Answer:
A. If the aerobic pathway—cellular respiration—cannot meet the energy demand, then the anaerobic pathway—lactic acid fermentation—starts up, resulting in lactic acid buildup and "oxygen debt."
C. After about 90 seconds of intense exercise, the muscles become depleted of oxygen, and anaerobic respiration can no longer function to produce ATP, resulting in "oxygen debt."
Explanation:
There are two sources of carbohydrates in the human's body for energy (ATP) production. 1) Creatine phosphate and 2) Glycogen. Creatine phosphate metabolizes easily and yields ATP quickly. Whereas glycogen is stored form of carbohydrate which yields energy more slowly. Therefore, initially, our bodies use creatine phosphate and then shift to glycogen. Within 60-90 seconds, the creatinine phosphate in the body is mostly utilized and then energy is produced by the use of glycogen in aerobic pathway. During areobic pathway, oxygen supply is sufficient and per cycle, it produces 32 molecules of ATP. However, when oxygen supply is limited or absent, the body will metabolize glycogen to lactic acid via fermentation and produce only 2 molecules of ATP. 
Now consider the example: Kenny hikes all day at a steady pace therefore the supply of oxygen is sufficient for aerobic cellular respiration for ATP production. In this scenario, the oxygen debt is minimal and Kenny relies on aerobic respiration pathway to obtain energy. On the other hand, Janelle runs fast (100 meters in 13.5 seconds) and her cellular respiration would be on the compense of aerobic pathway initially which will be shifted to anaerobic pathway after the supply of oxygen is reduced/minimum. Janelle will heavily rely on the anaerobic pathway because running fast needs energy which cannot be provided via aerobic pathway easily. Therefore, Janelle's body will produce lactic acid and suffer from oxygen debt.
 
        
             
        
        
        
I’m pretty sure it’s hydrogen if I’m wrong I’m really sorry
        
             
        
        
        
They are known as evolutionary biologists. Strictly speaking, anthropology is split up into a number of disciplines - physical (sometimes known as biological) anthropology is the study of evolution as it relates to human beings. Further to this, scientists who study evolution in the fossil record are known as evolutionary palaeobiologists or simply palaeobiologists.
        
                    
             
        
        
        
The correct answers are 2. arid climate and 4. oil resources
The climate always causes environmental climate, especially arid one, while oil both extraction and production creates environmental problems.
        
             
        
        
        
Answer:
Haploid cells are produced when a parent cell divides twice, resulting in two diploid cells with the full set of genetic material upon the first division and four haploid daughter cells with only half of the original genetic material upon the second.