ch.12
A characteristic ______ segregation in the F2 generation is referred to as the Mendelian ratio for a monohybrid cross.
3:1
type ____ is the universal blood donor and type _____ is the universal blood recipient
O AB
If a heterozygote displays a phenotype that is intermediate between the two homozygous individuals, then the trait must operate by
incomplete dominance
A 9:3:3:1 ratio is obtained in the F2 generation of a dihybrid cross when alleles assort _____ from one another
independently
In snapdragons, alleles resulting in red pigment and white pigment exhibit incomplete dominance. If red snapdragons are crossed with pure white snapdragons the offspring of the F1 generation will be
pink
An allele that has more than one effect on a phenotype is called ___
pleiotropic
sickle cell anemia is caused by a ______ allele because this mutation has more than one effect on the phenotype
pleiotropic
human height is an example of a trait that has a continuous distribution of phenotypes. Human height is therefore an example of ______ inheritance
polygenic
Continuous phenotypic variation results from
polygenic inheritance and independent segregation of genes
A trait that has multiple genes contributing to its expression is known as which of the following?
polygenic trait
genes influence the phenotype of an organism by specifying the kinds of _____ that are made in the organism's cell
proteins
How are proteins made in the eukaryotic cell?
proteins are synthesized by ribosomes in the cytoplasm
Which of these is commonly used to predict the results of simple genetic crosses?
punnets square
A ratio of 9 purple to 7 colorless seeds
purple seeds only
Which of the following is NOT a component of Mendel's five-element model (please note that the answers use the modern term gene instead of factor)?
the two alleles are usually the same
True or false: Populations usually contain several versions of each gene, due to the fact that DNA accumulates random mutations through time.
true
each parent carries _____ alleles of a gene that segregate from each other during gamete formation
two
Place the four stages of Mendel's experiments in the correct order from first (on top) to last.
- allow plants to self - cross to ensure they are true breeding - perform reciprocal crosses between true breeding varieties - allow hybrid offspring to self fertilize - count number of offspring of each variety
Choose statements that correctly refer to components of Mendel's five-element model (please note that the answers use the modern term gene instead of factor).
- alternative forms of genes are called alleles - the two alleles remain discrete - the presence of an allele doesn't ensure that it will be expressed - parents transmit genes to offspring
Prior to the 20th century, the two main ideas that provided the basis for most thinking about heredity were
- traits are transmitted directly from parents to offspring - heredity occurs within species
A Punnett square for a single trait should be set up as a ______ square.
2x2
A cross between heterozygotes for a single trait will lead to a genotypic ratio of 1:2:1. How many phenotypes will be observed if incomplete dominance is occurring?
3
Rank these steps of anthocyanin production in corn from first to last starting at the top.
1. starting molecule (colorless) 2. intermediate (colorless) 3. anthocyanin ( purple)
An individual can acquire only_______ alleles per trait; even if multiple alleles are present in the population
2
If a particular gene in a population has multiple alleles, how many alleles can a diploid individual inherit?
2
One of the parents in a dihybrid cross has the genotype AABb. How many types of gametes can this parent produce?
2
This ratio is obtained in the F2 generation of a dihybrid cross when alleles assort independently from one another.
9:3:3:1
homozygous heterozygous
= individual carries two identical alleles of a gene = individual carries two different alleles of a gene
A woman who has type B blood and a man who has type A blood could have children with which of the following blood types?
A B AB O
Which of the following statements describe pleiotropic alleles?
A pleiotropic allele can be dominant with respect to one trait and recessive with respect to another trait.
When Emerson crossed two parents that produced colorless seeds, he observed purple seeds only in the F1 generation. What did he observe in the F2 generation after crossing two F1 plants?
A ratio of 9 purple to 7 colorless seeds
In order to express a gene, a cell must first transcribe
DNA into a complementary RNA copy
In a typical monohybrid cross, all of the offspring in which generation will exhibit a single trait without blending?
F1
When two true-breeding varieties are crossed, they produce offspring that is typically called the ____.
F1 generation
When two true-breeding varieties are crossed, they produce a certain number of offspring. When this offspring is allowed to self-fertilize, they produce a generation that is referred to as the ____.
F2 generation
Which of the following alleles involved in human blood types are codominant?
I^A and I^B
Which of the following is true about transcripts in eukaryotic cells (such as a human cell)?
