Answer:
2. A change occurs in the environment.
4. Poorly adapted individuals have decreased survivorship.
1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
3. Genetic frequencies within the population change.
Explanation:
The natural selection theory was developed by Darwin to explain how evolution occur within a population. The environment is in constant state of changes and always select for organisms that are better adapted to it.
Poorly adapted organisms gradually reduce from the population as a result of decreased survival while well-adapted individuals multiply and contribute more to successive generation.
Well-adapted individuals pass on the adaptive alleles to their offspring, eventually leading to a change in gene frequencies within the population.
Hence, the sequence of events is 2, 4, 1 and 3.
A. Immune system
It helps our bodies fight everything that comes in our path.
Since the air is a great thermal isolator, the windows prevent heat exchange better than one made out of a single thick sheet of glass. The air between the thin blankets is not moving around and will form an isolating layer that acts exactly like another blanket, thus improving the thermal isolation