Rate of heart beat is determined by :
AV-node
SA-node
Purkinje fibres
Papillary muscles
C.
Purkinje fibres
Purkinje fibres are also called nodel tissue. It is a bundle of specialized cardiac muscle fibres. It receives rhythmical impulses of electrical excitation from the pace-maker and spreads the waves of contraction through the ventricle walls.
A person breathing normally at rest, takes in and expels approximately half a litre of air during each respiratory cycle. This is called :
tidal volume
vital capacity
inspiratory reserve volume
expiratory reserve volume
The first heart sound is produced when :
diastole begins
semilunar valve close quickly
interventricular pressure decreases
bicuspid and tricuspid valve close quickly
Mesophyll cells, which liberate malic acid at night time, are of :
C4 - plants
C3 - plants
C2 - plants
C1 - plants
The plants respond to photoperiods due to the presence of :
enzymes
stomata
phytochromes
phytohormones
Asthma is caused due to :
infection of lungs
infection of trachea
bleeding into pleural cavity
spasm in bronchial muscles
The name of process of aerobic respiration, in which energy is provided in steps in electron transport chain, is :
EMP-pathway
decarboxylation
photophosphorylation
oxidative phosphorylation