Midterm 1 Flashcards
If you wanted to directly and easily count the number of chromosomes in the sporophytic generation of an angiosperm, which of the following tissues would you choose?
Actively dividing root tip cells
The components of ribosomes are
coded for by nuclear genes.
In a Genbank entry, the gene sequence is given, by convention:
as DNA 5’ to 3’ .
One of the features of DNA that makes it an ideal genetic material is that it is capable of change. Which of the following terms best describes the “capability for change”?
Mutation
When would you expect to observe a bivalent?
Prophase I of meiosis
In any given diploid individual there are two alleles per locus but in a population of individuals there can be many alleles.
True
A promoter
Is where transcription of a gene by RNA polymerase is initiated.
Looking at a gene sequence, the open reading frame is the:
Consecutive DNA sequence from the start to the stop codon
Adenine and guanine are pyrimidines.
False
Which of the following sequences of events is most correct?
DNA is transcribed to RNA which is translated to protein.
The role of the antipodals is
Not known, according to the material presented in class
Translation of mRNA occurs in the __________ of the plant cell.
Cytoplasm
A diagnostic sequence that can predict the beginning of a gene is ATG.
True
Degeneracy refers to the fact that most amino acids are represented by more than 1 codon.
True
In reciprocal crosses between two homozygous parents with contrasting alleles at multiple loci, the eggs of the F1 will be the genetically the same but the F1 endosperms will be genetically different.
True
In 3n endosperm,
2 genomes trace to the female parent and 1 genome to the male parent
Meiosis starts with a 2n cell and ends with 4 identical n daughter cells.
False
A phosphodiester bond is the linkage between the 3’ carbon of one nucleotide and the 5’ carbon of another nucleotide.
True
In the 8-nucleate embryo sac, which of the following will contribute inherited genetic information to the next generation of seed?
Egg
In both the replication of DNA and the transcription of DNA
Synthesis of new strands proceeds 5’ to 3’, with nucleotides added to the ends of developing strands
The three principal classes of RNA are
informational, functional, and regulatory
___________ mutations result in a stop codon, which prematurely ends translation.
Nonsense
After double fertilization there are at least four independent genetically distinct generations coexisting in the angiosperm seed.
True
In the case of a gene encoding a protein, which of following ribonucleic acids is transcribed from the DNA?
mRNA
After an angiosperm megaspore mother cell that is heterozygous at many loci undergoes meiosis
Each of the four haploid cells is most likely to be genetically different
The number of tRNA genes in a plant genome will most likely be:
One hundred or more
Assuming a diploid plant, which of the following is the best working definition of homologous chromosomes?
A pair of chromosomes of similar structure and function, one of which is inherited from the mother and the other from the father
____________mutations result in a change in amino acid sequence.
Missense
A chromosome after the S phase consists of:
Two identical molecules of DNA, joined at the centromere
In the 8-nucleate embryo sac, which of the following will contribute inherited genetic information to the next generation of seed?
Egg
DNA replication is considered a __________________ process.
Semi-conservative
If a Megaspore Mother Cell is 100% homozygous, after meiosis it will produce four genetically distinct daughter cells.
False
In DNA replication, polymerases catalyze the formation of a phosphodiester bond between the 3’-OH of the deoxyribose of the terminal nucleotide in the developing and the 5’ phosphate of the dNTP precursor
True
A plant has the genome formula 2n = 2x = 36. Which of the following is true?
There will be 18 chromosomes in an unfertilized egg nucleus
Exons are always longer than introns.
False
___________ carry amino acids to the growing polypeptide chains.
tRNAs
The nitrogenous base attaches to the _________carbon of the sugar in a DNA nucleotide.
1’
Transcription and processing of mRNA occurs in the __________ of the plant cell.
Nucleus
During the S phase of both mitosis and meiosis there is
DNA replication
A nucleic acid containing a ribose and uracil is most likely DNA.
False
The template strand is also referred to as the sense or coding strand of DNA.
