Chapter 11 : specific features of meiosis

Meiosis has three unique features : The mechanism of cell division varies in important details in different organism. This is particularly true of chromosomal separation mechanism, which differ substantially in protists and fungi from the process in plants and animals that we will describe here. Meiosis in a diploid organism consists of two rounds of […]

Chapter 10 : meiosis

The sequence of events during meiosis involves two nuclear divisions ( meiosis I and meiosis II ). Prophase 1 In prophase 1 of meiosis, the DNA coils tighter, and individual chromosomes first become visible under the light microscope as a matrix of fine threads. Because the DNA has already replicated before the onset of meiosis, […]

Chapter 9 : Replication

 1) Definition The DNA replication is one of the key mechanisms of  cell cycle. It is a highly regulated biological process in which new synthesis and  repair mechanisms ensure the integrity of the genome. S phase or replication phase follows the G1 phase during which the cell synthesizes all the elements necessary for this replication. […]

Chapter 5 : exercices and exam questions (probability)

Problem 1: A marketing survey indicates that 60% of the population owns an automobile, 30% owns a house, and 20% owns both an automobile and house. Calculate the probability that a person chosen at random owns an automobile or a house, but not both. (A) 0.4               (B) 0.5                     (C) 0.6               (D) 07              (E) 09 Problem […]

Chapter2: torque and angular momentum in circular motion

Definitions: the torque and angular momentum are defined as vector products of position, force and momentum. Suppose a forceacts on a particle whose position with respect to the origin 0 is the displacement vector . Then the torque “about the point 0 and acting on the particle,” is defined as: Now suppose the particle has […]

Chapter 1: uniform circular motion

When an object has a circular motion even though its speed is constant, it is nonetheless accelerating because according to newton’s 1st law: an object continues in its state of rest or uniform motion unless acted on by an external force. So if the object was to be free in space then of course it will […]

گروه همیاری دانش اموختگان ایرانی مقیم اروپا

   -این گروه هیچگونه وابستگی به سازمان و یا دولت ویا تشکیلاتی را ندارد و تمامی مخارج ان از  کمکهای انسان   دوستانه تامین می شود .به همین دلیل توان مالی بسیار زیادی نداشته و تعداد معدودی بورس تحصیلی        در اختیار نوابغی که به علت فقر خانوادگی و یا هر دلیل دیگری قادر […]

Chapter 7 : Photosynthesis

                                 Photosynthesis Photosynthesis is the process that converts solar energy to chemical energy. Directly or indirectly, photosynthesis nourishes almost the entire living worlds -Autotrophs sustain themselves without eating anything derived from other organisms -Autotrophs are the producers of the biosphere, producing […]