12. The main source of genetic variation among humans is
(A) Gene flow
(B) Genetie drift
(C) The reshuffling of alleles in sexual reproduction
(D) Environmental effects

8. Which of the following statement is TRUE about epinephrine? (A) It is secreted in respon onse to short term stre resses through a hormone cascade pathway (B)  It is secreted from adrena nal cortex and its main function is to mediate varlous fight-or-flight responses (C)Its secretioni n is only in response to life-threatening danger (D) Epinephrine is a hormone with a wide range of effects, because it can binds to different receptors in the same cell type, or It can binds to the same receptor located on different cell types

9. Which of the following parameter is NOT essential for the resolution of a microscope? (A) (A)Magnification(B)Imaging wavelength(C)Refractive index (D)Numerical aperture 

10. Thomas Hunt Morgan's choice of Drosop phila melanog gaster (fruit fy) has been proven to be useful even today. Which of the following character has continued to make it one of the most useful and powerful model organism ims in research? (A) They have compound eyes (B) They have large and transparent embryos that can be easily studied (C) They have short life cycle with large n number of offspring (D) They can be used to model almost all human diseases

11. About polysaccharides, which of the following statement is NOT (A) They are polymers formed by dehydration of glucose monomers (B) Glycogen is a highly branched polysaccharide of glucose that serves as a form of energ gy storage in animals (C) Chitin is a polysac saccharide found in the cell wall of many fungi and form ned exoskeleton of anthropods (D) Both starch and cellu lymers s formed by glycosidic bonds. Starch is formed by 1,4 linkage of glucose, whereas cellulose is formed by 1,6 linkage ofglucose

13. Which of the following ovarian hormone directly controls cyelic changes in the uterus (A) Luteinizing hor ormone (LH) (B)Prostaglandin(C) Follicle stimulating hormone (FSH)(D)Progesterone

14. About anaerobic and aerobic respirations, which of the following statement is NOT TRUE (A) Both use glycolysis (B)Both use NAD+ as electron carrier(C)Both use oxygen acceptor (D) Aerobic respiration produces about 32 ATP, whereas anaerobic c respiration produces 2 ATP

15. Which of the following statement is NOT TRUE about photosynthesis (A) Light reactions generate ATP and increase the potentialenergy of electrons by moving them from H2O to NADPH(B) Both ATP and NADPH are produced on the side facing thestroma, where the Calvin cycle takes place(C) The Calvin cycle is a carbon fixation process that generatesoxygen as a by-product(D) Carbon enters the Calvin cycle as CO2 and leaves as glyceraldehyde 3-phospate (G3P)

16. About mutation, which of the following stateme ent is TRUE? (A) Silent mutations usually do not have obser rvable effects on phenotypes becaus se they are in-frame mutations (B) Missense mutations change a codon into a stop codon leading to a trunc cated protein (C) Nonsense mutation is a point mutation in which a single nucleotide change resulted in a a change in an amino acid (D) Insertions and deletions are additions or losses of nucleotide pairs in a gene that alter the reading frame producing out-of-frame mutations

17. FtsZ is a bacterial cytoskeletal protein that forms a co contractile ring involved in binary fission. Its function is similar to (A)1 The cleavage furrow of eukary yotic animal cells (B) The cell plate of eukary yotic plant cells ukaryotic cells (C) The mitotics spindle of eu (D) The microtubule-organizing center of eukaryotic cells

18. Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect only target cells because (A) Only target cells retain the appropriate DNA segments(B) Intracellular receptors are present only in target cells(C) Only target cells have enzymes that break down aldosterone(D) Only in target cells is aldosterone able to initiate thephosphorylation cascade that turns genes on