False
__________ and ___________ are key ribonucleic acids involved in the process of translating a mRNA.
tRNA and rRNA
The ________ is the site of pollen recognition:
stigma
Amino acids make up the __________ structure of proteins.
Primary
Crossing over occurs during _______ phase of Prophase of Meiosis I.
Pachynema
Mutations are more likely to be causal (in terms of change in phenotype) if they are in:
Exons
A megaspore mother cell is expected to be
2n
The -OH group attaches to the __________ carbon of the sugar in a DNA nucleotide.
3’
In angiosperms a sporophytic generation may be diploid or polyploid.
True
During the development of the male gametophyte the first post-meiotic mitosis gives rise to:
vegetative and generative nuclei
In angiosperms polyploidy is a rare occurrence.
False
Choose the incorrect base pairing:
Thymine-Cytosine
Post-transcriptional processing involves each of the following EXCEPT for:
Exon removal
The 8-nucleate embryo sac includes all of the following except:
Pollen
The role of the synergids is to
ttract the sperm to the egg
Two key roles of the centromere are: 1) it is the point of attachment between the sister chromatids at cell division; 2) it is the point of attachment of the spindle fibers during the separation of the sister chromatids.
True
All mutations are deleterious:
False
A chromosome is a DNA molecule complexed with ___________.
Histone proteins
Given the following DNA sense strand – 5’ ATG GCC TGG ACT TCA 3’, what is the corresponding mRNA?
5’ AUG GCC UGG ACU UCA 3’
Mutations that involve insertions and/or deletions of single or multiple nucleotides are referred to as __________.
INDELs
The only useful DNA mutations are those that lead to changes in phenotype.
False
It is possible that a mutation at an exon/intron splice site could lead to a nonsense mutation.
True
DNA codons specify for __________.
Amino acids
If a plant is 2n = 42, how many pairs of sister chromatids do you expect at Metaphase of mitosis?
42
Mitosis can occur in all cells at all times in the life of a cell, while meiosis can only occur in specialized reproductive cells at specific times during the life of a cell.
True
Which of the following statements is FALSE?
Ribosomes are required for transcription
The two sperm in a pollen grain are expected to have the same genetic composition
True
One of the features of DNA that makes it an ideal genetic material is that it is capable of faithful replication. Which of the following best describes its “capability of faithful replication”?
Complementary base pairing and repair machinery
During DNA replication, a new nucleotide is added to the ___________carbon sugar of the previous nucleotide via a phosphodiester bond.
3’
During Meiosis I, the random alignment of chromosomes at the Metaphase plate is the basis for ____________.
Independent Assortment
The pistil consists of the following plant parts:
stigma, style, and ovary
During the development of the female gametophyte the megaspore mother cell undergoes:
A single round of meiosis followed by 3 post-meiotic mitoses
Transfer RNAs (tRNAs)
are very specialized, with each tRNA able to carry a specified amino acid
If you know the primary structure of a protein you can deduce the exact DNA code of the corresponding gene.
False
The total DNA content doubles during the ________ phase of the mitotic cell cycle.
S
Double fertilization in angiosperms results in which of the following:
A 2n embryo and a 3n endosperm
Imagine a 2n=32 cell going through the anaphase of mitosis. If the spindle fibers fail to do their job, what happens to the daughter cells?
One will have 64 chromosomes, the other will have none
The expected monohybrid genotypic ratio in the F2 is 1AA:2Aa:1aa. If you chose one of the F2 Aa individuals and selfed it, you would expect its F3 progeny to segregate in a genotypic ratio of 1AA:2Aa:1aa.
True
When a cross between two plants is written, which of the following is the generally accepted convention?
The female is given first
Which of the following statements makes the most sense, in the context of a diploid plant that is 2n = 2x = 20?
A large number of alleles are possible in a population of the species but only two alleles occur at one time in any given plant
Which of the following best describes a Mendelian genetic analysis in a hermaphroditic plant?