RNA transcripts have to be edited to remove unnecessary information before exiting the nucleus
A parent with a genotype of RrYy can produce which of the following gametes?
Ry RY ry rY
How is the pigment anthocyanin produced in corn?
Through the activity of two enzymes that act sequentially.
Which of these blood phenotypes is NOT properly matched with the sugar exhibited on red blood cells?
Type O
The trait for round (R) peas is dominant over the trait wrinkled (r) peas. What would happen if true-breeding round peas are crossed with true-breeding wrinkled peas?
all offspring will have round peas
Mendel's observations supported the independent ______ hypothesis
assortment
'' When continuous traits are graphed with the phenotype on the X-axis and the number of individuals with that phenotype on the Y-axis, a ____ shaped curve results
bell
The concept of inheritance which suggested that parents make equal contributions to their offspring and that their genetic material blends together is called
blending inheritance
The heterozygote shows some aspect of both homozygotes in which of the following?
codominance
The expression of two different alleles simultaneously in the heterozygote is called A situation where a single individual expresses two different alleles is referred to as
condominance
Mendel performed his hybridization experiments with the garden pea in four stages. What was the first stage?
confirm that parental plants are true breeding.
Mendel called the trait that was expressed in the F1 offspring of a monohybrid cross ____.
dominant
If a true-breeding tall pea plant is crossed with a true-breeding dwarf pea plant and all of the offspring are tall plants, the trait "tall plant" is
dominant over "dwarf plant"
If a cross between heterozygotes for a single trait results in three separate phenotypes, which of the following types of inheritance is the likely reason?
incomplete dominance
When the expression of one gene obscures the effects of another gene, this is called When the interaction of genes alters genetic ratios, this is called
epistasis.
Which of these are what Mendel referred to as "factors" that are passed intact from one generation to the next?
genes
Mendel postulated that every individual carries two ______ called alleles, for a given character
genes/factors
The entire set of DNA molecules found in a cell is referred to as that cell's
genome
An individual's total set of alleles for a particular trait is called his/her
genotype
type A Type b type AB type O
have galactosamine have galactose have galactosamine and galactose have neither sugar
What distinguished Mendel's results from earlier investigators?
he quantified his results
Consider the "tall"/"short" traits of pea plants. A pea plant that carries two "tall" alleles is
homozygous
Humans with the sickle cell mutation suffer from sickle-cell disease which is often fatal. Despite that fact certain areas of Africa which have a high incidence of malaria are inhabited by human populations, in which the sickle-cell mutation has a very high prevalence. How can we explain that?
individuals heterozygous for the sickle cell gene are resistant to maleria, so they have an adaptive advantage in those areas
Which type of cellular division involves the pairing and subsequent segregation of homologous chromosomes? Segregation of alleles occurs during which of the following processes?
meiosis
the 3;1 ration observed in the F2 generation of a monohybrid cross is referred to as the _____ ratio.
mendelian
An experimental cross where only a single characteristic is considered (for example, flower color) is called
monohybrid
The inheritance patterns of many traits are (more or less) complex than simple Mendelian patterns.
more
During the replication of a DNA molecule a T in the original strand was changed to a G in the replicated strand due to a random mistake in the copying process. This is an example of
mutation
In the monohybrid crosses performed by Mendel, the F1 plants always displayed ____
one trait
When Mendel performed monohybrid crosses one of the parental traits was never expressed in the F1 generation. What did he call that trait?
recessive
according to Mendel, the _____ trait was the one that was not expressed in the F1 generation of a monohybrid cross
recessive
in a eukaryotic cell, ____- read the information in mRNA and use it to synthesize_______ from amino acids
ribosomes proteins
The principle of ______ is that 2 alleles for a genes separate during gamete formation and are rejoined at random, one from each parent, during fertilization.
segregation
Individuals have two alleles for each gene and when gametes form by meiosis, the two alleles
separate
In order for Mendel's simple ratios to hold true, the following assumption must be made:
that the traits are inherited independently
Mendel designated a dominant trait as the one
that was expressed in the F1 generation
incomplete dominance codominance
the heterozygote is an intermediate in appearance between the two homozygotes the heterozygote shows some aspect of both homozygotes
Mendel's work involved quantitative experiments and careful analysis of the offspring carrying specific traits. He paid the most attention to which of the following?
the numbers of every different type of offspring
Examples of environmental influences on phenotype include
the pattern of coat color in Siamese cats the pattern of coat color in Himalayan rabbits