Answer:
Humans have greatly increased the level of in the atmosphere. O A. argon B. oxygen O . C. carbon dioxide O D. nitrogen
=carbon dioxides
Answer:
The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.
Explanation:
Air passes through is: Nostrils → nasal cavity →Pharynx → Larynx →Trachea → Bronchi (with cartilaginous rings) →Bronchioles (without rings) → Alveoli (air sacs). Alveoli are the seat of exchange of O2 / CO2 between lungs and blood.