Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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- A. TAC
- B. ATC
- C. UAC
- D. UTC
Explanation: AUG is the start codon that signals ribosomes to place in the amino acid methionine because the tRNA that has methionine attached to it…
Correct answer: UAC- A. Transcription
- B. Replication
- C. Polymerization
- D. PCR
Explanation: The process by which DNA is copied to RNA is called transcription.
Correct answer: Transcription- A. AAUOCGT
- B. UUAACGA
- C. TTAACGA
- D. UUTTCGT
Explanation: RNA polymerase uses one of the DNA strands (the template strand) as a template to make a new, complementary RNA molecule.
Correct answer: UUAACGA- A. Poly genes
- B. Genome
- C. Promoter
- D. Pleiotropy
Explanation: The first step in transcription is initiation, when the RNA pol binds to the DNA upstream (5′) of the gene at a specialized sequence…
Correct answer: Promoter- A. 30S and 40S
- B. 70S and 10S
- C. 50S and 30S
- D. 60S and 40S
Explanation: Ribosomes are non-membrane-bounded organelles that are present in large numbers in all living cells and serve as the site of protein…
Correct answer: 60S and 40S- A. Arginine
- B. Glutamine
- C. Tryptophan
- D. Valine
Explanation: A codon is a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis.
Correct answer: Tryptophan1767. Stop codons are:
- A. UAA,UAG,UGA
- B. UGC,UCG,AAA
- C. UUG,UCG,UCA
- D. UAA,UGC,UCA
Explanation: Stop codons are codons (triplets of nucleotides) in messenger RNA (mRNA) that signal the termination of protein synthesis.
Correct answer: UAA,UAG,UGA- A. Phagosome
- B. Perosome
- C. Polysome
- D. Punosome
Explanation: When multiple ribosomes are attached to a single mRNA molecule, it forms a structure called a polysome.
Correct answer: Polysome- A. Arginine
- B. Tryptophan
- C. Methionine Stop Codon
- D. 1-butene.
Explanation: In mitochondrial DNA, the codon AGG indeed codes for the amino acid arginine.
Correct answer: Arginine- A. 4
- B. 8
- C. 16
- D. 20
Explanation: If a codon consisted of only two nucleotides, there would be 4 possible combinations for each position (since there are 4 different…
Correct answer: 16- A. Nuclear envelope
- B. Chromosome
- C. rRNA
- D. Cytoplasm
Explanation: The nucleolus is a region within the nucleus of eukaryotic cells where ribosome synthesis occurs.
Correct answer: rRNA- A. rRNA
- B. mRNA
- C. DNA
- D. Nucleotides
Explanation: A DNA molecule is a double helix carrying the genetic information of an organism.
Correct answer: DNA- A. CACGTC
- B. TAGCATG
- C. TACGAG
- D. GACGTG
Explanation: In DNA, the base pairs are complementary to each other. Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with…
Correct answer: TACGAG- A. Parallel
- B. Antiparallel
- C. ......
- D. None
Explanation: Each strand has a backbone made up of alternating sugars and phosphate groups.
Correct answer: Antiparallel- A. Cytosine
- B. Adenine
- C. Uracil
- D. Thymine
Explanation: Purines, such as adenine and guanine, have a double-ringed structure - one hexagonal pyrimidine ring and an imidazole ring.
Correct answer: Adenine- A. AUAGA
- B. ATACA
- C. UAUGU
- D. ATACT
Explanation: Nucleotides are the building blocks of nucleic acids, i.e., DNA and RNA.
Correct answer: ATACT- A. One
- B. Two
- C. Three
- D. Four
Explanation: RNA (Ribonucleic Acid) and DNA (Deoxyribonucleic Acid) differ in their sugar components.
Correct answer: One- A. Interphase
- B. Prophase
- C. Metaphase
- D. Anaphase
Explanation: The correct answer is Interphase. During interphase, the cell prepares for division, and the DNA in the nucleus replicates.
Correct answer: Interphase- A. Bacteria
- B. Virus
- C. Eukaryote
- D. All of the above
Explanation: In eukaryotes, such as humans, DNA replication occurs at approximately 50 base pairs per second.
Correct answer: Eukaryote- A. Straight direction
- B. Parallel but straight
- C. Antiparallel and straight
- D. Antiparallel and spirally twisted
Explanation: DNA is a double helix formed by two strands of nucleotides. These strands run in opposite directions (antiparallel) and are twisted around…
Correct answer: Antiparallel and spirally twisted