Biology - Mendelian Genetics & Mechanisms of Heredity

Use a Punnett Square to figure out what percentage of pea plants would have purple flowers in the following cross: A purple flowered pea plant (PP) crossed with a white flowered pea plant (pp). (P is the dominant allele and p is the recessive allele)

100% would have purple flowers.

How many phenotypes are typically produced by a dihybrid cross?

4

How would you define a dihybrid cross?

A cross between two individuals heterozygous at two different genes.

The locus is _____.

A specific location on a chromosome

Alleles A and B are linked on chromosome 1 (such that you have A-B and a-b). Alleles C and D are linked on chromosome 2 (you have C-D and c-d). If a crossover event does not occur between either set of genes, which gamete genotype could NOT be produced by an individual heterozygous at each locus? •A-B; c-d •A-B; C-D •a-b; c-d •A-B; C-d

A-B; C-d

Alleles A, B, C and D are linked on one chromosome, and alleles a, b, c and d are linked on the homolog. During meiosis, a crossover event occurs between genes A and B. Which of the following is an example of a chromatid that could be found in one of the resulting gametes? •a-b-c-d •A-b-c-d •A-B-c-d •A-B-C-d

A-b-c-d

Based on Mendel's pea plants, if P is an allele that codes for purple flowers and p is an allele that codes for white flowers, what can you say about a plant that has the alleles Pp? •The plant carries the allele for white flowers. •All answers are correct. •The flower is purple. •The plant may have white flowered offspring.

All answers are correct.

Consider the following experiment: A scientist determines that the number of dorsal spines of her experimental fish is determined by a single locus. She mates a fish with 1 dorsal spine with a fish of the same species with 2 dorsal spines. The mating produces ten fish, which all have 1 dorsal spine. Which of the following statements does not fit with this result? •The '2-spine' parent fish has a homozygous genotype at the dorsal spine locus. •The progeny fish may be capable of producing progeny with only 1 spine. •The '1-spine' parent fish has a homozygous genotype at the dorsal spine locus. •'2 dorsal spines' is a recessive phenotype. •All progeny fish are homozygous for the '1-spine' allele.

All progeny fish are homozygous for the '1-spine' allele.

You have the following alleles: B=blue, b=green, H=two-horned and h=one-horned: Which of the following crosses most likely produced the following results? 54 blue, two-horned lizards 18 blue, one-horned lizards 18 green, two-horned lizards 6 green, one-horned lizards •BBHH x bbhh •Bb x Bb •BbHh x BbHh •BBHh x BbHh Worksheet

BbHh x BbHh

Which phenotype(s) do the red blood cells from a person with AB blood type exhibit?

Both the 'A' and 'B' phenotype in each red blood cell

The following results were observed from a mating between two black and white speckled cats: 5 black cats, 12 black and white speckled cats, and 4 white cats. Which term describes the relationship between the alleles of the coat color gene? •Mendelian •Polygenic •Incomplete dominance •Codominance

Codominance

All of the following statements are correct EXCEPT: •Creating new combinations of alleles makes new combinations of phenotypes. •Creating new combinations of alleles decreases the genetic diversity of the population. •Whether or not the linkage between alleles is altered is determined by the location of crossover events during meiosis. •If two alleles of different genes are linked, they are inherited together.

Creating new combinations of alleles decreases the genetic diversity of the population.

Which of the following is NOT an example of a phenotype? •Wheat resistance to fungal infection •Height of a giraffe •DNA sequence of the alcohol dehydrogenase gene •Color of a feather

DNA sequence of the alcohol dehydrogenase gene

A _____ is a cross between two individuals that are heterozygous at two loci.

Dihybrid cross

What type of organism has two copies of every gene?

Diploid

The trait which is expressed in a heterozygous state is known as

Dominant

Which of the following statements could NOT be used to describe a multifactorial trait? •The phenotypic consequences of genes affecting the trait are additive. •An environmental factor affects the trait. •A continuous range of traits is possible. •Gene homozygosity and heterozygosity determine the trait. •Two independent genetic pathways affect the trait.

Gene homozygosity and heterozygosity determine the trait.

You could draw which of the following conclusions from a dihybrid cross which produces a 9:3:3:1 ratio of phenotypes? I. The alleles of one gene sort independently of another gene. II. The alleles of the two genes in question exhibit a simple dominant/recessive relationship. III. The animals which were crossed were both homozygous with respect to at least one locus in question.

I and II

Evaluate each of the following sets of data separately. Which of them provide evidence that the trait is polygenic? I. The genotype at loci A, B and C each produces a protein that influences the length of an organism by an average of 0.6, 0.4 and 0.3 cm, respectively. II. Three different alleles of gene D affect the length of an organism by an average of 0.6, 0.4 and 0.3 cm, respectively. III. Loci E, F and G each modulates an independent pathway, which plays a role in determining the length of an organism.

