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Yogita Ingle 7 years, 1 month ago
Two exotic breeds of honey-bee brought to India for increasing the commercial production of honey. pis dorsata, Apis indica , Apis florae are indigenous species of honey bee.
Apis mellifera and Apis adamsoni are the exotic species used in apiculture.
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Yogita Ingle 7 years, 1 month ago
- Electrons revolve around the nucleus in stable orbits without emission of radiant energy. Each orbit has a definite energy and is called an energy shell or energy level.
- An orbit or energy level is designated as K, L, M, N shells. When the electron is in the lowest energy level, it is said to be in the ground state.
- An electron emits or absorbs energy when it jumps from one orbit or energy level to another. When it jumps from a higher energy level to lower energy level it emits energy while it absorbs energy when it jumps from a lower energy level to a higher energy level.
Posted by Vaidehi Kumari ??? 7 years, 1 month ago
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Rahul Ostwal 7 years, 1 month ago
Harshvardhan Singh 7 years, 1 month ago
Yogita Ingle 7 years, 1 month ago
Rutherford developed a nuclear model of atom on the basis of his experiment and observations. The Rutherford atomic model has the following features:
- The centre of an atom is called nucleus. It is positively charged and almost all mass of the atom resides in it.
- Electrons spin around the nucleus in a circular path.
- Comparatively, the size of the nucleus is smaller than the size of the atom.
Posted by Vaidehi Kumari ??? 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
Thomson’s atomic model: J.J. Thomson was the first to put forward a model to explain the structure of an atom.
Thomson's atomic model is also called water melon model or Christmas pudding model.
He compared the electrons with the raisins in the Spherical Christmas pudding and to seeds in a watermelon.
Postulates of Thomson’s Model:
- An atom consists of a positively charged sphere, with electrons set within the sphere.
- An atom is electrically neutral as the positive and negative charges within it are equal.
Posted by Rupali Roy 7 years, 1 month ago
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Rahul Ostwal 7 years, 1 month ago
Yogita Ingle 7 years, 1 month ago
The atom is made up of three particles: electrons, protons and neutrons. The electron is a subatomic particle that carries a negative charge. Electrons are bound to the nucleus of the atom in, what are called, sub-shells. There are free electrons too which are not bound to any atom. Electrons are represented as e or ß. As mentioned earlier, electrons are negatively charged and is measured in Coulomb (the charge of an electron is given as <nobr></nobr><nobr>1.60x10−19C</nobr> .
Posted by Rajan Kr 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
Intermolecular space: is the space between two molecule or atom. In solids it is very little, in liquids is more the solids but less than liquids and in gases its the maximum.
Intermolecular forces: are forces of attraction or repulsion which act between neighboring particles (atoms, molecules or ions).
Posted by Simran Samrat 7 years, 1 month ago
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Posted by Kajal Joon 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
Lysosome is called polymorphic organelle because it can occur in more than one form inside the cell. Lysosomes are small, membrane-bound organelles that originate from the Golgi apparatus in animal cells. There are four types of lysosomes depending upon their morphology and function:
(a) Primary lysosomes: They are newly pinched off vesicles from the Golgi apparatus which fuse with some endosome to become fully functional. These are small in size and contain hydrolytic enzymes in the form of granules.
(b) Secondary lysosomes: They are also called digestive vacuoles. A secondary lysosome is formed by the fusion of food containing phagosome with lysosome. Digestion occurs and the digested food passes out into the cytoplasm. Finally, the secondary lysosome is left with undigested food.
(c) Residual bodies: They are those lysosomes in which only indigestible food materials have been left. The residual bodies or lysosomes pass outwardly and fuse with the plasma membrane to throw out the debris into external environment by exocytosis.
(d) Autophagic vacuoles: They are produced by the fusion of a number of primary lysosomes around worn out or degenerate intracellular organelles.
Posted by Ritesh Mahant 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
Endocytosis is a form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in an energy-using process. example – iron is transported in the blood complexed to a protein called transferr in. Cells have receptors for transferr in on their surface.
It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane. The opposite process is exocytosis.
Kajal Joon 7 years, 1 month ago
Posted by Kajal Joon 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
The plasma membrane allows the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. Hence it is called a selectively permeable membrane.
Kajal Joon 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
Reverberation is the phenomenon of overlapping of sound caused by multiple reflections. Reverberation causes the overlapping of several reflected waves. If the time gap between the reflected waves is so short that these cannot be distinguished. So we hear multiple noisy sounds.
Example: reverberation of sound occurs in small cave almost the gap between the walls is approximately 17 m.
Posted by Rohit Poddar 7 years, 1 month ago
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Yogita Ingle 7 years, 1 month ago
An alloy is the homogeneous mixture of two or more metals or metals and non metals. For example brass is an alloy of copper and zinc. The properties of alloys are different from the properties of constituent metals.Alloys are stronger than the metal which they are made.
Posted by Abhishek Sreedhar 7 years, 1 month ago
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Gaurav Seth 7 years, 1 month ago
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Milch animals refers to those that yield milk. For example cows, goat etc.
- The cattle that are used for doing labour in the fields such as carting, irrigation, tilling etc are called draught animals
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Ashok Kumar 7 years, 1 month ago
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