6. The word precious in the passage is closest in meaning to
(A) Exact
(B)Scarce
(C)Valuable
(D)Initial

2. According to paragraph 1, which of the following is NOT true of climax communities? (A) They occur at the end of a succession. (B) They last longer than any other type of community. (C) The numbers of plants in them and the mix of species do not change (D) They remain stable for at least 500 years at a time.

3. According to paragraph 2, which of the following principles of ecosystems can be learned by studying a pond? (A) Ecosystem properties change more slowly than individuals in the system. (B) The stability of an ecosystem tends to change as individuals are replaced. (C) Individual organisms are stable from one year to the next. (D) A change in the members of an organism does not affect an ecosystem's properties

4. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans? (A) It clearly indicates that cetaceans are mammals. (B) It cannot conceal the fact that cetaceans are mammals. (C) It is the main difference between cetaceans and land-dwelling mammals.

5. Which of the following can be inferred from paragraph 1 about early sea otters? (A) It is not difficult to imagine what they looked like (B) There were great numbers of them. (C) They lived in the sea only.

7. Pakicetus and modern cetaceans have similar (A) Hearing structures (B) Adaptations for diving (C) Skuli shapes

8. The word it in the passage refers to (A) Pakicetus(B)Fish(C) Life(D)ocean

9. The word exposed in the passage is closest in meaning to (A) Explained (B) Visible(C)Identified (D) Located

10. The hind leg of Basilosaurus was a significant find because it showed that Basilosaurus (A) Lived later than Ambulocetus natans (B) Lived at the same time as Pakicetus (C) Was able to swim well (D) Could not have walked on land

11. It can be inferred that Basilosaurus bred and gave birth in which of the following locations (A) On land (B) Both on land and at sea (C) In shallow water (D) In a marine environment

12. Why does the author use the word Iuckily in mentioning that the Ambulocetus natans fossil included hind legs? (A) Fossil legs of early whales are a rare find. (B) The legs provided important information about the evolution of cetaceans. (C) I he discovery allowed scientists to reconstruct a complete skeleton of the whale.