Answer:
Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. People who are lactose intolerant cannot extract energy from milk because no lactase to digest the sugar into energy. To overcome the problem, food manufacturers began to create milk without lactose.
Explanation:
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Answer:

Explanation:
We are asked to find how much of a 40 gram sample remains after 12 years. 
Iron-55 has a half-life of 3 years. Therefore, after 12 years, 4 half-lives have been completed. 
- 12 years/3 years = 4 half-lives
Every time a half-life is completed, half of the sample's mass decays. Remember we start with a 40 gram sample. 
- 1 half- life: 40 g / 2 = 20 g 
- 2 half-lives: 20 g / 2= 10 g 
- 3 half-lives: 10 g / 2 = 5 g
- 4 half-lives: 5 g / 2 = 2.5 g
There is also a formula that can be used to solve this problem. 

Where A₀ is the initial amount, t is the time, and hl is the half-life. 
We know 40 grams is the inital amount, 12 years is the time, and 3 years is the halflife. 




After 12 years, <u>2.5 grams </u> of Iron-55 will remain. 
 
        
             
        
        
        
Ribosomes, mitochondria, ER and chloroplast.