An electrocardiogram (ECG) provides information about B) the rhythm of heart contractions
The rhythm of heart contractions can be known by an electrocardiogram (ECG).
An ECG or Electrocardiogram is a method to diagnose the heart conditions to check the normal functioning of the heart.
The process to measure the electrical signals of the heart can be done by using this machine.
In this technique, three leads are attached to both the wrist and the left ankle to measure the electrical activity of Heart. The rhythm of the heart contraction and relaxation can be used to find out any heart abnormality.
It is used to investigate the heart problems associated due to bad health or some chronic inflammation affecting the functioning the body. Shortness of breath or nausea is investigated by using an ECG machine to help the patient and doctor to find out the cause.
It consists of QRS complex which measures the heart beat.
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Ans.
Sickle-cell disorder shows defected red blood cells, due to mutation in gene that code for hemoglobin. The mutated genes for sickle-cell disease are found in higher percentage of sub-Saharan African population as it provides protection against malaria as compared to population of United States.
Malaria is common in sub-Saharan Africa region and there, natural selection favored gene for sickle cells, because it might be beneficial to people having sickle cell disease that makes them able to survive in such condition and transmit their genes to offspring.
On the other hand, in those Africans, who moved to United States, where malaria is uncommon or absent, natural selection favored normal, wild type genes, resulting in fewer people with defected sickle cell.
Thus, the evolutionary process behind this is 'natural selection.'
