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 20 of 32
- A. tRNA
- B. mRNA
- C. rRNA
- D. All are present in same proportion.
Explanation: The most abundant RNA molecule in a cell is typically ribosomal RNA (rRNA).
Correct answer: rRNA- A. Fungi
- B. Animals
- C. Bacteria
- D. Plants
Explanation: Spliceosomes help in the removal of introns. They will not occur in prokaryotes because prokaryotes do not have introns and thus…
Correct answer: Bacteria- A. DNA replication is occurring
- B. The DNA is condensed into a chromatin fibre
- C. The DNA double helix is exposed
- D. Transcription is occurring
Explanation: Histones help in the packaging of DNA. In eukaryotes, DNA packaging is carried out with the help of positively charged basic proteins…
Correct answer: The DNA is condensed into a chromatin fibre384. DNA dependent RNA polymerase catalyzes transcription on one strand of the DNA, which is called:
- A. Template strand
- B. Coding strand
- C. Alpha strand
- D. Anti-strand
Explanation: The template strand serves as the template for RNA synthesis (transcription). It is also known as the antisense strand.
Correct answer: Template strand- A. UAA
- B. UAG
- C. AUG
- D. UGA
Explanation: Polypeptide synthesis is signaled by two initiator codons or start codons, i.e., AUG (methionine codon) and rarely by GUG (valine codon).
Correct answer: AUG- A. Heterocyclic nitrogenous bases
- B. Chargaff's rule
- C. Complementary base pairing
- D. 5' phosphoryl and 3' hydroxyl ends
Explanation: Chargaff's rules apply only to double-stranded DNA molecules. These do not apply to single-stranded DNA or RNA molecules.
Correct answer: Chargaff's rule- A. Polysaccharide synthesis
- B. RNA and protein synthesis
- C. Lipid synthesis
- D. Nucleotide synthesis
Explanation: In certain development stages, the polytene chromosomes bear conspicuous swellings called chromosome puffs.
Correct answer: RNA and protein synthesis388. Gene regulation governing the lactose operon of E.coli that involves the lac I gene product is:
- A. Negative and repressible because the repressor protein prevents transcription
- B. Feedback inhibition occurs because an excess of β-galactosidase can switch off transcription
- C. Positive and inducible because it can be induced by lactose
- D. Negative and inducible because the repressor protein prevents transcription
Explanation: The control of expression of the lac operon is negative (as it is turned off normally) and inducible.
Correct answer: Negative and inducible because the repressor protein prevents transcription- A. A-Transcription, B-Translation, C-Francis Crick
- B. A-Translation, B-Extension, C -Rosalind Franklin
- C. A-Transcription, B-Replication, C-James Watson
- D. A-Translation, B-Transcription, C-Ervin Chargaff
Explanation: The expression of the genetic material occurs normally through the production of proteins. This involves two consecutive steps.
Correct answer: A-Transcription, B-Translation, C-Francis Crick- A. Transacetylase
- B. Lactose permease and transacetylase
- C. β-galactosidase
- D. Lactose permease
Explanation: A nonsense mutation stops polypeptide synthesis due to the formation of a termination or nonsense codon.
Correct answer: β-galactosidase- A. Non-overlapping
- B. Ambiguous
- C. Degeneracy
- D. Universal
Explanation: The genetic code is non-ambiguous. A non ambiguous code means that there is no ambiguity about a particular code.
Correct answer: Ambiguous- A. Looping
- B. Inducing
- C. Slicing
- D. Splicing
Explanation: Introns, which mainly occur in eukaryotes, are transcribed into messenger RNA (mRNA) but are then removed from the transcript before…
Correct answer: Splicing- A. TTAGU
- B. UAGAC
- C. AACTG
- D. ATCGU
Explanation: In RNA, thymine is substituted with uracil; thus, the RNA strand complementary to the DNA strand ATCTG will be UAGAC.
Correct answer: UAGAC- A. Lysosomes
- B. Nucleolus
- C. Nucleoplasm
- D. Ribosomes
Explanation: The nucleolus is the centre for the synthesis of ribosomal RNA (rRNA) that forms ribosomal subunits.
Correct answer: Nucleolus- A. tRNA
- B. hnRNA
- C. mRNA
- D. rRNA
Explanation: In eukaryotes, RNA polymerase enzymes (Type I, II, III) catalyse the synthesis of RNA using as a template either an existing DNA strand or…
Correct answer: tRNA- A. Bacterium
- B. Fungus
- C. Viroid
- D. Bacterial virus
Explanation: Avery, MacLeod, and McCarty first established that DNA was the genetic material by working on the same bacteria as Griffith.
Correct answer: Bacterial virus- A. Pea
- B. Mucor
- C. Chlamydomonas
- D. HIV
Explanation: The oneway flow of information from DNA to mRNA and then to protein is known as the central dogma of molecular biology by F.H.C.
Correct answer: HIV- A. (ii) and (iii)
- B. (i) and (iii)
- C. (ii) and (iv)
- D. (i) and (ii)
Explanation: The two French scientists, Jacob and Monod, proposed the lac operon of E.coli.
Correct answer: (ii) and (iv)- A. Ribosomes
- B. Nucleus
- C. Dictyosomes
- D. Endoplasmic Reticulum
Explanation: Unlike in prokaryotes, where transcription and translation take place in the same compartment, in eukaryotes, the primary transcript is…
Correct answer: Nucleus400. Whose experiments cracked the DNA and discovered unequivocally that the genetic code is a "triplet"?
- A. Hershey and Chase
- B. Morgan and Sturtevant
- C. Beadle and Tatum
- D. Nirenberg and Mathaei
Explanation: Marshall Nirenberg and J. Heinrich Matthaei were pioneering scientists who, in 1961, performed a landmark experiment that cracked the…
Correct answer: Nirenberg and Mathaei