Q. What is the role of a diode in a rectifier circuit? (2022)
A.
To amplify signals
B.
To store charge
C.
To allow current in one direction
D.
To increase voltage
Show solution
Solution
In a rectifier circuit, a diode allows current to flow in one direction, converting AC to DC.
Correct Answer: C — To allow current in one direction
Learn More →
Q. What is the role of a Punnett square? (2023)
A.
To determine the phenotype of an organism
B.
To predict the genotypes of offspring
C.
To identify mutations
D.
To analyze genetic disorders
Show solution
Solution
A Punnett square is used to predict the genotypes of offspring from a genetic cross.
Correct Answer: B — To predict the genotypes of offspring
Learn More →
Q. What is the role of a resistor in a semiconductor circuit? (2023)
A.
Increase current
B.
Limit current
C.
Store charge
D.
Amplify signal
Show solution
Solution
A resistor is used to limit the current flowing through a semiconductor circuit to prevent damage.
Correct Answer: B — Limit current
Learn More →
Q. What is the role of a transformer in an AC circuit? (2023)
A.
To convert AC to DC
B.
To increase or decrease voltage
C.
To store energy
D.
To measure current
Show solution
Solution
A transformer is used to increase or decrease voltage in an AC circuit.
Correct Answer: B — To increase or decrease voltage
Learn More →
Q. What is the role of Agrobacterium tumefaciens in biotechnology? (2021)
A.
Gene delivery
B.
Protein synthesis
C.
Cell division
D.
DNA replication
Show solution
Solution
Agrobacterium tumefaciens is used as a vector for gene delivery in plant biotechnology.
Correct Answer: A — Gene delivery
Learn More →
Q. What is the role of Agrobacterium tumefaciens in genetic engineering? (2022)
A.
It acts as a vector
B.
It is a source of restriction enzymes
C.
It is used for DNA sequencing
D.
It helps in protein synthesis
Show solution
Solution
Agrobacterium tumefaciens is used as a vector to transfer genes into plant cells.
Correct Answer: A — It acts as a vector
Learn More →
Q. What is the role of aldosterone in the body? (2021)
A.
Increase blood glucose
B.
Regulate sodium and potassium levels
C.
Stimulate milk production
D.
Enhance immune response
Show solution
Solution
Aldosterone is a hormone produced by the adrenal cortex that helps regulate sodium and potassium levels, thus influencing blood pressure.
Correct Answer: B — Regulate sodium and potassium levels
Learn More →
Q. What is the role of an oxidizing agent in a redox reaction? (2020)
A.
It gains electrons
B.
It loses electrons
C.
It remains unchanged
D.
It increases the temperature
Show solution
Solution
An oxidizing agent gains electrons during a redox reaction, causing another species to be oxidized.
Correct Answer: A — It gains electrons
Learn More →
Q. What is the role of biopesticides in agriculture? (2021)
A.
Increase soil fertility
B.
Control pest populations
C.
Enhance crop yield
D.
Improve water retention
Show solution
Solution
Biopesticides are used to control pest populations in an environmentally friendly manner, reducing the reliance on chemical pesticides.
Correct Answer: B — Control pest populations
Learn More →
Q. What is the role of calcium ions in muscle contraction? (2022)
A.
To provide energy
B.
To bind to troponin
C.
To stimulate nerve impulses
D.
To form cross-bridges
Show solution
Solution
Calcium ions bind to troponin, causing a conformational change that allows myosin to bind to actin.
Correct Answer: B — To bind to troponin
Learn More →
Q. What is the role of chlorophyll in leaves? (2023)
A.
Water storage
B.
Nutrient absorption
C.
Photosynthesis
D.
Gas exchange
Show solution
Solution
Chlorophyll is essential for photosynthesis as it captures light energy to convert carbon dioxide and water into glucose.
Correct Answer: C — Photosynthesis
Learn More →
Q. What is the role of chloroplasts in plant cells? (2021)
A.
Respiration
B.
Photosynthesis
C.
Digestion
D.
Reproduction
Show solution
Solution
Chloroplasts are responsible for photosynthesis, converting light energy into chemical energy.
Correct Answer: B — Photosynthesis
Learn More →
Q. What is the role of condoms in reproductive health? (2021)
A.
To enhance pleasure
B.
To prevent pregnancy and STIs
C.
To increase fertility
D.
To promote sexual activity
Show solution
Solution
Condoms are used to prevent both pregnancy and the transmission of sexually transmitted infections (STIs).
Correct Answer: B — To prevent pregnancy and STIs
Learn More →
Q. What is the role of cyclins in the cell cycle? (2019)
A.
To inhibit cell division
B.
To promote apoptosis
C.
To regulate the cell cycle
D.
To repair DNA
Show solution
Solution
Cyclins are proteins that regulate the progression of the cell cycle by activating cyclin-dependent kinases (CDKs).
Correct Answer: C — To regulate the cell cycle
Learn More →
Q. What is the role of DNA ligase in recombinant DNA technology? (2021)
A.
To cut DNA
B.
To join DNA fragments
C.
To replicate DNA
D.
To transcribe RNA
Show solution
Solution
DNA ligase is an enzyme that joins DNA fragments together, which is crucial for creating recombinant DNA molecules.
Correct Answer: B — To join DNA fragments
Learn More →
Q. What is the role of DNA polymerase? (2021)
A.
Transcription
B.
Replication
C.
Translation
D.
