Answer:
What impact does a decrease in pH have on urchins?
Decrease in pH simply means high degree of acidity which affects every living organism. The impact of high acidity affects there food intake, development of their young ones (juvenile)
Explanation:
IF:
Number of cells:

DNA lenght:

Distance from Earth to Sun:

Then:
a) <span>Over how many miles would the total DNA from the average human stretch?
The answer is product of multiplication of the number of cells (C) and the DNA length (D):
Total DNA: </span>

⇒

⇒

⇒
The total DNA from the average human will stretch 
b) How many times would the total DNA from the average human stretch from Earth to the Sun and back?
The answer is concluded from the ratio of the total DNA length (T) and the <em>twice </em>(because of stretch to the Sun and back, thus, <em>two directions</em>) of distance from <span>Earth to the Sun (ES) and :
Ratio: </span>

⇒

⇒

⇒

<span> ⇒

</span><span> ⇒ [tex]R = 667.7
</span>
Thus, 667,7 times will the <span>
total DNA from the average human stretch from Earth to the Sun and back.</span>
I assume the mountainous area.
Explanation: Hydroponic describes planting without soil. When there is erosion on a mountain area, any soil or dirt would likely go away.
Hope this helps!
An astronomical unit (AU) is the approximate distance from the earth to the sun. The answer is D.