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 98 of 124
- A. Histidine
- B. Uracil
- C. Cytosine
- D. Thymine
Explanation: According to Chargaff's base pairing rule:Adenine (A) always pairs with Thymine (T) → by two hydrogen bondsCytosine (C) always pairs with…
Correct answer: Thymine- A. T. H Morgan
- B. Griffith
- C. Walther
- D. Mendel
Explanation: Walther Flemming first observed chromosomes in 1879 during his studies on cell division (mitosis) using a light microscope.
Correct answer: Walther- A. DNA and protein
- B. DNA and RNA
- C. RNA and lipids
- D. RNA and proteins
Explanation: A chromosome is composed primarily of DNA, proteins, and a small amount of RNA.
Correct answer: DNA and protein- A. Reduction in oxygen-carrying capacity of haemoglobin
- B. Linkage between the polypeptide chains in the haemoglobin molecule
- C. Single amino acid substitution in the haemoglobin molecule
- D. Viral infections of RNA viruses
Explanation: Sickle cell anemia is caused by a genetic mutation in the HBB gene, which provides instructions for making hemoglobin, the protein in red…
Correct answer: Single amino acid substitution in the haemoglobin molecule- A. DNA to Protein
- B. DNA to mRNA
- C. RNA to Protein
- D. DNA to tRNA
Explanation: Transcription is the first step, where DNA is used to synthesize messenger RNA (mRNA).
Correct answer: DNA to mRNA- A. Homochromatin
- B. Heterochromatin
- C. Semi-heterochromatin
- D. Semi-homochromatin
Explanation: Heterochromatin is the tightly packed form of DNA, making it less transcriptionally active.
Correct answer: Heterochromatin- A. DNA
- B. Protein
- C. Both DNA and Protein
- D. Neither DNA nor Protein
Explanation: DNA carries genetic information and is responsible for inheritance.
Correct answer: DNA- A. Osmotic pressure
- B. Hydrolic pressure
- C. Air pressure
- D. Mutation pressure.
Explanation: Mutation pressure refers to changes in the genetic code due to base substitutions, influencing evolution.
Correct answer: Mutation pressure.- A. 11
- B. 33
- C. 333
- D. 1
Explanation: In RNA, each codon is made up of three nucleotide bases, and each codon codes for a specific amino acid.
Correct answer: 33- 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 fibre1953. 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 synthesis1957. 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