Carmel Valley Invitational — Heredity

Heredity · Division B · Carmel Valley Invitational · 2026

82 questions · 175 points · 50 min· 11 questions from the original omitted

Original test source

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Section 1: MCQ

Question 1

2 pts

A population shows 36% recessive phenotype ( q² = 0.36 ). What is the dominant allele frequency?

Question 2

2 pts

After 20 perfect PCR cycles, approximately how many copies of a single DNA template exist?

Question 3

2 pts

A heterozygous plant produces gametes in the ratio A : a = 48% : 52%. Which process most likely caused this deviation?

Question 4

2 pts

A restriction enzyme recognizes a 4-bp sequence. On average, how often will it cut random DNA?

Question 5

2 pts

A pedigree shows unaffected mothers producing affected sons; affected males do not pass the trait to their sons. Most likely inheritance?

Question 6

2 pts

A codon for serine mutates into a stop codon. What type of mutation is this?

Question 8

2 pts

Two genes produce a 9:7 phenotypic ratio. What interaction is this?

A. CodominanceB. Duplicate recessive epistasisC. Recessive lethalD. Overdominance

Question 9

2 pts

A heterozygote (Dd) shows a faint 1000-bp band (D) and a bright 600-bp band (d). What explains the unequal intensities?

A. D allele is longerB. d allele amplifies more efficientlyC. Ethidium bromide binds only to small fragmentsD. Smaller fragments migrate more and concentrateE. Larger fragments degrade faster

Question 10

2 pts

A tRNA has anticodon 3′-GAC-5′. Which codon does it bind?

A. 5′-CUG-3′B. 5′-GUC-3′C. 5′-GAC-3′D. 5′-CGU-3′

Question 11

2 pts

Two genes are 15 map units apart. What percentage of offspring from a testcross is recombinant?

Question 12

2 pts

What occurs during the 95°C step of PCR?

Question 13

2 pts

A DNA sample contains 30% adenine. What percent is cytosine?

Question 14

2 pts

A cell with nondisjunction in Meiosis I produces gametes with which chromosome numbers? (if 2n = 6)

Question 15

2 pts

Which enzyme creates RNA primers during DNA replication?

Question 16

2 pts

Which molecule binds to the operator of the lac operon?

Question 17

2 pts

A 9:3:4 ratio indicates:

Question 18

2 pts

Crossing-over occurs mainly during:

Question 19

2 pts

DNA polymerase adds nucleotides to which end of a growing DNA strand?

A. Only 5′B. Only 3′C. Either 3′ or 5′D. Depends on template

Question 20

2 pts

Which structure is present on the lagging strand but not the leading strand?

Question 22

2 pts

Which step of transcription occurs first?

Question 23

2 pts

A mutation in the promoter of a gene most likely affects:

Question 24

2 pts

What is the role of helicase?

Question 25

2 pts

A dihybrid cross results in only parental phenotypes. Which is the best explanation?

Question 26

2 pts

Which molecule delivers amino acids to the ribosome during translation?

Question 27

2 pts

A DNA mutation that does not change the amino acid sequence is called:

Question 28

2 pts

In PCR, which factor most strongly determines specificity?

Question 29

2 pts

A gene with multiple phenotypic effects is described as:

Question 30

2 pts

Which of the following occur during the metaphase of mitosis?

A. Sister chromatids separate and are pulled toward opposite ends of the cellB. Chromosomes line up in the middle of the cellC. Chromosomes start moving toward the center of the cellD. The nuclear membrane begins to break down

Question 31

2 pts

In which stage of mitosis does the nuclear envelope reform (now at each end of the cell):

Question 32

2 pts

Human chromosomes and mitochondrial chromosomes differ most in which of the following?

Question 33

2 pts

Your half-brother Ayden is about to drown in a freezing river. According to Hamilton’s rule, at least what chance of success would you need to have in order to justify trying to rescue him? Assume both of you survive if you succeed, both of you die if you try but fail, and he dies while you survive if you do not try to rescue him.

Question 34

2 pts

Treatment of a linear DNA molecule with the palindromic endonuclease DpnII (5-GATC-3) produces 50 fragments. How many fragments would you expect to be produced when the same original linear molecule is treated with BamHI (5 - GGATCC-3)?

Question 35

2 pts

An autosomal dominant condition causes death in 1 out of every 50 offspring in the Australian mouse population. Assume the condition is lethal in 80% of affected individuals. What is the frequency of the disease allele in the population?

Challenge Studies

Question CS1

4 pts

A well-established geneticist, Dr. Kanone, is famous for experiments on the common plant Camellia japonica. In particular, Dr. Kanone has several mutant, true-breeding lines of C. japonica. Line A gives off a sweet odor, line B gives off a musty odor, and line C gives off no odor at all. When he crosses lines A and B, he obtains only sweet-odor plants. When he crosses lines B and C, he obtains only musty-odor plants. Moreover, when he self-crosses the offspring of lines A and B, he gets mostly sweet-odor plants, some musty-odor plants, and a few no-odor plants. Which of the following statements must be not true?

A. This is an example of dominant epistasis.B. This is not an example of pleiotropy.C. If he self-crossed the no-odor plants from the last cross, Dr. Kanone would get some sweet-odor offspring.D. The enzyme responsible for creating the intermediate that gives off the sweet odor is not in the same pathway as the enzyme responsible for creating the intermediate that gives off the musty odor.E. If he self-crossed the musty-odor plants from the last cross, Dr. Kanone would get some no-odor offspring.F. The musty-odor allele is always dominant to the sweet-odor allele

Question CS2

4 pts

Your professor Dr. Umbra is studying a population of Vulpes glacialis, a common mammal. She is interested in two phenotypes: black-haired V. glacialis and blue-haired V. glacialis. It is thought that the blue-hair phenotype is the recessive phenotype. Interestingly enough, however, in a sample of 5000 male V. glacialis and 5000 female V. glacialis, Dr. Orange finds that there are 1600 male blue-haired V. glacialis but only 512 female blue-haired V. glacialis. Which of the following is the best explanation of this phenomenon?

A. There are two genes that control hair color.B. Dr. Orange used too small of a sample size to get a reliable result.C. The species V. glacialis exhibits the temperature-dependent sex determination system.D. The allele responsible for blue hair is not autosomal.E. The blue-hair phenotype is not actually the recessive phenotype.F. V. glacialis has a retroplastic allele system

Question CS3

4 pts

Interference occurs when crossing over in one part of a chromosome influences crossing over in other regions of the same chromosome. Interference (I) can be calculated from the coefficient of coincidence (C) by the following equations. Note: DCO = number of double crossovers. Using the data from the reference map with the a, b and c genes in Rosophilo, what is the interference from this cross? Select ONE.

Reference Map: c — 1.64 cM — a — 6.39 cM — b

Question CS4

4 pts · select all that apply

A scientist was interested in the expression rate of the herpes DNA polymerase during a herpes infection. She collected samples 8 and 14 hours post-infection and generated cDNA. The samples from 8 hours postinfection were labeled with a green fluorescent dye and the samples from 14 hours post- infection were labeled with a red fluorescent dye. During microarray analysis, spots corresponding to the DNA polymerase sequence on the microchip were yellow. Which of the following TWO statements BEST interprets these results?

A. The assay is conclusively determined to have been performed inaccurately .B. DNA polymerase is expressed only at 8 hours post-infection.C. DNA polymerase is expressed only at 14 hours post-infection.D. DNA polymerase is expressed similarly at both 8 hours post-infection and 14 hours post-infection.E. DNA polymerase is much more expressed at 8 hours post- infection than at 14 hours post-infection.F. The relative abundance of DNA polymerase mRNA is approximately equal in both samples.

Question CS6

4 pts · select all that apply

After being treated with a drug, a cell line suddenly contains abnormally low levels of protein. However, transcriptomic profiling shows that mRNA levels are still high. By which of the following mechanisms could the drug be decreasing protein levels? SELECT ALL POSSIBLE ANSWERS.

A. Increased transcriptional repression.B. Increased protein ubiquitination.C. Inhibition of amino-acyl tRNA synthetases.D. Increased RNA interference activity.E. Destruction of ribosomes in the cell.F. miRNA is not transcriptomic it is cryptomic

Case Study 2

Question CS2-1

3 pts

Now based on this information, what is the probability that the newborn daughter (III-1) will develop Idol syndrome later in life?

Question CS2-2

2 pts

For the following problem, assume Hardy Weinberg equilibrium: Roughly 5% of human males are colorblind. This is caused by a recessive mutation carried on the X chromosome. If an XX female is not colorblind herself, what is the probability that she carries at least one copy of the mutant allele for colorblindness?

Question CS2-3

2 pts

Which of the following equations is an identity of the Hardy-Weinberg equilibrium theory that relies on random mating?

A. −qqqq = qq² − qqB. qq² + 2qqqq = 2qq − qq²C. qq³ + 3qq²qq + 3qqqq² + qq³ = 1D. The probability that the theory is acceptable is near 0%E. All of these identities rely on random mating.

Question CS2-4

2 pts

In the biolistic gene-gun method, DNA is coated onto microscopic particles before being shot into cells. Which particles are most commonly used for this technique?

FRQ #1 - Diagrams

FigureFor questions FRQ1-1a, FRQ1-1b, FRQ1-2a, FRQ1-2b

Question FRQ1-1a

1 pt

Disease Name (row 1a)

Question FRQ1-1b

2 pts

Explanation of disease symptoms and how you identified it from the karyotype (row 1b)

Question FRQ1-2a

1 pt

Disease Name (row 2a)

Question FRQ1-2b

2 pts

Explanation of disease symptoms and how you identified it from the karyotype (row 2b)

Question FRQ1-1

1 pt

What type of inheritance does this pedigree show?

Question FRQ1-2

2 pts

What reasoning did you use to make this conclusion?

FRQ #2 - Mutations

Question FRQ2-1

2 pts

What is the complement strand to the following sequence: 5’-TACCCGTACGATATT-3’

Question FRQ2-2

2 pts

What is the resultant amino acid peptide:

Question FRQ2-3

3 pts

Say that a mutation in the original sequence resulted in 5’-TAC A CCGTACGATATT-3’, what kind of mutation is this and list multiple consequences?

Question FRQ2-4

3 pts

Now say that a mutation in the original sequence resulted in 5’-TACCCGTAC T ATATT-3’, what kind of mutation is this and list multiple consequences?

Question FRQ2-5a

2 pts

Explain the following mutations: Silent Mutation

Question FRQ2-5b

2 pts

Explain the following mutations: Missense Mutation

Question FRQ2-5c

2 pts

Explain the following mutations: Nonsense Mutation

Question FRQ2-5d

1 pt

Give an example of a disease caused by a Missense Mutation

FRQ #3 - DNA Replication

Question FRQ3-1

2 pts

Explain the functions of the following enzymes in DNA replication: Helicase

Question FRQ3-2

2 pts

Explain the functions of the following enzymes in DNA replication: Topoisomerase

Question FRQ3-3

2 pts

Explain the functions of the following enzymes in DNA replication: Primase

Question FRQ3-4

2 pts

Explain the functions of the following enzymes in DNA replication: DNA Polymerase (general functions)