The respiratory system, functionally, can be separated in two zones namely the conducting zone (nose to bronchioles) form a path for conduction of the inhaled gases and respiratory zone (alveolar duct to alveoli) where the gas exchange takes place. Anatomically, respiratory tract is divided into upper (organ outside thorax-nose,pharynx and larynx) and lower respiratory tract (organ within thorax-trachea, bronchi, bronchioles, alveolar duct and alveoli). Airway closure is a normal phenomenon in the body, with reopening of airways during the succeeding inspiration.
The appropriate choice would be the supraglottic portion of the laryngeal vestibule. It is the portion of the cavity of the larynx above the vocal cords. It is wide and triangular in shape, it is inlet to another cavity in the lateral wall of larynx, the laryngeal ventricle.
Answer:
lichens and bacteria also fungi are all example of pioneer species
Explanation: they are because of where they live how they grow and why they do what they do to help the environment.
Answer:
The atmospheric oxygen initially came from the water molecule
Explanation:
Condition on the primitive Earth , about 4 billion year ago were such which favored chemical evolution. . When the temperature of the Earth was less than 100 degree Celsius. Its atmosphere had nitrogen in the form of ammonia, carbon in the form of carbon dioxide and oxygen in the form of water vapour. There was no free oxygen available and so the atmosphere was reducing.
Then spontaneously biomolecules originated which further gave rise to protobionts. These protobionts evolved into several unicellular organisms among which one was cyanobacteria.
Cyanobacteria are considered as the organisms which added the first molecule of free atmospheric oxygen into the atmosphere. They carried out photosynthesis and split the water molecules to release oxygen as the bye product of the process.
Proteins are made up of one or more polypeptide molecules. The amino acids are linked covalently by peptide bonds. The graphic on the right shows how three amino acids are linked by peptide bonds into a tripeptide. One end of every polypeptide, called the amino terminal or N-terminal, has a free amino group