Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: Figure 43.17 Rising and falling hormone levels result in progression of the ovarian and menstrual cycles. (credit: modification of work by Mikael Haggstrom). Answer: hormones

A: Rising and falling levels of what will result in progression of the ovarian and menstrual cycles?
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Q: Passage: The atmosphere protects living things from the Sun's most harmful rays. Gases reflect or absorb the strongest rays of sunlight. Figure below models this role of the atmosphere. Answer: the atmosphere

A: What is the name of the protective layer of gases that surrounds the earth and blocks harmful rays from the sun?
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Q: Passage: Next, we identify the least precise measurement: 13.7 kg. This measurement is expressed to the 0.1 decimal place, so our final answer must also be expressed to the 0.1 decimal place. Thus, the answer is rounded to the tenths place, giving us 15.2 kg. Significant Figures in this Text In this text, most numbers are assumed to have three significant figures. Furthermore, consistent numbers of significant figures are used in all worked examples. You will note that an answer given to three digits is based on input good to at least three digits, for example. If the input has fewer significant figures, the answer will also have fewer significant figures. Care is also taken that the number of significant figures is reasonable for the situation posed. In some topics, particularly in optics, more accurate numbers are needed and more than three significant figures will be used. Finally, if a number is exact, such as the two in the formula for the circumference of a circle, c = 2r , it does not affect the number of significant figures in a calculation. Answer: significant

A:
What type of numerical figure is important in considering the precision and accuracy of a number?
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