1 prokaryotic- a cell that lacks a nucleus and membrane-bound organel
2 eukaryotic-a cell that has a nucleus
3. Cell theory the theory that states that the cell is the basic unit of life and that cells come only from existing cells
4 cell - the basic unit of life 
 
        
             
        
        
        
The words which comes in the blanks are NADH and electron.
<span>A molecule generated in both glycolysis and krebs cycle, called NADH , donates electrons to the first protein in the electron transport chain.
Kerbs cycle is also known as citric Acid cycle or tri-carboxylic acid cycle.
</span>NADH<span>, stands for nicotinamide adenine dinucleotide, and it is an important pyridine nucleotide.</span>
        
             
        
        
        
The planets Mercury, Venus, Earth, and Mars, are called terrestrial because they have a compact, rocky surface like Earth's terra firma. The terrestrial planets are the four innermost planets in the solar system. ... Without life, most of the oxygen would soon become part of the compounds on the planet's surface.
        
             
        
        
        
Answer:
The correct option is A
Countercurrent multiplication is the process whereby energy is used to generate an osmotic gradient in which water is reabsorbed from the tubular fluid to produced concentrated urine.
Explanation:
Countercurrent multiplication moves sodium chloride from tubular fluid into interstitial space deep within the kidneys. The concurrent multiplication process build up osmotic gradient interstitial fluid in a single effect. Here, sodium chloride is driven by active transport out of the tubular fluid in the thick ascending limb into the interstitial fluid, which becomes hyperosmotic. This result to water moving passively down its concentration gradient out of the tubular fluid in the descending limb into the interstitial space to a point where it attains a state of equilibrium. 
Therefore,the correct option is A, where the ions leaves the ascending limb to make water comes out of descending limb.