A new copy of DNA is built from individual genes . The enzyme unwinds the DNA molecule, allowing replication to begin.

This question is incomplete, the question is asking which enzyme unwinds the DNA molecule during DNA replication.

The answer is DNA HELICASE

Explanation:

DNA replication is the process whereby DNA molecule (genetic material) is duplicated in the genome i.e. DNA makes an identical copy of itself. The process of DNA replication is carried out in a step by step manner with various enzymes functioning specifically throughout the process.

The first step is to unwind the double-stranded DNA molecule into two single strands. The two single strands serves a templates to synthesize another pairing strand to make two DNA molecules in total. The unwinding of the DNA strands is carried out by an enzyme called DNA helicase.

A new copy of DNA is built from individual  

✔ nucleotides

.

The enzyme  

✔ helicase

unwinds the DNA molecule, allowing replication to begin.

Explanation:

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.