Answer:
a. is converted to NAD+ by an enzyme called dehydrogenase
Explanation:
The electron transport chain of cellular respiration is the final step that oxidized NADH and FADH2. These reducing powers are formed during glycolysis and Kreb's cycle. Complex I of the electron transport chain present in the inner mitochondria membrane is NADH dehydrogenase. This protein complex accepts electrons from NADH and oxidizes it into NAD+. NADH dehydrogenase couples oxidation of NADH with the pumping of proton towards the intermembrane space.
 
        
             
        
        
        
Answer:
Cranial capacity increased the most from 2 million years ago to the present.
Explanation:
The rate of change is greatest between 2 million years ago and the present.
 
        
                    
             
        
        
        
Answer:
1. give up 1
2. give up 2
3. give up 3 
4. gain 3
5. gain 2
6. gain 1
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Answer:
Dust bowl resulted from extreme drying and loosening of the soil that resulted in soil erosion by wind. Thus, it can be related that poor agricultural practices like over plowing , over grazing and leaving the land barren are human activities that must have contributed to the dust bowl.
Explanation:
- Dust bowl is referred to a period in early twentieth century when the the American and Canadian prairies faced severe dust storms.
- These dust storms resulted from severe drought and failure of practices to prevent soil erosion.
- Several people and livestock died as a result of choking.
- Over plowing, removal of top soil and  small grasses exposed the soil to eroding winds and caused the dust storms.
 
        
             
        
        
        
Its A. it prevents sperm from reaching the egg and fertilizing it.