Explain commercial application of plant hormones.

 Commercial Applications

Commercial Application

Auxins

• Discovery of IAA led to the synthesis of wide range of compounds by chemists. The synthetic auxins are economical than IAA to produce and often more active because plants generally do not have necessary enzymes to break them down.

Synthetic Auxins:

• NAA ( Naphthalene acetic acid)
•  Indole propionic acid

Stimulates fruiting- help natural fruit set. Sometimes causes fruit setting in absence of pollination (Parthenocarpy).

• 2,4D (2,4 Dichloro phenoxy acetic acid)

Selective weed killer. Kills broad leaved species (dicots). Used in cereal crops and lawns to eliminate weeds.

Inhibits sprouting of potatoes.

Prevents premature fruit drop ( retard abscission).

Gibberellins

• GA promote fruit setting e.g. in tangerines and pears and are used for growing seedless grapes. (Parthenocarpy) and also increase the berry size.

• GA3 is used in the brewing industry to stimulate a-amylase production in barely and this promotes malting.

• To delay ripening and improve storage life of bananas and grape fruits.

Cytokinins 

• Cytokinins delay aging of fresh leaf crops, such as cabbage and lettuce (delay of senescence) as well as keeping flowers fresh. They can also be used to break dormancy of some seeds.

Abscisic Acid

•  Abscisic acid can be sprayed on tree crops to regulate fruit drop at the end of the season. This removes the need for picking over a large time- span.

Ethene

•  Ethene induces flowering in pineapple. Stimulates ripening of tomatoes and citrus fruit. The commercial compound ethephon break down to release ethene in plants and is applied to rubber plant to stimulate the flow of latex.

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Write down plants hormones.

 Plant Hormones

Some of the special substances produced by the plants which influence the growth and plant responses to various stimuli are given below.

Plant Hormones

(a) Auxins:

• In stem, promote cell enlargement in region behind apex. Promote cell division in cambium.

• In roots, promote growth at very low concentration. Inhabit growth at higher concentration e.g. geotropism. Promote growth of roots from cuttings and calluses.

• Promote bud initiation in shoots but sometimes antagonistic to cytokinins and is inhibitory.

• Cause delay in leaf senescence in a few species.

(b) Gibberellins:

• Promote cell enlargement in the presence of auxins. Also promote cell division in apical meristem and cambium.

• Promote "bolting" of some rosette plants.

• Promote bud initiation in shoots of chrysanthemum callus.

• Cause delay in leaf senescence in few species.

• Break bud and seed dormancy.

• Promote leaf growth and fruit growth.

(c) Cytokinins:

• Promote stem growth by cell division in apical meristem and cambium.

• Promote stomatal opening.

• Cause delay in leaf senescence.

• Inhibitory primary root growth.

• Promote lateral root growth.

• Promote bud initiation and leaf growth.

(d) Abscisic:

• Promote bud and seed dormancy.

• Promote flowering in short day plants, and inhibits in long day plants.

• Sometimes promotes leaf senescence.

• Promote abscission.

• Promote closing of stomata under condition of  water stress.

(e) Ethene:

• Inhibits root growth.

• Break dormancy of bud.

• Promotes fruit ripening.

• Promotes flowering in pineapple.

• Inhibits stem growth.

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Write a note on Ear.

 Ear

Hearing is important as vision. Our ear helps us in hearing and also to maintain the balance or equilibrium of our body.

Ear

 Ear has three parts.

• External Ear
• Middle Ear
• Inner Ear

External Ear:

                           External ear consists of pinna, auditory canal and ear drum (tympanum). 

Pinna is the broad external part, made of cartilage and covered with skin. It helps to direct sound waves into auditory canal.

There are special glands in the walls of auditory canal, which produce wax. The wax and the hairs in auditory canal protect ear from small insects, gems and dust. 

In addition to this, they help to maintain the temperature and dampness of auditory canal. Auditory canal ends in ear drum. This thin membrane separates external ear from middle ear.

Middle Ear:

                        Middle ear is a chamber after external ear. Three small bones, called middle ear ossicles, are present in a chain in middle ear. Those movable bones includes malleus, incus and stapes. 

Malleus is attached with ear drum, them comes out incus and finally stapes that is connected with a membrane called oval window. Oval window separates middle ear from inner ear. Middle ear also communicates with nasal cavity through Eustachian tube. This tubes regulates the air pressure on both sides of ear drum.

Inner Ear:

                     Inner ear consists of three parts 

• Vestibule
• Semicircular canals
• Cochlea

Vestibule is present in the center of inner ear.

Three canals called semicircular canals are posterior to the vestibule.

The  cochlea is made of three ducts and wraps itself into a coiled tube. Sound receptor cells are present within the middle duct of cochlea.

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Write a note on Spinal Cord?

 Spinal Cord

The spinal cord is in fact a tubular bundles of nerves. It starts from brain stem and extends to lower back. Like, brain, spinal cord is also covered by meninges. The vertebral column surrounds and protect spinal cord.

Spinal Cord

The outer region of spinal cord is made of white matter (containing myelinated axons). The central region is butterfly shaped that surrounds the central canal. Its made of grey matter (containing neuron cell bodies).

