Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
1. The genetic material in the vast majority of organisms is:
A. DNA
B. Protein
C. Carbohydrate
D. Lipid
Answer: A. DNA
Explanation: Experiments by Griffith, Avery-MacLeod-McCarty, and Hershey-Chase established DNA as the primary hereditary material in most organisms.
2. The Watson-Crick model describes the structure of DNA as a:
A. Double helix
B. Single stranded molecule
C. Triple helix
D. Circular protein
Answer: A. Double helix
Explanation: Watson and Crick proposed that DNA consists of two antiparallel strands coiled around each other to form a double helix.
3. In the DNA double helix, adenine specifically pairs with:
A. Thymine
B. Cytosine
C. Guanine
D. Uracil
Answer: A. Thymine
Explanation: Adenine forms two hydrogen bonds with thymine, one of the defining complementary base pairing rules of DNA.
4. The process by which a DNA molecule produces an identical copy of itself is called:
A. Replication
B. Transcription
C. Translation
D. Transformation
Answer: A. Replication
Explanation: DNA replication ensures that genetic information is accurately copied and passed on during cell division.
5. The enzyme mainly responsible for synthesizing RNA using a DNA template is:
A. RNA polymerase
B. DNA polymerase
C. DNA ligase
D. Helicase
Answer: A. RNA polymerase
Explanation: RNA polymerase catalyzes the transcription process, synthesizing an RNA strand complementary to the DNA template.
6. The central dogma of molecular biology describes the flow of genetic information as:
A. DNA → RNA → Protein
B. Protein → RNA → DNA
C. RNA → DNA → Protein
D. DNA → Protein → RNA
Answer: A. DNA → RNA → Protein
Explanation: The central dogma outlines the general direction of information flow within a cell, from DNA to RNA to functional protein.
7. A codon, the basic unit of the genetic code specifying one amino acid, consists of:
A. Three nucleotides
B. One nucleotide
C. Two nucleotides
D. Four nucleotides
Answer: A. Three nucleotides
Explanation: Each set of three consecutive nucleotides on mRNA (a codon) specifies a particular amino acid or a stop signal during translation.
8. The process by which the mRNA sequence is decoded to synthesize a polypeptide chain is called:
A. Translation
B. Transcription
C. Replication
D. Splicing
Answer: A. Translation
Explanation: Translation occurs at the ribosome, where the mRNA sequence is read in codons to assemble a corresponding chain of amino acids.
9. The type of RNA responsible for carrying specific amino acids to the ribosome during protein synthesis is:
A. tRNA
B. mRNA
C. rRNA
D. hnRNA
Answer: A. tRNA
Explanation: Transfer RNA (tRNA) molecules recognize specific codons on mRNA and deliver the corresponding amino acids to the growing polypeptide chain.
10. The lac operon in bacteria is a classic and well-studied example of:
A. Gene regulation in prokaryotes
B. Gene regulation occurring only in eukaryotes
C. A type of spontaneous mutation
D. The process of DNA replication
Answer: A. Gene regulation in prokaryotes
Explanation: The lac operon demonstrates how bacterial gene expression is switched on or off in response to the availability of lactose in the environment.
11. The Human Genome Project was primarily aimed at:
A. Sequencing and mapping all the genes present in human DNA
B. Cloning human beings
C. Treating genetic diseases directly
D. Identifying human blood groups only
Answer: A. Sequencing and mapping all the genes present in human DNA
Explanation: This international scientific effort successfully determined the complete sequence of nucleotide base pairs that make up human DNA.
12. DNA fingerprinting is a technique that relies mainly on analyzing:
A. Repetitive DNA sequences (VNTRs) that are unique to individuals
B. Overall protein sequences
C. The total chromosome number
D. An individual's blood type
Answer: A. Repetitive DNA sequences (VNTRs) that are unique to individuals
Explanation: Since the number of repeats in these variable regions differs greatly between individuals, they provide a unique genetic identifier.
