Approximately one billion oxygen molecules. that is because there are about 250 million molecules of haemoglobin in each cell, and each haemoglobin molecule binds to 4 oxygen molecules
The answer is Permian-Triassic extinction.
The Permian-Triassic extinction was 252 million years ago. It is known as The Great Dying because about 95% of all species died out due to environmental changes (volcanic eruptions, dry climate, melting of ice sheets, etc). This is also the only event in which many insect species wiped out.
Answer:
<u><em>PROPHASE</em></u>
Explanation:
The first stage in Meiosis I is prophase I. During this stage the DNA condenses into chromosomes. During prophase I, homologous chromosomes pair up and exchange sections of DNA. This is called recombination or crossing over
