Which of the following is a group of cells that sends signals to control the heart rate? atrium pacemaker septum valve

The relationship between intron and exon

Can someone pretty me with this ? it’s urgent.compare the three theories of emotion. here are the three theories of emotion. cannon-bard theory of emotion: the belief that both psychological arousal and emotional experience are produced stimultaneously ( at the same time) by the same nerve stimulus. james-lange theory of emotion: the belief that emotional experience is a reaction to bodily events occurring as a result of an external situation. ( “ i feel sad because i am crying.) schachter-singer theory of emotion: the belief that emotions are jointly determined by a nonspecific kind of psychological (bodily function) arousal and its interpretation, based on environmental ( natural surroundings) cues. which of these theories makes most sense to you? why. your response should be written using proper english spelling and grammar. and it needs to be 10 complete sentences.

How do the sperm cells get from the stigma to the ovules?