Question

1. how many species are estimated to be living on earth?a. between 10,000 and 1,000,000b. between 500,000 and 1 millionc. between 1 and 5 milliond. between 10 and 50 million15. why are there so many species still unknown to modern science?a. many of these species are found in remote environmentsb. smaller species receive less attention than large organisms.c. cataloging these species is a huge task.d. all of the above16. where are many critical biodiversity hotspots located?*a. cities and developed areas of the worldb. islands, tropical rain forests, and coastal areasc. desert and polar environmentsd. all of the above17 it is often difficult to save individual species because

Explanation:

• Question 14: Estimates of the number of species on Earth vary, but many recent studies suggest a range between 10 - 100 million. Among the given options, "between 10 and 50 million" (option d) is the most reasonable as it aligns with broader scientific estimates.
• Question 15:
• Option a: Remote environments (e.g., deep - sea trenches, dense rainforest canopies) are hard to access, so species there may be unknown.
• Option b: Smaller species (e.g., many insects, microscopic organisms) are less likely to be studied compared to large, charismatic species (like elephants or whales).
• Option c: Cataloging all species requires extensive fieldwork, taxonomic expertise, and resources. Since all these factors contribute, "all of the above" (option d) is correct.
• Question 16:
• Option a: Cities and developed areas have often lost much of their original biodiversity.
• Option b: Islands (e.g., Madagascar), tropical rain forests (e.g., Amazon), and coastal areas (with unique marine and terrestrial ecosystems) are known biodiversity hotspots.
• Option c: Desert and polar environments are generally less biodiverse compared to the areas in option b. So, option b is correct.

Answer:

1. d. between 10 and 50 million
2. d. all of the above
3. b. Islands, tropical rain forests, and coastal areas