下载APP
【单选题】
Which mechanism can explain two strands are synthesized in the opposite direction, in the replication fork?（ ）
A.
semiconservative replication
B.
priming of DNA synthesis
C.
semidiscontinuous replication
D.
bidirectional replication
举报
参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【多选题】The correct description about decompression reflex is that（ ）
A.
The receptors are located in the carotid sinus and the aortic arch
B.
The efferent nerves are the sympathetic and vagus nerves
C.
Reflexes only result in lower blood pressure
D.
The center is located in the medulla oblongata
E.
The afferent nerves are the aortic and sinus nerves
【多选题】The main factors affecting pulmonary ventilation are （ ）.
A.
Area and thickness of respiratory membrane
B.
Body weight
C.
Breathing rhythm
D.
Vital capacity
E.
Alveolar ventilation/blood flow ratio
【多选题】Active reabsorption of renal tubules（ ）
A.
H2O
B.
K+
C.
Glucose and amino acids
D.
Na+
E.
Urea and H+
【多选题】The 1:1 transmission of excitation at the nerve-muscle junction is due to（ ）
A.
The end plate potentials generated are large enough
B.
High excitability of endplate membrane
C.
The absolute refractory period of endplate membrane is long
D.
A nerve impulse releases a sufficient number of transmitters from the nerve endings
E.
Ach was hydrolyzed by cholinesterase in the joint clearance in time
【单选题】Which component of the prokaryote RNA polymerase holoenzyme is involved in recognizing promoters specific to certain types of genes? （ ）
A.
α
B.
β
C.
σ
D.
β’
【单选题】Etiology of centripetal obesity（ ）
A.
Excessive glucocorticoid secretion
B.
Lack of protein in food
C.
iodine deficiency in food
D.
Insufficient growth hormone secretion in childhood
E.
Hypothyroidism in childhood
【多选题】The characteristics of nerve fiber conduction excitation are（ ）
A.
Sum
B.
Bidirectional conduction
C.
Insulation
D.
Fatigue
E.
Structural and functional integrity
【多选题】Factors that can increase myocardial contractility include（ ）
A.
Increased Ca2+ affinity for troponin
B.
reduced ventricular preload
C.
increased catecholamines
D.
Increased myosin ATPase activity
E.
Increased Ca2+ concentration in extracellular fluid
【单选题】We usually call codons contains 5 characteristics, among which the degeneracy of the genetic code means?（ ）
A.
Most amino acids have more than one set of codons
B.
There are many rare bases in the code which translate rare amino acids
C.
A triplet codon can lack or insert a purine or pyrimidine base
D.
At least nine codons apply to more than one amino acid