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Answer: a. Impulse stimulates the release of chemical neurotransmitter from the surface of presynaptic knob or bouton of axon terminal. Neurotransmitter e. Write one function of each part. Delhi Comptt. Answer: a Plant Hormones: Phytohormones are chemical substances other than nutrients produced naturally in plants which regulate growth, development, differentiation and a number of physiological processes, e. B-Medulla Function: Reflex centre, cardiac centre, respiratory centre.
C-Cerebellum Function: Maintains equilibrium and coordinates muscular activities. How do tendrils reach the support when they do not have any sensory structures. Answer: Tendrils do not have any sensory structures but still they are able to find their support just as we grope in the dark for finding the switch-board. Tendrils perform circumnutation from their apical regions. In this the terminal parts of tendrils move in all directions.
Wherever they come in contact with a support, they stop performing cicumnutation. Instead, the contacted region shows little growth while the other side grows rapidly so that the tendril coils over the support. Name the nervous system which controls the functioning of internal organs. How does this system work? Answer: Autonomous or visceral nervous system. The system does not consult the will of the individual.
It works on its own inputs. Autonomous nervous system consists of only motor nerve fibres that innervate all organs and glands of the body. Depending upon the input, autonomous nervous system stimulates, slows down or stops the activity of an organ. For its working, autonomous or visceral nervous system has two components, sympathetic and parasympathetic. Sympathetic nervous system originates from thoracico-lumbar region, forms two ganglionic chains which send out long nerve fibres to various organs.
The sympathetic nerve fibres activate the organs by release of nor-adrenaline. Parasympathetic nervous system is called cranio-sacral as it originates from some cranial and sacral nerves. It has long preganglionic fibres and ganglia attached to organs that are innervated. Its post ganglionic fibres secrete acetylcholine into organs for moderating or reducing their activity. Which system is working when you start sweating during exercise?
What is its function? Answer: Reflex activity of the nervous system. It is automatic, involuntary and spontaneous response to a stimulus without consulting the will of the individual. Exercise increases body temperature. This can be harmful. Reflex action stimulates the sweat glands for releasing their secretion. Part of the sweat evaporates and cools, down the body.
You can become moody by simply switching on night bulb daily. How can this happen? Answer: Night bulb reduces the secretion of melatonin hormone. Melatonin controls our day-night or circadian rhythm, healthy digestive and immune system, sexual cycle and moods.
A reduced secretion causes insomnia and mood changes besides affecting health of our digestive and immune system. Control and co-ordination in animals and plants: Tropic movements in plants; Introduction to plant hormones; Control and co-ordination in animals, nervous system; voluntary, involuntary and reflex action; Chemical co-ordination: animal hormones.
Formulae Handbook for Class 10 Maths and Science. Question 1 What is the function of receptors in our body? Solution: Receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on.
So gustatory receptors will detect taste while olfactory receptors will detect smell. Question 2 Draw the structure of neuron and explain its function. Solution: The specialised tips of some nerve cells detect all information from our environment. These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on.
This information, acquired at the end of the dendritic tip of a nerve cell, sets off a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron.
This is a general scheme of how nervous impulses travel in the body. A similar synapse finally allows delivery of such impulses from neurons to other cells, such as muscles cells or gland. It is thus no surprise that nervous tissue is made up of an organized network of nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.
Question 3 How does phototropism occur in plants? Solution: Phototropism is a growth movement induced by a light stimulus. Growth towards a source of light is called positive phototropism, that away from the source is termed negative phototropism. The tips of shoots are usually positively, that of roots negatively phototropic. Charles Darwin and his son Francis discovered in that the phototropic stimulus is detected at the tip of the plant.
The Darwins used grass seedlings for some of their experiments. When grass seeds germinate, the primary leaf pierces the seed coverings and the soil while protected by the coleoptile, a hollow, cylindrical sheath that surrounds it.
Once the seedling has grown above the surface, the coleoptile stops growing and the primary leaf pierces it. The Darwins found that the tip of the coleoptile was necessary for phototropism but that the bending takes place in the region below the tip. If they placed an opaque cover over the tip, phototropism failed to occur even though the rest of the coleoptile was illuminated from one side.
However, when they buried the plant in fine black sand so that only its tip was exposed, there was no interference with the tropism � the buried coleoptile bent in the direction of the light. From these experiments, it seemed clear that. Question 4 How does chemical coordination occur in plants? Solution: It has been found that the growth of plants is regulated by certain chemical substances which are synthesized by the plants in very small amounts.
These are known as plant hormones or phytohormones. They are the organic substances which either promote or inhibit growth. A phytohormones can be defined as a chemical substances which are produced naturally in plants and are capable of translocation and regulating one or more physiological processes when present in low concentration. Main categories of plant hormones are:.
Auxins and Gibberellins stimulate cell elongations, cytokinins stimulate cell division ethylene promotes transverse or isodiametric growth and abscisic acid is a growth inhibitor. Question 5 What is the need for a system of control and coordination in an organism?
