76 Questions
What distinguished Mendel's approach from that of earlier investigators?
He conducted additional crosses to test his hypotheses.
What characteristic of garden pea plants allowed Mendel to conduct multiple experiments in a relatively short time?
Self-fertilizing nature and many offspring
Why were the loci for any two characters in Mendel's dihybrid crosses considered to be independent?
They were located far apart in most cases.
What did Mendel's experiments focus on determining as the primary factor influencing traits?
Genotype
Which factor enabled Mendel to recognize distinct patterns in his data?
Keeping careful records and using mathematics
What delayed Mendel's publication of his results after 10 years of experimentation?
Technological limitations regarding microscopes
What crucial aspect of garden pea plants most facilitated artificial cross-pollination in Mendel's experiments?
Self-fertilizing nature
What is the order of dominance in coat color in rabbits, from highest to lowest dominance?
C > Cch > Ch
In Himalayan rabbits, which allele provides pigmentation only in colder parts of the body?
Ch
What type of mutation results in the synthesis of a nonfunctional gene product that can be tolerated in the heterozygous state?
Recessive lethal mutation
Which type of mutation causes ectopic production or overexpression of a toxic product?
Dominant lethal mutation
Why are dominant lethal alleles very rare?
Negative selection by nature and late lethality phenotype
Which allele causes the death of an organism during an early stage of development, often before birth?
'H' locus allele
'Essential Genes' are primarily affected by which type of lethal mutations?
Recessive lethal mutations
'Lethal Alleles' may be of which nature according to the text?
'Conditional' lethal alleles
What is the term used to describe human males who have one X and one Y chromosome in their somatic cells?
Hemizygous
Which cells in human females contain two X chromosomes?
Somatic cells
What determines maleness in the XX-XY system?
Presence of Y chromosome
Which ducts are undifferentiated in each human embryo?
Wolffian ducts
How many genes are there on the Y chromosome compared to the X chromosome?
~75 genes on Y compared to 900–1400 on X
At what stage of gestation do gonadal tissues arise as a pair of gonadal ridges?
Fifth week
Which part of neutral gonadal tissue is capable of developing into an ovary?
Cortex
In the XX-XO sex determination system, which of the following correctly describes the gametes produced by females?
Gametes with X chromosomes only
What type of sex chromosomes do males carry in the ZZ-ZW system found in birds?
ZZ
What determines maleness in the XX-XO sex determination system?
Absence of X chromosome
Which group of insects exhibit the haplodiploidy sex determination system?
Ants, bees, and wasps
What type of sex chromosomes do females carry in the ZZ-ZW system found in birds?
ZW
How do males in the ZZ-ZW system determine their maleness?
Presence of Z chromosome
What is the sex chromosome composition for females in the XX-XO system?
XX
Which sex determination system is based on the number of chromosomes found per cell?
Haplodiploidy System
What does the binomial expansion help solve in genetics problems?
Calculate all possibilities for a given set of two unordered events
In a monohybrid cross, what does a 6!/(4! 2!) x (½)^4 x (½)^2 expression represent?
Probability of having 4 girls and 2 boys
What is the probability of having exactly 5 girls in a family of six children?
$6!/(5! 1!) x (½)^5 x (½)^1$
What does 'n' represent in the binomial probability calculation?
Number of trials
What is the purpose of using the binomial equation in genetics problems?
To calculate all possible outcomes for a set of events
What is the probability of having at least four girls in a family with six children?
$6!/(4! 2!) x (½)^4 x (½)^2$
How does the binomial expansion help solve complex genetics problems related to probability?
By calculating all possibilities for a given set of two unordered events
What does 'p + q = 1' signify in the context of genetics probability calculations?
'p' represents the probability of an event occurring, while 'q' represents the probability of another event occurring.
What did Mendel's experimental approach involve, unlike many earlier investigators?
Conducting additional crosses before formulating hypotheses
In Mendel's pea plants, what largely determined the characters?