Making a cross and analyzing the patterns of inheritance in the progeny of the cross
You make a cross between two inbred parents that have alternative alleles at many loci. With each generation of selfing after the F1, you expect the percentage of heterozygosity to decrease by
50%
Assume you have two homozygous (diploid) corn plants. The plants differ from each other in having different alleles at approximately half the loci in the corn genome. F1 plants will be heterozygous at approximately how many loci?
15,000
Two good reasons for not saving selfed (or inter-crossed) seed produced by F1 hybrid plants are: (1) the population of F2 plants you grow from the saved seed will be highly variable, and (2) in the case of some varieties, it may be against the law to save and re-plant seed.
True
If you observe a 1:1:1:1 ratio for two qualitative traits in a test-cross population, what might you hypothesize?
Two unlinked genes determine these traits
A test-cross is a
Type of backcross, where the F1 is crossed to the recessive parent
If you study inheritance using only doubled haploids, you can easily determine if an allele is dominant or recessive.
False
A pollen mother cell (PMC) has the genotype VvQQ. The tetrad of microspores resulting from meiosis of the PMC will have which genotypes?
VQ,VQ,vQ,vQ
If a trait is reported to show quantitative inheritance, it will be a perfect candidate for Mendelian analysis.
False
In a diploid species such as Hordeum vulgare, one would expect to see a __________ ratio in a doubled haploid population.
1:1
A classic explanation for quantitative traits is that they are controlled by multiple loci, and alleles at these loci each have small effects.
True
It is useful to include parents in phenotypic frequency distributions (histograms) in order to develop preliminary hypotheses regarding the inheritance of the target trait.
True
The expected phenotypic dihybrid F2 ratio for two unlinked loci (assuming the parents are completely inbred and the alleles show complete dominance) is:
9:3:3:1
If two unrelated homozygous parents are crossed to produce an F1 and the F1 is heterozygous at all loci for which the parents have different alleles, the F1 is selfed, and all F2 plants are selfed, what is the expected % of heterozygosity in the F3 generation?
25%
In barley, the covered and naked seed phenotypes are an example of a ________ trait.
Qualitative
In a dioecious species, making a cross involves removing the anthers from each flower while leaving the pistil intact.
False
The advantage of doubled haploids for plant breeding and genetics is that by doubling the chromosome number you make plants that are
Homozygous at all loci
Producing doubled haploids from a highly heterozygous F1 will lead to
A set of completely homozygous progeny representing a snapshot of the genetic variation in gametes produced by the F1 plant.
Inheritance of traits from the cytoplasmic genome is bi-parental.
False
A fundamental expectation underlying the F1 hybrid seed industry is that the F1 of the cross of two inbred parents is expected to be 100% heterozygous at the loci where the parents have alternative alleles.
True
A researcher interested in studying the order of genes on a chromosome would most likely use __________ as plant material because the method produces related, homozygous, progeny that represent a mosaic of the genetic content of the parental lines.
Recombinant inbred lines
The expected monohybrid genotypic ratio in the F2 is 1AA:2Aa:1aa. If you chose one of the F2 Aa individuals and selfed it, you would expect its F3 progeny to segregate in a genotypic ratio of 1AA:2Aa:1aa.
True
You produce a test-cross generation (e.g. F1 x homozygous recessive parent) of 100 plants. The cross history is as follows: A Roundup resistant homozygote was crossed with a non-Roundup resistant homozygote to produce an F1. Assume resistance to Roundup is dominant. What ratio of living: dead do you expect?
50 resistant: 50 susceptible
If you hypothesize a 1:1:1:1 ratio, how many degrees of freedom will you have to make a chi square test?
3
A good fit of an observed to an hypothesized ratio is most likely with a:
Small calculated chi square value
The expected phenotypic dihybrid ratio in an unknown generation for two unlinked loci (assuming the parents are not completely inbred and there is interaction between alleles at the two loci) is:
9:3:3:1
Gregor Mendel established the foundation for genetic inheritance theory by studying quantitative traits in peas.
