#Question id: 40212
#Applied Microbiology
Read the following statements regarding the steps of a standard PCR cycle and choose the correct option.
Statement I: The denaturation step involves the breaking of phosphodiester bonds to separate the double-stranded DNA into single strands.
Statement II: The annealing temperature is usually set 3 -5 0 C lower than the melting temperature (Tm) of the primers to ensure specific binding.
#Question id: 40213
#Applied Microbiology
In the following question, a statement of Assertion (A) is followed by a statement of Reason (R).
Assertion (A): The annealing step must be performed at a significantly lower temperature than the denaturation step.
Reason (R): High temperatures destabilize hydrogen bonds, while lower temperatures favor the formation of hydrogen bonds required for primers to hybridize with the template.
#Question id: 40214
#Applied Microbiology
Which of the following represents the correct sequence of temperature changes during one single cycle of PCR amplification?
#Question id: 40215
#Environmental Science
Match the geological eons/events in List I with the biological milestones in List II.
| List I (Time Period/Event) | List II (Biological Milestone) |
| A. 4.0 - 3.8 Billion years ago | I. Appearance of first Eukaryotes |
| B. 3.5 Billion years ago | II. Oxygen Revolution (Great Oxidation Event) |
| C. 2.7 - 2.5 Billion years ago | III. Appearance of first cellular life (Prokaryotes) |
| D. 2.0 - 1.5 Billion years ago | IV. Formation of life precursors (RNA/Protocells) |
#Question id: 40216
#Environmental Science
#Question id: 40217
#Environmental Science
Consider the following statements about the Endosymbiotic Theory:
Statement I: It explains the origin of mitochondria and chloroplasts in eukaryotic cells.
Statement II: Mitochondria and chloroplasts have their own circular DNA, similar to bacteria.
Statement III: The theory proposes that these organelles originated as free-living prokaryotes that were engulfed by a host cell.