Shailesh Koirala 
Truly land plant with a well-developed vascular system. Also called vascular cryptogams. Sporophyte is the main plant body which reproduces by the spores. It has been derived from a Greek origin (Pteron-Feather and phyton-plant i.e. plants with feather like leaves). Their leaves are called fronds. Assemblage of seedless vascular plants that have successfully invaded the … Read more
1.Diagnostic Features Mostly annual or perennial herbs, sometimes shrubs (Hibiscus rosa-sinensis) or trees. Stem possesses mucilage and stellate hairs. Leaves alternate and stipulate (stipules often deciduous). Epicalyx usually present. Image source: pullupyour Flowers actinomorphic, bisexual and hypogynous. Stamens numerous monadelphous and epipetalous, anthers monothecous and reniform. Ovary multicarpellary, syncarpous with axile placentation. Fruit a … Read more
The word Protozoa is derived from two Greek words: protos means first; zoon means animal. They are the first animals with a protoplasmic grade of body organization. They are simple, unicellular microscopic organisms which may be solitary or colonial. All the vital activities are performed by a single cell so no physiological divison of labour … Read more
Evolution is a process by which living things change over time and adapt to the conditions of their environment. It may be also defined as the gradual development of the characteristics of plants and animals over time. Everything in this world changes continuously through space and time. Changes relate to plants and animals (living organisms) … Read more
Nerves are the communication lines for transmitting impulses from one part of the body to another. They are elongated, slender, thread-like structures arising from the brain and spinal cord. They vary in length i.e. from 0.1 mm to several metres. In certain cases they may be almost equal to the body length. They are of … Read more
S.N Rod cells Cone cells 1. They are more in number. They are less in number. 2. They respond to lower light intensities. They respond to bright light intensities. 3. Usually located around the periphery of retina. Usually located in the centre of retina. 4. They contain pigment rhodopsin. They contain iodopsin. 5. A small … Read more
The menstrual cycle is the regular natural change that occurs in the female reproductive system (specifically the uterus and ovaries) that makes pregnancy possible. It refers to the series of events that occur in the ovaries of sexually mature and non-pregnant females and culminate in menses. The menstrual cycle is approximately 28 days long. The cycle is required for the production of oocytes. … Read more
S.N Medullated nerve fibre Non-medullated nerve fibre 1. It is also known as myelinated nerve fibre. It is also known non-myelinated nerve fibre. 2. The nerve fibre with medullary sheath is called medullated fibre. The nerve fibre without medullary sheath is called non-medullated nerve fibre. 3. It is found in white matter of brain … Read more
The organs which enable us to perceive the undergoing changes in the external environment and body’s internal environment and make aware of them are called sense organs. These sense organs are responsible for senses in the human body. They are provided with specialized receptor cells or sensory receptors. A receptor is the part of the … Read more
Biotechnology is the controlled use of biological agents such as microorganism or cellular components for beneficial use. It is comparatively a new discipline of science in which the latest technology has been applied to biological organisms for human welfare. The recent progress in biotechnology is due to understanding and application of principles of molecular biology, … Read more