False
What is a phenotype?
A trait: a manifestation of the gene visible to the naked eye.
To make a population of recombinant inbred lines (RILs) consisting of (almost) homozygous plants representing a snapshot of the genetic variation in F2 gametes, which of the following strategies will be most effective?
Harvesting F2 plants separately and planting one F3 seed (or a few F3 seeds) of each F2 plant. Continue harvesting separetely for many generations.
Chloroplast inheritance patterns usually not follow Mendelian expectations in most angiosperms because
Chloroplasts usually show maternal inheritance
Failure of spindle fibers to “pull” sister chromatids to opposite poles at the _______ stage of mitosis can be exploited for the production of doubled haploids.
Anaphase
Chi square values that approach a value of zero would imply that:
The observed phenotypes fit the predicted values based on inheritance patterns.
By convention, which parent is written first in a cross? In other words, if the cross is written A x B, A is
the female
Consider the following scenario: Two inbred parents are crossed. The parents have different alleles, showing complete dominance, at a locus of interest. These alleles are coded as “N” and “n.” The F1 is selfed, to give the F2. In the F2, it would be theoretically possible to select nn plants and these plants would be homozygous in all subsequent generations of selfing.
True
The ___________ method is a technique often used by plant breeders interested in introgression of novel genes into adapted parental genetic backgrounds.
Backcross
Which of the following is the best working definition of an allele?
The specific form of a gene that is found at a specific position on one of a pair of homologous chromosomes
Which of the following terms are almost synonymous:
Phenotype and trait
A transcription factor, such as the protein encoded by Vrs1, regulates the expression of another target gene (or genes) in which way?
it binds to the DNA of the target gene(s)
According to the reading by Komatsuda et al., the source of new vrs1 alleles is:
Mutation
Loss of function at the Vrs1 locus lead to the six-rowed phenotype in barley.
True
Traits such as variegation and male sterility are always inherited via the nuclear genome.
False
If you expect a 9:3:3:1 ratio, how may df will you use for your chi square test?
3
What matters for genetic analysis is the ploidy level – it doesn’t matter if the parents are homozygous or heterozygous or what generation of progeny you are studying.
False
heterosis
hybrid vigor; basis of seed industry
F1 seeds heterozygous so that F2 seeds will be highly variable if kept and replanted
how to produce a cross of a hermaphrodite
anthers can be removed from one plant so that it is effectively male; female protected from undesired pollen via bag, etc.
how to produce a cross of a monoecious plant
male flowers (e.g. tassels) can be removed, effectively making the plant female; female flowers/plants will be protected from undesired pollen via bag, etc.
how to produce a cross of a dioecious plant
pollen is transferred from a male to a female plant; the female flowers/plants are protected from undesired pollen via bag, etc.
If two opposite homozygous parents cross to produce an F1, and then F1 is selfed to produce F2, how identical are are the individuals in each generation (F1 and F2)?
All F1 will be identical (heterozygous)
All F2 will be unique due to segregation and independent assortment in meiosis
Recombinant Inbred Lines (RILS)
a cross between two parents, with multiple F2 plants advanced to subsequent generations of selfing to generate a population of inbred siblings
Under what circumstances might DH-produced plants not breed true?
Mutation
Cross pollination
Mechanical mixture
What are expected vs. observed ratios in cross progeny a function of?
Degree of homozygosity of the parents Generation studied Role of dominance Degree of interaction between genes Number of genes determining trait
Epistasis
degree of interaction between genes; affects the genotype but not the phenotype
Transgressive segregates
Progeny that show phenotype beyond the phenotypic range of the parents
Independent assortment
genes are on different chromosomes or far apart on the same chromosome –> unlikely to be inherited together
What are some types of analyses that can be used for quantitative traits?
Biparental Quantitative Trait Loci (QTL) Mapping
Genome Wide Association Studies (GWAS)
Autosomal chromosomes
alleles on non-sex chromosomes
If a plant has sex chromosomes, do they follow Mendelian inheritance patterns?
