【简答题】固体培养基是在液体培养基中加入2%~3%的 ,加热溶化经冷却凝固后即成。
【单选题】The following description about Na + -K + pump is wrong
A.
Only distributed on the cell membrane of excitable cells
B.
is a protein embedded in the cell membrane
C.
Capable of decomposing ATP
D.
Can constantly move Na + out of the cell membrane and K + into the cell membrane
【单选题】Which statment is not correct description about the Na+---K+ pump?
A.
Na+--K+ pump is ATPase.
B.
It pumps K+ intothe cell and Na+ out of the cell.
C.
Na+--K+ pump is a transmembrane protein complex.
D.
It pump Na+ and K+ along their concentrayion gradient.
【单选题】以下叙述错误的是
A.
培养基按其物理性状可分为固体、半固体、液体3类
B.
根据细菌在固体培养基上的生长特点,可将菌落分为S型、R型、M型3型
C.
细菌在液体培养基中可出现浑浊生长、沉淀生长和菌膜生长3种状态
D.
挑取一个菌落接种到另一培养基中培养称为纯培养
E.
在液体培养基中加入2%~3%琼脂,即为半固体培养基
【单选题】设某消费者仅消费X、Y两种商品,其价格分别为8角、2元,已知达到消费者均衡时消费的X为5件,第5件提供的边际效用为28单位,则这时消费的最后一单位Y提供的边际效用为()
【单选题】设某消费者仅消费X、Y两种商品,其价格分别为5角、1元,已知达到消费者均衡时消费的X为5件,第5件提供的边际效用为28单位,则这时消费的最后一单位Y提供的边际效用为()
【判断题】对于年轻游客在用于上要注意称呼,要有礼貌,对名胜古迹要作详细介绍,并重复。( )
【单选题】The Na + /K + pump ( )
A.
moves 3 K + in and 2 Na + out each cycle.
B.
moves 2 K + in and 3 Na + out each cycle.
C.
moves 3 K + in and 3 Na + out each cycle.
D.
moves 2 K + in and 2 Na + out each cycle.
【多选题】How does the Na + pump undergo a series of conformational changes as it exchanges Na + ions for K + ?
A.
The binding of cytosolic Na + (1) and the subsequent phosphorylation by ATP of the cytosolic face of the pump (2) induce the protein to undergo conformational changes that transfer the Na + across the membrane and release it outside the cell (3).
B.
The high-energy linkage of the phosphate to the protein provides the energy to drive the conformational changes.
C.
The binding of K + from the extracellular space (4) and the subsequent dephosphorylation (5) allow the protein to return to its original conformation, which transfers the K + across the membrane and releases it into the cytosol (6).
D.
The real pump in mammalian cells contains three binding sites for Na + and two for K + . The net result of one cycle of the pump is therefore the transport of three Na + out and two K + in. Ouabain inhibits the pump by preventing K + binding (4).
【单选题】设某消费者仅消费X、Y两种商品,其价格分别为每单位1元、2元,已知达到消费者均衡时消费最后一单位的Y边际效用为20,则这时消费的最后一单位X的边际效用大约为()