1st Year Biology Chapter 13 Test13. Chromosome and DNA

Q1. Multiple choice questions (Attempt all · 10 × 1 = 10)

1. What is the basis for the difference in how leading & lagging strands of DNA molecules are synthesized?
   1. The origins of replication occur only at 5'end.
   2. DNA ligase works only in the 3'----5' direction
   3. Polymerase can only work on one strand at a time
   4. DNA polymerase can join new nucleotides only to the 3' end of a growing strand.
2. The enzyme that catalyzes amino acid activation is
   1. Gyrase
   2. Peptidyl transferase
   3. RNA ligase
   4. Aminoacyl-tRNA synthetase
3. The genetic cause of Down syndrome is
   1. Trisomy 21
   2. Trisomy 18
   3. Monosomy X
   4. XXY condition
4. In eukaryotic cells, transcription cannot begin until:
   1. The two DNA strands have completely separated and exposed the promater.
   2. Several transcription factors have bound to the promoter
   3. The DNA introns are removed from the template
   4. DNA nucleases have isolated the transcription unit
5. Mustard gas and nitrous gas are examples of
   1. Chemical mutagens
   2. Physical mutagens
   3. Biological mutagens
   4. Natural mutagens
6. The substitution of one base by another is known as
   1. Insertion
   2. Deletion
   3. Base substitution
   4. Duplication
7. Errors during meiosis or DNA replication cause
   1. Induced mutations
   2. Frame mutations
   3. Beneficial mutations
   4. Natural mutations
8. The enzyme used for RNA splicing is
   1. RNA ligase
   2. RNA polymerase
   3. DNA ligase
   4. Helicase
9. The strand synthesized discontinuously away from the replication fork is called
   1. Template strand
   2. Daughter strand
   3. Lagging strand
   4. Leading strand
10. The idea that DNA makes protein through RNA is called
    1. Central dogma
    2. Genetic theory
    3. Protein hypothesis
    4. Transcription rule