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. 
 
        
             
        
        
        
Answer: p53
Explanation:
In most cases, the p53 gene is mutated, giving rise to a stable mutant protein whose accumulation is regarded as a hallmark of cancer cells.
 
        
             
        
        
        
Deoxyribose+phosphate group+polymerase can be found in DNA molecule.
        
             
        
        
        
Answer: Some consequences of building the road are that it will provide loggers access to highly-valued trees, provide a more accessible trade route for merchants and farmers, affect the wildlife and water quality in the area, and possibly cause indigenous populations to relocate.
Explanation:
 
        
             
        
        
        
Answer:
The correct answer is - regulation of the heavy metal and their toxicity.
Explanation:
Metallothionein is a group of cysteine-rich, small in size, and highly conserved proteins that bind to various metal ions and regulate their activity or toxicity in transcriptional level.
Metallothionein IIA is one of the metallothioneins that binds to heavy metal and helps cells to be protected from the toxicity of these heavy metals. These proteins are present in almost every eukaryotic organisms virtually. These proteins are highly induced to express highly in the present of heavy metals.
Thus, the correct answer is - regulation of the heavy metal and their toxicity.