Free Chromosomes MCQs with Answers
633 Chromosomes MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Chromosomes are DNA-protein structures that carry genes and become visible during cell division. Coverage includes chromatin, centromeres, sister chromatids, homologous chromosomes, chromosome number, and the distinction between diploid and haploid cells, with links to DNA replication, mitosis and meiosis.
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633 questions · page 26 of 32
501. Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a "triplet"?
- A. Hershey and Chase
- B. Morgan and Sturtevant
- C. Beadle and Tatum
- D. Nirenberg and Mathaei
Explanation: The genetic code was discovered in the 1960s by Crick, Ochoa, Nirenberg, Matthaei and Khorana.
Correct answer: Nirenberg and Mathaei- A. Beadle and Tatum
- B. R. Franklin
- C. Hershey and Chase
- D. A. Garrod
Explanation: In 1948, Beadle and Tatum proposed the one gene oneenzyme hypothesis which states that a gene controls the metabolic machinery of the…
Correct answer: Beadle and Tatum503. Which antibiotic inhibits the interaction between tRNA and mRNA during bacterial protein synthesis?
- A. Tetracycline
- B. Erythromycin
- C. Neomycin
- D. Streptomycin
Explanation: Neomycin is a broad spectrum antibiotic which was first isolated from a strain of Streptomyces feadiae.
Correct answer: Neomycin- A. Simple protein
- B. RNA
- C. Ribonucleoprotein
- D. Repetitive DNA
Explanation: Telomerase is a ribonucleoprotein molecule that is enzymatic in nature.
Correct answer: Ribonucleoprotein- A. On plates with and without streptomycin
- B. On plates with minimal medium
- C. Only on plates with streptomycin
- D. Only on plates without streptomycin
Explanation: Streptomycin is a broad-spectrum antibiotic (active against both Grampositive and Gramnegative bacteria) and was the first effective…
Correct answer: Only on plates with streptomycin- A. DNA polymerase
- B. RNA polymerase
- C. Reverse transcriptase
- D. DNA dependant RNA polymerase
Explanation: The answer to this question is reverse transcriptase.Reverse transcriptase is an enzyme that uses an RNA template to synthesize DNA.
Correct answer: Reverse transcriptase- A. Regulator gene
- B. Operator gene
- C. Structural gene
- D. Promoter gene
Explanation: In the lac operon of E.coli, due to the activity of the regulator gene, the synthesis of repressor molecules occurs.These repressor…
Correct answer: Operator gene- A. The DNA is complexed with histone in prokaryotes
- B. The DNA is circular and single stranded in prokaryotes
- C. Repetitive sequences are present in eukaryotes
- D. Genes in the former case are organized into operons.
Explanation: (b) : Genome refers to the total sets of chromosomes carried by each cell of the organism.
Correct answer: The DNA is circular and single stranded in prokaryotes- A. Thymidine
- B. Deoxyribose sugar
- C. Uracil
- D. Adenine
Explanation: DNA synthesis can be specifically measured by estimating the incorporation of radio-labeled thymidine.Thymidine is one of the four…
Correct answer: Thymidine- A. DNA ligase
- B. DNA topoisomerase I
- C. DNA gyrase
- D. DNA polymerase I
Explanation: DNA is a double helical molecule and it opens to form a replication fork or its replication.
Correct answer: DNA topoisomerase I- A. Termination
- B. Initiation
- C. Elongation
- D. Transcription
Explanation: Transcription is the mechanism of copying the message of DNA on RNA with the help of the enzyme RNA polymerase.
Correct answer: Transcription- A. Griffith
- B. Watson
- C. Boveri and Sutton
- D. Hershey and Chase
Explanation: Hershey and Chase proved that DNA is a basic genetic material. In 1952, Alfred Hershey and Martha Chase conducted an experiment on…
Correct answer: Hershey and Chase- A. DNA proof-reading
- B. DNA repair
- C. Unwinding
- D. Annealing
Explanation: DNA polymerase enzyme has three types: DNA polymerase-I is involved in proof-reading activities.
Correct answer: DNA proof-reading- A. Attachment of primer
- B. Opening of double helix
- C. Binding of RNA polymerase
- D. Formation of GC hair pin
Explanation: The first step of transcription is the binding of RNA polymerase by using its sigma factor with the promoter region.
Correct answer: Binding of RNA polymerase- A. 4
- B. 16
- C. 8
- D. 64
Explanation: We know that In the genetic code, each codon is made up of three nucleotides.
Correct answer: 8- A. From the 5' toward the 3' end of the new strand being assembled
- B. From the replication centers in two directions called replication forks
- C. From the 3' to the 5' end of the strand being assembled
- D. In both directions if DNA ligase is present
Explanation: DNA polymerase can only add new nucleotides at the 3' end. The process of replication is 5' to 3' at the end of the growing strand.
Correct answer: From the 5' toward the 3' end of the new strand being assembled- A. Small ribosomal subunit
- B. Initiation factor
- C. Elongation factor
- D. Large ribosomal subunit
Explanation: The two amino acids which lie adjacent to each other undergo a chemical reaction, catalyzed by the large ribosomal subunit, which releases…
Correct answer: Large ribosomal subunit- A. DNA and histone protein.
- B. RNA and histone protein.
- C. nitrogenous base and sugar.
- D. nitrogenous base, sugar and phosphate.
Explanation: A nucleosome is the fundamental unit of DNA packaging in eukaryotic cells, consisting of a segment of DNA wound around a core of histone…
Correct answer: DNA and histone protein.- A. Stained darker
- B. Not able to transcribe
- C. Generally not very active
- D. Condensed only during cell division
Explanation: Euchromatin is less condensed compared to heterochromatin and is actively involved in transcription.
Correct answer: Condensed only during cell division- A. I only
- B. III only
- C. I and II
- D. II and III
Explanation: Reduction division, or meiosis, occurs in sexually reproducing organisms to produce gametes with half the chromosome number.
Correct answer: III only