Yes, if the expected number of male vs. female progeny is equal
Cytoplasmic Genomes
Chloroplast (usually maternally inherited in angiosperms) and mitochondria (usually paternally inherited)
Homeobox genes
transcription factors
transcription factors
special type of gene in which the protein encoded by the gene regulates another gene, causing gene interaction
What types of mutations caused Vrs1 to become vrs1?
Complete deletion of the gene (no transcription) Deletions of (or insertions into) key regions of the gene (no transcription/no translation/incorrect translation) Nucleotide changes leading to transcription but incorrect translation (non-functional protein)
When might a mutation cause no change to phenotype?
SNP that leads to the same amino acid
SNP in noncoding sequence
monohybrid doubled haploid
cross between two inbred lines that have different alleles in the same locus –> DH of F1
What is the expected phenotypic ratio of a monohybrid DH?
1:1
What is the expected phenotypic ration of a dihybrid DH?
1:1:1:1
What is the expected phenotypic ratio of a monohybrid F2 generation?
3:1
A key feature of apomixis is that in megagametogenesis all four megaspores survive and produce embryo sacs
False
Genetically speaking, apomixis is clonal propagation by seed.
True
A genome formula for a plant is given as 2n = 4x= 28. This means that the plant
is a tetraploid in the sporophytic generation
Which of the following methods could potentially be used to create genetic variability in a contemporary garlic variety?
Induced mutation, gene editing, restoring sexual fertility
Apomixis is found in both dicots and monocots
True
Aspen can only reproduce asexually, and that is why the aspen clones of the Rocky Mountains are endangered.
False
This term refers to the development of seeds without sex.
Apomixis
In a situation where a plant can only be reproduced asexually, genetic variation will occur only in the event of:
allotetraploid
The genetic basis of apomixis is well-understood and most corn, tomato, and pepper F1 hybrids sold today are apomicts.
False
A trivalent at meiosis
is likely to lead to sterility due to unequal distribution of chromosomes to gametes
One of the shortcuts currently used to develop F1 hybrid corn varieties is to produce doubled haploids from obligate apomictic F1s.
False
In both autopolyploids and allopolyploids, bivalent pairing is the key to full fertility
True
Homologous chromosomes are found only in diploids; they do not occur in polyploids.
False
Gene flow from an obligate apomict could lead to a “frozen gene pool” for the species.
True
In terms of the genetics of parents and progeny, asexual reproduction from somatic tissue and propagation from apomictic seeds are equivalent.
True
Where would you expect to find the most genetic diversity?
In ancestral citrus species with obligate sexual reproduction
You read that the genome size of an allopolyploid species is 10,000 Mb and that this species is 2n = 6x = 42. What type of cell does this genome size refer to?
n (e.g. gamete)
In euploids, the total chromosome number is:
An exact multiple of the basic chromosome number (x), including even and odd numbers (e.g. 3x, 4x, 5x, 6x)
If a diploid organism is 2n = 2X = 32, how many pairs of homoeologous chromosomes will it have?
0
In allopolyploids, because bivalent pairing occurs specifically within each parental genome, there will always be 50% of the alleles coming from each parent.
True
Polyploids are always bigger and better than diploids and this is because they have more copies of each gene and all of these copies are expressed at the same time.
False
Both parthenogenesis and parthenocarpy can occur in citrus species
True
Based on the formula “2n = 4x = 24” you can tell if the organism is an allotetraploid or an autotetraploid.
False
The apple is an example of a plant where plant breeders have the best of both worlds: selection of somatic mutations can lead to new varieties, and new varieties can be created by crossing and subsequent asexual propagation of selected plants.
True
Match the left side with the right side:
Sexual fertilization
The megaspore mother cell goes through one cycle of meiosis and 3 sequential mitosis to form the embryo sac.
