All Free Biology MCQs with Answers
Every Biology question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
19,844 questions · page 953 of 993
- A. Lateral ventricle
- B. Thalamus
- C. Spinal cord
- D. Hypothalamus
Explanation: The hypothalamus is a section of the brain that controls thermoregulation.
Correct answer: Hypothalamus- A. HBV
- B. HAV
- C. HCV
- D. None of these
Explanation: Hepatitis C virus (HCV), is an enveloped single-stranded RNA virus which appears to be distantly related (possibly in its evolution) to…
Correct answer: HCV- A. Enveloped RNA.
- B. DNA Virus.
- C. RNA tumor.
- D. Both B and C.
Explanation: b) DNA Virus: This is the correct option. Herpes simplex is caused by herpes simplex virus (HSV), which is a DNA virus.
Correct answer: DNA Virus.19044. Which one of the following diseases caused by enveloped RNA virus and spread in epidemic form?
- A. Influenza
- B. Herpes Simplex
- C. Polio
- D. Smallpox
Explanation: [A] Influenza is RNA based virus and enveloped also[B] Herpes is not caused by Enveloped RNA virus[C] Polio is caused by non-enveloped RNA…
Correct answer: Influenza- A. DNA virus
- B. RNA enveloped virus
- C. DNA enveloped virus
- D. RNA virus
Explanation: Influenza is caused by an enveloped RNA virus.
Correct answer: RNA enveloped virus- A. Hepatitis
- B. Cholera
- C. Influenza
- D. Candidiasis
Explanation: Hepatitis B and Hepatitis C are blood borne diseases, which can be transferred to other individuals by blood contact.
Correct answer: Hepatitis19047. What are the sequences of steps in which a bacteriophage attacks bacteria and injects its DNA?
- A. Landing → Tail contraction → Penetration → DNA Injection
- B. Penetration → Landing → Tail contraction → DNA Injection
- C. Tail contraction → Landing → DNA Injection → Penetration
- D. Landing → Penetration → Tail contraction → DNA Injection
Explanation: The phage first attaches itself by its tail to the cell wall of bacterium at a point called receptor site.
Correct answer: Landing → Tail contraction → Penetration → DNA Injection- A. Ectoparasites
- B. Endoparasites
- C. Obligative Intracellular Parasites
- D. Facultative Intracellular Parasites
Explanation: Intracellular obligate parasites depend on the host not only for nutrition but also for reproduction.
Correct answer: Obligative Intracellular Parasites- A. Mycoplasma
- B. Escherichia coli
- C. Herpes virus
- D. Diplococcus
Explanation: Herpes virus is essentially a virus and since viruses do not fall under the category of cellular beings, herpes virus is a non-cellular…
Correct answer: Herpes virus19050. The viruses can reproduce:
- A. Without invading any cell.
- B. In bacterial cell.
- C. By Mitosis
- D. By Meiosis
Explanation: Viruses are incapable of reproducing on their own, so they hunt for a host cell for hijacking.
Correct answer: In bacterial cell.- A. Transduction
- B. Temperate phage cycle
- C. Lytic cycle
- D. Lysogenic phage cycle
Explanation: In the lytic cycle the phage infects a bacterium, hijacks the bacterium to make lots of phages, and then kills the cell by making it…
Correct answer: Lytic cycle- A. Nucleocapsid
- B. Prion
- C. Envelope
- D. Capsomeres
Explanation: The capsid and nucleic acid together are known as the nucleocapsid.A prion is a type of protein that can trigger normal proteins in the…
Correct answer: Nucleocapsid- A. Enveloped Phage
- B. Virulent Phage
- C. Temperate phages
- D. Bacteriophage
Explanation: Temperate phages are some bacteriophages which display a lysogenic life cycle.
Correct answer: Temperate phages- A. Capsid
- B. Cosmid
- C. Capsomere
- D. Chromophore
Explanation: The outer protein coat of a virus is known as 'the capsid'. It consists of several oligomeric structural subunits made of a protein called…
Correct answer: Capsid19055. In moths male is _.
- A. Heterogametic
- B. Dieogametic
- C. Homogametic
- D. Both B and C
Explanation: Moths and butterflies, have a female heterogametic sex chromosome system, with most females having a ZW constitution while males are ZZ.
Correct answer: Homogametic- A. X-linked
- B. Autosomal
- C. Y-linked
- D. X and Y-linked
Explanation: [A] X-linked traits are not only transmitted from father to son but can be also transmitted to her daughter[B] Autosomal disease can be…
Correct answer: Y-linked- A. XY
- B. SRY
- C. SYX
- D. SXX
Explanation: Y chromosome has an SRY gene. It is the sex determining region Y gene. It is Y linked gene because it is found only on the Y chromosome.
Correct answer: SRY- A. Y-chromosome
- B. X-chromosome
- C. Autosome 7
- D. Autosome 9
Explanation: Red- Green Color blindness is a sex-linked recessive disease which is passed down through the X chromosomes.
Correct answer: X-chromosome- A. Lymphocytes
- B. RBC
- C. T_Cell
- D. B_ cells
Explanation: While HIV can infect other types of cells, including monocytes, macrophages, and dendritic cells, it has a particular affinity for…
Correct answer: T_Cell- A. 50 molecules per virion
- B. 40 molecules per virion
- C. 30 molecules per virion
- D. 20 molecules per virion
Explanation: In summary, the specific number of reverse transcriptase molecules per HIV virion can vary due to factors like viral strain and infection…
Correct answer: 50 molecules per virion