【单选题】Which one of the following statements concerning plasmids is true?
A.
All plasmids can be transferred between bacteria by conjugation
B.
Much of the information coded in the plasmid is essential to the survival of the bacteria cell.
C.
R plasmids carry genes for antibiotic resistance.
D.
R plasmids cannot be transferred to other bacterial cells
E.
Plasmids lack an origin of replication
【单选题】Which of the following statements about genetic exchange in bacteria is NOT true?
A.
In conjugation there has to be a physical connection between the donor cell and the recipient cell.
B.
Plasmids do not have to integrate into the host cell chromosome in order to be replicated.
C.
Interrupted conjugation results in the production of Hfr strains.
D.
The order of gene transfer is not the same for different Hfr strains.
E.
Antibiotic resistance can be transferred from one bacterial cell to another by conjugation.
【单选题】《尼伯龙根的指环》分为四夜,其顺序是:( )
【单选题】Which one of the following is the most accurate description of the structural differences between gram-positive bacteria and gram-negative bacteria?
A.
Gram-positive bacteria have a thick peptidoglycan layer whereas gramnegative bacteria have a thin layer.
B.
Gram-positive bacteria have an outer lipid-rich membrane whereas gramnegative bacteria do not.
C.
Gram-positive bacteria form a sex pilus that mediates conjugation whereas gram-negative bacteria do not.
D.
Gram-positive bacteria have plasmids whereas gram-negative bacteria do not.
E.
Gram-positive bacteria have capsules whereas gram-negative bacteria do not.
【单选题】将相关系数及卡方检验应用于心理学与教育研究中的是
【单选题】电梯封闭式井道内应设置照明,并道最高与最低处各装设一灯外,中间灯距不超过()m。