Once a species goes extinct, its contribution to biodiversity is lost forever.?

Yes, at least it is now. In the future, we will have the technology to engineer genes so if we have a sample or we have fully characterized the genome of that species, we should be able to recreate that species or, maybe, engineer a particular trait into other species.

Yes, technically this is true.

However, there are currently a number of projects such as bio-banking that endeavour to preserve a diversity genetic material from as many different species as possible, so that in the future we may still have access to biodiversity after it has been lost. This is very dependent on developing the technologies required to achieve this, many of which are very real possibilities today, such as cloning and species surrogacy.

However, this raises a number of ethics dilemmas, all of which need to be considered seriously. For example, just because we can clone an extinct species, does that mean we should? Such questions come with a list of considerations: Where would the revived species live? What will theyy eat? Are all the resources they require still available in great enough abundance to support a population? What impact would they have on existing species? What impact will they have on human life? How will they be managed? And so on. It is important to also understand that extinction is also a natural process, and if a species went extinct for non-anthropogenic reasons, then there is a good reason for it and in such a case we should seriously assess our decisions.

Ultimately, the real aim should be to preserve biodiversity as it is, but unfortunately this is ideal and not always practical, feasible, or popular in the shadow of human interests.

I would say not necessarily. If other species branched off of it then the root species would have contributed to biodiversity.

yea i think its true but not necessarily...