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 836 of 993
- A. More sweating, vasoconstriction
- B. Less sweating, vasodilation
- C. Less sweating, vasoconstriction
- D. More sweating, vasodilation
Explanation: When the body is overheated, sweating and vasodilation are the primary mechanisms employed to regulate body temperature.
Correct answer: More sweating, vasodilation- A. Athlete's foot
- B. Herpes simplex
- C. Mad cow disease
- D. Mumps and Measles
Explanation: Prions are misfolded proteins that can cause neurodegenerative diseases. They are infectious particles solely composed of proteins.
Correct answer: Mad cow disease- A. I only
- B. III only.
- C. I and II
- D. II and III
Explanation: Induction is the process where the prophage is activated and excises itself from the host chromosome, initiating the lytic cycle.
Correct answer: III only.- A. Prions
- B. Viroid
- C. Retrovirus
- D. Bacteriophage
Explanation: Creutzfeldt-Jakob disease (CJD) in humans is caused by prions, which are infectious proteins.
Correct answer: Prions- A. Synthesise viral genome
- B. Dissolve bacterial cell wall
- C. Break down bacterial DNA
- D. Speed up the formation of proteins
Explanation: In the lytic cycle, the correct function of lysozymes is to dissolve the bacterial cell wall, which allows the newly formed phage…
Correct answer: Dissolve bacterial cell wall- A. Viruses
- B. Ingestion
- C. Binary fission
- D. Physical contact
Explanation: Transduction is a process of genetic recombination in bacteria where DNA is transferred from one bacterium to another through a…
Correct answer: Viruses- A. Virus
- B. Bacillus
- C. Viroid
- D. Prion
Explanation: Hepatitis D, also known as delta hepatitis, is indeed caused by the hepatitis D virus (HDV).HDV is a small, circular RNA virus that…
Correct answer: Virus- A. The protein of T2 and DNA of T4
- B. The protein of T4 and DNA of T2
- C. The protein and DNA of T2
- D. The protein and DNA of T4
Explanation: The phages produced in the host cell would have the protein coat of phage T2 and the DNA of phage T4.
Correct answer: The protein of T2 and DNA of T4- A. Carrier mother and a colour blind father
- B. Carrier mother and an unaffected father
- C. Colour blind mother and an unaffected father
- D. Unaffected, non-carrier mother and a colour blind father
Explanation: The correct answer is a carrier mother and a color blind father. A carrier mother has one normal X chromosome and one affected X…
Correct answer: Carrier mother and a colour blind father- A. Protenor bugs
- B. Grasshoppers
- C. Butterflies
- D. Fruit flies
Explanation: The correct answer is butterflies. In the ZW sex-determination system, which is observed in butterflies, moths, and birds, the female is…
Correct answer: Butterflies- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: In the cross mother should be XX, father should be XY and son should be XY. Option D gives the correct representations.
Correct answer: Option D- A. Mother is carrier, father is normal
- B. Mother is hemophiliac, father is normal
- C. Mother is carrier, father is hemophiliac
- D. Mother is normal, father is hemophiliac
Explanation: C is the correct option.For a female to have haemophilia, she must inherit an affected X chromosome from each parent.
Correct answer: Mother is carrier, father is hemophiliac- A. Red-eyed males
- B. White-eyed males
- C. Red-eyed homozygous females
- D. White-eyed homozygous females
Explanation: Red eye homozygous female is not possible because female will inherit one white eye allele from father. So option C is correct.
Correct answer: Red-eyed homozygous females- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: A son must have the genotype XY, with X being inherited from mother and Y from father. Option B correctly represents it.
Correct answer: Option B- A. X chromosomes relative to the number of autosomes
- B. Y chromosomes relative to the number of autosomes
- C. Autosomes relative to the number of XY chromosomes
- D. Y chromosomes relative to the number of X chromosomes.
Explanation: In Drosophila, sex determination is based on the ratio of X chromosomes to sets of autosomes (A), rather than the presence of a Y…
Correct answer: X chromosomes relative to the number of autosomes- A. He inherited the recessive allele from his mother
- B. He inherited the dominant allele from his father
- C. He can pass the disease to a son
- D. He can pass a dominant allele to a daughter
Explanation: This statement is correct. Since hemophilia is an X-linked recessive disorder, a male with hemophilia inherits the affected X chromosome…
Correct answer: He inherited the recessive allele from his mother- A. Beard growth
- B. Baldness
- C. Haemophilia
- D. Tfm
Explanation: Testicular feminization, also known as androgen insensitivity syndrome (AIS), is a genetic condition in which individuals with XY…
Correct answer: Tfm- A. Mother: Carrier, Father: Normal
- B. Mother: Colour blind, Father: Carrier
- C. Mother: Normal, Father: Carrier
- D. Mother: Normal, Father: Color blind
Explanation: Since color blindness is an X-linked recessive disease so if the the mother is color blind and the father is normal only then the son…
Correct answer: Mother: Normal, Father: Color blind- A. Y-linked recessive
- B. Sex influenced
- C. Sex limited
- D. Sex linked recessive
Explanation: Hemophilia is more common in males because the gene responsible for hemophilia is located on the X chromosome, making it a sex-linked…
Correct answer: Sex linked recessive- A. Saad, Ahmed, and Ali
- B. Ahmed, Ali, Alia, and Ayesha
- C. Saad and Sara
- D. Alia and Ayesha
- E. Ahmed and Ali
Explanation: Hemophilia is an X-linked recessive disorder, meaning that males (XY) need only one affected X chromosome to express the disorder, while…
Correct answer: Alia and Ayesha