There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
Considering that homeostasis is restored in the patient, his blood pH range would return to normal levels (7.35-7.45), and his hydrogen ion concentration in the blood would normalize. The effect of normalizing the body by getting rid of excess hydrogen ions is achieved by concentrating these ions into the urine for expulsion, therefore increasing the pH levels of urine.
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Explanation:
Acidosis is the condition wherein excessive acid build-up within the body causes the blood pH to become lower than normal (normal pH range 7.35-7.45). This may be due to an excessive loss of bicarbonate in the blood, also known as metabolic acidosis, or due to an impairment in the elimination of carbon dioxide in the blood from poor lung function, also known as respiratory acidosis. The body's natural response to acidosis is to increase the breathing rate to eliminate carbon dioxide in the blood, restoring the natural pH of the body.
In people with diabetes mellitus type I, the lack of insulin causes cells to breakdown fat aside from glucose as an energy source. This process produces ketones as a metabolic by-product for energy but also causes the body to be acidic. This is known as diabetic ketoacidosis.
Answer:
Transitional epithelium has dome shaped cells on the apical surface.
To find the average they also take into account the salary of the president, who probably makes a lot more than $20,000.
Answer:
D) Sea otters are a keystone species as they prevent a herbivorous species from completely destroying a plant species.
Explanation:
