Q. If a plant with genotype AaBb is crossed with another AaBb plant, what fraction of the offspring will be homozygous recessive for both traits?
A.1/16
B.1/4
C.3/16
D.9/16
Solution
The fraction of offspring that are homozygous recessive (aabb) from the cross AaBb x AaBb is 1/16.
Correct Answer: A — 1/16
Q. If a solution is diluted from 1000 ppm to 100 ppm, what is the dilution factor?
A.1:10
B.1:5
C.1:20
D.1:50
Solution
The dilution factor is 1:10, as the concentration is reduced by a factor of 10.
Correct Answer: A — 1:10
Q. If a sterilization cycle takes 30 minutes at 121°C, how long would it take at 134°C?
A.10 minutes
B.15 minutes
C.20 minutes
D.25 minutes
Solution
At 134°C, the sterilization time can be reduced to approximately 20 minutes due to the increased temperature.
Correct Answer: C — 20 minutes
Q. If a trait is controlled by a single gene with two alleles, what is the maximum number of different genotypes possible in a population?
A.1
B.2
C.3
D.4
Solution
For a single gene with two alleles, the maximum number of different genotypes possible is 3: homozygous dominant, heterozygous, and homozygous recessive.
Correct Answer: D — 4
Q. If a vaccine has a 90% success rate and is administered to 500 individuals, how many individuals are expected to remain unprotected?
A.50
B.100
C.200
D.300
Solution
With a 90% success rate, 10% will remain unprotected. 10% of 500 is 50 individuals.
Correct Answer: A — 50
Q. In a case of septic shock, which immune response is primarily responsible for the symptoms observed?
A.Adaptive immune response
B.Innate immune response
C.Humoral immune response
D.Cell-mediated immune response
Solution
Septic shock is primarily driven by the innate immune response, which leads to systemic inflammation and shock.
Correct Answer: B — Innate immune response
Q. In a case study, a hospital outbreak was traced back to improperly sterilized endoscopes. What is the best practice to prevent such outbreaks?
A.Use single-use instruments
B.Increase the frequency of cleaning
C.Implement strict sterilization protocols
D.Use chemical disinfectants only
Solution
Implementing strict sterilization protocols is essential to prevent outbreaks associated with reusable medical instruments.
Correct Answer: C — Implement strict sterilization protocols
Q. In a case study, a surgical instrument was found to be contaminated with Staphylococcus aureus. Which sterilization method would be most effective?
A.Boiling water
B.Ethylene oxide gas
C.Alcohol wipes
D.Ultraviolet light
Solution
Ethylene oxide gas is effective for sterilizing heat-sensitive instruments and can eliminate Staphylococcus aureus.
Correct Answer: B — Ethylene oxide gas
Q. In a clinical trial, a vaccine shows a 70% efficacy rate. If 1,000 individuals are vaccinated, how many are expected to be protected?
A.700
B.300
C.500
D.900
Solution
With 70% efficacy, 70% of 1,000 individuals would be protected, which equals 700 individuals.
Correct Answer: A — 700
Q. In a cross between two pea plants, one with round seeds (R) and one with wrinkled seeds (r), what is the phenotype of the F1 generation if round is dominant?
A.Round
B.Wrinkled
C.Both
D.Neither
Solution
The phenotype of the F1 generation will be round seeds since round (R) is dominant over wrinkled (r).
Correct Answer: A — Round
Q. In a dihybrid cross, what is the expected phenotypic ratio in the F2 generation?
A.3:1
B.1:2:1
C.9:3:3:1
D.1:1:1:1
Solution
The expected phenotypic ratio in the F2 generation of a dihybrid cross is 9:3:3:1, representing the combinations of two traits.
Correct Answer: C — 9:3:3:1
Q. In a dihybrid cross, what is the expected phenotypic ratio of the offspring?
A.1:1
B.3:1
C.9:3:3:1
D.1:2:1
Solution
The expected phenotypic ratio of a dihybrid cross is 9:3:3:1, representing the combinations of two traits.
Correct Answer: C — 9:3:3:1
Q. In a double helix, the two strands of DNA are held together by which type of bond?
A.Covalent bond
B.Hydrogen bond
C.Ionic bond
D.Disulfide bond
Solution
Hydrogen bonds between complementary nitrogenous bases hold the two strands of the DNA double helix together.
Correct Answer: B — Hydrogen bond
Q. In a laboratory diagnosis of tuberculosis, which test is most commonly used to assess cell-mediated immunity?
A.ELISA
B.Mantoux test
C.Blood culture
D.PCR
Solution
The Mantoux test is used to assess cell-mediated immunity to Mycobacterium tuberculosis.
Correct Answer: B — Mantoux test
Q. In a laboratory setting, which method is most appropriate for sterilizing heat-sensitive liquids?
A.Autoclaving
B.Filtration
C.Incineration
D.Chemical sterilization
Solution
Filtration is the most appropriate method for sterilizing heat-sensitive liquids without altering their properties.
Correct Answer: B — Filtration
Q. In a pedigree chart, what does a filled circle represent?
A.A male
B.A female
C.An affected individual
D.A carrier
Solution
A filled circle in a pedigree chart represents an affected female individual.
Correct Answer: C — An affected individual
Q. In a plant with a 3:1 ratio of dominant to recessive traits, how many offspring would you expect to show the dominant trait out of 100?
A.25
B.50
C.75
D.100
Solution
In a 3:1 ratio, 75 out of 100 offspring would be expected to show the dominant trait.
Correct Answer: C — 75
Q. In a population of plants, if 60% are hermaphroditic and the rest are dioecious, what is the number of dioecious plants in a population of 200?
A.40
B.60
C.80
D.100
Solution
If 60% are hermaphroditic, then 40% are dioecious, which equals 80 dioecious plants in a population of 200.
Correct Answer: A — 40
Q. In a study, 200 patients were infected with a virus. If 40% of them developed symptoms, how many patients showed symptoms?
A.80
B.60
C.40
D.20
Solution
40% of 200 patients is 0.4 * 200 = 80 patients who developed symptoms.
Correct Answer: A — 80
Q. In a test cross, an individual with a dominant phenotype is crossed with which type of individual?
A.Homozygous dominant
B.Heterozygous
C.Homozygous recessive
D.Any individual
Solution
A test cross is performed by crossing an individual with a dominant phenotype with a homozygous recessive individual to determine the genotype.
Correct Answer: C — Homozygous recessive
Q. In a test cross, an individual with an unknown genotype is crossed with a homozygous recessive individual. What is the purpose of this cross?
A.To determine the dominant allele
B.To determine the recessive allele
C.To determine the genotype of the unknown
D.To determine the phenotype of the offspring
Solution
The purpose of a test cross is to determine the genotype of an individual with a dominant phenotype by crossing it with a homozygous recessive individual.
Correct Answer: C — To determine the genotype of the unknown
Q. In a test cross, what is the purpose of crossing an individual with a homozygous recessive?
A.To determine the dominant allele
B.To identify the genotype of the individual
C.To produce offspring
D.To analyze gene expression
Solution
A test cross with a homozygous recessive individual helps determine the genotype of the individual in question.
Correct Answer: B — To identify the genotype of the individual
Q. In angiosperms, what is the role of the endosperm?
A.To protect the seed
B.To provide nourishment to the developing embryo
C.To facilitate pollination
D.To aid in seed dispersal
Solution
The endosperm provides nourishment to the developing embryo within the seed.
Correct Answer: B — To provide nourishment to the developing embryo
Q. In C4 plants, where does the initial carbon fixation occur?
A.In the mesophyll cells
B.In the bundle sheath cells
C.In the stroma
D.In the thylakoid membranes
Solution
In C4 plants, the initial carbon fixation occurs in the mesophyll cells.
Correct Answer: A — In the mesophyll cells
Q. In C4 plants, where does the initial fixation of CO2 occur?
A.In the mesophyll cells
B.In the bundle sheath cells
C.In the stroma
D.In the thylakoid membranes
Solution
In C4 plants, the initial fixation of CO2 occurs in the mesophyll cells before it is transferred to bundle sheath cells.
Correct Answer: A — In the mesophyll cells
Q. In cloning, what is the purpose of using a vector?
A.To provide a means of introducing foreign DNA into a host cell
B.To degrade unwanted DNA
C.To amplify RNA
D.To sequence DNA
Solution
Vectors are used to introduce foreign DNA into host cells, allowing for replication and expression of the inserted gene.
Correct Answer: A — To provide a means of introducing foreign DNA into a host cell
Q. In cloning, what is the role of a vector?
A.To provide a template for DNA synthesis
B.To carry foreign DNA into a host cell
C.To amplify RNA
D.To degrade unwanted DNA
Solution
A vector is a DNA molecule used to deliver foreign genetic material into a host cell for cloning purposes.
Correct Answer: B — To carry foreign DNA into a host cell
Q. In DNA, adenine pairs with which base?
A.Cytosine
B.Thymine
C.Guanine
D.Uracil
Solution
In DNA, adenine pairs with thymine through two hydrogen bonds.
Correct Answer: B — Thymine
Q. In eukaryotic cells, what modification occurs to pre-mRNA before it becomes mature mRNA?
A.Addition of a poly-A tail and 5' cap
B.Splicing out of exons
C.Replication of DNA
D.Translation into protein
Solution
Pre-mRNA undergoes capping at the 5' end and polyadenylation at the 3' end, along with splicing to remove introns, to become mature mRNA.
Correct Answer: A — Addition of a poly-A tail and 5' cap
Q. In eukaryotic cells, where does transcription occur?
A.Cytoplasm
B.Nucleus
C.Mitochondria
D.Ribosome
Solution
Transcription occurs in the nucleus of eukaryotic cells, where the DNA is located.
