The world’s largest tropical rainforest Amazon rain forests are called "Lungs of the Earth". It is so called because it produces 20% of the Earth's oxygen, and is also a vast carbon sink, absorbs more than 1 billion tons of atmospheric carbon which is emitted by the burning of fossil fuels annually.
A tetrad is best described by Four chromatids. It is formed from two homologous chromosomes, each consisting of two chromatids in the first stage of meiosis called prophase1.