Answer:
A
Explanation:
Today, the atmosphere holds about 21 per cent oxygen. ... When the first simple organisms appeared in the oceans more than 3.5 billion years ago, the atmosphere was mostly nitrogen, hydrogen, water vapor, and carbon dioxide
Answer: Stem cell research has the potential to treat diseases that are currently burdened with high health care costs—especially chronic conditions such as heart disease, Alzheimer's disease or diabetes, the costs of which threaten to cripple the healthcare system.
In an exothermic reaction, it takes less energy to break bonds in the reactants than is released when new bonds form in the products. The word "exothermic" literally means "turning out heat." Energy, often in the form of heat, is released as an exothermic reaction occurs.
Answer:
one in four plants had two alleles for the recessive trait
Explanation:
Hope it helps.
