(b) Vestigeal organs : There are present in the body of animals certain structures which have no function and are very much reduced. These structures are quite developed and functional in allied animals. Such useless organs are termed as vestigeal and are more... | Asexual Reproduction | Sexual Reproduction |
| It involves no formation and fusion of gametes. | It involves formation and fusion of gametes. |
| It is always uniparental. | it is generally biparental except, Taenia, Fasciola etc. |
| Reproductive units are somatic cells of parent. | Reproductive units are germ cells of parent. |
| It involves only mitotic divisions. | It involves meiosis during gamete formation. |
| Offsprings are generally similar to parents. | Offsprings are genetically different from parent. |
| Occurs by binary fission or multiple fission or budding or fragmentation. | Occurs by gametogenesis (formation of gametes) followed by fertilization.. |
| Organism | Average life span |
| May-fly | 1 day |
| Silk moth | 2-3 days |
| Wheat | 5 months |
| Rat | 4 years |
| Rabbit | 13 years |
| Monkey | 26 years |
| Dog | 20-30 years |
| Cat | more...
(1) Levels of Organization common in both living and non-living
(i) Atomic level : The lowest level of organization in both living and non-living is the atom. All living organisms are basically made up of four chemical elements carbon (C), hydrogen (H), oxygen (O) and nitrogen (N) with only about 1% other elements. The non-living matter may possess other elements (such as silica, calcium, iron, etc.) in variable composition.
(ii) Molecular level : Atoms combine to form molecules, which undergo chemical reactions to form organelles.
Atoms \[\to \] Molecules \[\to \] Inorganic compounds \[\to \] Simple organic compounds \[\to \] Complex organic compound \[\to \] Protoplasm \[\to \] Cell.
(2) Levels of Organization found only in living organisms
(i) Cellular level : All multicellular organisms are made up of cells. The cell is considered as basic unit of life and constitutes the smallest level of organisation of the living organisms.
(ii) Tissue level : In multicellular organisms similar or dissimilar cells, having a common origin and a common function, combine to form a tissue. Each tissue performs a specific role (e.g., xylem conducts water and minerals in plants).
(iii) Organ level : Different tissue are organised to form distinct organs. For example, xylem, phloem chlorenchyma, parenchyma get organised to form a leaf.
(iv) Organs System level : A group of organs that coordinates to performs a major function forms the organs system. For example, the brain works with the spinal cord and a network of nerves to form the nervous system.
(v) Individual or Organismic level : A multicellular individual, having many organ systems, forms an organismic level of organisation.
Cell \[\to \] Tissue \[\to \] Organ \[\to \] Organ system \[\to \] Individual.
(3) Levels of organization beyond the individual organism
(i) Population level : All the individuals of a species in a particular area, where they interact with each other, belong to a population. For example, there is a population of Oak trees in a temperate deciduous forest.
(ii) Community level : The populations of different species of plants and animals present in a particular area make up biotic community.
(iii) Ecosystem level : Populations of different plants and animals interact among themselves and with the non-living components of the area form as ecosystem.
(iv) Biosphere level : The different ecosystems (small or big) of all the geographical regions of the world form the biosphere or the entire livable part of the earth.
The laws of thermodynamics describe the basic properties of energy. All interactions among pieces of matter are governed by the two laws of thermodynamics. The laws of thermodynamics deal with ?isolated systems? which are any parts of the universe that cannot exchange either matter or energy with any other parts.
First Law of Thermodynamics : The first law of thermodynamics states that energy can neither be created nor destroyed; but energy can change from one form to another.
In other words, within an isolated system the total quantity of energy remains constant. The first law is therefore often called the law of conservation of energy.
Second law of Thermodynamics : The second law of thermodynamics states that the amount of useful energy always decreases when energy is converted from one form to another.
In other words, every transfer or transformation of energy makes the universe disordered; no physical process or chemical reaction is 100 per cent efficient.
Entropy is a measure of the disorder or randomness within a system.
Kinetic energy is the energy of movement and this include not only movement of large objects but also movements such as electrical energy (movement of electrons) and heat (movement of atoms and molecules).
Potential energy is stored energy that can be released as kinetic energy under right conditions.
The food which you eat has chemical potential energy, some of which is converted into kinetic energy.
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