The answer is true. They cannot only replicate themselves within cells, but they cannot outside of a cell.
Answer: There is a lot
Explanation:
You're made partly of carbon, so is clothing, furniture, plastics and your household machines. There is carbon in the air we breathe. Diamonds and graphite are also made of carbon.
Answer:
(c) directional selection
Explanation:
Directional selection is a type of natural selection that occurs when members of a population of a species with a particular extreme phenotype is selected or favored against the other phenotypes when natural forces act on the population of a species. Individuals having the particular traits that are favored survive and become more common that others with traits that are less favored.
Directional selection may likely result in the species of butterflies in which darkly collared butterflies are not preyed upon, ensuring their survival, while the other butterflies with other colors will be phased out with time. Darkly colored butterfly will be selected for while the others will be selected against.

In humans, the medulla region of the brain is mainly responsible for the regulation process of respiration. It is also called the respiratory rhythm centre. The chemosensitive area located near the respiratory centre sends signals across nerve impulses to alter the rate of expiration to eliminate compounds.
Answer:
Regulated gene expression is crucial to the proper growth & survival of an organism and cannot be over-emphasized. Without it, the genetic code of a chromosome is the equivalent of a computer data file without the appropriate application to run it.