Genotype
What did Mendel's careful record-keeping and use of mathematics allow him to do?
Compute ratios of different traits
What characteristic of garden pea plants facilitated artificial cross-pollination in Mendel's experiments?
Self-fertilizing nature
What was the advantage of studying garden pea plants in Mendel's experiments regarding character variation?
Detectably distinct characters like seed color
What allowed Mendel to conduct thorough and patient experiments for 10 years before publishing?
The annual life cycle of pea plants
What genetic phenomenon was observed in most cases during Mendel's dihybrid crosses?
Independent assortment
Which scientist independently confirmed Mendel's conclusions around the year 1900?
Hugo de Vries
What did Mendel term as dominant traits in his experiments?
Traits that appear in the F1 heterozygous offspring
According to the Concept of Dominance, when two different alleles are present in a genotype, which trait is observed?
Trait encoded by the dominant allele
What does Mendel's Principle of Segregation state regarding alleles during gamete formation?
One allele goes into each gamete
Which theory was developed in the early 1900s by Sutton and Boveri?
Chromosomal Theory of Heredity
In monohybrid crosses, what did Mendel reason about the F1 plants?
They possess two genetic factors encoding a characteristic
What did Mendel observe about the alleles of an individual plant?
They separate with equal probability into gametes
Which characteristic determines dominant and recessive traits according to Mendel's Law of Dominance?
Expression levels of the alleles
What gene interaction is demonstrated in a cross between two true-breeding strains of white-flowered sweet peas?
Duplicate recessive epistasis
In the context of the text, when do all other genotype combinations yield white flowers in sweet peas?
When the presence of at least one dominant allele of each of two gene pairs is essential
What kind of gene interaction occurs when two recessive mutations happen at the same locus?
Complementation test
In what scenario does the heterozygote condition rescue the function lost in the homozygous recessive state according to the text?
In complementary gene interaction
What type of gene interaction is indicated by the presence of a gene masking the expression of another locus' dominant allele?
Dominant epistasis
What does a phenotypic ratio of 13:3 observed in certain cases of gene interaction suggest?
Dominant epistasis
Which type of mutation occurs at the same locus according to the text?
Allelic mutations
When two mutations occur in different genes, what term is used to describe them according to the text?
"Non-allelic mutations"
What is the phenotypic ratio resulting from a recessive lethal allele according to the text?
2:1
In Huntington's disease, what is the age range of onset for the disease and eventual lethality in heterozygotes?
30-50 years
Which gene interaction type involves mutations in the wingless gene masking mutations in the crossveinless gene?
Epistasis
What is the expected ratio in a dihybrid cross due to gene-gene interactions listed in the text?
9:3:3:1
Which type of allele is responsible for killing under only a specific temperature?
Conditional lethal allele
What characterizes gene-gene interactions according to the text?
Common contribution of numerous gene products to a single phenotype
In which gene interaction type do genes at multiple loci determine a single phenotype?
Complementary gene action
What does epistasis refer to according to the text?
Expression of one gene masking or modifying another gene's expression
In codominance, how is the phenotype of the heterozygote different from the phenotype of the homozygotes?
The heterozygote expresses both phenotypes found in the homozygotes.
What is the blood type of individuals with the genotype LNLN at the MN blood-group locus?
Blood type N
For individuals with genotype LMLN at the MN blood-group locus, what antigens are expressed on their red blood cells?
Both M and N antigens
What genotypic ratio is typical for codominance?
1:2:1
In Tay-Sachs disease, individuals with only a single copy of the mutant gene are known as:
Heterozygotes
What is the enzyme activity level in heterozygotes compared to homozygous normal individuals in Tay-Sachs disease?
About 50 percent
Which statement best describes the expression of phenotypes in Tay-Sachs disease?
Homozygotes express 100% of enzyme activity while heterozygotes express 50%
Learn about Gregor Mendel's skills in experimental approach, hypothesis formulation, mathematical interpretation, and pattern recognition in genetics.
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