Which is not true of mature red blood cells? a. they have a nucleus b. they have a biconcave structure c. they contain hemoglobin d. they transport small amounts of carbon dioxide

Its B because every cell has a nucleus and red blood cells are actually rich with hemoglobin and they  release the carbon dioxide picked up from body tissues and become saturated with oxygen. (im sorry if this is wrong but im 89% sure im right)

a. seed plant structure. 1. the three main plant organs are roots, stems, and leaves. a fourth kind of tissue, meristematic tissue, is responsible for plant growth. meristematic tissue is the only plant tissue that produces new cells by mitosis. plants can lose water out of their leaves as they exchange gases with the air

explanation: