Beta diversity is calculated by taking the total number of habitats divided by the number of species in each habitat of a given environment. 

Total number of habitats:

Number of species in each habitat: 

Solve:

Gamma diversity refers to the total number of species within a region. This can also be referred to as regional diversity. Gamma diversity is useful in order to investigate biodiversity from a broad scale or at the landscape level.

Biological diversity is concerned with not only the number, variety and variability of species within ecosystems but the number of ecosystems on the Earth and genetic diversity within species. 

The correct response is 1%. The majority of species that have ever lived on Earth are extinct. Mass extinctions have occurred throughout geological history due to large disturbances such as meteor crashes and ice ages. Life is fragile and disturbances can cause millions of species to go extinct rather quickly - such as most recent mass extinction when the dinosaurs disappeared. Thus, the species still alive today represent a tiny portion of the variety of life that has existed throughout the geological history of Earth.

Riparian zones prevent erosion and are incredibly high in biodiversity. Riparian areas are thin and ribbon-like, accompanying streams and rivers, but often long and dense.

Every species is important because of its niche in its ecosystem. Additionally, all species are potentially of scientific and medical/economic value.

Ocean acidification is most accurately described by the answer choice that talks about carbon dioxide being emitted into the atmosphere before being absorbed by ocean water to react with carbonate ions and form carbonic acid.

Image: "Ocean Acidification." NOAA PMEL Carbon Program. NOAA. Web. 6 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/Ocean Acidification>.

Red tide is caused by algal blooms, which occur due to eutrophication of waterways. Red tides set off harmful chain reactions in ecosystems, because of the toxins the algae produce. The toxins get concentrated in higher trophic levels (biomagnification).

Since there has been a significant population decline over a substantial time period, but there is still an extensive range and population, this species would best be categorized as "threatened." A species classified as threatened is vulnerable to becoming endangered in the future and is still being impacted significantly by habitat loss and human activities. This frog species would be categorized as endangered if they were at immediate threat of becoming extinct.

Conservationists advocate to manage resources for sustainable continued use by humans. Preservationists are in favor of prohibiting human usage rather than actively managing.