Answer:
only 30% of total energy will be useful ..
So, Useful energy =

13.5J energy is useful
Answer:
Your answer would be a <u><em>NICHE</em></u>.
Explanation:
when an animal in an ecosystem consisting of such things as what it eats, when it eats, and where it lives would be called a <u><em>NICHE</em></u>.
The correct answer is c trachea
Answer:
When the females tend to form a solitary group, the adult males have an advantage of mating with females in different social groups thus enhancing on the productivity of the species.
Explanation:
When both the sexes of the species tend to make a group, the males and the females of the group have to mate with the members of that particular group and hence the males have restricted mating options which reduce the size of the herd. When the females have a separate social group, the males can mate with the members of different groups and raise the herd size in a short period of time. This helps in the increase in the population size and also helps in avoiding inbreeding depression which happens among small grouped animals.