Answer the following question given this paragraph: Labor and Birth Labor is the physical efforts of expulsion of the fetus and the placenta from the uterus during birth (parturition). Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin. At this time, the baby reorients, facing forward and down with the back or crown of the head engaging the cervix (uterine opening). This causes the cervix to stretch and nerve impulses are sent to the hypothalamus, which signals for the release of oxytocin from the posterior pituitary. The oxytocin causes the smooth muscle in the uterine wall to contract. At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions. A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin. As more smooth muscle cells are recruited, the contractions increase in intensity and force. There are three stages to labor. During stage one, the cervix thins and dilates. This is necessary for the baby and placenta to be expelled during birth. The cervix will eventually dilate to about 10 cm. During stage two, the baby is expelled from the uterus. The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery. The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall. If labor should stop before stage two is reached, synthetic oxytocin, known as Pitocin, can be administered to restart and maintain labor. An alternative to labor and delivery is the surgical delivery of the baby through a procedure called a Caesarian section. This is major abdominal surgery and can lead to post-surgical complications for the mother, but in some cases it may be the only way to safely deliver the baby. Q: What kind of relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of the hormone oxytocin during childbirth? Choices: - pressure feedback - affirmative feedback - currents feedback - positive feedback A:
positive feedback
Answer the following question given this paragraph: The second major step is cytokinesis. As in prokaryotic cells, the cytoplasm must divide. Cytokinesis is the division of the cytoplasm in eukaryotic cells, resulting in two genetically identical daughter cells. Q: What is the name for the division of the cytoplasm in eukaryotic cells, resulting in two genetically identical daughter cells? Choices: - mitosis - vegetative division - metamorphosis - cytokinesis A:
cytokinesis
Q: Answer the following question given this paragraph: The driest climates are deserts . Most occur between about 15 and 30 latitude. This is where dry air sinks to the surface in the global circulation cells. Deserts receive less than 25 centimeters (10 inches) of rain per year. They may be covered with sand dunes or be home to sparse but hardy plants (see Figure below ). With few clouds, deserts have hot days and cool nights. Q: What has hot days and cool nights, and are typically covered with sand dunes or sparse but hardy plants? Choices: - rain forest - tundra - arctic - deserts A:
A: deserts
Question: Answer the following question given this paragraph: After food is broken down into nutrient molecules, the molecules are absorbed by the blood. Absorption is the process in which nutrients or other molecules are taken up by the blood. Once absorbed by the blood, nutrients can travel in the bloodstream to cells throughout the body. Q: What type of fertilization do most reptiles use to reproduce? Choices: - mechanical - external - asexual - internal A:
Answer: internal
*Question*
Answer the following question given this paragraph: Note The first controlled chain reaction was achieved on December 2, 1942, in an experiment supervised by Enrico Fermi in a laboratory underneath the football stadium at the University of Chicago. Although fairly simple in theory, an atomic bomb is difficult to produce, in part because uranium-235, the isotope that undergoes fission, makes up only 0.7% of natural uranium; the rest is mostly uranium-238, which does not undergo fission. (Remember that the radioactive process that a nucleus undergoes is characteristic of the isotope. ) To make uranium useful for nuclear reactors, the uranium in uranium-235 must be enriched to about 3%. Enrichment of uranium is a laborious and costly series of physical and chemical separations. To be useful in an atomic bomb, the uranium in uranium-235 must be enriched to 70% or more. At lesser concentrations, the chain reaction cannot sustain itself, so no explosion is produced. Fusion is another nuclear process that can be used to produce energy. In this process, smaller nuclei are combined to make larger nuclei, with an accompanying release of energy. One example is the hydrogen fusion, which makes helium. While the steps of the process are complicated, the net reaction is: 41H 4He + 2.58 1012 J Saylor URL: http://www. saylor. org/books. Q: Fusion is another nuclear process that can be used to produce energy. in this process, smaller nuclei are combined to make larger nuclei, with an accompanying release of this? Choices: - food - mineral - cells - energy A:
**Answer**
energy
Answer the following question given this paragraph: There are about 27,000 species of bony fish ( Figure below ), which are divided into two classes: ray-finned fish and lobe-finned fish. Most bony fish are ray-finned. These thin fins consist of webs of skin over flexible spines. Lobe-finned fish, on the other hand, have fins that resemble stump-like appendages. Q: What is the second class of fish after ray-finned fish? Choices: - pine - finned fish - spar - finned fish - star-finned fish - lobe-finned fish A:
lobe-finned fish