Hemoglobin levels being lower would be considered a normal change associated with aging.
Answer: Responsible for formation of reproduction cells/gametes
Explanation: Meiosis is significant because it makes sure that all organisms (which were produced via reproduction) contains the correct number of chromosomes. Also, Meiosis produces genetic variation by the process of recombination.
Vascular tissue
Of course plants don't have hearts, but they do have vessels which transport water, minerals, and nutrients through the plant. These vessels are the vascular tissue.