PEARSON EDEXCEL BIOLOGY Unit 4 - 6 PRACTICE EXAM Q & A 2026 (Complete And Verified Study material) (16pages) LEARNEXAMS

Unit 4:

1. Energy: Describe the process of cellular respiration and

its role in energy production. Include the specific

molecules involved and where each step occurs within the

cell. (Answer: Cellular respiration is the process through

which cells convert glucose and oxygen into carbon

dioxide, water, and ATP. The process occurs in three main

stages: glycolysis, the Krebs cycle, and oxidative

phosphorylation. Glycolysis takes place in the cytoplasm

and breaks down glucose into two molecules of pyruvate.

The Krebs cycle occurs in the mitochondria and further

breaks down pyruvate into carbon dioxide, while

generating ATP, NADH, and FADH2. Oxidative

phosphorylation takes place in the inner mitochondrial

membrane and uses the high-energy electrons from NADH

and FADH2 to generate ATP.)

2. Environment: Explain the greenhouse effect and its

impact on global warming. Include the role of greenhouse

gases and their contributions to the Earth's temperature

regulation. (Answer: The greenhouse effect is a natural

process where certain gases in the atmosphere trap heat

from the sun, preventing it from escaping into space. This

helps to regulate the Earth's temperature and keep it warm

enough to support life. However, human activities have

increased the concentration of greenhouse gases, such as

carbon dioxide and methane, in the atmosphere. This

enhanced greenhouse effect leads to global warming, as the

additional gases trap more heat, causing an increase in