12. Consider this pathway: bitter molecules → G-protein→ phospholipase C → IP3 →raised [Ca^{2 +}]→ cellular response. Identify the second messenger.
(A) G-protein
(B) IP₃ 
(C) Ca^{2 +}
(D) Band C
(E) A, B and C

8. What is the reason for fluid being forced out of systemic capillaries at the arteriole end? (A) The osmotic pressure of the interstitial fluid is greater than that of the blood. (B) The hydrostatic pressure of the blood is less than that of the interstitial fluid. (C) The hydrostatic pressure of the blood is greater than the osmotic pressure of the blood. (D) The osmotic pressure of the interstitial fluid is greater than the hydrostatic pressure of the blood. (E) The osmotic pressure of the blood is greater than the hydrostatic pressure of the interstitial fluid.

9. Which of the following is a correct sequence of processes that takes place when a flowering plant reproduces? (A) meiosis-fertilization-ovulation -germination. (B) fertilization-meiosis-nuclear fusion-formation of embryo and endosperm. (C) meiosis-pollination-nuclear fusion-formation of embryo and endosperm. (D) growth of pollen tube-pollination-germination-fertilization. (E) meiosis-mitosis-nuclear fusion-pollen.

10. When an illuminated rod or cone stimulates a horizontal cell, the horizontal cell inhibits more distant photoreceptors and bipolar cells that are not illuminated, making the light spot appear lighter and the dark surrounding even darker. This form of integration, called (A) horizontal inhibition. (B) horizontal amplification. (C) lateral inhibition. (D) lateral amplification. (E) cone stimulation.

11. Lipolysis and gluconeogenesis are stimulated when (A) insulin and glucagon are both decreasing. (B) insulin and glucagon are both increasing. (C) insulin is increasing and glucagon is decreasing. (D) insulin is decreasing and glucagon is increasing. (E) glucagon is not associated with lipolysis.

13. The thick band of nerve fibers that connect the right and left cerebral hemispheres in placental mammals, enabling the hemispheres to process information together, is called (A) corpus callosum. (B) hippocampus. (C) suprachiasmatic nuclei. (D) limbic system. (E) reticular formation.

14. The capillary system that serves the loop of Henle, is called (A) vas deferens. (B) macula densa. (C) vasa recta. (D) juxtaglomerular apparatus. (E) henle plexus.

15. Which of the following occurs when a skeletal muscle fiber contracts? (A) The myosin head is bound to ATP. (B) The myosin tail binds to actin, forming a cross-bridge. (C) Releasing ADP and Pi, myosin fixes the thin filament. (D) The tropomyosin is activated by ATP hydrolysis. (E) Ca+2 entry into sarcoplasmic reticulum.

16. The mechanism that is used by Drosophila melanogaster to prevent the shortening of the chromosome ends is (A) transposition. (B) elongating the ends by telomerase. (C) apoptosis. (D) signal transduction. (E) recombination and mismatch repair.

17. Which of the following statements on eukaryotic mRNA is NOT true? (A) mRNA is usually capped at the 5' terminus. (B) mRNA always contains a poly-A tail. (C) Translation usually starts from the first AUG codon from the 5' terminus. (D) mRNA often contains an AAUAAA sequence in the 3' region as a polyadenylation signal. (E) mRNA does not contain a Shine-Dalgarno sequence for translation initiation.

18. Which of the following processes is most directly driven by light energy? (A) Creation of a pH gradient by pumping protons across the thylakoid membrane. (B) Carbon fixation in the stroma. (C) Reduction of NADP+ molecules. (D) Removal of electrons from chlorophyll molecules. (E) ATP synthesis.