The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
Answer:
The limitation of phylogenetic species concept is b. Evolutionary histories are not known for all species.
Explanation:
The species that share a common ancestor and have similar traits and functions are grouped together as a result of the phylogenetic species concept. The phylogenetic species concept shows a unique evolutionary history of one organism with another of the same group. The major set back in the phylogenetic species concept is the lack of evolutionary histories for certain species. So, these organisms cannot be grouped according to the phylogenetic species concept.
Answer:
In myopia the image is focused ahead of the retina. While in Hyperopia the image is focused beyond or behind the retina.
Explanation:
I'll start by defining the two key terms, Myopia and Hyperopia. Myopia is otherwise called short-sightedness. It is a condition where one cannot see the images of objects located far away from the eyes and tend to see images within a short distance from the eyes. Hyperopia on the otherhand is otherwise known as long-sightedness. It is an eye defect which manifests by one not seeing objects close to the eyes instead he or she see only objects far from the eyes. These two eye defects are a malfunction of the accomodation feature of the eye.
Normally when an object is viewed all the parts of the eye (the organ for vision) function to focus the image of that object on the retina but especially on a part of it called the *light spot*. This then translates the image to the brain using the optical nerve. The brain then interpretes what is being viewed
However in Myopia, images are focused ahead of the retina . This is as a result of the eyeball being too long in relation to the focusing power of the cornea and eye lens.
In Hyperopia on the other hand, images are focused behind the retina. This is by the diameter of the eye being too short or the cornea being too flat.
In conclusion, from the above stated points,it is glaring that Myopia and Hyperopia affect the lens's ability to focus images on the retina.
It would be substitution because an incorrect base pair is being replaced.... hopefully thats right?
