During embryonic development, which of the following germ layers forms the nervous system?
A. Ectoderm
B. Endoderm
C. Mesoderm
D. Exoderm
The three germ layers that form during embryonic development are the ectoderm, mesoderm, and endoderm. The ectoderm is the outermost layer, and it gives rise to the skin, hair, nails, and nervous system. The nervous system develops from a specialized region of the ectoderm called the neural plate, which invaginates to form the neural tube. The neural tube ulmately gives rise to the brain and spinal cord, which make up the central nervous system, as well as the peripheral nervous system. The endoderm gives rise to the lining of the digesve and respiratory tracts, while the mesoderm gives rise to the musculoskeletal system, circulatory system, and several other organs. The exoderm is not a germ layer and does not exist during embryonic development.
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: What are the steps involved in the scientific method?
A. Observation, hypothesis, prediction, experimentation, analysis, conclusion.
B. Hypothesis, observation, prediction, experimentation, analysis, conclusion.
C. Prediction, observation, experimentation, analysis, conclusion, hypothesis.
D. Observation, data collection, analysis, experimentation, hypothesis, conclusion.
Answer Explanation
The scientific method is a systematic approach used to answer questions or test hypotheses about the natural world. The steps involved in the scientific method are:
- Observation: This is the first step in the scientific method. It involves observing a phenomenon or a problem and gathering information about it.
- Hypothesis: After making an observation, a scientist forms a hypothesis, which is a tentative explanation for the phenomenon or problem.
3. Prediction: Based on the hypothesis, the scientist makes a prediction about what will happen in an experiment or what they will observe.
4. Experimentation: The scientist designs and conducts an experiment to test the hypothesis and prediction.
5. Analysis: The data collected from the experiment are analyzed to determine if they support or refute the hypothesis.
6. Conclusion: Based on the analysis of the data, the scientist draws a conclusion about whether the hypothesis is supported or refuted.
Option b) is incorrect because it starts with hypothesis before observation. Option c) is incorrect because prediction comes before experimentation. Option d) is incorrect because hypothesis comes after observation and data collection.
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Q #2: A researcher collects data on the number of cars passing through a busy intersection at different times of the day for a month. This data would be most useful to analyze which of the following:
A. traffic patterns during rush hour
B. pedestrian movement during the day
C. air pollution levels in the area
D. noise levels in the area
Answer Explanation
The data collected by the researcher on the number of cars passing through a busy intersection at different times of the day for a month would be most useful to analyze traffic patterns during rush hour.
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Q #3: What is the molecular geometry of a molecule of sulphur dioxide (SO2)?
A. Linear
B. Trigonal planar
C. Bent
D. Tetrahedral
Answer Explanation
The molecular geometry of a molecule of sulphur dioxide (SO2) is bent or V-shaped. This is because of the presence of two lone pairs on the sulfur atom, which cause repulsion and distort the bond angles in the molecule.
SO2 has a central sulfur atom bonded to two oxygen atoms by double bonds. The two double bonds and the two lone pairs of electrons on sulfur result in a trigonal planar arrangement of electron pairs around the sulfur atom. However, the repulsion between the lone pairs causes the two oxygen atoms to be pulled closer together, resulting in a bent or V-shaped molecular geometry.
The bent molecular geometry of SO2 affects its properties, such as its polarity and reactivity. SO2 is a polar molecule due to the asymmetric distribution of electrons, which results in a partial positive charge on the sulfur atom and partial negative charges on the oxygen atoms. This polarity makes SO2 a good solvent and reactant in chemical reactions, as well as a contributor to air pollution and acid rain.
