43. Which of these statements about muscle contraction is FALSE?
(A) Ca²⁺ is required for all muscle contraction.
(B) Troponin is present in skeletal muscles and smooth muscles.
(C) When a skeletal muscle shortens during contraction, the H band and sarcomere shorten.
(D) Skeletal muscles but not cardiac muscles require neural stimulation to contract.
(E) The sarcoplasmic reticulum and transverse tubules are well-developed in skeletal muscles and poorly developed in smooth muscles. 

39. Which of these statements best describes speciation? (A) Populations separated by a geographic barrier are known as sympatric populations. (B) Geographic isolation necessarily leads to new species. (C) For allopatric speciation to occur, changes in the gene pool must produce reproductive isolation. (D) In allopatric speciation, reproductive isolation develops and new species arises without geographic separation. (E) A small population is less likely to have its gene pool changed by genetic drift and natural selection.

40. ______ clinical trial tests on the target human population, and ______ clinical trial maximize the number of test subjects and include human subjects of both sexes, different ethnic groups, and those who have health problems besides the one that the drug is intended to benefit. (A) Phase I; phase II (B) Phase I; phase III (C) Phase II; phase III (D) Phase II; phase IV (E) Phase III; phase IV

41. Which of the following normal ranges for measurements of some fasting blood values is FALSE? (A) Glucose: 75-110 mg/dL (B) Arterial blood pH: 7.00-7.45 (C) Protein: 6.5-8 g/dL (D) Cholesterol: less than 200 mg/dL (E) Sodium: 135-145 mM

42. Which of these statements about a secondary immune response is FALSE? (A) Antibodies of the IgE class are produced. (B) Antibodies are made quickly and in great amounts. (C) Antibody production lasts longer than in a primary response. (D) Lymphocyte clones are believed to develop. (E) It provides active immunity against the specific pathogens.

44. What is the correct sequence of events involving cyclic AMP as a second messenger of glucagon hormone?  1. The stimulation of the activity of adenylate cyclase.  2. The activation of G-proteins. 3. The conversion of ATP to cyclic AMP.  4. The activation of of protein kinase A.  5. The stimulation of lipid mobilization.  6. An increase in the activity of hormone-sensitive lipase. (A) 213645 (B) 213456 (C) 214356 (D) 213465 (E) 214365 

45. Which of the following sequence of the steps is regular for Western Blotting Assay that is widely used for detection of the specific protein in a tissue?1. Tissues are broken down using a homogenizer or by sonication.  2. The protein is probed with an addition of the primary antibody. 3. The protein is transferred to a PVDF membrane.  4. Add secondary antibody conjugated with peroxidase.  5. The proteins of the tissues are separated using gel electrophoresis.6. The protein is detected with an addition of a peroxidase substrate.(A) 123456 (B) 153246 (C) 152346 (D) 154623 (E) 124653

46. All are stages in gene transcription EXCEPT: (A) binding of RNA polymerase holoenzyme at the promoter sites. (B) DNase I activity on RNA polymerase/DNA complex. (C) chain elongation. (D) initiation of polymerization. (E) chain termination.

47. The driving force that pushes the root tip through the soil is primarily ______. (A) the elongation of root hairs (B) continuous cell division of root cap cells (C) elongation of cells behind the root apical meristem (D) continuous cell division in the root cap at the tip of the root (E) continuous cell division just behind the root cap in the center of the apical meristem

48. Iron deficiency is often indicated by yellowing in newly formed leaves. This suggests that iron ______. (A) is a relatively immobile nutrient in plants (B) is concentrated in the xylem of older leaves (C) is tied up in formed chlorophyll molecules (D) is concentrated in the phloem of older leaves (E) is found in leghemoglobin and reduces the amount available to new plant parts

49. You find a new species of mouse that, compared to the house mouse you are familiar with, sprints extraordinarily rapidly but also fatigues quickly. Which type of muscle fiber (compared to an ordinary house mouse) would you expect to see an increase in ______? (A) slow glycolytic fibers (B) slow oxidative fibers (C) fast glycolytic fibers (D) fast oxidative fibers (E) fast and slow oxidative fibers