child together. The couple then have a second child. What is the probability that the second child will be albino?
You perform the cross: AAbb x aaBB where: A = big, a = small, B = dark and b = light. The genes sort independently. The F1 progeny are big and dark. If you cross two F1 progeny, what proportion of the F2 progeny would you expect to be big and light?
For the ABO antigen locus in humans, the A and B alleles produce A and B antigens, respectively, while the O allele produces no antigen. For which phenotypes could you be certain that an individual with that phenotype is homozygous?
A) type AB only
B) types A and B
C) type O only
D) type AB and O
E) type A only
hemophilia is caused by an X- linked recessive gene. Two brothers have hemophilia; their parents do not. The probability that their newborn sister will have hemophilia is most likely:
The trait being following in the human pedigree above is most likely:
A) X- linked recessive
B) autosomal recessive
C) autosomal dominant
D) either A or B
dN/ dt = rmaxN [(K - N)/ K] :The intrinsic growth rate for a population per year is 10%. Using the equation above, calculate how many individuals would be added to a population of 500 after if the carrying capacity of the environment is 1000.
In a population of deer mice, 910 mice were black and 90 were white. Black fur colour is dominant and white is recessive. Assuming that the population is in Hardy- Weinberg equilibrium, how many homozygous dominant individuals are in this population?
A study of cliff swallows on an island found that the smallest and largest adult birds contribute fewer offspring to the next generation than birds that are closer to the average size. These findings suggest that:
A) artificial selection is acting on this population
B) the population is experiencing stabilizing selection
C) the population is experiencing disruptive (diversifying) selection
D) the population is experiencing directional selection
D) Grow orchids from both populations in a greenhouse and show that they can interbreed
Which answer correctly describes a difference between meiosis and mitosis?
A) Cytokinesis only take place in mitosis
B) Exchange of genetic material occurs only in meiosis
C) DNA is replicated only before mitosis
D) Centromeres are found only in mitosis
E) Microtubule spindles only form in mitosis
Which statement(s) about homologous genes in an individual is CORRECT?
A) they are found on the sex chromosomes
B) they are two different genes found on same chromosome
C) they are copies of the same gene that differ in DNA sequence
D) they were contributed by the same parent
Which statement is FALSE ?
A) Nondisjunction refers to the failure of a pair of chromosomes to segregate properly during meiosis
B) Autosomes are cytoplasmic organelles that contain DNA and are capable of self- replication
C) Karyotype refers to the number, forms, and types of chromosomes in a cell
D) Prophase marks the onset of nuclear division
E) Centromere refers to the region where sister chromatids join
A) two or more genes affecting the same phenotype
B) when one gene affects the expression of another gene
C) the ability of a single gene to affect multiple phenotypic traits
D) when a heterozygote individual has a phenotype intermediate between those of the two types of homozygotes
E) when a heterozygote exhibits phenotypes for both its alleles
A man who carries an X- linked allele will pass this allele on to
A) half of his daughters
B) all of his sons
C) half of his sons
D) all of his daughters
E) all of his children
Which of the following determines a population’s intrinsic rate of increase (r)?
A) Amount of available resources
B) Maximum population size
C) Maximum reproductive rate
D) Carrying capacity of the environment
A population is in Hardy- Weinberg equilibrium. Which statement about the population is most likely to be CORRECT?
A) Females in the population choose their mates at random
B) The population is experiencing genetic drift
C) There are fewer than 500 individuals in the population
D) There is extensive gene flow in the population
Which of the following is a true statement concerning genetic variation?
A) It is created by the direct action of natural selection.
B) It arises in response to changes in the environment.
C) It must be present in a population before natural selection can act upon the population.
D) Small populations generally display higher genetic variation than large populations.
Which is essential for speciation to occur?
A) Sub- populations must become geographically isolated from each other
B) Hybrid offspring can be born, but are sterile 50% of the time
C) Gene flow between sub- populations must be restricted
D) Formerly isolated sub- populations must never re- occur in the same place
B) Variation in a population affects the chance a given individual will survive in its environment and reproduce
If the haploid number for a species is three, each dividing diploid cell will have __ sister chromatids at metaphase I.
A) 9 B) 12
C) 3 D) 6
If you cross a diploid individual that is homozygous recessive for a given trait with a heterozygous diploid individual, what is the probability of obtaining an offspring with the homozygous recessive phenotype?
In flies, round eyes is recessive to oval eyes; curled wings is recessive to straight wings. The two genes sort independently. Males heterozygous for both genes are mated to females that are heterozygous for eye shape, but homozygous for curled wings. What
proportion of the offspring should have oval eyes and normal straight wings?
Barbie's blood type is A. Ken's mother and father have type B blood. Barbie and Ken first child, Skip, has type O blood. Which answer best explains this result?
A) There had to be a mistake, as Skip should also have type A blood similar to Barbie
B) Barbie’s genotype is AA, and Ken’s genotype is OO
C) Ken cannot be Skip’s father
D) Barbie’s genotype is AO, and Ken’s genotype is BO or OO
E) Barbie’s genotype is AA, and Ken’s genotype is BB
Red- green color- blindness is controlled by a gene on the X chromosome. A man and woman with normal vision marry. Both their fathers were colour- blind. The probability their first child will be color- blind?
Which mode of inheritance best explains the pattern of occurrence of the trait in this pedigree?
A) Autosomal dominant
B) Autosomal recessive
C) either autosomal or X- linked recessive
D) X- linked recessive
E) none of the above
dN/ dt = rmaxN [(K - N)/ K]
The intrinsic growth rate for a population per year is 25%. Using the equation above, calculate how many individuals would be added to a population of 200 after if the carrying capacity of the environment is 1000.
A) 250 B) 25
C) 40 D) 50
The frequency of the dominant allele for a gene with two alleles is 0.6. What is the expected frequency of heterozygous individuals in a population at Hardy- Weinberg equilibrium?
You measures the average tail length of a wild population of birds. Several generations later, you measure the birds again and see an increase in average tail length. Which process could account for this increase?
i. Genetic drift iii. Natural selection
ii. Emigration iv. Immigration
A) iii only D) iii and iv only
B) i and iii only E) i, ii, iii, and iv
C) ii and iv only
B) Genetic variants of mosquitoes
resistant to the insecticide survived and transmitted their resistance to their offspring
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