All Free Biology MCQs with Answers

• A. Bacteria
• B. Virus
• C. Eukaryote
• D. All of the above

Explanation: In eukaryotes, such as humans, DNA replication occurs at approximately 50 base pairs per second.

• A. Straight direction
• B. Parallel but straight
• C. Antiparallel and straight
• D. Antiparallel and spirally twisted

Explanation: DNA is a double helix formed by two strands of nucleotides. These strands run in opposite directions (antiparallel) and are twisted around…

• A. 50 base pairs per second
• B. 40 base pairs per second
• C. 20 base pairs per second
• D. 30 base pairs per second

Explanation: Eukaryotic DNA replication typically occurs at a rate of approximately 50 base pairs per second.

• A. DNA
• B. RNA
• C. Both DNA and RNA
• D. Either DNA or RNA

Explanation: Plant genome assembly represents the complete genomic sequence of a plant species, which is assembled into chromosomes and other…

• A. Interphase
• B. Prophase
• C. Metaphase
• D. Anaphase

Explanation: DNA replication occurs during S-stage of interphase.

• A. Two nucleotide bases
• B. Amino acid
• C. Two sugar
• D. Nucleotides and phosphates

Explanation: In the polynucleotide, adjacent nucleotides are joined by a phosphodiester linkage, which consists of a phosphate group that links the…

• A. One
• B. Two
• C. Three
• D. Four

Explanation: The Adenine - Thymine base pair is held together by 2 hydrogen bonds while the Guanine - Cytosine base pair is held together by 3 hydrogen…

• A. 0.1%
• B. 2%
• C. 3%
• D. 5%

Explanation: Human beings share 99.9% of their genome sequence, making 0.1% the portion that accounts for individual genetic differences.

• A. Cytosine
• B. Thymine
• C. Guanine
• D. Uracil

Explanation: Cytosine, thymine, and guanine are nitrogenous bases found in DNA and RNA.

• A. Double ringed
• B. Single ringed
• C. Double bond
• D. Single bond

Explanation: Purines are a type of nitrogenous base found in DNA and RNA, characterized by a double-ring structure.

• A. Medulla
• B. Medulla oblongata
• C. Body fluid
• D. Hypothalamus

Explanation: The hypothalamus in the brain is the master switch that works as a thermostat to regulate the body's core temperature.

• A. Salamander
• B. Great white shark
• C. Polar bear
• D. Butterfly

Explanation: Polar bears are classified as endothermic animals because they can regulate their body temperature internally, independent of external…

• A. Receptor, Regulators, Effectors
• B. Receptors, Integrator, Effectors
• C. Sensors, Brain, Effectors
• D. All of the above

Explanation: The correct answer is Receptors, Integrator, Effectors. These are the three core components of a homeostatic mechanism:Receptor: Detects…

• A. -9oC
• B. 10oC
• C. -10oC
• D. 8.0oC

Explanation: Arctic snow fleas are tiny organisms that have adapted to survive in freezing temperatures as low as -10°C.

• A. Cholera
• B. Tuberculosis
• C. Typhoid
• D. Poliomyelitis

Explanation: Option A: cholera is caused by a bacterium called Vibrio cholera (hence incorrect).

• A. HAV
• B. HBV
• C. HCV
• D. HIV

Explanation: The correct answer is HBV. HBV, also known as Hepatitis B Virus, has a single circular double-stranded DNA genome.

• A. Abundant bacteria are present
• B. Abundant water is present
• C. Abundant nutrients are present
• D. They can only live at human body temperature

Explanation: Phages can translocate through the mucosa to lymph and internal organs and play a role as regulators of the bacterial population in the…

• A. Polyhedral shape
• B. Bad shape
• C. Tadpole shape
• D. Golf ball shape

Explanation: The polio virus has a polyhedral shape, which means it is roughly spherical with many flat sides or faces.

• A. Typhoid and plague
• B. Polio and measles
• C. Cholera and rabies
• D. Mumps and influenza

Explanation: Live attenuated vaccines are designed to provoke a strong immune response by using a weakened form of the virus.

• A. tetanus
• B. small pox
• C. tuberculosis
• D. diptheria

Explanation: Smallpox is caused by a virus, the variola virus, not a bacterium. Tetanus is caused by a bacterium called Clostridium tetani.