Answer:
3.9 billion years
Explanation:
The half-life of potassium-40 is the time it takes for half of it to decay.
After one half-life, half of the original amount will remain.
After a second half-life, half of that amount will remain, and so on.
We can construct a table as follows:

We see that the mass will drop to 10 g after three half-lives.
1 half-life = 1.3 billion years
3 half-lives = 3.9 billion years
Answer. D
Explanation:
After the messenger RNA (mRNA) is formed, it has to go trough different steps before being translated into proteins, also known as maturation of the mRNA. One of the most important steps is splicing, a process that removes the introns (regions of the sequence that do not codify for any particular amino acid sequence or protein). In other words, the splicing process removes sequences that do not generate any protein, leaving only the exons to be translated into protein. However, the genes (within our DNA) will contain exons and introns; Therefore, the gene sequence will have more kilobases compared to mature mRNA as the introns in this macromolecule have been spliced out.
I hope this clarify your question
.
The answer is true, I believe, correct me if I am wrong
Answer:
Option E.
In order for oxygen in the inspired air to reach hemoglobin, it must diffuse across all of the following structures, except: one or two smooth muscle cells.
Explanation:
- In the process of oxygen reaching hemoglobin it gets diffused across layer of surfactant, an endothelial cell, type I pneumocyte, and the plasma membrane of the erythrocyte.
- The molecule that is responsible for the carrying of oxygen into the blood cells is protein hemoglobin.
- The normal adult human's blood is the mixture of six different species of hemoglobin molecules. These all molecules consist of same function as well as structure.
The deep organs
Hope this helps :)