At room temperature and normal atmospheric pressure, covalent compounds may exist as a solid, a liquid, or a gas, whereas ionic compounds exist only as solids, Ionic compounds exist in stable crystalline structures. Therefore, they have higher melting and boiling points compared to covalent compounds.
Answer:
Neutron stars are one of the possible ends for a star. They result from massive stars which have mass greater than 4 to 8 times that of our Sun. After these stars have finished burning their nuclear fuel, they undergo a supernova explosion. ... It collapses so much that protons and electrons combine to form neutrons.
We do not use carbon dioxide to fuel our blood cells. It is a waste.
Arteries move blood from the heart to the rest of the body.
Veins carry the blood to the heart to be oxidized.
"D" is not correct.
"B" is not correct.
We know that veins carry blood to the heart, lungs exhale carbon dioxide.
"A" is the correct answer.
I hope this helps!
~kaikers
Answer:
Cytochrome c is an enzyme found in bacteria, fungi, plants and animals. Here it is given that the human amino acid sequence for cytochrome c differs at 12 locations from the sequence in horses and pigeons. This information might be useful for inferring in preliminary stages that horses and pigeons are closely related to each other since they both show similar amount of difference from humans.
However, this hypothesis is being made with respect to the the comparison between "humans and horses" and "humans and pigeons". To further test this hypothesis pigeons and horses should be directly compared to each other without the use of a third species like humans. Hence, the sequence for cytochrome c in horse and pigeon should be compared with each other rather than comparing to humans.
