4.It has been reported that long-term hormone replacement therapy (HRT) in women with menopause may increase the risk of cancer, possibly because
(A) Hormone opens channels in the membrane for other substances to enter
(B) Hormone receptor opens channels in the nuclear envelope for cytoplasmic molecules to enter
(C) Hormone enables water-soluble molecules to diffuse across membranes
(D) Hormone-receptor complex regulates gene transcription in the nucleus
(E) Hormone-receptor complex transfers the phosphate groups from ATP

複選題7.下列哪個称不是DNA在複製時需要用到了酶 (A)DNA聚合醇(DNA Polymerase) (B)DNA連接酸(DNA ligase) (C)DNA導引酸(DNA primase) (D)DNA甲基轉移(DNA methyItransferase)

1.Vioxx and other prescription nonsteroidal anti-inflammatory drugs (NSAIDs) are potent inhibitors ot the cyclooxygenase-2 (COX-2) enzyme. The inhibitory efficacy of these drugs is decreased in the presence of high substrate concentrations. These drugs are (A) allosteric regulators. (B) prosthetic groups. (C) feedback inhibitors. (D) competitive inhibitors. (E) noncompetitive inhibitors.

2. Three cells with distinct volumes and surface arcas are listed in the following table:Based on data from the table above, which of the following statements "best" explains which cell will 10.2um3 Cell 3 27.3 um2 eliminate wastes most inefficiently? (A) Cell 1 because it has the lowest ratio of surface area to volume, which will enable it to eliminate its wastes most inefficiently. (B) Cell 2 because it has the highest ratio of surface area to volume, which will enable it to climinate its wastes most inefficiently. (C) Cell 3 because it has the smallest volume, which will cnable it to eliminate its wastes most inefficiently. (D) Cell 3 because it has the smallest surface area, which will enable it to eliminate its wastes most inefficiently.

3. Of the following events, which best describes the steps in a signal transduction pathway? a)Tyrosine kinase receptor subunits dimerize； b) An enzyme cascade occurs, increasing of activated proteins； c) A reconfigured protein binds to DNA, altering gene expression； d) A signal molecule is bound by a transmembrane tyrosine kinase receptor protein； e) The receptor protcin complex phosphorylates other proteins. (A) adbec(B) adecb(C) daebc(D) deabc(E) aedcb

5.Individuals with the inherited disease familial hypercholesterolemia have a very high level of cholesterol in the blood because the cholesterol can't be transported by (A) pinocytosis (B) receptor-mediated endocytosis (C) exocytosis (D) phagocytosis (E) facilitated diffusion

6. The drug cytochalasin B binds to the barbed end of actin. Which of the following events of the cell cycle in animal cells would be most likely disrupted by cytochalasin B? (A) spindle formation (B) spindle attachment to kinetochores (C) separation of sister chromatids (D) movement of chromosomes to the poles during anaphase (E) cleavage furrow formation and cytokinesis

7.Which of the following statements describes one characteristic of each chromosome in a cell during the entire process of meiosis I? (A) Each chromosome is joined with its homologous pair to form a synaptonemal complex. (B) Each chromosome is paired with a homologous chromosome. (C) Each chromosome consists of two sister chromatids joined by a centromere. (D) Each chromosome consists of a single strand of DNA. (E) Sister chromatids cross over.

8. The sheep Dolly was cloned by which of the following processes? (A) isolation of stem cells from a lamb embryo and production of a zygote equivalent (B) transfer of an adult cell's nucleus into an enucleated sheep egg, followed by incubation in a surrogate (C) separation of an early-stage sheep blastula into separate cells, one of which was incubated in a surrogate sheep (D) replication and dedifferentiation of adult stem cells from sheep bone marrow (E) the nucleus of an embryonic cell was used to replace the nucleus of an adult cell, which was incubated in a surrogate sheep

9. The insulin gene is transcriptionally expressed in certain pancreatic cells, but not in skin cells. Which statement best explains this? (A) Pancreas cells express an activator protein that binds the insulin enhancer. (B) Pancreas cells have more enhancers in the insulin gene. (C) The insulin genes in pancreatic cells and skin cells have different promoters and, therefore, they respond to different regulatory proteins. (D) Skin cells lack an enhancer in the insulin gene. (E) Skin cells lack the insulin gene.

10. What is the correct sequence in which the following occur during a primary humoral immune response?   1. helper T cell activation； 2. B cell activation； 3. plasma cell differentiation and proliferation； 4. antibody secretion； 5. presentation of antigen on class II MHC proteins (A) 5,2,1,4,3 (B) 4,5,2,1,3 (C) 4,5,3,1,2 (D) 5,2,1, 3, 4 (E) 5,1,2,3,4