Answer:
Many parts of the cardiovascular system (including the heart) are influenced by gravity. On Earth, for example, the veins in our legs work against gravity to get blood back to the heart. Without gravity, however, the heart and blood vessels change – and the longer the flight, the more severe the changes.
The main structural difference between LDL and HDL is their compositions. Approximately 50% of the weight of an LDL particle is cholesterol and only 25% is protein. High-density lipoprotein particles, on the other hand, consist of 20% percent cholesterol by weight and 50% protein.
A diploid cell contains two complete sets of chromosomes, while a haploid cell only one set.
