Class 10 Science Chapter 7 Board Questions

Class 10 Science Chapter 7 Board Questions of Control and Coordination. Students need the collection of previous years’ questions for the preparation of Exams and School tests. Last 10 Years Papers also provide an idea about the type of questions coming in CBSE Board exams. It contains all the important questions from last 5 years’ board papers and CBSE Sample papers questions. It will help the students in preparing any chapter for the board exams. All the questions related to 10th Science Chapter 7, which are asked in CBSE board exams are given below with answers and explanation. UP Board students are now using NCERT Textbooks for their board exams.

So, questions are useful for UP Board also. In India, most of the states are now using NCERT Books for school study or competitive exams. Those who are preparing for school exams, board question or previous years question provides a brief idea about how the questions are asked in exams.

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Class 10 Science Chapter 7 Board Questions Answers

Class: 10Science
Contents:10th Science Chapter 7 Board Questions

10th Science Chapter 7 Board Questions for Exams

Practice here Class 10 Science Biology Chapter 7 Board Questions with answers. These questions are useful not only for the preparation of board exams but the revision of 10th Science Chapter 7 also. Answers of each question is given just below the question updated according to latest CBSE Syllabus 2020-2021. Use these question answers for the preparation of CBSE Board Exams 2020-2021.

10th Science Chapter 7 Board Questions Set – 1 (1 Mark)

Name the part of the brain which controls posture and balance of the body. [CBSE 2012]

Cerebellum in hind brain controls the posture and balance of the body.

Give one example of chemotropism. [CBSE 2012]

The growth of pollen tube towards a chemical produced by ovule during fertilization of flower is an example of chemotropism.

Name the two components of central nervous system in humans. CBSE 2012]

The two components of the central Nervous System in human are brain and spinal cord.

Mention the part of the body where gustatory and olfactory receptors are located. CBSE 2012]

Gustatory receptors are located in cerebrum of fore brain. Olfactory receptors are located in the olfactory lobe fore brain.

How is the spinal cord protected in the human body? [CBSE 2010]

Spinal cord is enclosed in a bony cage called vertebral column.

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10th Science Chapter 7 Board Questions Set – 2 (1 Mark)

A potted plant is made to lie horizontally on the ground. Which part of the plant will show (i) Positive geotropism? (ii) Negative geotropism? [CBSE 2010]

(i) Roots (ii) Shoot

Name the hormone that helps in regulating level of sugar in our blood. Name the gland that secretes it. [CBSE 2010]

Insulin helps in regulating blood sugar level. This hormone is secreted by pancreas gland.

Mention the function of the hind-brain in humans. [CBSE 2010]

Hind-brain coordinates the body movements and posture. It also controls respiration.

Name any two type of tropism. [CBSE 2010]

Phototropism and Geotropism.

Name one plant growth hormone which retard growth during extremely dry season. [CBSE 2009]

Abscisic acid

The Function of Adrenaline Hormone

The function of adrenaline hormone is to regulate blood pressure, heartbeat, breathing rate, carbohydrates metabolism and mineral balance in the body.

10th Science Chapter 7 Board Questions Set – 3 (1 Mark)

Name one organ where growth hormone is synthesized in case of plant and man. [CBSSE 2009]

Shoot tip in plants and pituitary gland in man.

A young green plant receives sunlight from directions only. What will happen to its shoots and roots? [CBSE 2009]

Shoots will bend towards the light and roots away from the light.

Name the plant hormones which help/promote: (i) Cell division (ii) Growth of stem [CBSE 2009]

The plant hormone which helps or promote:
(i) Cell division- Cytokinin
(ii) Growth of stem- Gibberellins

Name the main hormone secreted by thyroxine gland and state its one function. [CBSE 2009]

The main hormone secreted by thyroid gland is thyroxine. It regulated the metabolism of carbohydrates, fats and proteins in the body so as to provide the best growth balance.

Name two tissues that provide control and coordination in multicellular animals. [CBSE 2009]

The two tissues that provide control and coordination in multicellular animals are nervous and muscular tissues.

The Function of Thyroxine Hormone

Thyroxine hormone regulates the carbohydrate, protein and fat metabolism in the body so as to provide the best growth balance.



10th Science Chapter 7 Board Questions Set – 4 (1 Mark)

Which endocrine gland secrete the growth hormone? [CBSE 2009]

Pituitary gland secretes the growth hormone.

Which one of the following actions on touch is an example of chemical control? Movement on the touch-sensitive plant. [CBSE 2009]

Movement on the touch sensitive plant.

What is the use of iodised salt advisable? [CBSE 2008]

Iodised salt contains iodine which is necessary for the thyroid gland to synthesized thyroxine hormone. Thyroxine regulates carbohydrates, protein and fats metabolism in the body to provide growth balance. Its deficiency causes goitre.

