Starvation.
Disease.
Weather.
Lack of mate.
Offspring dying.
Hunting.<span />
The correct answer should be Carrying capacity
Carrying capacity is the the number of people, animals, and other life forms, that an ecosystem can sustain without starting to degrade, and all these upsets can destroy it because it can cause people and animals to migrate somewhere or they can destroy the carrying capacity of the already existing one.
Evolution is the gradual process resulting in the changes in the genetic material of a population over generations. The mechanism that Darwin proposed for evolution is the process of natural selection. Natural selection is the key mechanism of evolution which increases the frequency of advantageous alleles in a population. Due to the limited resources in nature, organism with heritable traits favoring their survival and reproduction produce more offspring. It causes the population to become adapted to their environment and results in organisms with better survival ability and reproduction. These traits become heritable due to the reproductive advantage and are passed from the parents to the offspring. Over generations, the advantageous heritable trait becomes dominant in the population. It is responsible for the variation in the gene pool of the population which increases their fitness.
The answer is <span>Topoisomerase.
Topoisomerase is an enzyme responsible for twisting of DNA helix. After DNA strand is untwisted by helicase enzyme, DNA must be twisted again so the normal function of DNA can be sustained. If left untwisted, the replication fork will continue to grow, the normal function of DNA will stop.</span>
