D
This is because of greenhouse gases and polution.
Answer:
The most important are the lungs, more precisely the alveoli.
Explanation:
Alveoli are structures of the lungs where gas exchange occurs. They allow oxygen from the air to pass into blood. Oxygen diffuses through the walls of alveoli into the capillaries that surround it. Oxygen is then bonded with the iron in red blood cells and travels to the heart. The heart then sends the oxygenated blood out to all the cells in the body.
Females have two copies of the X chromosome, while males have one X and one Y chromosome. The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype.
Of the 23 pairs of chromosomes, the first 22 pairs are called "autosomes." The final pair is called the "sex chromosomes." Sex chromosomes determine an individual's sex: females have two X chromosomes (XX), and males have an X and a Y chromosome (XY).
The human heart has only 4 chambers. Left and right atria and left and right ventricles.
A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
