Hydrogen bonding, ionic bonding, dipole-dipole interactions, and London dispersion forces!
        
                    
             
        
        
        
<span>A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation.</span>
        
             
        
        
        
Answer:
There was no sulfur compound added to the medium, that could be used as an electron donor.
Explanation:
Bacteria that use light for energy requirements mean that they get their energy from photosynthesis and transferring energy through the molecules.
Bacteria play a major part in the reductive and oxidative cycle of the sulfur which is mediated by the help of photosynthetic bacteria, so the sulfur or sulfur compounds are major requirements for their growth in the habitat or the medium.
Thus, the correct answer would be- There was no sulfur compound added to the medium, that could be used as an electron donor.
 
        
             
        
        
        
Answer:
Pacemaker cells are located in the <u>sinoatrial node.</u>
Contractile cells are located in the <u>Heart</u>
Explanation:
 
        
                    
             
        
        
        
There are four environments on Earth that are called spheres: hydrosphere, lithosphere, atmosphere, and biosphere.
<h3>Features associated with each of Earth's four spheres.</h3>
<h3>Hydrosphere </h3>
It is the set of all the water on the planet, including those that form clouds.
<h3>Lithosphere</h3>
 The continuous part of our planet, made up of rocks and soil. The most superficial part is called the earth's crust.
<h3>Atmosphere</h3>
It is the gaseous sphere that surrounds our planet, composed mainly of gas oxygen and gas.
<h3>Biosphere </h3>
It is the part of our planet that can support life
<h3>Internal processes</h3>
The atmosphere and hydrosphere are the main regulators of the planet's climate. Without both, the temperature changes would be very sudden: at night it would drop to minus 150°C and during the day above 100°C, making life on Earth difficult.
With this information, we can conclude that the spheres of the earth, support life, and make the planet earth unique.
Learn more about Spheres of the earth in brainly.com/question/1155156