13. What is the main nitrogenous waste excreted by birds?
(A) uric acid
(B)urea
(C) nitrate
(D) ammonia
(E) nitrite

9. Where does meiosis occur in flowering plants? (A) megasporocyte (B) microsporocyte (C) endosperm (D) pollen tube (E) megasporocyte and microsporocyte

10. Plants growing in a partially dark environment will grow toward light in a response called phototropism. Choose the incorrect statement regarding phototropism. (A) It is caused by a chemical signal. (B) One chemical involved is auxin. (C) Auxin causes a growth increase on one side of the stem. (D) Auxin causes a decrease in growth on the side of the stem exposed to light. (E) Removing the apical meristem prevents phototropism.

11. Why is the velocity of blood flow the lowest in capillaries? (A) The capillary walls are too thin to maintain the velocity of blood flow in capillaries. (B) Capillaries are far from the heart, and blood flow slows as the distance from the heart increases. (C) The diastolic blood pressure is too low to deliver blood to the capillaries at a high flow rate. (D) The total surface area of the capillaries is larger than the total surface area of the arterioles. (E) The systemic capillaries are supplied by the left ventricle, which has a lower cardiac output than the right ventricle.

12. The MHC (major histocompatibility complex) is important in a T cell's ability to_______. (A) identify specific viruses (B) recognize specific parasitic pathogens (C) distinguish self from nonself (D) identify specific bacterial pathogens (E) recognize differences between normal and cancer cells

14. Prostaglandins are local regulators whose basic structure is derived from_______.(A) oligosaccharides (B) fatty acids (C)steroids(D)amino acids (E) nitric oxide

15. Contact of sperm with signal molecules in the coat of an egg causes the sperm to undergo______. (A) mitosis (B) depolarization (C) apoptosis (D) vitellogenesis (E) the acrosomal reaction

16. The blood-brain barrier______. (A) is formed by oligodendrocytes (B) provides support to the brain tissue (C) is formed by tight junctions (D) tightly regulates the intracellular environment of the CNS (E) uses chemical signals to communicate with the spinal cord

17. Which of the following is controlled by the magnitude of the potential of a sensory receptor? (A) adaptation (B) perception (C) the rate of reaction of the brain (D) the rate of production of an action potential (E) the rate of response to a sensory neuron

18. Which of the following is true about imprinting? (A) It occurs only in birds. (B) It may be triggered by visual or chemical stimuli. (C) It happens to many adult animals, but not to their young. (D) It is a type of learning that does not involve innate behavior. (E) It causes behaviors that last for only a short time (the sensitive period).

19. Natural selection involves energetic trade-offs between______. (A) choosing how many offspring to produce over the course of a lifetime and how long to live (B) producing large numbers of gametes when employing internal fertilization versus fewer numbers of gametes when employing external fertilization (C) the emigration of individuals when they are no longer reproductively capable or committing suicide (D) increasing the number of individuals produced during each reproductive episode with a corresponding decrease in parental care (E) high survival rates of offspring and the cost of parental care