Match the left side with the right side:
Diplospory apomixis
The megaspore mother cell bypasses meiosis and goes through 3 sequential mitosis to form the embryo sac
Match the left side with the right side:
Apospory apomixis
The megaspore mother cell goes through one cycle of meiosis and bypasses the 3 sequential mitosis and does not form the embryo sac
If you double the chromosome number of a diploid banana species in order to create an autotetraploid, you would expect the plant to show sterility because of
non-bivalent pairing leading to imbalanced gametes.
In the citrus family tree, the Pummelo is
ancestral
An advantage of polyploids is allele redundancy, which:
Masks deleterious alleles
Autopolyploids will be fully fertile when
there is bivalent pairing.
If you had to estimate how many genes there are in an allopolyploid plant that is 2n = 6x = 42, which number would you pick?
90,000
Facultative apomixis is the situation where seed can only be produced via apospory.
False
A trivalent at meiosis
is likely to lead to sterility due to unequal distribution of chromosomes to gametes
In both autopolyploids and allopolyploids, bivalent pairing is the key to full fertility
True
In formulating hypotheses for chi-square tests, the expected monohybrid phenotypic ratios will be the same for testcross (BC1) and doubled haploid populations, assuming the parents were completely inbred and the alleles show complete dominance.
True
A classic explanation for quantitative traits is that they are controlled by multiple loci, and alleles at these loci each have small effects.
True
Based on the Vrs1 locus example, it is possible for a recessive mutation (loss of function) to lead to a gain of function phenotype (more florets per rachis node).
True
The specific type of backcross that involves the homozygous recessive parent is called a:
Testcross
In a chi square test, a very large difference between the observed and expected ratios (e.g. a calculated chi square value of 10.7 with 1 df) will cause you to accept the null hypothesis.
False
The numbers preceding “n” and “x” in a genome formula can be used interchangeably
False
The expected phenotypic frequency distributions (histograms) for qualitative and quantitative traits are expected to be:
Different
Consider the following scenario: Two inbred parents are crossed. The parents have different alleles, showing complete dominance, at a locus of interest. These alleles are coded as “N” and “n”. Doubled haploids are produced from the F1. The doubled haploids will be NN and nn and will be homozygous in all subsequent cycles of selfing.
True
How do doubled haploids benefit plant breeders?
Doubled haploids can be used to maintain inbred breeding lines indefinitely
Failure of spindle fibers at what stage in the cell cycle is most likely to lead to chromosome doubling in a haploid plant?
Mitosis
Gregor Mendel made his fundamental contribution to genetics by focusing on traits that showed
Qualitative Inheritance
Consider the following data from a diploid plant. Parent 1 is resistant to blight disease. Parent 2 is susceptible to blight disease. The parents are doubled haploids. You cross the two parents to produce and F1 and from the F1 you make 100 doubled haploids. You do not take note of the F1 blight phenotype. You observe the following phenotypes in the doubled haploids. 55 blight resistant:45 blight susceptible. Based on the data provided, there is no way to know which allele is dominant: the one conferring resistance or the one conferring susceptibility.
True
In the case of a transcription factor, the following scenario is possible: The transcription factor gene is transcribed in the nucleus, transported to the cytoplasm where it is translated and then exported back into the nucleus where it binds to (and regulates) another gene.
True
One reason for making a backcross is to:
Ensure cross progeny have a maximum genetic contribution from the recurrent parent
The number of df will be the same for a dihybrid example involving phenotypic ratios in the F2, testcross, and doubled haploid generations.
False
If two homozygous parents that have contrasting alleles at 10,000 loci are crossed to produce an F1 and the F1 is selfed, what is the expected % of heterozygosity in the F2 generation?
50%
A researcher interested in studying the order of genes on a chromosome would most likely use __________ as plant material because the method produces related, almost completely homozygous, progeny that represent a mosaic of the genetic content of the parental lines.
Recombinant inbred lines
Considering the vrs1 locus example presented in class, all naturally occurring 6-rows have a 17 kb deletion, as compared to the 2-rows.
