Download Genetics Open Ended Questions

Genetics Open Ended Questions:
Answer the following questions to the best of your ability: Make sure you read
each question carefully and provide answers to all of the parts of the question. Do
not leave any question blank.
Two traits studied in experiments involving the crossing of pea plants are seed shape and
seed color.


The shape of the seeds can either be round or wrinkled, and the alleles for these traits are
represented by R and r respectively. Allele R is dominant.
The color of the seeds can be yellow (Y) or green (y). The allele for yellow seeds is dominant.
A dihybrid cross is performed between two pea plants of genotype RrYy. Construct the
Punnett square for the cross in the table shown.
RY
1.
Ry
rY
ry
RY RRYY RRYy RrYY
RrYy
Ry
RRYy
RRyy
RrYy
Rryy
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy
rrYy
rryy
1. Explain how the Punnett square can be used to predict the probability that an offspring
from such a cross has a given phenotype (for example, yellow, wrinkled seeds). Explain
your answer with reference to Mendel's law of independent assortment.
Genetics
(BIO.B.2.1.1) Inheritance
Answer Key:
Rubric 3 pts Three key elements are present. 2 pts Two key elements are present. 1 pt One
key element is present. 0 pts No key elements are present. A: Parents: RrYy ×RrYy
RY
Ry
rY
ry
RY RRYY RRYy RrYY
RrYy
Ry
RRYy
RRyy
RrYy
Rryy
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy
rrYy
rryy
OR Other equivalent Punnett square. B: Mendel's law of independent assortment implies
that there is no relation between the inheritance of the alleles for seed shape and seed
color. Because of this independence, each genotype in the table is equally likely. OR Other
equivalent statement. C: Therefore, the probability that an offspring from such a cross has a
given phenotype is the fraction of cells in the table whose genotypes lead to that
phenotype. In this case, wrinkled, yellow seeds account for 3 of the 16 possible genotypes
or there is about a 19% chance that seeds will be wrinkled and yellow. OR Therefore, the
actual ratio of offspring phenotypes or a large number of offspring is the same as the ratio
of offspring phenotypes in the Punnett square. OR Other equivalent explanation.
Keywords:
independence, probability, Punnett, dihybrid, cross, trait, dominant, recessive
2.
2. Explain whether a mutation in any cell of an organism can be passed on to offspring of
the organism. Under what conditions is a mutation passed on to the next generation?
Answer Key:
Rubric
2 pts Two key elements are present.
1 pt One key element is present.
0 pts No key elements are present.
A:
No. Only mutations in sex cells can be passed on to the offspring of an organism. Mutations
in other body cells can only be passed on to descendant cells within the same organism.
OR
Other equivalent statements.
B:
A mutation is passed on if the mutated sex cell produces a gamete by meiosis, and the
gamete actually undergoes fertilization.
OR
Other equivalent statement.
Keywords:
sex, cell, somatic, body, descendant, fertilization, gamete, meiosis
3. What is genetic engineering, and what are the basic steps involved in it?
Be sure to mention the roles of recombinant DNA, genes, isolation, and culturing.
Answer Key:
Genetic engineering is a process in which recombinant DNA (rDNA) technology is used to
introduce desirable traits into organisms. It involves the introduction of foreign DNA or
synthetic genes into the organism of interest. The introduction of new DNA does not require
the use of classical genetic methods, however traditional breeding methods are typically
used for the propagation of recombinant organisms.
Genetic engineering generally involves choosing and isolating the gene to be inserted.
Isolation usually involves using polymerase chain reaction (PCR) to create multiple copies of
the gene. Once isolated, the gene is inserted into a bacterial plasmid. The gene to be
inserted into the genetically modified organism must be combined with other genetic
elements in order for it to work properly. The most common form of genetic engineering
involves inserting new genetic material randomly within the host genome. Other techniques
allow new genetic material to be inserted at a specific location in the host genome or to
create mutations at desired positions on the gene capable of knocking out original genes. In
order to make sure that every cell in the organism has the new gene, the organism must be
regrown from a single cell. In plants, this requires a tissue culture. In animals, the new DNA
must be inserted into an embryonic stem cell. Then organisms with the new DNA are bred
together to reproduce organisms with the new DNA.
Keywords:
PCR, gene, recombinant DNA, plasmid, inserted,
With regard to food, medicine, and human health, what are some positive and negative
effects of biotechnology and genetic engineering?
Genetics
(BIO.B.2.4.1) Genetic Engineering
Answer Key:
Genetically modified crops have been created to be more resistant to pests, herbicides,
diseases, droughts, frosts, and exposure to salt. They can also be modified to increase size,
nutritional content, or the availability of medicinal compounds. Finally, genetically modified
plants have been created to produce edible vaccines and to remove heavy metals and other
toxic materials from soil.
Genetically modified bacteria are producing human insulin and growth hormone for people
who need them. Also, bacteria are being modified in order to produce the chemical needed
to manufacture large amounts of medications. Other organisms, such as pigs and goats are
being genetically modified to produce organs for transplant (pigs) and to produce chemicals
used to make medications in their milk (goats).
The negative effects of biotechnology include unintended side effects from the plants, such
as caterpillar deaths from the pollen of genetically modified corn, insects with increased
resistance to pesticides, and possibly disrupted food webs in different ecosystems. These
plants could also spread to unintended areas and out-compete native plants. Also, the longterm effects of genetically modified foods have not been studied and could lead to health
problems for those people who consume them.
The animal modifications cause ethical delimmas, such as whether or not it is okay to kill a
pig in order to supply a person with a vital organ or whether goats should be forced to
reproduce in order to maintain their milk supply to make human medications.
Modified bacteria could lead to an increase in antibiotic resistant bacteria.
Keywords:
pest, disease, nutritional, chemical, insulin, growth hormone, food, antibiotic, vaccines,
4. Mutations can occur due to changes in the nucleotide sequence in DNA. The changes can
be caused by insertion, deletion, frameshift mutations and point mutations. Compare and
contrast mutations caused by insertion and deletion.
Answer Key:
Insertion mutations are caused when one or more nucleotide is mistakenly inserted or
combines with existing sequences of nucleotides. This can cause serious errors when the mRNA is read as a series of nucleotide triplets during translation. Each group of three
nucleotides, or codon, codes for an amino acid in protein synthesis. Every codon after the
insertion might be affected.
Deletion mutations are caused when one or more nucleotide is mistakenly deleted or left out
of a sequence of nucleotides. This also can cause serious errors in translation. Each group of
nucleotides or codon after the deletion might be altered in the specific amino acid used in
protein synthesis.
Keywords:
protein synthesis, amino acid, insertion, deletion, mutation, translation
5. Explain the process of crossing over and how it increases genetic diversity.
Answer Key:
Meiosis can generate still more genetic variation through crossing over, during which
chromosome partners physically swap sections with one another, generating hybrid
chromosomes that are a patchwork of the original pair. This rearrangement of the genetic
material expands the number of possible genetic configurations for the daughter cells,
further increasing diversity
Keywords:
meiosis, crossing, over, chromosome