12th class Biology Chapter 2 Support and Movements Short Question Answers
12th class Biology Chapter 2 Support and Movements Short Question Answers Below
1.What does growth ring indicates?
Since one growth ring is formed in one year a count of the rings at the base of trunk indicates the age of trees at the time it was cut.
2.What is function of heart wood?
In most species the heartwood accumulates a variety of chemicals such as resins oils,gums and tannins.These provide a resistance to decay and insect attack for example in red cedar and conifers.
3.What are sleep movements?
Bean plants and some members of legume family lower their leaves in the evening and raise them in the morning.These are known as sleep movements.
4.What is Nyctinasty?
The nyctinastic movements are shown by the organs in response to external stimuli leading to differential growth.These are due to turgor and growth changes.
5.What is cartilage?
Cartilage is much softer than bone.It is a form of connective tissue.It covers ends of the bone at the joint,and also supports the flexible portion of nose and external ears.No blood vessels penetrate into this cartilage.
6.In how many categories joints are classified?Name them.
Joins are classified on the basis of the amount of movement allowed by them into three categories. (i)Immovable joints (ii) Slightly moveble joints (iii) Freely moveble joint
7.What is sciatica?
It is characterized by stabbing pain radiating over the coures of sciatic nerve results due to injury of proximal sciatic nerve which might follow a fall a herniated disc or improper administration of an injection into the buttock.
8.How many steps are involved in repairing of broken bones?Also name them?
The repair process of a simple fracture takes place in four phases. (i)Haematoma formation (ii) Callus formation (iii)Bony callus formation (iv) Remodelling
9.Why heart muscles are known as cardiac muscles?
Cardiac muscles are actually the muscles of heart.They constitute most of the mass of the heart walls.These muscles are also striated and involuntary.Therefore heart muscles are known as cardiac muscles.
10.What are digitigrades?
The mammals which tend to walk on their digits only are called digitigrades.They run faster than plantigrade animals e.g.rabbit rodents etc.
11.What are cross bridges?
The heads of myosin are called cross bridges which make links with actin during muscle contraction.
12.What do you understand from”Rigor Mortis?
After death the amount of ATP in the body falls.Under these circumstances the bridges cannot be broken and so they remain firmal bound.This results in the body becoming stiff a condition known as Rigor Mortis.
A sarcomere is the region of a myofibril between two successive Z-lines and is the smallest contractile unit of muscle fibre.
14.What are chondrocytes?
The living cells of cartilage are called chondrocytes.These cells secrete flexible elastic non-living matrix collagen that surrounds the chondrocytes.
15.What is spondylosis?
It is the disease which causes immobility and fusion of vertebral joint.
16.What is hydroskeleton or hydrostatic skeleton?
Animals may have a filled gastrovascular cavity or coelom which can act as hydroskeleton or hydrostatic skeleton.Hydrostatic skeleton provides support and resistance to the contraction of muscles so that motility results.
17.What is the hyaline cartilage?
It is most abundant type of cartilage in human body.It is found at the moveable joints.
18.What provides support in plants and animals?
The collenchymatous cells in plants give support to the baby plants and sclerenchymatous cells to the adult plants.In animals muscles.Cartilage and bones provide support.
19.What is Turgor pressure?
The living cells of epidermis cortex and pith take in water by osmosis.An internal hydrostatic pressure called turgor pressure develops which keeps them rigid resistant to bending and maintain the turgidity.
20.What is Bundle cap?
In the stem of some plants;For example sunflower the vascular bundles are strengthened by additional sclerenchyma fibers which form bundel cap.
21.What is tonoplast?
The membrane that bounds vecuole is called tonoplast which contains a number of active transport systems that pump ions into the vacuoles.
22.What are Fibers or Tracheids?
These are long and cylindrical and they may exist in solid bundles in xylem or as bunble caps.
23.What are Sclereids?
These are shorter than fibers and are found in seed coats and nutshells and provide protection.
24.What are vessels or Trachea?
Long tubular structures join end to end to from long water conducting pipe in Xylem.
25.Define secondary growth?
Growth due to lateral meristem or cambium is called secondary growth.Or an increase in plant girth due to the activity of vascular cambium is called secondary growth.The result of secondary growth is most evident in woody perennial plants like trees shrubs and vine.
26.Which meristems are involved in secondary growth?
Secondary growth occurs due to cell division in: (i) Vascular Cambium (ii) Cork Cambium
27.What is Sapwood and heartwood?
As trees grow older only few annual growth rings are active in conduction at one time.The active portion is called sapwood.The inactive non-conducting wood is called heartwood.
28.What is Callus or wood tissue?
An important function of the cambium is to form callus or wood tissue on or over the wound.Soft parenchymatous tissues are repidly formed on or below the branches during budding and grafting.
29.What is difference between animal and plant movements?
Animals move in response to external stimuli by motion,similarly plants also show movements.Animals change their location in response to stimulus.Plants are fixed therefore they change their growth pattern.
30.What are main types of movements in plants?
There are two types of movements. (i)Autonomic Movements (ii) Paratonic Movements
31.What are Autonomic movements.Also give their main types?
Autonomic movements are spontaneous movements due to internal causes.Autonomic movements are of three types. (i) Tactic movements (ii) Turgor movements (iii)Growth movements.
