*Question*
Answer the following question given this paragraph: Q: Oxygen, carbon, hydrogen and what other element make up approximately 96% of living matter? Choices: - calcium - helium - silicon - nitrogen A:
**Answer**
nitrogen

*Question*
Answer the following question given this paragraph: Microevolution is the process by which organisms change in small ways over time. Q: What is the process by which organisms change in small ways over time? Choices: - spontaneous mutation - natural selection - adaptation - microevolution A:
**Answer**
microevolution

*Question*
Answer the following question given this paragraph: Plants have evolved three pathways for carbon fixation. The most common pathway combines one molecule of CO 2 with a 5-carbon sugar called ribulose biphosphate (RuBP). The enzyme which catalyzes this reaction, ribulose-1,5-bisphosphate carboxylase oxygenase (nicknamed RuBisCo ), is the most abundant enzyme on earth! The resulting 6-carbon molecule is unstable, so it immediately splits into two much more stable 3-carbon phosphoglycerate molecules. The 3 carbons in the first stable molecule of this pathway give this largest group of plants the name "C-3. ". Q: How many pathways do plants have for carbon fixation? Choices: - one - four - two - three A:
**Answer**
three

*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? Choices: - signaler stem cell - omnipoten stem cell - schwann stem cell - totipotent stem cell A:
**Answer**
totipotent stem cell