Answer:
fully oxygenated blood returning to the amphibian heart can undergo additional pumping to reach higher pressures.
Explanation:
Fishes have a two-chambered heart with one atrium and one ventricle. The blood is pumped from the atrium into the ventricle. Ventricle pumps blood into a single circuit of blood vessels. Blood is oxygenated as it passes through capillaries in the gills. As blood circulates through the gill capillaries, it has low blood pressure and therefore, is delivered very slowly to the other organs.
The amphibian heart has two atria and one ventricle. A sinus venosus collects oxygen-poor blood and pumps it into the right atrium. Oxygenated blood from the lungs passes directly into the left atrium. The left atrium pumps the oxygen-rich blood into the arteries that conduct it to the various tissues of the body. Therefore, a three-chambered heart in reptiles allows the delivery of oxygenated blood with high blood pressure.
There are approx 100 billion
Answer: The shape of the skull and the supraorbital height tell us the following about each species-
- It can tell us about the intelligence of species and what all senses they were dependent upon for their survival
- Most of the species possess similar skulls as mostly their structures are oval shaped, sloped or round shaped.
- Species have different food habits that is determined by the teeth, which vary from long and dull to short and dull.
- Variation in teeth and face shapes could also be due to different geological locations.
- In particular, the foramen magnum be located where the spine connects can be attributed to how the species gathered food through hunting and what kind of food they sought after.
- Overall, the shape and the supraorbital height of each skull informs us the advantages and disadvantages each species had in its ecosystem.
- It also tells what probable causes of death would be when the species died.
Answer:
they have thin membranes to allow diffusion of substance for short distance
they are numerous to increase the surface area of absorption
hope this helps