When does extinction of species happen?
I. When some of the species dies III. When the last number of species dies
II. When population of species decline rapidly IV. When the population has become so low
A. I only B. III only C. I, II, III D. III, IV

9. Which of the following is the main cause of extinction in plant and animal species?
A. Acid rain B. Increase in population C. Loss of habitat D. Pollution
10. Which of the following is not a major cause of deforestation?
A. Forest fire B. Illegal logging C. Kaingin system D. Soil erosion
11. Coral reefs and coastal mangrove forest in the Philippines serve as breeding ground and nurseries of marine fisheries. Which of the following causes their destruction?
A. Forest fire B. Kaingin system C. Muro-ami D. Typhoon
12. If an extinction event is to take place, which organisms will most likely to go extinct?
A. Organisms that generally serve as pray
B. Organism that lack the necessary adaptation to the new environment
C. Organisms that have a high population which will lead to competition
D. Organisms that have a low population because it will be hard for them to reproduce
13. Which of the following describes a DNA molecule?
A. Double helix of glucose sugars and phosphates
B. Ladder-like structure composed of fats and sugars
C. Double chain of nucleotides joined by hydrogen bonds
D. A chain of alternating phosphates and nitrogenous bases
14. If a DNA strand consists of the nitrogen base sequence C-A-T-T-A-G-C-G-A, what is the nitrogen base sequence of its complementary strand?
A. C-A-T-T-A-G-C-G-A C. T-G-C-C-G-A-T-A-G
B. G-T-A-A-T-C-G-C-T D. A-C-G-G-C-T-A-T-C
15. Oxygen is essential in cellular respiration. Which of the following is the role of oxygen in the electron transport chain?
A. It provides a high energy proton. C. It serves as the final acceptor.
B. It releases an electron. D. It forms water.
16. Which of the following are the correct products of the chemical reaction for photosynthesis?
A. Carbon dioxide + water C. Glucose + oxygen
B. Carbon dioxide + glucose D. Water + glucose
For numbers 17-19, identify the internal structure of the leaf. Choose from the letters below:
A. Epidermis B. Phloem C. Stomata D. Xylem


Look at the diagram below and answer the question that follow.

20. Which of the following terms in the diagram is considered a process?
A. ATP B. Glucose C. Pyruvate D. Glycolysis