二、申論題(共 75 分)1. 分層抽樣(stratified sampling)和叢集抽樣(cluster sampling)都是社會科學研究的常見抽樣方式。請描述這兩種抽樣的實施方式並說明優缺點。(15 分)若有一研究要針對新北市國中學生進行問卷調查，請各舉一個分層抽樣和叢集抽樣的例子。(10 分)

II.Short Questions (40%) 1. A nonapeptide was determined to have the following amino acidcomposition: (Lys)2, (Gly)2, (Phe)2, His, Leu, Met. The native peptidewas incubated with 1-fluoro-2, 4-dinitrobenzene (FDNB) and thenhydrolyzed 2,4-dinitrophenylhistidine was identified by HPLC. Whenthe native peptide was exposed to cyanogen bromide (CNBr), anoctapeptide and free glycine were recovered. Incubation of thenative peptide with trypsin gave a pentapeptide, a tripeptide, andfree Lys. 2,4-Dinitrophenyl- histidine was recovered from thepentapeptide, and 2,4-dinitrophenylphenylalanine was recoveredfrom the tripeptide. Digestion with the enzyme pepsin produced adipeptide, a tripeptide, and a tetrapeptide. The tetrapeptide wascomposed of (Lys)2, Phe, and Gly. What is the native sequence?(10%)

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