Hello Janvi,

The Note of Metagenesis is given below-

1. Metagenesis is the occurrence, during life cycle of an organism, of two types of of individual, both diploid, both of which reproduce, one sexually and other asexually.

2. Metagenesis can also be defined as the reproduction in which there is alterations of an asexual with sexual generations.

3. Metagenesis is sometimes used as a synonym for alterations of generations.

4. For example, In hydrozoans like Obelia, the life cycle includes two clearly defined phases or forms, a fixed polypoid phase also called as hydroid colony and a pelagic medusoid form. Hydroid colonies produce no gonads and reproduce asexually through budding to give rise to medusa forms. On the other hand medusa reproduces only by sexual method and produces ova and sperms. These ova and sperm in turn give rise to new hydroid colonies.

The respiratory organs and their functions are given below:

1. In humans, the respiratory system is divided into two parts-

Upper Respiratory Tract and Lower respiratory tract.

The Upper respiratory tract consists of :

• Nose
• Nasal Cavity
• Sinuses
• pharynx
• some part of Larynx

The Lower Respiratory Tract consists of :

• lower part of Larynx
• Trachea
• Bronchi
• Bronchioles
• Lungs ( including Alveoli)

2. The air is inhaled through Nasal Cavities or mouth, which then travel from throat to Trachea, which is then divided into air passages called bronchiolis tubes.

3. As the bronchial tubes pass through your lungs, they divide into smaller air passages called bronchioles. The bronchioles end in tiny balloon-like air sacs called alveoli. Human body has about 600 million alveoli.

4. The alveoli are surrounded by a mesh of tiny blood vessels called capillaries. Here, oxygen from inhaled air passes into the blood.

5. After absorbing oxygen, blood goes to heart. The heart then pumps it through the body to the cells of  tissues and organs.

6. As the cells use the oxygen, they make carbon dioxide that goes into blood. The blood then carries the carbon dioxide back to the lungs, where it’s removed from the body when humans exhale.

The Functions of other organs involved in respiratory system are:

1. Sinuses- They are used to maintain the moisture inside the nose.

2. Larynx - It is useful for production of voice with the help of  air.

3. Pharynx - It allows the passage of air from nose and mouth to the Larynx.

Hope it helps. Best Wishes.