- Nastic Movement: The turgor movements of plant parts which are influenced by the presence of stimulus but not directed by it sometimes leading to growth is called so.
- Nematocyst: It is the stinging organ of coelenterates.
- Nematode: Worms having unsegmented thread like bodies with absence of body cavity.
- Nephridium: Excretory organ in many invertebrates consisting of a tube through which waste products passes to the exterior.
- Nocturnal: Animal that is active chiefly at night.
- Nomenclature: It is a system of naming and classification.
- Notochord: A flexible rod like structure in some lower vertebrates that provides dorsal support and gives rise to spine in higher vertebrates.
- Nucellus: Centre of ovule of a plant containing the embryo sac.
- Nucleuolus: A small, round body present in the nucleus of the cell composed of protein and RNA.
- Nucleoplasm: The part of protoplasm within the nucleus.
- Nucleus: A complex, spherical body present in the cell that is responsible for the transmission of hereditary characters from parents to offspring and controls the growth and reproductive of cell.
- Nytinastic Movement: Turgor movement of plant parts which are influenced by light and temperature.
- Ontogeny: The development of an organ or organism as a whole is called so.
- Order: Taxonomic category constituting of a group of related families.
- Organ: A number of tissue systems together make an organ adapted for a specific function.
- Organelle: A structure within a cell that is specialized for a specific function.
- Osmoregulation: The maintenance of a correct proportion of water and salts in the body of a living animal.
- Osmosis: The diffusion of solvent molecules through a semi-permeable membrane until there is equal concentration of solution on both the sides of the membrane.
- Osmotic Pressure: The pressure developed during osmosis which is required to stop the diffusion of the solvent molecules through the membrane.
- Oviparous: Organisms that produce egg which hatch outside the body.
- Parasite: An organism that grows feeds and lives on another organism leading to its death.
- Parenchyma: Plant tissue with thin walled cells.
- Parthenocarphy: The production of fruit without fertilization or seed formation.
- Pectin: It is a complex colloidal substance of high molecular weight found in ripe fruits.
- Perennial: Having a life span of more than two years.
- Pericycle: It is a single layer of cells surrounding the stele.
- Permeable: A membrane that allows both solute and solvent to pass through.
- Pesticide: A chemical that is used to kill pests.
- Phanerogams: These are flowering plants.
- Phloem: The food conducting tissue of the plant consisting of sieve tubes, companion cells and phloem parenchyma.
- Photosynthesis: It is a physiological process by which the cells of plants containing chlorophyll convert light energy to chemical energy and prepare food using carbon dioxide and water and releasing oxygen as a by product.
- Photolysis: It is the splitting up of water molecule in the presence of light.
- Photophosphorylation: It is the conversion of ATP to ADP during the light phase of photosynthesis.
- Phototropism: Movement of plant part in response to the source of light.
- Phyllotaxy: It refers to the arrangement of leaves on the stem.
- Phylogeny: It is the evolutionary history of an individual.
- Phylum: It is a taxonomic division directly above class.
- Physiology: It is the science of essential and characteristic life processes.
- Pitcher Plant: These are insectivorous plants that have their leaves modified to jug like organs for trapping insects.
- Pith: Soft central part in the internal organization of stem.
- Plant: Organism which grows by synthesizing organic substances generally lacks the power of locomotion and nervous system along with specialized sense organs.
- Plasma Membrane: The semi-permeable membrane enclosing the cytoplasm of the cell.
- Plasmagel: The jelly like substance of cytoplasm near the periphery of the cell.
- Plasmolysis: Shrinkage of protoplasm caused by the loss of water due to exosmosis.
- Plastid: Specialized cytoplasmic structure in the plant cells containing pigments.
- Platyhelminthes: Worms, parasitic and non-parasitic characterized by a flattened body.
- Pollen: Round structures produced by anther and functions as the male element in fertilization.
- Pollen Tube: The slender tube arising from the pollen and grows down the style to the ovule of the female flower which has received the pollen and releases the male gametes which fertilize the egg cell.
- Pollination: The process of transmission of pollen from the anther to the stigma of flower.
- Pollutant: Any waste matter released into the environment that results in disruption of its composition.
- Pollution: The contamination of environment by the release of waste matter.
- Polyp: A Coelenterate having a cylindrical body and an oral opening usually surrounded by tentacles.
- Porifera: They are aquatic with a number of pores on the body surface and a single opening called osculum. They have pseudo central cavity called spongocoel.
- Promycelium: A germ tube produced by certain fungal spores.
- Protoplasm: A complex jelly like colloidal substance constituting the living matter of all plant and animal cells.
- Pseudo Fossils: Fossil like impressions formed on rocks due to deposition of minerals.
- Pseudopodium: Temporary projections from protoplasm which help in locomotion.
- Pteridophyte: It is a non-flowering plant that reproduces by spore and has vascular tissue.
- Radial Symmetry: Arrangement of organism or its parts in such a way that any plane passing through it give two halves which are mirror images of each other.
- Reptile: It is a cold blooded Vertebrate which reproduces by laying eggs, has its outer surface covered by scales and breathes with the help of lungs.
- Respiration: It is a catabolic process by which an organism assimilates oxygen, oxidizes organic substance and releases carbon dioxide, water vapour and energy.
- Respirometer: It is an apparatus used to measure the rate of respiration.
- Respiroscope: It is an apparatus used to demonstrate the process of respiration.
- Rhizoid: A stem like part found in lower group of plants which function as means of anchorage and absorption.
- Rhizome: A stem like portion growing along the ground and giving rise to root like structures below and shoot like structures above.
- Ribosome: It is the site of protein synthesis in the cell.
- Root: It is the underground part of the plant usually serves as means of anchorage and absorption and sometimes storage.
- Rootlet: It is a small root or its division.
- Root Pressure: The collective force exerted by cortical cells in order to force water in to the xylem vessels.
- Sclereids: Cells that constitute the sclerenchyma:
- Sclerenchyma: Plant tissue where cells are thick walled and thickening material is lignin.
- Seismonastic Movement: Tugor movement of plant part influenced by the stimulus of touch.
- Self-Pollination: The transfer of pollen from the anther to the stigma of the same flower.
- Semi-Permeable: Natural or artificial membrane that allows the passage of some molecules of a mixture but not all.
- Senescence: The latter part of the development process that ultimately leads to death of an organism.
- Speciation: It is the origin of a new species.
- Species: A group of organisms which are morphologically and physiologically similar to each other and can interbreed to produce fertile offspring.
- Sporangium: Asexual spore bearing structure in cryptogams.
- Spore: Single celled reproductive organ produced by non-flowering plants.
- Starch: It is a carbohydrate found stored in different parts of plants such as seeds, fruits, leaves and stems.
- Stem: It is the ascending part of an axis bearing leaves, flowers, fruits and buds.
- Stigma: The part of the flower that receives the pollen during pollination.
- Stipule: Small paired leaf like appendage at the base of the leaf.
- Stomata: Minute pores on the leaf surface specially on the lower side through which transpiration and respiration occurs.
- Sub-Phylum: Taxonomic category between a phylum and a class.
- Substrate: Surface on which an organism shows attachment and growth.
- Tactile: Perceptible to the sense of touch.
- Taxonomy: Process of classifying organisms according to the similarities and dissimilarities into well defined categories.
- Thallophyte: Plant body undifferentiated into root, stem and leaf is called so.
- Thermonastic Movement: Movement of plant influenced by the presence of heat.
- Thigmotropism: Movement of plant part in response to the stimulus of touch.
- Tissue: A group of cells having a common origin and performing the same function come together to form so.
- Tonicity: It refers to the external osmotic environment of a cell.
- Tropism: The directional growth movement of plant part in response to external stimulus.
- Turgidity: The condition of cell due to the pressure exerted by cell contents on the cell wall.
- Vascular Tissue: A conductive and supportive tissue constituting the xylem and the phloem.
- Vestigial Organs: These are those organs of the body that are non functional in the possessor but were functional in the ancestor.
- Virus: It is submicroscopic pathogen made up of essentially a nucleic acid core surrounded by a protein coat land capable of replicating only within the host cell.
- Whorl: Arrangement of three or more parts from a common point of origin.
- Wilt: Condition to which plant is led by loss of water.
- Xerophyte: Plant that grows in desert and is adapted to an environment deficient in moisture.
- Xylem: The water conducting tissue of plant.
- Zoology: The biological study of animals.
- Zygospore: A thick walled spore formed from the zygote.