Solution: Co-ordination in this sense refers to the regulation or control of body activity. Plants need very little in the way of a control system. Since growth and reproduction are about the only things that are regulated, a rapid control system is not required and hormonal control is all they possess. Animals are continually moving through new environments that may pose all types of changes and threatening situations to the organism.
This requires the rapid and precise control of a nervous system. Hormones regulate slower activities, such as growth, development and reproduction. Question 6 How are involuntary actions and reflex actions different from each other?
Solution: All reflex actions are involuntary in nature but all involutary actions are not reflexes as the beating of heart is an involuntary action but is not reflex action. Reflex actions are very quick but all involutary actions may not be very fast as in heart beating. A reflex action may involve any muscle or a gland as we withdraw our hand on touching a hot object but all involuntary actions involve only smooth i.
Reflex actions are at the level of spinal cord whereas the involuntary actions generally involve brain too. Nerves and autonomious nervous system can increase or decrease the rate of involuntary actions but reflex actions can be controlled by great will only and are not usually controllable.
Reflex actions are done to meet emergencies where as an inv. What is the correct direction of flow of electrical impulses? Three directions in which nerve impulses can travel in the nervous system are listed below: i Away from the central nervous system ii Towards the central nervous system iii Within the central nervous system In which direction do impulses in sensory and relay intermediate neurons travel?
Answer: d Sensory neuron transmits impulses towards CNS, i. In a nerve pathway, the following events take place in a coordinated order. Thus, the correct sequence is ii , iv , iii and i. The diagram shows a section of the brain and different parts labelled as W,X, Y and Z. Study the figure and correlate the regions which control balance, heart rate and temperature in human body? Answer: b Out of the options given, the region X, i. Which of the following endocrine glands is unpaired?
Testes are paired glands present in males and secrete male sex hormone. Pituitary gland is present just below the brain and is unpaired. It is also called master gland as it secretes a number of hormones. Ovaries are paired glands present in females and secrete female sex hormones. Dramatic changes of body features associated with puberty are mainly because of secretion of [NCERT Exemplar] a oestrogen from testes and testosterone from ovary b oestrogen from adrenal gland and testosterone from pituitary gland c testosterone from testes and oestrogen from ovary d testosterone from thyroid gland and oestrogen from pituitary gland Answer: c.
Coordination is the process through which two or more organs interact and complement the functions of one another. The neural system provides an organised network of point-to-point connections for a quick coordination. The endocrine system provides chemical integration through hormones.
They are specialized for conducting information via electrical impulses from one part of the body to another. Plants have neither nervous system nor muscles. Their movements or responses are either growth dependent or growth independent. The plants also use electrical-chemical means to convey information from cell to cell, but unlike in animals, there is no specialised tissue in plants for the conduction of information.
Secondly, plant cells change shape by changing the amount of water in them, resulting in swelling or shrinking. In contrast, animal muscle cells have special proteins that change both their shape and their arrangement in the cell in response to nervous electrical impulses.
The movement of a plant in response to the stimulus is called as tropism. The movement in the direction of the response is called as positive tropism and movement away from the stimulus is termed as negative tropism. The timing and amount of hormone released are regulated by feedback mechanisms Examples:. If you have any question or doubt related to this article, drop your comments in the comment box below and we will get back to you as soon as possible.
Answer: Reflex action Walking 1. It is the action which is performed automatically. It is a response to the information transmitted by nerve to muscles of the legs.
In this case, thinking is involved. It is controlled and coordinated by spinal cord. Brain instructs and controls leg muscles to move. It is an involuntary action. It is a voluntary action. Some major concepts discussed in this chapter are:. Life Processes chapter deals with the various biological processes and reaction taking place in organisms. Some major topics covered in this chapter are:.
Control and Coordination chapter gives details of different ways in which organisms respond to the stimuli. Here you also get to know about the human nervous system, automatics and voluntary actions, exocrine and endocrine glands, etc.
How do Organisms Reproduce chapter students get to learn different methods of reproduction in plants and animals and get aware of the various methods of birth control in humans. Some of the important topics discussed in this chapter are:. Heredity And Evolution chapter deals with the details related to heredity and evolution of different species. Go through the major topics mentioned below:. Light Reflection and Refraction explains the concepts of reflection and refraction of light.
Some important topics to learn from this chapter are:. The Human Eye and Colorful World chapter students get to know each and every detail of the human eye from its structure to its working. Various defects of vision are also discussed here. It also explains atmospheric refraction and various phenomena related to it. Mention the functions of receptors in human body. List down the main categories of plant hormones.
Auxins, gibberellins, cytokinins, ethylene, and abscisic acid. Which hormone is secreted by the thyroid gland? Thyroxine is secret by thyroid glands. Name two endocrine glands that exist in pairs. Adrenal glands and ovaries.
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