Free Cell Structure and Function MCQs with Answers
2,478 Cell Structure and Function MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Animal, plant, prokaryotic and eukaryotic cells are compared through their membranes, cell walls, nuclei and cytoplasmic organelles. The work includes the structures and functions of mitochondria, chloroplasts, ribosomes, endoplasmic reticulum, Golgi apparatus and lysosomes, as well as chromosome organization and the distinction between chromatin and chromosomes.
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Read the Cell Structure and Function notesFree MDCAT chapter notes with key terms2,478 questions · page 104 of 124
- A. Negative and repressible because repressor protein prevents transcription
- B. Feedback inhibition because excess of b-galactosidase can switch off transcription
- C. Positive and inducible because it can be induced by lactose
- D. Negative and inducible because 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 repressor protein prevents transcription2062. The diagram shows an important concept in the genetic implication of DNA. Fill in the blanks A to C:
- 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 is the one that stops polypeptide synthesis due to the formation of a termination or nonsense codon.
Correct answer: β-galactosidase- A. A-Maurice Wilkins, B-Transcription, C-Translation
- B. A-James Watson, B-Replication, C-Extension
- C. A-Erwin Chargaff, B-Translation, C-Replication
- D. A-Francis Crick, B-Translation, C-Transcription
Explanation: The expression of the genetic material occurs normally through the production of proteins. This involves two consecutive steps.
Correct answer: A-Francis Crick, B-Translation, C-Transcription- A. Viroids
- B. Prions
- C. Bacteriophages
- D. Plant viruses
Explanation: Plant viruses often contain parasites of their own, referred to as satellites.
Correct answer: Plant viruses- A. tRNA
- B. hnRNA
- C. mRNA
- D. rRNA
Explanation: In eukaryotes, RNA polymerase enzymes (Type I, II, III) catalyze the synthesis of RNA using as a template either an existing DNA strand or…
Correct answer: tRNA- 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. One DNA strand with the other DNA strand
- B. One nucleoside with another nucleoside
- C. One nucleotide with another nucleotide
- D. One nitrogenous base with a pentose sugar
Explanation: The phosphodiester bonds are formed between the phosphate group, which is connected to carbon 5' of the sugar residue of one nucleotide…
Correct answer: One nucleotide with another nucleotide- A. The centromere is found in animal cells, which produces an aster during cell division
- B. The gene for producing insulin is present in every body cell
- C. The nucleosome is formed from nucleotides
- D. DNA consists of a core of eight histones
Explanation: The Insulin gene is found in every body cell but is not expressed in all cells. A nucleosome consists of a core of eight histones.
Correct answer: The gene for producing insulin is present in every body cell2070. 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 Tatum2072. 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 prokaryotes2078. DNA synthesis can be specifically measured by estimating the incorporation of radio-labelled:
- 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