The study of life in biology goes well beyond the observation of its existence; it investigates the complex systems that allow creatures to respond to their surroundings. A major tenet of this relationship is “Support and Movements.” This article’s overarching goal is to serve as a comprehensive introduction to the 12th grade biology chapter titled “Support and Movements,” which delves into the ways in which living things keep their structures together and move about.
12th class Biology Chapter 2 Support and Movements Short Question Answers Below
The supporting tissues in plants are the collenchyma and the sclerenchyma.
The pressure exerted by the water content of a fully, turgid cell against the cell wall is known as the turgor pressure, it is important in maintaining turgidity in plants which gives rigidity and support, to otherwise weak tissues.
The turgor pressure is generated in a plant cell by high osmotic pressure (water potential) of its vacuole.
It is known as the tonoplast.
The fibers and sclerides (stone cells) are the kinds of dead and thick-walled sclerenchymatous cells, of which the former are long and cylindrical and the latter are polyhedral, rounded or slightly elongated.
The collenchymatous cells are living but the sclerenchymatous cells are dead.
The tracheid’s are long thick-walled, cylindrical cells which form bundles in the xylem or in the bundle caps.
These are long, tubular structures (pipes) developed from longitudinal rows of cells whoso transverse walls break down. They serve as water conducting pipes in the xylem.
The growth in thickness of a dicot, woody plant due to the activity of vascular cambium is called secondary growth.
The age of a tree can be determined by cutting the T.S. of its woody stem and counting the number of annual growth rings.
In an old tree the central part of the wood becomes filled with rosins, oils, gums and tannins etc. This inactive, non-conducting part of the wood is called heartwood whereas the outer active, conducting part is known as the sapwood.
Callus is a mass of parenehymatous cells produced by the cambium at the wounded surface of the stem or root.
These are the movements of entire organism or of their motile organs (movements of locomotion) which are induced by external stimuli.
If an organism or a motile organ responds to move towards the source of stimulus, the tactic movement is called positive and if it moves away from the stimulus, the movement is called negative.
These are the tactic movements which occur is response to the stimulus of light or chemicals respectively.
The chloroplasts move and arrange themselves along the side walls of palisade culls of the leaf during intense light and along the upper and lower walls during weak light, in order to receive as much light as possible. This is an example of photo tactic movements.
The movements of sperms of liverworts, mosses and ferns towards the archegonia in response to stimulus of nucleic acid released by the ovum is an example of chemotactic movement.
The turgor movements are due to differential changes in turgor and size of the cells as a result of the gain or loss of water and are easily reversible whereas growth movements are irreversible and are due to differential growth rates of cells in different parts of the concerned organs.
The drooping and folding of leaves of some plants (leguminous plants) at night, due to turgor changes in the cells of the pulvini are called sleep movements.
These are the movements of plant organs which are induced by the exteral stimuli.
These are the nastic movements which are induced by variation in the degree of temperature. The flowers of crocus and tulip close at night (low temperature) but remain open during the day (high temperature).
Auxins are the plant hormones. They play major role in controlling certain plant movements like phototropism, gravitropism (geotropism) and epinasty etc.
It is indole acetic acid (IAA).
It is the gibberellins.
The skeleton is tough and rigid framework of the body of animals which provides protection, shape and support to the body organs.
The animal skeleton is usually composed of inorganic or organic substances or both.
These are the hydrostatic skeleton, exoskeleton and endoskeleton.
The fluid-filled gastro vascular cavity (or coelom) is the hydrostatic skeleton in those animals which lack a hard skeleton. It provides support and resistance to the contraction of muscles so as to cause to the contraction of muscles so as to cause movements. It is found in Cnidarians (Coelenterates), annelids and other soft-bodied coelomate invertebrates.
The skeleton which lies outside the body of an animal is called exoskeleton while that which lies inside the body is known as endoskeleton.
The red and white blood cells are commonly manufactured in the mammals in the bone marrow.
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Importance of Support and Movements
All living things, from the tiniest microbes to the greatest animals, require both support and the ability to move about in order to survive. These processes not only make it possible for organisms to adapt to the environments in which they live, but they also make it easier for them to perform essential life activities like getting food, evading predators, and reproducing.