1 2 3 4 5 6 7 8 9 10 The structure of DNA resembles a twisted ladder. Which structural components form the rungs of the ladder?
deoxyribose sugars
phosphate groups
nitrogenous base pairs
ribosomes

Nitrogenous base pairs

a community that experiences major changes undergoes progress

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.