Answer:
Unlike typical mammalian red blood cells, those from amphibians, such as frogs, contain a DNA-bearing nucleus that is visible in the center of the cell. The circulatory system of amphibians is rather unusual, their hearts having three chambers, two atria, and a single ventricle.
NegativePositive
Positive
The design of the amphibian circulatory system is curious because blood accumulates oxygen in the lungs and is then returned to the heart before being pumped into the rest of the circulatory system. Therefore, a mixing between oxygenated and deoxygenated blood occurs as blood returning to the heart from the lungs is mixed with incoming blood from the body. Frogs handle this situation by having a very slow metabolism and by absorbing some oxygen through their skin. In addition, the ventricle does have some directional control over the distribution of the blood.
Negative
The presence of a nucleus in amphibian red blood cells allows researchers easy access to large quantities of amphibian DNA. Frog blood has both a solid and a liquid portion. The liquid plasma carries solid elements such as red and white blood cells. Blood can be collected from frogs and the red blood cells isolated by centrifugation. After removal of the residual plasma, purified cells can be treated with specific enzymes and detergents to digest the cellular envelope and release DNA from its protein complex. The DNA is then useful for scientific studies and experiments.
Featured in: Phase Contrast
Explanation:
Answer:
The parameters of the area when organizing the population of the biosphere is called a specie.
B. They had adapted to their surroundings.
Adaption observed by Darwin on the Galapagos Islands also lead to the idea of Natural Selection: that those better suited to survive in their environment will continue to live and reproduce, passing on the traits to help the descendants survive as well.<span />
Answer:
The correct answer would be thrombin.
The last step in the blood clotting is the formation of a fibrin clot.
Thrombin is the serine protease (protein) enzyme which activates fibrin.
It converts the soluble fibrinogen into the insoluble fibrin which then results in the blood coagulation.
Answer:
The annual average CO2 concentration for 2021 could be around 416.3ppm, according to Meteorological Office estimates. An annual rise of about 2.5 ppm is possible, which can potentially make 2021 the first year with the annual average CO2 at 50 per cent above pre-industrial levels, the estimates noted
