Biology Blogs For Class11th, 12th and NEET

                                      Menstruation cycle Every month females in their life passes through their reproductive cycle. In this cycle, the female prepares itself for a possible pregnancy if the pregnancy not happens then the body aborts all its preparation done for pregnancy and starts again for a possible pregnancy. Generally, this cycle starts when a female attains it’s s puberty stage called Menarche . After a particular age i.e., 40-50 this cycle stops and known as Menopause.            Duration - generally the duration of this cycle is ideally 28 days but in some cases, its duration extends from 28 to 32 .                                           Phases -  This cycle completed in four phases -        Menstrual Phase        Pre - Ovulatory Phase         Ovulatory Phase          Post-Ovulatory Phase   Menustartion Phases -   During days 1-5, a low level of female sex hormone in the body causes the endometrium to disintegrate and its blood ves

                                     Spermatogenesis                                                                                     Spermatogenesis is the process of formation of sperms from the germinal epithelium of the seminiferous tubules of the testes. The germinal epithelium contains cuboidal primordial germ cells and tall somatic cells called Sertoli cells or nurse cells. Thesertoli cells anchor the differentiating cells and provide nourishment to the developing sperms. Phases of spermatogenesis - It involves the following two phases - A. Formation of spermatids - It includes the following phases - Multiplication phase - The sperm mother cells or spermatogonia mitotically divides to form new sex cells. Some of these cells move towards the lumen of the seminiferous tubules and enter the growth phase known as Primary spermatocyte . Some cells produced this way remain in their original position and continue to divide giving rise to primary spermatocyte

                           Hatch and Slack Pathway / C4 Cycle                                                    In 1967  Hatch and Slack proposed a pathway for dark reaction occur in sugarcane and maize plants. The first stable product is OAA, which is  4C, dicarboxylic acid. That is why the hatch and the slack pathway is also known as the C4 cycle. the detailed process is explained below -                                         Process - The primary acceptor of carbon dioxide in C4 cycle plants is phosphoenol pyruvic acid (PEP). It accepts carbon dioxide and forms oxaloacetic acid (OAA). OAA is the first stable product which is having four-carbon dicarboxylic acid. The reaction is catalyzed by PEP carboxylase. This is called beta carboxylation . This takes place in the mesophyll cell. OAA is reduced to malic acid. The electron necessary for this reduction is supplied by NADPH. The enzyme malic dehydrogenase catalyzes the reduction. The carboxylation of PEP and redu

                                   Conducting System of the Heart      The right and left bundle branches of the AV node, the SA node, the Purkinje fibre, and the AV bundle make up the heart's conductive system. The sinoatrial node (SA) located in the wall of the right atrium near the superior vena cava.  The specialized muscle fiber that makes up this structure is unique that they can continually and mathematically send impulses ( send signals to contract )without any stimulation from the nervous system. This means the SA node is said to be self-exciting and that's the reason why the " SA node is known as the natural pacemaker of the heart."  Now, before directly enters into the  AV node, the electrical impulse from the SA node is spread on to the right and left atria and gets depolarized. Due to this both the atria (right &left) contract simultaneously. When the impulse reaches the AV node, there is a slight delay that allows the atria to finish thei

                                    Bacterial Growth Curve  In any biological system growth can be defined as the orderly increase of all chemical component . Increase of mass weight not really reflect growth curve because of the cells could be simply increasing their content of storage product such as glycogen .   The idea of the bacterial growth curve was developed through careful observations and experiments done by early scientists in the late 1800s. They studied how bacteria grow and divided their growth process into different stages . Bacterial growth in batch culture can be modeled with four different phases -                                      Lag Phase        Exponential Growth Phase       Stationary Phase           Death Phase                                                                                             Figure of Growth Curve                                                                  Lag Phase -     During Lag Phase , bacteria a

                                                                                           Oogenesis The process of formation of the female egg is known as oogenesis. The process takes place in ovaries. Generally,  in most higher organisms,  this process starts when the female fetal is developing in the womb. The whole process can be studied in three phases -      Multiplication Phase  Growth Phase  Maturation Phase             Read also - oocyte structure in human being  Multiplication phase -   In the fetal embryo, the ovum mother cell or we can say oogonia start to multiply through mitosis and a  large number of diploid oogonia i.e., millions of oogonia are produced. Growth Phase -   Like spermatogenesis, oogonia grow in their size and shape to form primary oocyte with a diploid number of chromosomes. If we talk about other higher animals except for human then this phase is one of the largest phases of oogenesis. During the growth phase, se