Biology Genetics Closed Note Test

Which of the following is an example of a biological trait?
A) regional accent
B) personality
C) hair style
D) eye color
Eye Color
An allele is dominant in a heterozygote when it is
A) expressed and the other allele is not.
B) the stronger of the two alleles.
C) more desirable than the other allele.
D) a very common allele in a population.
Expressed and the other allele is not
What do the letters inside the grid of a Punnett square represent?
A) phenotypes of parents
B) testcrosses of offspring
C) chromosomes of parents
D) genotypes of offspring
Genotypes of offspring
What is the probability that the offspring of a cross between a homozygous recessive parent and a heterozygous parent will be homozygous recessive?
A) 1/8
B) 1/1
C) 1/4
D) 1/2
The term for a cross that involves parents that are both heterozygous for just one trait, such as pod shape, is called a
A) dihybrid cross.
B) test cross.
C) homozygous cross.
D) monohybrid cross.
Monohybrid Cross
What is the phenotypic ratio of a monohybrid cross between two heterozygous parents?
A) 3:1
B) 1:2:2:1
C) 1:2:1
D) 9:3:3:1
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Which of the following observations did Mendel make as a result of his experiments with dihybrid crosses?
A) Dominant traits are inherited together.
B) Different traits are inherited separately.
C) Recessive traits are inherited unpredictably.
D) Similar traits are inherited in pairs.
Different traits are inherited seperately
Which phrase best describes the process of crossing over?
A) Pairs of homologous chromosomes exchange segments.
B) Pairs of homologous chromosomes become linked.
C) Pairs of sister chromatids become linked.
D) Pairs of sister chromatids exchange segments.
Pairs of homologous chromosomes exchange segments
Suppose a gene that codes for flower color is linked with a gene that codes for leaf shape. Which statement is true of this pair of genes?
A) They have similar loci on different chromosomes.
B) They cross over separately during recombination.
C) They are close together on the same chromosome.
D) They likely will be inherited separately.
They are close together on the same chromosome
Mendel began his experiments with purebred pea plants. This approach enabled him to determine that variations among offspring were the result of
A) genetic uniformity.
B) his crossings.
C) random mutations.
D) self-pollination.
Which of the following is a result of the study of gene linkage?
A) The relative distances between genes can be calculated.
B) The specific characteristics of offspring can be predicted.
C) The exact order of genes on a chromosome can be found.
D) The precise genes in the human genome have been mapped.
The relative distance between genes can be calculated
A person who is heterozygous for a disorder caused by recessive alleles is a carrier of the disorder. A carrier is a person who
A) does not have the disorder but can pass it on to offspring.
B) passes the disorder to offspring on the Y chromosome only.
C) can develop the disorder later in life but cannot pass it on.
D) has a dominant normal allele that has been inactivated.
Does not have the disorder but can pass it on to the offspring
Genes that are located on sex chromosomes are called
A) alleles.
B) recessive.
C) XY.
D) sex-linked.
sex linked
Which statement is true when a sex-linked recessive gene is present?
A) In an XY male, one copy is always inactivated.
B) In an XX female, it is always passed to offspring.
C) In an XX female, only one copy is needed for expression.
D) In an XY male, this recessive gene is always expressed.
In an XY male, this recessive gene is always expressed
A plant that is homozygous for red flowers is crossed with a plant that is homozygous for white flowers. In the case of incomplete dominance, the flowers of the offspring will be
A) red only.
B) pink only.
C) white only.
D) red and white.
Pink Only
In the case of codominant alleles, a plant that is homozygous for red flowers that is crossed with a plant that is homozygous for white flowers will produce flowers that are
A) red and white spotted.
B) completely white.
C) dark pink all over.
D) pink and red.
Red and White Spotted
Eye color, hair color, and skin color are polygenic traits. Polygenic traits result from
A) codominant genes.
B) many genes.
C) epistatic genes.
D) recessive genes.
Many Genes
When Mendel crossed plants that were purebred purple-flowered with plants that were purebred white-flowered, the resulting offspring all had purple flowers. When allowed to self-pollinate, this F generation gave rise to white-flowered plants as well as purple. As a result, Mendel determined that individual traits are
A) lost in the pollination process.
B) inherited as discrete units.
C) diluted in offspring.
D) merged with successive generations.
inherited as discrete units
Identical twins who are raised apart can have differences that last a lifetime. This is evidence that
A) environment and genotype interact to affect phenotype.
B) genotype can change over time.
C) codominance affects genotype.
D) phenotype differences happen through epistatic genes.
Environment and genotype interact to affect phenotype
Which conclusion is a result of Thomas Hunt Morgan’s research with fruit flies?
A) The physical distance between genes cannot be determined.
b) Chromosome assortment during meiosis is not random.
C) Linked genes are located on the same chromosome.
D) Genes recombine independently during mitosis.
Linked Genes are located on the same chromosome
Two genes on a given chromosome that are most likely to be inherited together are
A) 10 map units apart.
B) 18.5 map units apart.
C) 6.8 map units apart.
D) 2 map units apart.
2 map units apart
Suppose the cross-over percentages for three gene pairs are: A to B = 9.5%, B to C = 14.5%, and A to C = 5%. Which of the following sequences could represent the order of these genes on a chromosome?
What is the main difference between the carrier of a sex-linked disorder and the carrier of an autosomal disorder?
A) Male carriers of a sex-linked disorder always have mothers who had the disorder.
B) All carriers of autosomal disorders have two dominant alleles for the disorder.
C) The carrier of a sex-linked disorder is always female but does not have the disorder.
D) Female carriers of an autosomal disorder pass the disorder to all offspring.
The carrier of a sex-linked disorder is always female but does not have the disorder
A chart that traces the phenotypes and genotypes within a family is called a
A) chromosome map.
B) pedigree.
C) karyotype
D) Punnett square.
A genetic disorder is traced within a family. The disorder occurs mostly in males. The gene for this disorder is most likely
A) carried only by males.
B) on the X chromosome.
C) an autosomal allele.
D) not sex-linked.
On the X chromome
Mendel was able to identify predictable patterns of heredity. He succeeded mainly because he chose to study traits that
A) tended to be recessive.
B) had only two forms.
C) could be diluted.
D) were always dominant.
had only 2 forms
Which of the following conclusions was a result of Mendel’s observations?
A) Organisms that self-pollinate do not have “either-or” features.
B) Organisms that give rise to purebreds are genetically superior.
C) Organisms inherit two copies of each gene, one from each parent.
D) Organisms that have intermediate features are self-pollinating.
Organisms inherit two copies of each gene, one from each parent.
Hair color and eye color are examples of a person’s
A) genotype.
B) phenotype.
C) dominant alleles.
D) recessive traits.
When an organism has two different alleles for one trait, the organism is called
A) dominant.
B) recessive.
C) purebred.
D) heterozygous.
If a pea plant were homozygous recessive for height, how would its alleles be represented?
B) tT
C) tt
D) Tt