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 813 of 993
- A. In combination with haemoglobin only
- B. Dissolved in blood plasma
- C. In the form of bicarbonate ions
- D. As carbaminohaemoglobin and as carbonic acid
Explanation: Most of the carbon dioxide in the blood is transported to the lungs as bicarbonate ions, formed when CO₂ reacts with water in red blood…
Correct answer: In the form of bicarbonate ions- A. Filtration
- B. pH adjustment
- C. Moistening
- D. Temperature adjustment
Explanation: The nasal cavity does not significantly change the pH of the air we breathe.
Correct answer: pH adjustment- A. Abdominal cavity
- B. Thoracic cavity
- C. Pelvic cavity
- D. Pleural cavity
Explanation: The cavity bounded by the ribs and diaphragm is called the thoracic cavity, or chest cavity.
Correct answer: Thoracic cavity- A. Indicted
- B. Battered
- C. Vindicated
- D. Destitute
Explanation: The best answer is C. "Vindicated" means "cleared of suspicion or doubt" and "authenticated" means "proved to be genuine." The rest of the…
Correct answer: Vindicated- A. and
- B. His
- C. lately
- D. I
Explanation: The error in the sentence is in option (D) "I." It should be corrected to "me" to maintain correct grammar and syntax.
Correct answer: I- A. Only conclusion I follows
- B. Only conclusion II follows
- C. Either I or II follows
- D. Neither I nor II follows
- E. Both I and II follow
Explanation: According to the statement, funding is necessary to improve quality and Pakistan is allocating funds to education.
Correct answer: Only conclusion I follows- A. 1
- B. 2
- C. 3
- D. 4
Explanation: Multiplying the digits of each number gives: 9×7×2=126; 9×3×8=216; 8×9×5=360; 8×6×3=144; 6×9×2=108; 5×3×6=90.
Correct answer: 4- A. Saeed
- B. Kashif
- C. C. Ghafoor
- D. D. Rizwan
Explanation: By combining the information, we can see that Ghafoor is listed as being good at cricket and volleyball, and also at football and…
Correct answer: C. Ghafoor- A. Statement I is the cause and statement II is its effect
- B. Statement II is the cause, and statement I is its effect
- C. Both the statements I and II are independent causes
- D. Both the statements I and II are effects of independent causes
Explanation: "Closing the schools for a week and the parents withdrawing their wards from the local schools are independent issues", which must have…
Correct answer: Both the statements I and II are effects of independent causes- A. A
- B. B
- C. C
- D. D
Explanation: Option A correctly identifies X as amino acid, Y as tRNA and Z as mRNA. X (Amino Acid): The building blocks of proteins.
Correct answer: A- A. mRNA from a DNA template
- B. A polypeptide from mRNA template
- C. mRNA from the molecules of tRNA
- D. A strand of DNA from mRNA template
Explanation: RNA polymerase does not synthesize DNA from an mRNA template; that process is called reverse transcription and is carried out by the…
Correct answer: mRNA from a DNA template- A. I only
- B. II only
- C. I and III
- D. II and III
Explanation: The correct answer is Option B: II only. RNA polymerase is an enzyme that is critical for the process of transcription, where RNA is…
Correct answer: II only- A. Amino acids → Proteins → DNA
- B. DNA → Carbohydrates → Proteins
- C. DNA → RNA → Proteins
- D. DNA → RNA → Carbohydrates
Explanation: This is the correct option. The central dogma of molecular genetics outlines the unidirectional flow of genetic information from DNA to…
Correct answer: DNA → RNA → Proteins- A. tRNA with anit-condon ACU
- B. tRNA with anit-condon AUG
- C. tRNA with anit-condon TGA
- D. tRNA with anit-condon TCU
Explanation: The codon is a sequence of three bases on mRNA that determines an amino acid.
Correct answer: tRNA with anit-condon AUG- A. tRNA
- B. cDNA
- C. rRNA
- D. mRNA
Explanation: The sequence of three nucleotides called an anticodon is part of a transfer RNA (tRNA) molecule.
Correct answer: tRNA- A. tRNA with anticodon ACU
- B. tRNA with anticodon ACT
- C. tRNA with anticodon TGA
- D. tRNA with anticodon TCU
Explanation: A sequence of three nucleotides on a tRNA molecule that bond to a complementary sequence on an mRNA molecule.
Correct answer: tRNA with anticodon ACU- A. Zero
- B. One
- C. Two
- D. Three
Explanation: To determine the number of alanine molecules present in the polypeptide, we need to count the number of occurrences of the mRNA codon…
Correct answer: Three- A. P site
- B. E site
- C. mRNA
- D. A site
Explanation: During translation, the aminoacyl-tRNA complex attaches to the small ribosomal subunit at the A site (Answer D) of the ribosome.
Correct answer: A site- A. UGA
- B. UAG
- C. UAA
- D. AUG
Explanation: AUG is not a stop codon; it is the start codon (specifically, the initiation codon) that signals the beginning of protein synthesis during…
Correct answer: AUG- A. mRNA
- B. tRNA
- C. rRNA
- D. sRNA
Explanation: Ribosomal RNA (rRNA) is the most abundant type of RNA in the cell. It is a component of the ribosome, which is the cellular machinery that…
Correct answer: rRNA