Davisson and Germer Experiment :- The wave nature of electrons was first experimentally verified by C. J. Davisson and L. H. Germer in 1927 and independently by G. P. Thomson in 1928. The experimental arrangement consists of an electron gun which comprises of a tungsten filament ‘F’ , coated with barium oxide and heated by…
Mutation and Its Types:- Mutation is a phenomenon which results in alternation of DNA sequences and consequently results in changes in the genotype and phenotype of an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA. Causes of mutations :- There are many chemical and physical factors that induce…
Sex Determination in Human :- sex determination is a biological system that determines the development of sexual characteristic in an organism. Sex determination in human by chromosomal difference. Most organisms that created their offspring using sexual reproduction have two sexes. In human beings a sex chromosome that carries the genes for male characters is called…
मानव में लिंग निर्धारण (Sex determination in humans) :- मानव के प्रत्येक कोशिका में 23 जोड़े गुणसूत्र पाए जाते हैं जिसमें 22 जोड़े को अलिंग गुणसूत्र (Autosomes) तथा अंतिम 23वें जोड़ा को लिंग गुणसूत्र (Sex Chromosomes) कहते हैं। द्विगुणित अवस्था में मादा का लिंग गुणसूत्र XX तथा नर का लिंग गुणसूत्र XY होता है। मानव…
Crossing Over :- Crossing over is a mechanism by which a group of genes on one chromosome changes it’s place with a similar group on it’s homologous chromosome. Term crossing over were first given by Morgan & Castle in 1912. Mechanism of crossing over :- Mechanism can be explained under the following steps – 1….
क्राॅसिंग ओवर (Crossing Over) वैसी प्रक्रिया जिसमें एक गुणसूत्र पर स्थित जीन्स का एक समूह समजात गुणसूत्र पर स्थित समान जीनों के समूह द्वारा स्थान परिवर्तन कर लेता है, उसे विनिमय या क्रॉसिंग ओवर कहते हैं। क्रॉसिंग ओवर का महत्व (Importance of Crossing Over) क्रॉसिंग ओवर के महत्व निम्नलिखित हैं :
Polarisation of Light :- polarisation of light is the property of transverse wave that can oscillate with more than one orientation. A light wave that is vibrating in more than one plane is referred to as unpolarised light. The process of transforming unpolarised light into polarised light is known as polarisation of light. If the…
मेंडल की वंशागति नियमों के अपवाद निम्नलिखित हैं (Exceptions to Mendel’s Law of Inheritance) :- अपूर्ण प्रभाविता (Incomplete dominance) :- जब विपरीत लक्षणों के जोड़े में एक लक्षण दूसरे लक्षण पर प्रभावी न होकर एक दूसरे पर पूर्ण रूप से प्रभावी हो जाता है अर्थात दोनों अपने-अपने लक्षण को आंशिक रूप से प्रकट करते हैं…
Resolving power of Optical Instruments :- Resolving power of Optical Instruments is the ability of an Imaging device to separate points of an object that are located at a small angular distance or It is the power of an optical instrument to separate far away objects, that are close together into individual images. Consider a…
Diffraction of Light :- Diffraction of light is the slight bending of light as it passes around the edge of an object. The amount of bending depends on the relative size of the wavelength of light to the side of the opening. Explanation of the Intensity distribution in the diffraction pattern :- Figure shows a…
Interference of Light Waves :- When two light waves from different sources meet together, then the distribution of energy due to one wave is distributed by the other. This modification of light energy due to superposition of two light wave is called interference of light waves. Coherent sources :- Those sources of light which emit…
de Broglie Wavelength Equation :- In 1924 Louis de Broglie proposed that just as light has both wave like and particle like properties, electrons also have wave like particles. de Broglie proposed that the wavelength λ is associated with a particle of momentum p is given as λ = h/p Or The equation is known…
