Energy from the sun heat and chemicals
As covalent bonds are strong it makes the sugar phosphate backbone a stable molecule which will HV less chances for a mutation while the huydrogen bonds exist for the ease of DNA replication as they are strong in a way but weak for the replication to take place easily.
Northern hemisphere : Summer because it is tilted towards the sun.
Southern Hemisphere : Winter because it is tilted away from the sun.
Answer:
the fourth one. biomagnofication is when an organism ingests other plants or animals that have toxins in them. the toxins are widely distributed
