Biology Exam 4

What are the uses of Punnett squares?

-Predict phenotypes of offspring -Predict the ratio of offspring expected by known the parents' genotypes

You made a cross between two plants differing in a single trait such as height where tall is dominant over dwarf. In the F2 generation, you have 140 plants, how many plants you would expect in each height group

105 tall 35 dwarf

In humans there are three blood type alleles: A, B, and O. The blood type alleles A and B are fully expressed when they are present. Neither allele is considered dominant or recessive and neither is diluted when both alleles are present. The allele O is considered recessive and indicates a lack of either the A or B allele. How many blood type alleles are found in a given individual? What are the possible genotypes of an individual with type A blood in which only the A allele is expressed?

2 alleles, AO/AA

If an individual is a carrier for a recessive disorder (with one copy of the recessive allele) and his or her partner is also a carrier, what is the probability that they will produce a child affected by the disorder? Explain your answer.

25%

Different versions of a given gene

Allele

If two different alleles for the same trait have an equal effect on the phenotype, what are the alleles called?

Codominant

What type of cross did Mendel use to help him form the law of independent assortment?

Dihybrid

In Mendel's controlled mating experiments, what is the name the individuals produced by crossing two true-breeding parents?

F1 generation

The basic unit of information affecting a genetic trait

Gene

When Mendel proposed the law of segregation, what information did he NOT have?

He did not know the location of the gene

_____ consists of one dominant allele and one recessive allele

Heterozygous

Based on Mendelian inheritance, would it be necessary to have both the genotype and phenotype for an organism when attempting to predict the inheritance pattern for a trait, such as hair color, in offspring?

If you know the genotype you can determine the phenotype

What do Mendel's laws explain in genetics?

Law of Segregation: The two alleles of a gene are separated during meiosis and end up in different gametes- egg or sperm cells (Explains how a single trait will be inherited). Law of independent assortment: when gametes form, the two alleles of any given gene segregate during meiosis independently of any two alleles of other genes (predicts how multiple traits will be inherited).

_____ traits controlled by a single gene and unaffected by environmental conditions

Medellin

Name the event during which Mendel's laws of segregation and independent assortment are applicable.

Meiosis

The individual who used data from breeding garden peas to discover the patterns of inheritance that form the foundation of modern-day genetics was

Mendell

What are the ratios of Mendel's monohybrid and dihybrid crosses?

Monohybrid: 3:1 Dihybrid: 9:3:3:1

_____ is any change in the DNA sequence that makes up a gene

Mutation

Jennifer uses a dihybrid cross of fruit flies to examine inheritance patterns for eye color (black or white) and head shape (round or elongated). These crosses produce 10,000 offspring, and the ratio is 1 (black eyes, round head): 1 (black eyes, elongated head): 1 (white eyes, round head): 1 (white eyes, elongated head). Is this what Jennifer should have expected from a dihybrid cross? Explain why or why not.

No, the dominant alleles should have been expressed more. Dihybrid cross (9:3:3:1)

Physical expression of a gene

Phenotype

Differentiate between pleiotropy and polygenic traits.

Pleiotropy: 1 gene control many traits. Polygenic: many genes control 1 trait

_____ traits are controlled by more than one gene.

Polygenic

In a particular plant, two genes control leaf shape and color. Round leaves (R) are dominant to jagged leaves (r). Yellow fruits (Y) are dominant to white fruits (y). A true-breeding round-leaved, yellow-fruited plant is mated with a true-breeding jagged-leaved, white-fruited plant. What are the genotypes of the plants involved in this cross?

RRYY, rryy

Write down the genotype of a diploid organism representing any three genes.

TT/Tt, RR/Rr, YY/Yy

Explain how genetically identical plant clones can exhibit dramatic phenotype variation?

The environment around it changes the phenotype

State Mendel's Law of Segregation

The two alleles of a gene are separated during meiosis and end up in different gametes—egg or sperm cells.

A single gene with one dominant allele for black hair (B) and one recessive allele for brown hair (b) controls hair color in mice. A male mouse with black hair mates with a female mouse with brown hair and they have 12 offspring. Are you able to determine the predicted ratio of hair color in their offspring using a Punnett square? Explain your answer

We don't know whether the male is heterozygous, or dominant (Bb or BB)

Is it possible for two organisms with the same genotype to have different phenotypes? Explain your answer.

Yes, the environment around it will affect the growth

Each homologous pair consists of one from each parent

chromosome

The separation of two alleles into different cells during meiosis is Mendel's law of

conservation

A punnett square shows the possible ways that alleles combine to form

gamete

Most traits in humans involve complex inheritance where the trait is governed by the action of more than one _____.

gene

The genetic makeup of an organism, such as Gg, is its

genotype

In a genetic cross in which the heterozygous phenotype is intermediate between the two homozygous phenotypes, _____ dominance is expressed

incomplete

According to Mendel's law of _____, when gametes are formed, the separation of alleles for one gene is unrelated to the separation of alleles for other genes.

independent assortment

Mendel used _____ as his research organism to study patterns of genetic inheritance

pea

The observable physical characteristics of an organism are known as its

phenotype

The _____ of an event is the chance that it will occur

probability