Answer:
The nitrogenous bases guanine and adenine are A. purines.
Explanation:
Adenine and guanine are purines, whereas the other two bases in DNA (thymine and cytosine) are pyrimidines. The main difference between purines and pyrimidines is the number of rings that the base has: purines have two rings while pyrimidines only have one ring.
In addition, phosphate group and sugar group cannot be the answer to this question because these two elements in addition to a nitrogenous base makes up a nucleotide.
Hope this helps!
Could you add the picture please?
<span>descriptions of the number, size, and arrangement of parts of the organism.</span>
The laboratories have initiated Phase 1 clinical trials for the use of human pluripotent embryonic stem cells to treat paralyzed patients following spinal cord injury. The first step is to estimate the risks and tolerance of cell transplantation in a man. The fate of stem cells (multipotent or pluripotent) in the body is still poorly understood, and it is not excluded that uncontrolled cell multiplications occur, leading to the appearance of teratomas (tumor developed from pluripotent cells).
Advantages are:
* The safety of the cells also seems to be proven (in short term)
* Rats transplanted seven days after the injury had benefited from reactivation of myelinization of neurons by oligodendrocytes, attenuation of motor neuron loss and improvement of limb motor function.
The disadvantages are:
* Constraints of the ethical and religious order, it is necessary the consent and the approval of the donor and the recipient for the transplant to take place.
* The development of the technique is still new, there is a chance that side effects of the transplant appear years after the operation.
