What is the name of the genetic disorder caused by the presence of an extra chromosome 21?
A. Turner syndrome
B. Klinefelter syndrome
C. Down syndrome
D. Huntington's disease
Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is also known as trisomy 21, because affected individuals have three copies of chromosome 21 instead of the normal two.
The extra chromosome 21 in Down syndrome occurs due to a random error in cell division, which leads to the production of an abnormal gamete (egg or sperm) with an extra copy of the chromosome. When this gamete fuses with a normal gamete during fertilization, the resulting zygote has 47 chromosomes instead of the usual 46, and develops into a fetus with Down syndrome.
Down syndrome is characterized by a range of physical and intellectual symptoms, including developmental delays, intellectual disability, distinctive facial features, heart defects, and increased risk of certain medical conditions such as leukemia and Alzheimer's disease. However, the severity and expression of these symptoms can vary widely among affected individuals.
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Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
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Q #1: Which of the following substances is excreted by the kidneys to regulate blood pressure?
A. renin
B. erythropoietin
C. calcitriol
D. urobilinogen
Answer Explanation
Renin is an enzyme that is produced by the kidneys and it acts to elevate blood pressure. When blood pressure falls, the kidneys secrete renin into the bloodstream ³.
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Q #2: What is the name of the joint that allows for rotation of the arm at the shoulder?
A. Elbow joint
B. Hip joint
C. Knee joint
D. Shoulder joint
Answer Explanation
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Q #3: 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.
- Prediction: Based on the hypothesis, the scientist makes a prediction about what will happen in an experiment or what they will observe.
- Experimentation: The scientist designs and conducts an experiment to test the hypothesis and prediction.
- Analysis: The data collected from the experiment are analyzed to determine if they support or refute the hypothesis.
- 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.
