A: 250
B: 350
C: 500
D: 650
举一反三
- Which of the following cells in the testis contain the most smooth endoplasmic reticulum?() A: Spermatogonium B: Leydig cell C: Smooth muscle cell D: Sertoli cell E: Spermatid
- 中碳钢也叫调质钢,常用来制造综合性能要求高的零件,淬火后常用的回火温度是( )。 A: 150~250℃ B: 250~350℃ C: 350~500℃ D: 500~650℃
- A bacterial cell transfers chromosomal genes to F- cells, but it rarely causes them to become F+. The bacterial cell is: A: Hfr. B: lysogenic. C: Auxotrophic. D: lytic.
- 中温回火的温度在( )℃范围内. A: 150~250 B: 250~500 C: 500~650 D: 650~727
- If two genes from a parent cell are on the same chromosome, which of the following best explains why the daughter cells may not have the same alleles as the parent for both genes? A: they are linked genes B: they are unlinked genes C: crossing-over D: genetic mutation
内容
- 0
Which of the following statements pertaining to the acinar cells<br/>of pancreas is true() A: The nucleus is located at apex of the cells B: The base of the cell is basophilic duo to RER C: The Golgi complex is located on the basal side of the nucleus D: The cells contain mucigen granules E: The secretory granules contain active form of enzymes
- 1
中温回火的温度一般控制在（）范围内。 A: 150℃～250℃ B: 250℃～500℃ C: 500℃～650℃ D: 250℃～450℃
- 2
In positive regulation, most of the genes are usually inactive (that is, RNA polymerases do not bind to the promoters) and the cell synthesizes only the activator proteins needed to promote transcription of the subset of genes required in the cell at that time.
- 3
Tumor suppressor genes encode proteins that normally restrain cell division. Mutation in one or more of these genes can lead to tumor formation.
- 4
The patient, male, 30 years old, was found HIV antibody positive in physical examination. Which kind of cells in his body is most significantly reduced A: CD4 + T cells B: CD8 + T cells C: B cells D: NK cells E: Monocytes