One of these gases is required for the germination of pea seeds

The correct answer is oxygen.

Seed germination is the process by which a dormant seed resumes metabolic activity and grows into a seedling. For a pea seed to germinate successfully, it requires specific environmental conditions: water, a suitable temperature, and oxygen.

During the early stages of germination, the seed absorbs water, which activates various enzymes. These enzymes break down stored food reserves (such as proteins and starches) within the cotyledons into simpler, usable forms like glucose. To convert these nutrients into usable energy (ATP) for growth and cell division, the seed must perform cellular respiration.

Aerobic cellular respiration is the metabolic process that requires oxygen to efficiently break down glucose, yielding energy, water, and carbon dioxide. Without oxygen, the germinating seed cannot generate sufficient energy to support the rapid growth of the embryo (the radicle and plumule), causing the germination process to halt. Therefore, oxygen is the gas essential for the germination of pea seeds.