Repair
Show solution
Solution
DNA polymerase is an enzyme that synthesizes new DNA strands during replication.
Correct Answer: B — Replication
Learn More →
Q. What is the role of doping in semiconductors? (2022)
A.
To increase resistance
B.
To decrease conductivity
C.
To introduce charge carriers
D.
To create a magnetic field
Show solution
Solution
Doping introduces additional charge carriers (electrons or holes) into the semiconductor, enhancing its conductivity.
Correct Answer: C — To introduce charge carriers
Learn More →
Q. What is the role of enzymes in the human body? (2021)
A.
Store energy
B.
Speed up chemical reactions
C.
Transport oxygen
D.
Regulate temperature
Show solution
Solution
Enzymes act as catalysts that speed up chemical reactions in the body, facilitating various metabolic processes.
Correct Answer: B — Speed up chemical reactions
Learn More →
Q. What is the role of fossils in understanding evolution? (2020)
A.
They provide evidence of past life forms and their changes over time
B.
They are the only source of genetic information
C.
They show the exact lineage of species
D.
They have no role in evolution
Show solution
Solution
Fossils provide crucial evidence of past life forms and their changes over time, helping scientists understand the process of evolution and the history of life on Earth.
Correct Answer: A — They provide evidence of past life forms and their changes over time
Learn More →
Q. What is the role of genetic drift in evolution? (1930)
A.
It increases genetic variation
B.
It leads to random changes in allele frequencies
C.
It promotes adaptation to the environment
D.
It is a form of natural selection
Show solution
Solution
Genetic drift is a mechanism of evolution that leads to random changes in allele frequencies in a population, particularly in small populations.
Correct Answer: B — It leads to random changes in allele frequencies
Learn More →
Q. What is the role of genetically modified organisms (GMOs) in agriculture? (2022)
A.
Increase biodiversity
B.
Reduce crop yield
C.
Enhance resistance to pests
D.
Decrease nutritional value
Show solution
Solution
GMOs are engineered to enhance resistance to pests, thereby increasing crop yield.
Correct Answer: C — Enhance resistance to pests
Learn More →
Q. What is the role of genetically modified organisms (GMOs) in food production? (2021)
A.
Increase in food safety
B.
Reduction of food waste
C.
Enhancement of food quality
D.
All of the above
Show solution
Solution
GMOs are designed to enhance food quality, safety, and reduce waste, thus all options are correct.
Correct Answer: D — All of the above
Learn More →
Q. What is the role of glucagon in the body? (2021)
A.
Increase blood sugar levels
B.
Decrease blood sugar levels
C.
Stimulate growth
D.
Regulate metabolism
Show solution
Solution
Glucagon is a hormone produced by the pancreas that raises blood sugar levels by promoting the conversion of glycogen to glucose in the liver.
Correct Answer: A — Increase blood sugar levels
Learn More →
Q. What is the role of helicase in DNA replication? (2022)
A.
To synthesize RNA
B.
To unwind the DNA double helix
C.
To join Okazaki fragments
D.
To add nucleotides
Show solution
Solution
Helicase unwinds the DNA double helix during DNA replication.
Correct Answer: B — To unwind the DNA double helix
Learn More →
Q. What is the role of hemoglobin in respiration? (2019)
A.
Transporting oxygen
B.
Filtering air
C.
Regulating pH
D.
Producing carbon dioxide
Show solution
Solution
Hemoglobin in red blood cells binds to oxygen in the lungs and transports it to tissues throughout the body.
Correct Answer: A — Transporting oxygen
Learn More →
Q. What is the role of iron in plants? (2022)
A.
Oxygen transport
B.
Chlorophyll synthesis
C.
Water uptake
D.
Sugar transport
Show solution
Solution
Iron is essential for chlorophyll synthesis and plays a role in various enzymatic reactions.
Correct Answer: B — Chlorophyll synthesis
Learn More →
Q. What is the role of keystone species in an ecosystem? (2022)
A.
They are the most abundant species.
B.
They have a disproportionately large impact on their environment.
C.
They are the largest species in the ecosystem.
D.
They are the first species to colonize an area.
Show solution
Solution
Keystone species have a disproportionately large impact on their environment, affecting many other organisms in the ecosystem.
Correct Answer: B — They have a disproportionately large impact on their environment.
Learn More →
Q. What is the role of MnO4⁻ in acidic medium during redox reactions? (2020)
A.
Oxidizing agent
B.
Reducing agent
C.
Neutral agent
D.
Catalyst
Show solution
Solution
MnO4⁻ acts as an oxidizing agent in acidic medium, as it gains electrons and is reduced.
Correct Answer: A — Oxidizing agent
Learn More →
Q. What is the role of moderators in nuclear reactors? (2023)
A.
To increase the temperature
B.
To slow down neutrons
C.
To absorb radiation
D.
To enhance fission
Show solution
Solution
Moderators are used in nuclear reactors to slow down fast neutrons, making them more likely to induce fission in the fuel.
Correct Answer: B — To slow down neutrons
Learn More →
Q. What is the role of mutations in evolution? (2018)
A.
They are always harmful
B.
They provide genetic variation
C.
They prevent evolution
D.
They are irrelevant
Show solution
Solution
Mutations provide genetic variation, which is essential for evolution as it introduces new traits that may be subject to natural selection.
Correct Answer: B — They provide genetic variation
Learn More →
Showing 2971 to 3000 of 4667 (156 Pages)