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

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

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

50. Which of the following is true about short-term and long-term memory processes? (A) Both short-term and long-term memory processes require protein synthesis. (B) Neither short-term nor long-term memory processes require protein synthesis. (C) Invertebrate animals like Aplysia and Drosophila do not show long-term memory processes. (D) Short-term memory processes act through second messenger systems while long-term memory processes require protein synthesis. (E) Long-term memory processes act through second messenger systems while short-term memory processes require protein synthesis. .

51. An open circulatory system differs from a closed one in that: (A) The open circulatory system has a combination of blood vessels and large thin-walled sinuses whereas a closed circulatory system has only vessels. (B) An open circulatory system opens into the heart whereas the closed circulatory system does not. (C) An open circulatory system opens into arteries and is drained by veins whereas in a closed one it is just the reverse. (D) An open circulatory system drains into the mantle cavity whereas a closed circulatory system drains into the hemolymph. (E) A closed circulatory system is completely encased in the body cavity whereas the open one is not. 

52. In the above graph, curve ______ is most likely the oxygen-binding curve for normal adult human hemoglobin. Curve ______ is most likely that of llama hemoglobin (from a llama population that has lived in the mountains of Peru for thousands of years). Curve ______ is most likely that of myoglobin. (A) A, B, C (B) A, C, B (C) B, C, A (D) B, A, C (E) C, B, A

53. A small island has stable populations of plants and animals, including one species of hawk as the only predator. A ship docks at the island, and the ship's cat has recently had a litter of kittens. One of the young cats accidentally goes ashore in a small boat, jumps to land and runs into the brush. No one notices, and they leave the cat on the island. What do you think is a likely consequence of the cat's presence on the island? (A) The insect populations will decline. (B) The fish in the lagoon will decrease due to predation. (C) It's only one cat and will make no difference to the island. (D) Some species of ground-nesting birds may go extinct within a few years. (E) The increase in nitrogenous waste from the cat will increase the size of many plants.

54. Which is NOT CORRECT? (A) Introduced species are sometimes a problem because they usually are better competitors. (B) For carbon cycle, the CO2 would be returned to the atmosphere when the trees died and decayed. (C) Global warming is caused by increased CO2 and CH4 levels. (D) UV-B radiation is increasing due to increased CH4 concentration in the polar region. (E) CO2 level increased due to enhanced human activities.