Use the Following to Answer Questions

question 64

Multiple Choice

Use the following to answer questions
A student carries out PCR using the following steps:
Step 1: 94°C for 1 minute
Step 2: 60°C for 30 seconds
Step 3: 72°C for 30 seconds
-After subjecting his PCR reaction to gel electrophoresis, the student sees no PCR product on the gel. What error(s) might he have made? (Select all that apply.)

• A) He carried out step 1 at too low a temperature.
• B) He carried out step 1 at too high a temperature.
• C) He carried out step 2 at too low a temperature.
• D) He carried out step 2 at too high a temperature.
• E) He carried out step 3 for too short a time.

---

Definitions:

Extinct

A status describing species that no longer exists anywhere on Earth.

Amphibians

Cold-blooded vertebrates that include frogs, toads, salamanders, and newts, known for their ability to live both in water and on land during different life stages.

Atmospheric CO₂

The concentration of carbon dioxide in Earth's atmosphere, a crucial factor influencing climate change and global temperatures through the greenhouse effect.

Keystone Species

A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.