31 pairs of spinal nerves arise along spinal cord. These are " Mixed Nerves" because each contains axons of both sensory and motor neurons.

At the point where a spinal nerve arises from spinal cord, There are two roots of spinal nerve.

•  The dorsal root contains sensory axons and ganglion where cell bodies are located.
• The ventral root contains axons of motor neurons.

Functions:

• It serves as a link between body parts and brain. Spinal cord transmits nerve impulses from body parts to brain and from brain to body parts.
• Spinal cord also acts as coordinator, responsible for some simple reflexes.

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Who is the largest part of brain & write its part?

 Brain

Forebrain is the largest parts of brain. It is most highly developed in humans.

FOREBRAIN

Parts:

There three parts of forebrain.

• Thalamus
• Hypothalamus
• Cerebrum

Thalamus:

                    Lies just below the cerebrum. It serves as a relay center between various parts of brain and spinal cord. It also receives and modifies sensory impulses (except nose) before they travel to cerebrum. Thalamus is also involved in pain perception and consciousness (sleep and awakening).

Hypothalamus:

                                Lies  above midbrain and just below thalamus. In humans, it is roughly the size of  an almond. One of the most important functions of hypothalamus is to link nervous system and endocrine system. It control the secretions of pituitary gland. It also controls feelings such as rage, pain, pleasure and sorrow.

Cerebrum:

                      It is the largest parts of forebrain. It controls skeletal muscles, thinking, intelligence and emotions. It is divided into two cerebral hemisphere.

Cerebral hemisphere:

                                          The anterior parts of cerebral hemisphere are called Olfactory bulbs which receive impulses from olfactory nerves and create the sensation of smell. 

Upper layer: 

                        The upper layer of cerebral hemispheres i.e. cerebral cortex consists of grey matter. The grey matter of nervous system consists of cell bodies and non myelinated axons.

Lower layer:

                          This layer consists of white matter. The white matter of nervous system consists of myelinated axons.

Cerebral cortex has large surface area and is folded in order to fit in skull. It is divided into four lobes.

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Explain Neuron & Write three classification of nerve.

 Neuron

Nerve cell or neuron is the unit of the nervous system. The human nervous system consists of billions of neurons plus supporting cell. Neuron are the specialized cells that are able to conduct nerve impulses from receptors to coordinators and from coordinators to effectors. In this way the communicate with each other and with other types of body cell.

Location:

                   The nucleus and most of the cytoplasm of neurons is located in the cell body. 

Dendrites & Axons:

                                          Different processes extend out from the cell body. These are called dendrites and axons.

Dendrites conduct impulses towards cell body and axons conduct impulses away from the cell body.

Schwann cells:

                              Schwann cells are special neurological cells located at regular intervals along axons, In some neurons Schwann cell secrete fatty layer called myelin sheath.

Nodes of Ranvier:

                                   Between the areas of myelin on an axon,  there are no myelinated points called Nodes of Ranvier. 

Saltatory: 

                     Myelin sheath is an insulator so the membrane coated with this sheath does not conduct nerve impulse. In such impulses are called saltatory (jumping) impulses. This increases the speed of nerve impulse.

On the basis of the function, neuron are of three types.

• Sensory neurons
• Interneurons
• Motor neurons

Sensory Neuron:

                                  Conduct sensory information (nerve impulse) from receptors towards the CNS. Sensory neurons have on dendrite and one axon.

Interneuron:

                          From brain and spinal cord. They receive information, interpret them and stimulate motor neurons. They have many dendrites and axons.

Motoneuron:

                          Carry information from interneurons to muscle or glands (effectors). They have many dendrites but only one axon.

Nerve

 A nerve means the union of several axons that are enveloped  by covering made of lipid.

Classification:

• Sensory nerve
• Motor nerve
• Mixed nerve

Sensory nerve:

                              Contain the axons of sensory neurons only.

Motor nerve: 

                           Contain the axons of  motor neurons only.

Mixed neuron:

                              Contain the axons of both i.e. sensory and motor neurons.

Write down the steps of functionality of kidney.

 Functioning of kidney

The main function of kidney is urine formation, which takes place in three steps.

• Pressure Filtration
• Selective Reabsorption
• Tubular Secretion

Functioning of kidney 

Pressure Filtration:

                       When blood enters the kidney via the renal artery, it goes to many arterioles, and then to the glomerulus . The pressure of blood is very high and so most of the water, salt, glucose and urea of blood is forced out of glomerulus capillaries. This material passes into the Bowman's capsule and is now called Glomerulus Filtrate.

Selective Reabsorption:

                                               The second step is the selective reabsorption. In this step about 99% of the glomerulus filtrate is reabsorbed into the blood capillaries surrounding renal tubule. It occurs through osmosis, diffusion and active transport. Some water and most of the glucose is reabsorbed from the proximal convoluted tubule. Here, salts are reabsorbed by active transport and then follows by osmosis. The descending limb of loop of Henle allows the reabsorption of water while the ascending limb of loop of Henle allows the reabsorption of salts. The distal convoluted tubule again allows the reabsorption of water into the blood.

Tubular Secretion:

                                      The third step is tubular secretion . Different ions, creatinine, urea etc. are secreted from blood into the filtrate in renal tubule. This is done to maintain blood at normal pH (7.35 to7.45).

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