34. Which of the following statements about circulatory systems is FALSE?
(A) Arthropods and earthworms have open circulatory system.
(B) The pulmonary circuit carries blood between the heart and gas exchange tissues in the lungs.
(C) The systemic circuit carries blood between the heart and the rest of the body.
(D) Salmon has a single circuit of blood flow and two heart chambers.
(E) Mammals have two atria and two ventricles in their hearts.

30. Which of the following statements about signal transduction is FALSE ? (A) Signal transduction only can start with a signal to a membrane receptor, and ends with a change in cell function. (B) The signal must be amplified in a cascade manner within the cells. (C) Signal transduction can link with all cellular responses respond to external stimuli. (D) Signal transduction closely links with gene expression to alter metabolism. (E) Signal transduction is largely carried out by second messenger molecules.

31. Which of the following statements is FALSE? (A) The cells of the mucous membrane lining human air tubes carry cilia that sweep mucus up and out of the respiratory system. (B) Adipose tissue is a type of connective tissue. (C) Epithelial tissues cover both external and internal body surfaces. (D) The most common type of connective tissue in the human body is fibrous connective tissue. (E) Connective tissue is different from the other major tissue types in that the cells are sparsely scattered through a nonliving matrix.

32. Which of the following structures does NOT belong to the human lymphatic system? (A) tonsils (B) thymus (C) pancreas (D) appendix (E) bone marrow

33. Which of the following statements regarding the nervous system is FALSE? (A) Schwann cell is also a kind of nerve cell and found in the peripheral nervous system (PNS). (B) The functional unit of the nervous system is the neuron. (C) Sensory neurons convey signal from sensory receptors into the central nervous system (CNS). (D) Motor neurons convey signals from the CNS to effector cells. (E) PNS has ganglia, clusters of neuron cell bodies.

35. In eukaryotic cells, 5S rRNA gene is transcribed by _____. (A) RNA polymerase I (B) RNA polymerase II (C) RNA polymerase III (D) RNA polymerase IV (E) RNA polymerase V

36. ________ is produced in the roots of plants. It promotes cell division and growth, and retards the aging of flowers and leaves? (A) Ethylene (B) Abscisic acid (C) Karrikins (D) Cytokinins (E) Gibberellins

37. Which of the following statements regarding cytoskeleton is true? (A) The subunit of microfilaments is tubulin. (B) The subunit of intermediate filaments can be dyneins. (C) The subunit of intermediate filaments can be keratin. (D) The subunit of intermediate filaments can be kinesins. (E) Microtubules are polymers of alpha and beta actin.

38. Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is needed by all forms of life? (A) calcium (B) iron (C) iodine (D) sodium (E) potassium

39. Which is a functional group that helps stabilize proteins by forming covalent cross-links within or between protein molecules? (A) amino group (B) carboxyl group (C) sulfhydryl group (D) carbonyl group (E) phosphate group

40. Which of the following is (are) the mechanism(s) of epigenetic varivations? (A) histone acetylation (B) single nucleotide substitution (C) DNA methylation (D) both A and C (E) all of A, B, and C