Can new species appear or disappear in the biosphere?

Of course they can. This is exactly what evolution is aimed at – to weed out species that cannot adapt to environmental conditions, over time, more perfect individuals appear that can survive and give fertile offspring. This can happen both by natural selection and artificial, when a person intervenes. For example, the Amur tiger suffered precisely because of human hands, from natural selection we can isolate Archeopetrix or some kind of elephant turtles.

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.