Question

Lungs are important organ for excretion of
A. Water
B. Urea
C. Oxygen
D. Carbon dioxide

Answer 1

Hint: During respiration, we breathe in oxygen and breathe out carbon dioxide. The inhaled oxygen goes to the lungs and the carbon dioxide that is produced in our body by cellular metabolism is carried by the blood to the lungs and we exhale it.

Complete Answer:
- In humans and many other animals the lungs are the main organs for the respiratory system, including a few fish and snails. Two lungs are found on either side of the heart in mammals and in most other vertebrates along the backbone. Their work in the respiratory system is to extract oxygen to the bloodstream from the atmosphere and release carbon dioxide in the air from the bloodstream.
- Respiration in various organisms is powered by various muscular systems. In humans, the diaphragm is the primary muscle of breathing. The lungs also provide airflow that facilitates vocal sounds and human speech. People have two lungs, one right lung, and the other left lung. They are found within the chest. The right lung is larger than the left lung.
- The lungs are the respiratory organ that helps to extract our body's carbon dioxide from the air we breathe. During food oxidation, carbon dioxide is produced. It's a waste product. It is carried out by blood in the lungs. It may also be called an excretory organ.

Thus, the correct answer is option D, i.e, Carbon dioxide.

Note: The lungs are a pair of air-filled spongy organs on both sides of the chest. The trachea carries inhaled air into the lungs through its branches, known as bronchi. The bronchial branches are then separated into smaller branches. The bronchioles finish in microscopic air sac clusters called alveoli. The oxygen from air is sucking up into the blood by the alveoli. Carbon dioxide, a metabolism waste, passes from the blood to the alveoli to be exhaled.