I and III

Which of the following statement(s) accurately describes an advantage provided by model organisms? I. The laboratory environment can be controlled. II. True-breeding strains can be generated. III. Specific combinations of alleles can be engineered.

I, II and III

Which of the following statements is true? I. The one-thousandth base pair on chromosome one of an organism is an example of a locus. II. Changing the DNA in a gene by one base pair could create a new allele. III. Cells in a diploid organism possess two copies of each chromosome (except gametes).

I, II and III

Which of the following statements is/are true? I. A human with an X chromosome and a Y chromosome is male. II. A human with only one type of sex chromosome (an X chromosome) is female. III. All children of a color blind woman and a man who is not color blind will carry a color blind allele.

I, II and III

Genes A and B are located on the same chromosome arm in the following orientation: centromere, gene A, gene B, telomere. Which of the following recombinant chromatids could be produced by a crossover event between B genes in a heterozygote in which the dominant alleles are linked on one homolog and the recessive ones are linked on the other homolog? I. A B II. a B III. A b IV. a b

II and III

Hemophilia is an X-linked recessive trait. Consider a cross between a woman who is a carrier and a man who suffers from hemophilia. Which of the following statements is/are true? I. All sons of these parents will be a hemophiliac. II. A son who suffers from hemophilia received the hemophilia allele from his mother. III. Half of the daughters of this cross are predicted to be hemophiliacs.

II and III

Which of the following statements is true? I. A dihybrid cross is a cross between individuals heterozygous at one gene. II. The law of independent assortment describes the relationship between alleles of a single gene. III. The law of segregation describes the manner in which genes on different chromosomes segregate. IV. Homologous chromosomes segregate into different gametes.

IV

Which type of dominance describes a situation in which heterozygotes demonstrate a phenotype which is intermediate between the homozygotes?

Incomplete dominance

A Punnett square is useful when determining phenotypic output, for all of the following reasons EXCEPT: •It allows you to predict the ratio at which the phenotypes will occur. •It makes you look at only one gene at a time. •It helps to visualize Mendelian inheritance. •It organizes the potential combinations of maternal and paternal alleles.

It makes you look at only one gene at a time.

Which two laws of Mendel help us predict how chromosomes are allotted to the gametes?

Law of segregation and Law of independent assortment

When two genes are located on the same chromosome, they are said to be _____.

Linked

Joe is in urgent need of a blood transfusion. His blood genotype is AA. Mike has an oo genotype, and Mary has a BB genotype. Who would be able to donate blood to Joe, and why?

Mike can donate, because oo doesn't produce an extracellular sugar

Let's say P is an allele that codes for purple flowers and p is an allele that codes for white flowers. A plant has alleles Pp. According to the Law of Segregation, what alleles would each gamete have?

One gamete would have P and one would have p.

An allele is _____.

One version of genetic variation at a particular locus

A _____ is a trait which is determined by two or more genes, but not any environmental factors.

Polygenic trait

The trait which is not expressed in a heterozygous state is known as

Recessive

Which of the following is NOT an example of a homozygous genotype? •GG •Rr •tt •ww

Rr

A scientist is studying an animal and determines that a gene is located on autosome two. It controls antler production in the male animals. Note that females do not produce antlers. This is an example of a:

Sex-limited trait

In humans, _____ is determined by the presence or absence of the _____ chromosome.

Sex; Y

Skin cancer is a multifactorial trait. Which of the following is plausible? •Skin cancer can be diagnosed by testing for proteins coded by the culprit gene. •Skin cancer is difficult to predict in a susceptible family. •Skin cancers results from allele variations of a gene on chromosome 9. •Skin cancers can be prevented by avoiding excessive sunlight. •Skin cancer can be cured by targeting multiple promoters of the skin cancer gene.

Skin cancer is difficult to predict in a susceptible family.

The law of independent assortment states that:

The alleles of one gene sort into the gametes independently of the alleles of another gene

Autosomes are:

The chromosomes in the genome which are not sex chromosomes

Incomplete dominance governs the pigment gene of a flower. A mating between heterozygotes yields the following phenotypic ratio: 15 red flowers, 32 pink flowers and 14 white flowers. Which statement describes the situation? •The flower pigment gene is defined by a red and a white allele. •The heterozygotes were red. •The flower pigment gene is defined by a pink and red allele. •The heterozygotes were white.

The flower pigment gene is defined by a red and a white allele.

Mendel's second law is also known as:

The law of independent assortment

Some people have blue eyes and some people have brown eyes. Which answer best explains why this is the case? •All answers are correct. •They have different genes. •One gene is recessive. •They have different alleles.

They have different alleles.

When an organism is diploid, that means it has _____.

Two versions of each chromosome

Gregor Mendel is famous for his involvement in _____.

genetics