Answer and Explanation:
Observing population directly gives you accurate result .
Direct observation does not need any intermediary as they themselves go for survey.
So, it is cost efficient.
Whereas indirect observing may involve manipulations.
It requires someone or many to hire who helps in surveying.
It incurs cost.
Thus, direct observation is always better than indirect observation.
B. some species die out when environmental changes occur
True aka pollution from machines smoke carbon emissions etc
Answer:
Signposts that determine the fate of cells.
Explanation:
Embryos for humans and other animals often look alike at certain developmental stages because they share ancient genes. This expression means that a more advanced organism, like humans, will resemble less advanced species during it's development stages.
