When a person starts exercising (running) the increase in energy expenditure causes an elevation of oxygen consumption and carbon dioxide production. To compensate for this the respiratory control center senses the LOW oxygen level in blood and the HIGH carbon dioxide level and signals the diaphragm to contract and relax more often (INCREASE THE RATE).
The answer is B
        
                    
             
        
        
        
oml that cat is so cute!!!! Animal cells come in many different shapes and sizes. The shapes of cells have evolved to help them carry out their specific function in the body, so looking at a cell's shape can give clues about what it does.
 
        
             
        
        
        
M phase, or mitosis. 
(You don't need to know this for your course but more properly cell division could also refer to meiosis or binary fission.)
        
                    
             
        
        
        
Answer:
<u>acetylcholine</u>
Explanation:
In the pre-synaptic knob there are vesicles which contain a transmitter substance called acetylcholine. When an impulse reaches the synaptic knob, it stimulates the vesicles to move towards the pre-synaptic membrane releasing the acetylcholine.
The transmitter substance makes the membrane permeable. The neuromuscular junction contains the sensory neurone(afferent), motor neurones(efferent) and the relay neurones(connector).
 
        
             
        
        
        
B. Crystalline structure
C. Types of chemical elements
And
D. Amounts of chemical elements