Answer:
a prezygotic barrier
Explanation:
Both wild tigers and lions are said to be reproductively isolated.
Reproductive isolation is defined as the existence of barrier between organisms of different species such that they cannot reproduce.
The mechanisms of reproductive isolation varies. While some act to prevent the formation of zygotes (in case of mating) between organisms of different species, some ensures that the resulting zygotes are invalid.
Reproductive isolation mechanisms that act to prevent fertilization and formation of zygotes are referred to as prezygotic mechanisms while those that ensure that invalid zygotes result (in case of successful fertilization) are referred to post zygotic mechanisms.
<em>The natural differences in the ranges of wild tigers and lions ensure that both animals do not mate with each other, let alone results in zygote. This is a form of pre-zygotic reproductive isolation mechanism.</em>
The gradual decline in men's testosterone levels in middle age can reduce their sex drive
Nonsense mutations make stop codons. If the mutation is towards the beginning of a gene, then the protein that gets created will be cut short and not function properly. But if it was towards the end, there is still a chance that the protein will still be able to work.
The estimated daily basal metabolic rate for a man who weighs 150 lb is 1636 kcal.
Basal metabolic rate is the rate of energy expenditure per unit time by endothermic animals at rest. Metabolism comprises the processes that the body needs to function. It is the amount of energy per unit time that a person needs to keep the body functioning at rest. Any increase to the metabolic weight, such as exercise, will increase the basal metabolic rate.
