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 22 of 32
- A. First member of a codon
- B. Second member of codon
- C. Entire codon
- D. Third member of a codon
Explanation: Degeneration of a genetic code is attributed to the third codon member.
Correct answer: Third member of a codon- A. 20%
- B. 40%
- C. 30%
- D. 60%
Explanation: In a DNA, the percentage of guanine is equal to the percentage of cytosine, and the percentage of adenine is equal to the percentage of…
Correct answer: 30%- A. E.coli
- B. Diplococcus pneumoniae
- C. Salmonella
- D. Pasteurella pestis
Explanation: The transformation experiment was first conducted by Frederick Griffith in 1928 using the bacterium Streptococcus pneumoniae, also known…
Correct answer: Diplococcus pneumoniae- A. All prokaryotes
- B. All prokaryotes and some eukaryotes
- C. All prokaryotes and all eukaryotes
- D. All prokaryotes and some protozoans
Explanation: The operon model was given by Jacob and Monod (1961) for the regulation of protein synthesis in prokaryotes only.
Correct answer: All prokaryotes- A. Proteins
- B. Lipid
- C. Carbohydrates
- D. Phospholipids
Explanation: DNA transcribes to form mRNA. Its function is to carry coded information from DNA for the synthesis of proteins.
Correct answer: Proteins426. In negative operon,
- A. Co-repressor binds with repressor
- B. Co-repressor does not bind with repressor
- C. Co-repressor binds with inducer
- D. cAMP have negative effect on lac operon
Explanation: The tryptophan operon (trp operon) in bacteria is repressible. Here, the repressor is inactive, and it becomes active as DNA DNA-binding…
Correct answer: Co-repressor binds with repressor- A. One cistron contains many genes
- B. One gene contains many cistrons
- C. One gene contains one cistron
- D. One gene contains no cistron
Explanation: A gene is a hereditary unit consisting of a sequence of DNA and occupying a specific position or locus within the genome.
Correct answer: One gene contains one cistron- A. 3.4 nm
- B. 0.34 nm
- C. 20 nm
- D. 10 nm
Explanation: B-DNA is an antiparallel double helix. The double-strand or duplex is coiled plectonemically in a right-handed fashion around a common…
Correct answer: 3.4 nm- A. Both are polymer of nucleotides
- B. Both have similar pyrimidine
- C. Both have similar sugar
- D. Both are genetic material
Explanation: Deoxyribonucleic acid and ribonucleic acid are made up of several nucleotide monomers.
Correct answer: Both are polymer of nucleotides- A. Bacteria do not reproduce sexually
- B. RNA sometime controls the production of DNA and proteins
- C. DNA is the genetic material
- D. Bacteria undergo binary fission
Explanation: Transformation was first discovered by Griffith (1928) in Pneumococcus (Streptococcus pneumoniae), which causes pneumonia.
Correct answer: DNA is the genetic material- A. Nucleolus
- B. Nucleus only
- C. Cytoplasm only
- D. None of these
Explanation: DNA is mainly found in the nucleus. It is associated with RNA and proteins to form compact chromosomes.
Correct answer: Nucleus only- A. Linear DNA without histones
- B. Circular DNA without histones
- C. Linear DNA with histones
- D. Circular DNA with histones
Explanation: The genetic material of prokaryotes is circular and single-stranded DNA. It has no association with histones.
Correct answer: Circular DNA without histones- A. Redundant genes
- B. Regulatory genes
- C. Polymorphic genes
- D. Operator genes
Explanation: Operator genes are a region of DNA sequence capable of interacting with a specific repressor molecule, and in doing so, they affect the…
Correct answer: Operator genes- A. Cistron
- B. Transposons
- C. Exons
- D. Introns
Explanation: DNA elements that can switch their position are called transposons. Transposons are mobile DNA sequences that can move from one location…
Correct answer: Transposons- A. rRNA
- B. RNA
- C. mRNA
- D. tRNA
Explanation: Transfer RNA or tRNA helps in the transfer of amino acids to the ribosomes, mRNA complex to form the polypeptide chain.
Correct answer: tRNA- A. The lac operon is induce
- B. E.coli cells stop dividing
- C. The lac operon is repressed
- D. All operons are induced
Explanation: When E.coli bacteria are transferred to a medium containing lactose, the lac operon is induced.
Correct answer: The lac operon is induce- A. Depressor
- B. Controlling element
- C. Regulator
- D. Inducer
Explanation: An environmental agent that triggers transcription from an operon is an inducer.
Correct answer: Inducer- A. CAT GAT GATG
- B. A nonsense mutation
- C. ATG ATG ATG
- D. CA TGA TGA TG
Explanation: A nonsense mutation is a mutation which interconverts a nonsense codon to or from a sense-coding triplet, resulting in an abnormally…
Correct answer: CAT GAT GATG- A. Exons
- B. Cistrons
- C. Introns
- D. Operons
Explanation: Split genes are those genes that consist of a continuous sequence of nucleotides (coding sequences) interrupted by intervening sequences.
Correct answer: Exons- A. 'I' gene
- B. Promoter gene
- C. β-galactosidase
- D. Lactose
Explanation: The lac operon in E. coli is induced by β-galactosidase, an enzyme meant for the hydrolysis of lactose in glucose and galactose.
Correct answer: β-galactosidase