False
In a cross between two inbred parents, the F1 will be heterozygous at all loci where the parents have contrasting (different) alleles and homozygous at all loci where the parent have the same alleles.
True
You are interested in a trait – in an angiosperm – that is reported to be determined by a gene in the mitochondrion. It does not matter which parent you use as the female in a cross.
False
The key role of colchicine in the production of doubled haploids is that it
Prevents the formation of spindle fibers
The example of CMS with an unwanted pleiotropic effect involved
mitochondria and susceptibility to disease
Male sterility is the situation where the plant produces viable pollen but the pollen fails to germinate in a self-pollination event.
False
The ancestral condition of angiosperm flowers is thought to be:
Hermaphroditic
Feminization of seeds in Cannabis describes which of the following
Converting female plants to male plants whose pollen can be used to produce seed that will give rise to all female plants
Male sterility can be encoded by genes in the nucleus or the cytoplasm.
True
In your new position as supervisor of hybrid seed production for Company X, you are given two sacks of seed. One is labelled “RfRf Normal” and the other is labelled “rfrf cms”. Which one will you use as the female?
rfrf cms
In microsporogenesis of an F1 hybrid plant of wheat (2n = 6x = 42), which of the following is most likely?
Microspores will be genetically different
Doubled haploids can only be made from diploids – not from polyploids
False
In triploid watermelon fruit production, about 30% of the field is planted to diploid cultivars to:
Pollinize the triploid plants, thus, stimulating parthenocarpy
In the example of sporophytic self-incompatibility in Brassica, the term “complex locus” was used to describe
The linkage of three genes that is so tight that alleles at these loci are inherited together
Which of the following is the most important determinant of the degree of heterozygosity in a plant species?
Mating biology – e.g. is the species dioecious, monoecious, or hermaphroditic.
In a dioecious species, making a cross involves removing the anthers from each flower while leaving the pistil intact.
False
All autopolyploids are sterile, except for those that are obligate apomicts.
False
Which of the following are examples of autopolyploids?
Alfalfa, potato, and banana
In cytoplasmic male sterile hybrid seed production, the maintainer line is used to maintain the female parent, and as such, is:
Genetically identical to the female parent except that it does not have the CMS mutant allele(s)
In the example of CMS and restorer system described in rice, genes at the Rf1 complex locus restore fertility in plants with a mutant apt6 mitochondrial gene by
Reducing transcription of the mutant apt6 allele, or destroying the mutant allele transcript
The abortion of floral organs that leads to unisexual flowers
occurs at different developmental stages in different species
The immediate result of an incompatible reaction in hazelnut involves
failure of pollen tube growth
Male sterility is most likely to be
Favored by targeted selection in agriculture and/or horticulture
The percentage of outcrossing in angiosperms, including those with perfect and uni-sexual flowers, ranges from
near 0 to near 100%
If 2n = 6x = 42 wheat (AABBDD) is crossed with 2n = 2x = 14 rye (RR) and the F1 plant is doubled with colchicine, the F2 plants will be
2n = 56
One of the disadvantages of high rates of cross-pollination is “unwanted gene flow”. How do genes flow?
as pollen
The wild type allele at the Ph1 locus in hexaploid wheat promotes which of the following?
homologous pairing
Male sterility is best described as the situation where alleles at a Self Incompatibility locus in the pollen and the stigma determine if viable pollen will germinate, grow, and fertilize.
False
In asparagus, supermale (YY) plants are produced by:
Deriving doubled haploids from XY male plants.
Monoecy and self-incompatibility are mutually exclusive; in other words, there are no plants with both mechanisms for ensuring higher rates of cross-pollination.
False
In hops, Cannabis, and asparagus, female plants of all three crops are more economically valuable than male plants
False
You are hired to breed seedless (3x) watermelons. Which of the following strategies is likely to be most successful and efficient?
Cross tetraploids with diploids to produce triploids.
The hazelnut is a species with self-incompatibility. This phenotype is expected to show
qualitative inheritance
