Read the scenario.

a graduate student is running a pcr reaction to study dna extracted from an egyptian mummy. the reaction does not seem to be working, so he checks his notes to see what he added to the reaction mix. he find the following list: mummy dna, dna polymerase, and dna nucleotides.

what is the error in the setup?

a. he forgot to add dna ligase.
b. he should have added dna ligase instead of dna polymerase.
c. he forgot to add primers.
d. he should have recognized that pcr cannot work on dna extracted from a mummy.

C. He forgot to add primers.

Explanation:

The major components of a PCR include:

The graduate student forgot to add primers which are essential as a starting point on which the synthesis of new DNA strand is based. DNA ligase is not needed for PCR, but during DNA replication.

The correct option is C.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.