Identify the route of oxygen transport in the body from earlier to later:

Question

Accepted Answer

The correct option is (4):
This sequence accurately maps the journey of an oxygen molecule as it is transported from the atmosphere to the systemic tissues of the body. First, inhaled air travels down the windpipe, or **Trachea**. Next, the air reaches the air sacs of the lungs, the **Alveole**, where gas exchange takes place. Oxygen then diffuses from the alveoli into the **Blood** (specifically the pulmonary capillaries), where it binds to hemoglobin. This oxygenated blood travels to the left side of the **Heart**. Finally, the heart's powerful contractions pump this oxygenated blood out through the **Artery** (the aorta and subsequently smaller systemic arteries) to deliver it to the rest of the body's cells.

The incorrect option is (1):
The sequence begins incorrectly with **Alveole** followed by **Trachea**. Physiologically, the air must travel down the respiratory passages, starting with the trachea, to reach the deep lung structures, including the alveoli. The order of these first two steps is fundamentally reversed, making the entire transport route incorrect from the initial respiratory phase.

The incorrect option is (2):
This option incorrectly starts with **Blood**. Oxygen is picked up by the blood *after* it has travelled through the air passages (**Trachea** and **Alveole**) and diffused across the respiratory membrane. Placing "Blood" as the initial step in the transport process ignores the entire, necessary phase of ventilation and gas exchange that must occur in the lungs first. Furthermore, the rest of the sequence mixes the circulatory and respiratory structures incorrectly.

The incorrect option is (3):
This sequence correctly begins with the respiratory pathway, **Trachea** followed by **Alveole**. However, the sequence for the circulatory system, which immediately follows, is flawed. After gas exchange in the alveoli, oxygen enters the **Blood** and travels to the **Heart**. The sequence then places **Artery** before **Heart** and ends with **Blood**, which is anatomically wrong. Oxygenated blood must enter the heart from the lungs before the heart pumps it into the arteries for systemic distribution.