أكتوبر 9th, 2018

 

abscisic acid حمض الأبسيسيك

A plant hormone (C15H20O4) and weak acid that generally acts to inhibit growth, induces dormancy, and helps the plant tolerate stressful conditions by closing stomata. Abscisic acid was named based on a belief that the hormone caused the abscission (shedding) of leaves from deciduous trees during the fall. At times when a plant needs to slow down growth and assume a resting stage (dormant), abscisic acid is produced…

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ABO blood groups زمر (أنواع فصائل) الدم

Blood group antibodies (A, B, AB, O) that can destroy red blood cells bearing the antigen to which they are directed; also called “agglutinins.” These red-cell antigens are the phenotypic expression of inherited genes, and the frequency of the four main groups varies in populations throughout the world. The antigens of the ABO system are an integral part of the red-cell membrane as well as all cells throughout…

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