32.Define Tactic Movements?
These are the movements of an entire cell or organism i.e.Locomotion due to external stimulus.The tactic movement may be positive if it towards the stimulus or negative if it is away from the stimulus.
33.What is Phototactic Movement?
It is movement in response to stimulus of light.The best example of positive tactic movement is the passive movement of chloroplast due to cyclosis.This movement helps the chloroplast to absorb maximum light for CO2 fixation.
34.What is chemotactic Movement?
The movement in response to stimulus of chemicals is called chemotactic movements.The movements shown by sperms of liver- worts mosses ferns towards archegonia in response to stimulus of nucleic acid released by the ovum are such examples.
35.What is turgor movement?
Turgor movement is due to differential changes in turgor and size of cells as a result of gain or loss of water.Rapid movements of leaflets in touch me not plant and sleep movements of the plants fall under this category of movements.
36.What are growth Movements?
Growth movements are due to unequal growth on two sides of plant organs like stem root tendrils buds etc.
It is shown by leaves petals etc.The upper surface of leaf in bud condition shows more growth as compared with the lower surface.This leads to opening of buds.
If growth in the lower surface of the leaf in bud condition is more than that of the upper surface then the bud will remain closed.
The growing tip of young stem moves in zig zag fashion due to alternate changes in growth on opposite side of the apex.This mode of growth is called nutation.
40.What are Tropic movements?
It is the movement in curvature of whole organ towards or away from stimuli such as light gravity and touch.
It is the movement in response to stimulus of light and is caused due to differential growth of a plant part like stem or root.
It is the movement in response to stimulus of touch for example climbing vines.When they come in contact with some solid object the growth on the opposite side of contact increases and the tendril coils around the support.
The movement in response to some chemicals is called chemotropisrn.The hyphae of fungi are chemotropic.
The movement of plant parts in response to stimulus of water is called hydrotropism.Roots show positive hydrotropism and shoots show negative hydrotropism.
45.Define Geotropism or Gravitropism?
It is the response to gravity.Roots display positive geotropism and shoots negative geotropism.
46.What are Nastic movements?
These are the non-directional movements of parts of plant in response to external stimuli.
The principal stimulus is the photoperiod.Flowers open and close due to light intensity.
It is due to temperature.The flowers of tulip close at night because of rapid growth in the lower side by upward and inward bending of the petals.
49.Define Haptonastic movement?
It occurs in response to contact e.g the action of the Venus fly trap.
50.What is Skeleton?
The skeleton is tough and rigid framework of the body of animals which provides protection shape and support to the body organs.
Name the supporting tissues in plants?
The supporting tissues in plants are the collenchyma and the sclerenchyma.
Define turgor pressure. What is its importance?
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.
How is turgor pressure generated in a plant cell?
The turgor pressure is generated in a plant cell by high osmotic pressure (water potential) of its vacuole.
What is the membrane surrounding the vacuole known as?
It is known as the tonoplast.
Differentiate between fibers and sclerides?
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.
Are the collenchymatous and sclerenchymatous cells living or dead?
The collenchymatous cells are living but the sclerenchymatous cells are dead.
What are tracheid’s and where are they found?
The tracheid’s are long thick-walled, cylindrical cells which form bundles in the xylem or in the bundle caps.
Describe vessels or tracheae.
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.
Give definition of secondary growth in plants.
The growth in thickness of a dicot, woody plant due to the activity of vascular cambium is called secondary growth.
How can the age of a tree be known?
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.
Differentiates between sapwood and heartwood.
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.
Explain callus (or wood tissue).
Callus is a mass of parenehymatous cells produced by the cambium at the wounded surface of the stem or root.
What are tactic movements?
These are the movements of entire organism or of their motile organs (movements of locomotion) which are induced by external stimuli.
What does positive and negative tactic movements mean?
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.
Differentiate between photo tactic and chemotactic movements?
These are the tactic movements which occur is response to the stimulus of light or chemicals respectively.
Quote an example of photo tactic movements?
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.
Give an example of chemotactic 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.
Differentiate between turgor and growth movements?
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.
What are sleep movements in plants?
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.
What do you mean by paratonic movements?
These are the movements of plant organs which are induced by the exteral stimuli.
Describe thermo nasty and quote examples?
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).
What are auxins? How do they affect plant movements?
Auxins are the plant hormones. They play major role in controlling certain plant movements like phototropism, gravitropism (geotropism) and epinasty etc.
Name a naturally occurring auxin?
It is indole acetic acid (IAA).
Which plant hormone brings about hyponasty?
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.
What is the animal skeleton usually composed of?
The animal skeleton is usually composed of inorganic or organic substances or both.
Name the kinds of skeleton in animals?
These are the hydrostatic skeleton, exoskeleton and endoskeleton.
What is hydrostatic skeleton and in which animals is it found?
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.
Differentiate between the exoskeleton and the endoskeleton?
The skeleton which lies outside the body of an animal is called exoskeleton while that which lies inside the body is known as endoskeleton.
Where red and white blood cells are commonly manufactured in the mammals?
The red and white blood cells are commonly manufactured in the mammals in the bone marrow.
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