input: OPTIONS:
- signaler stem cell
- omnipoten stem cell
- schwann stem cell
- totipotent stem cell Now, answer this question: Answer the following question given this paragraph: ability to diversify at each step. The totipotent stem cell is the zygote, or fertilized egg. The totipotent (toti- = "all") stem cell gives rise to all cells of the human body. The next level is the pluripotent stem cell, which gives rise to multiple types of cells of the body and some of the supporting fetal membranes. Beneath this level, the mesenchymal cell is a stem cell that develops only into types of connective tissue, including fibrous connective tissue, bone, cartilage, and blood, but not epithelium, muscle, and nervous tissue. One step lower on the hierarchy of stem cells is the hemopoietic stem cell, or hemocytoblast. All of the formed elements of blood originate from this specific type of cell. Hemopoiesis begins when the hemopoietic stem cell is exposed to appropriate chemical stimuli collectively called hemopoietic growth factors, which prompt it to divide and differentiate. One daughter cell remains a hemopoietic stem cell, allowing hemopoiesis to continue. The other daughter cell becomes either of two types of more specialized stem cells (Figure 18.4): Lymphoid stem cells give rise to a class of leukocytes known as lymphocytes, which include the various T cells, B cells, and natural killer (NK) cells, all of which function in immunity. However, hemopoiesis of lymphocytes progresses somewhat differently from the process for the other formed elements. In brief, lymphoid stem cells quickly migrate from the bone marrow to lymphatic tissues, including the lymph nodes, spleen, and thymus, where their production and differentiation continues. B cells are so named since they mature in the bone marrow, while T cells mature in the thymus. Myeloid stem cells give rise to all the other formed elements, including the erythrocytes; megakaryocytes that produce platelets; and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes: neutrophils, eosinophils, and basophils. Q: Which cell gives rise to all cells of the human body? A:
A:
output: totipotent stem cell

Answer the following question given this paragraph: The esophagus is a narrow tube that carries food from the throat to the stomach. Food moves through the esophagus because of peristalsis. At the lower end of the esophagus, a circular muscle controls the opening to the stomach. The muscle relaxes to let food pass into the stomach. Then the muscle contracts again to prevent food from passing back into the esophagus. Q: What causes food to move through the esophagus? A:

OPTIONS:
- photosynthesis
- proteolysis
- apoptosis
- peristalsis

Answer: peristalsis

Problem: OPTIONS:
- hormones
- steroids
- pesticides
- medicines
Q: Answer the following question given this paragraph: The ocean floor is home to many species of living things. Some from shallow water are used by people for food. Clams and some fish are among the many foods we get from the ocean floor. Some living things on the ocean floor are sources of human medicines. For example, certain bacteria on the ocean floor produce chemicals that fight cancer. Q: Some living things on the ocean floor are sources of what human necessity? A:
Answer: medicines

Problem:OPTIONS:
- neutron
- protons
- electron
- nucleus

Answer the following question given this paragraph: The cell body contains the nucleus and other organelles. Q: The cell body contains what central structure along with other organelles? A:
****
A: nucleus

Answer the following question given this paragraph: In catalysis, if a molecule forms strong bonds to the catalyst, then the catalyst may become poisoned. Experiments on various catalysts showed the following results: a. Fe, Ru, and Os form weak bonds with N2; however, O2, alkynes, alkenes, CO, H2, and CO2 interact more strongly. CO2 and H2 form weak bonds with a Co or Ni surface. Rh, Pd, Ir, and Pt form weak bonds with H2 but do not bond with CO2. Cu, Ag, and Au form weak bonds with CO and ethylene. Explain why Fe was chosen as a catalyst to convert nitrogen and hydrogen to ammonia. Why is Fe more suitable than Ru or Os? f. Because alkenes generally interact more strongly with metal surfaces than does H 2, what catalyst would you choose for hydrogenation of an alkene such as ethylene? g. Although platinum is used in catalytic converters for automobile exhaust, it was not found to be a particularly effective catalyst for the reaction of H2 with a mixture of carbon monoxide and carbon dioxide to produce methane. Why? h. If you were interested in developing a catalyst to reversibly bind ethylene, which of the catalysts listed here would you choose? 14. Nonstoichiometric metal oxides can be effective catalysts for oxidationreduction reactions. One such catalyst is Ni1xO, found to be effective for converting CO to CO2when oxygen is present. Why is it so effective? 15. The chemical reactions in an organism can be controlled by regulating the activity of certain enzymes. Efficient regulation results in an enzyme being active only when it is needed. For example, if a cell needed. Q: What happens if a molecule forms strong bonds to the catalyst? A:
OPTIONS:
- molecules gets poisoned
- surface gets poisoned
- membrane gets poisoned
- catalyst gets poisoned
catalyst gets poisoned

Answer the following question given this paragraph: Digestion of Carbohydrates Carbohydrate digestion begins in the mouth (Figure 20.5 "The Principal Events and Sites of Carbohydrate Digestion"), where salivary -amylase attacks the -glycosidic linkages in starch, the main carbohydrate ingested by humans. Cleavage of the glycosidic linkages produces a mixture of dextrins, maltose, and glucose. (For more information about carbohydrates, see Chapter 16 "Carbohydrates". ) The -amylase mixed into the food remains active as the food passes through the esophagus, but it is rapidly inactivated in the acidic environment of the stomach. Figure 20.5 The Principal Events and Sites of Carbohydrate Digestion. Q: Where does carbohydrate digestion begin in the body? A:
OPTIONS:
- stomach
- intestines
- throat
- mouth

Answer:
mouth