Genetics : Genetics

Study concepts, example questions & explanations for Genetics

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Example Questions

Example Question #151 : Genetics

If an embryo inherits both A alleles, the embryo will not develop to term. If they only have 1 allele, the child will have dwarfism.

What percentage of child will be of normal height out of a cross of two parents with dwarfism?

Possible Answers:

33%

67%

50%

25%

Correct answer:

33%

Explanation:

When you do a punnet square you will see the portion of genotypes being 25% AA, 50% Aa and 25% aa. The AA allele is not viable, however, so only the Aa and aa genotypes would make it to term. Since 1 out of 3 children would have aa then the percentage would be 33%.

Example Question #152 : Genetics

You are a dog breeder and want to figure out the genotype of the female brown dog you have. Brown is the dominant phenotype, while white is the recessive. You decide to breed her with a male who is also brown and has strictly dominant brown alleles. If the female is heterozygous, what percentage of her litter should be white?

Possible Answers:

50%

25%

0%

75%

Correct answer:

0%

Explanation:

Since the father has only dominant alleles for the brown phenotype, all of the litter will be brown. However, half the litter should carry the recessive allele. The punnet square below shows the dad's genotype on top and the mom's genotype on the left. The outcome is that half the progeny will have the genotype BB and half will have the genotype Bb. Therefore, all offspring will have the brown phenotype.

      B      B

B  BB    BB

b  Bb     Bb

Example Question #153 : Genetics

Which of the following is not true about autosomal recessive inheritance?

Possible Answers:

A carrier has a 50% chance of passing the affected gene to their offspring.

An affected individual and a carrier have a 50% chance of having an affected offspring.

An affected individual can only have a homozygous genotype.

An affected individual may not be seen in every generation.

An affected offspring must have affected parents.

Correct answer:

An affected offspring must have affected parents.

Explanation:

In order for an offspring to be affected, it must receive an affected allele from both its parents. Hence, the parents can be either carriers or affected. This would give the affected offspring a homozygous recessive genotype (only possibility).

Example Question #154 : Genetics

Which of the following differentiates mitochondrial inheritance from X-linked inheritance?

Possible Answers:

No mother to daughter transmission 

None of the other answers is correct.

No father to daughter transmission

No mother to son transmission

No father to son transmission

Correct answer:

No father to daughter transmission

Explanation:

Mitochondrial inheritance only involves mother-to-offspring (son or daughter) transmission. Hence, both those choices can be eliminated. Both mitochondrial and X-linked inheritance do not include father-to-son transmission. Hence, the only differentiating transmission is father-to-daughter (not seen in mitochondrial).

Example Question #26 : Inheritance Patterns, Pedigrees, And Genetic Disorders

Based on conventional representation on a pedigree, which of the following symbols indicates a male affected by the genetic disorder being studied?

Possible Answers:

Set 01   female aff

Set 01   male unaff

Set 01   female unaff

Set 01   male aff

Set 01   undef squiggle

Correct answer:

Set 01   male aff

Explanation:

In conventional usage, each individual on the "family tree" that a pedigree represents is shown using a single shape. Males get square shapes; females get circular shapes. (Sometimes, individuals whose sex is not known or not specified will be shown with triangular shapes.)

Since pedigrees are often used to study genetic disorders, it is important to track who was affected by the disorder of interest across the family history. Affected individuals are shown with shaded, colored, etc. shapes, while individuals who did not have the disorder are shown with unfilled, "clear" shapes.

This question asks about an affected male. Since the individual is male, the shape is square; since the individual is affected by the genetic disorder, the shape is solid/filled.

Example Question #155 : Genetics

Which of the following is NOT an autosomal recessive disorder?

Possible Answers:

Tay-Sachs disease

cystic fibrosis

Marfan's Syndrome

anemia

Correct answer:

Marfan's Syndrome

Explanation:

The correct answer here is Marfan's syndrome. If you chose any of the other options, remember what it means to have an autosomal dominant disease vs. an autosomal recessive disorder. If a child has one of their alleles marked for the an autosomal dominant disease, they will exhibit the symptoms of this disease. This is correct for Marfan's disease. For all the other syndromes listed, a child must have both of their alleles marked with disease to exhibit the disease. 

Example Question #1 : Central Dogma Of Biology

What is meant by the term "Karyokinesis"

Possible Answers:

The process of exiting the G0 phase of the cell cycle

The process of converting RNA to proteins

Division of the nucleus

The process of entering the G0 phase of the cell cycle

The process of converting DNA to RNA

Correct answer:

Division of the nucleus

Explanation:

Karyokinesis is the division of the cell's nucleus during mitosis. A similar (but different meaning) word is cytokinesis. Cytokinesis is the division of the cell cytoplasm, which occurs at the end of mitosis. The other answer choices do not reflect the meaning of karyokinesis.

Example Question #1 : Central Dogma Of Biology

What is the enzyme used during transcription?

Possible Answers:

DNA Polymerase II

RNA Polymerase III

RNA Polymerase

DNA Polymerase III

DNA Polymerase

Correct answer:

RNA Polymerase

Explanation:

Transcription begins when RNA polymerase binds to promoter DNA sequences on a gene. This leads to the production of a RNA chain, complimentary to the original (template) DNA strand.

Example Question #2 : Central Dogma Of Biology

What is the size of the prokaryotic ribosome and its subunits?

Possible Answers:

30S and 40S subunits, 70S ribosome

30S and 30S subunits, 60S ribosome

 

50S and 50S subunits, 70S ribosome

 

50S and 30S subunits, 70S ribosome

50S and 30S subunits, 80S ribosome

 

Correct answer:

50S and 30S subunits, 70S ribosome

Explanation:

Prokaryotic ribosomes consist of two unequally sized subunits, large and small, which form a complete ribosome unit.

Example Question #1 : Central Dogma Of Biology

Which of the following most accurately describes the central dogma of biology?

Possible Answers:

Protein to RNA to DNA

DNA to protein to RNA

DNA to RNA to protein 

RNA to protein to DNA

Correct answer:

DNA to RNA to protein 

Explanation:

The central dogma of biology dictates that the coded genetic information stored in DNA is transcribed into single stranded RNA, which is then translated into protein. 

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