Name the hormone the secretion of which is responsible for dramatic changes in appearance of girls when they approach 10-12 years of age. [CBSE 2008]

Hormone estrogen in females.

Name the largest part of the hind brain? [CBSE 2016]

Cerebellum.

Neuron

Neuron is the largest cell in the body. It is an elongated branched cell having three components Cell body, Dendrites and Axon. Neuron are therefore the structural and functional unit of the nervous system.

10th Science Chapter 7 Board Questions Set – 5 (1 Mark)

Name the system which facilitates the communication between the central nervous system and the other body part of the body. [CBSE 2016]

Peripheral nervous system.

State the role played by ovaries in a human female. [CBSE 2015]

Roles of ovary:
(i) Ovaries produce female gametes ova.
(ii) It also produces a female sex hormone called estrogen. Estrogen is essential for development of secondary sense organs in female as well as secondary sexual characters like high pitch voice, development of mammary glands.

Name the longest cell present in the human body. [CBSE 2008]

Neuron is the longest cell present in the human body.

Name the gland and the hormone secreted by the gland which are associated with followings problems: (i) a girl has grown extremely tall. (ii) a woman has a swollen neck. [CBSE 2016]

(i) Pituitary gland- Growth hormone.
(ii) Thyroid gland- Thyroxine hormone.

Different parts of brain are associated with specific functions. Name the parts of human brain which perform the following functions: (a) Sensation of feeling full (b) Vomiting (c) Picking up a pencil (d) Riding a bicycle. [CBSE 2017, 2018]

(a) Cerebrum- Forebrain
(b) Medulla- Hindbrain
(c) Cerebellum- Hind brain
(d) Cerebellum- hind brain

What are tropic levels? Make a food chain of four tropic levels. [CBSE 2017, 2018]

Each step/level of the food chain where energy transfer takes place is called a tropic level.
Example:
(i) Plants < Grasshopper < Frog < Snake (ii) Plants < Deer < Hyena < Tiger

After going through the Class 10 Science NCERT Book, students must see the Important questions related to all chapters. It will make student more confident in concepts.




10th Science Chapter 7 Board Questions Set – 6 (2 Marks)
Name the two main organs of our central nervous system. Which one of them plays a major role in sending command to muscles to act without involving thinking process? Name the phenomenon involved. [CBSE 2010]

The two main organ of CNS are brain and spinal cord. Spinal cord plays a major role in sending command to muscles to act without involving thinking process. This phenomenon is called reflex action.

Name the hormone secreted by human testes. State its functions. [CBSE 2010]

Testes secretes male sex hormone called testosterone. The function of testosterone is to regulate male accessory sex organs and secondary sexual characters like moustache, beard and voice.

Name and explain the function of the hormone secreted by pituitary gland in humans. [CBSE 2010]

Hormones secreted by pituitary gland along with their functions are:
(i) Growth hormone: It regulates growth and development of bones and muscles.
(ii) Trophic hormone: It regulates secretion of hormones from of other endocrine glands.
(iii) Prolactin hormone: It regulates the function of mammary gland in females.
(iv) Vasopressin hormone: It regulate water and electrolyte balance in the body.
(v)Oxytocin hormone: It regulates ejection of milk during lactation.

List the sequence of events that occurs when a plant is exposed to unidirectional light, leading to bending of a growing shoot. Also name the hormone and the type of movement. [CBSE 2009]

Auxin diffuses towards shady side. Causes elongation on one side resulting in bending of growing shoot. The hormone responsible for bending is auxin and the movement is phototropic movement.

Write the name and functions of any two parts of the human hind-brain. [CBSE 2009]

Any two parts of human hindbrain with their function are as follows:
(i) Cerebellum which controls the coordination of body movement and posture.
(ii) Medulla oblongata, which regulates the center of swallowing, coughing, sneezing and vomiting.

Plant Hormones

Plant hormones can be defined as a chemical substance which is produced naturally in plants and are capable of translocation and regulating one or more physiological process when present in low concentration. Two important function of auxin are that it promotes cell division elongation, root formation, cell division etc.

10th Science Chapter 7 Board Questions Set – 7 (2 Marks)
What are nastic and curvature movements? Give one example of each. [CBSE 2009]

Nastic movement is the non-directional movement of turgor or growth where the movement is determined by the structure of the responding organ irrespective of the direction of stimulus which is generally diffuse.
Example:
Bending and drooping of leaves on touching in touch-me-not plant.

Curvature movements are changes in orientation of different plant parts in relation to one another like bending, twisting and elongation. They are of two type turgor and growth movement.
Example: Telegraph plant.

Explain the cause of shoots of the plant blending toward light. [CBSE 2008]

The cause of shoots of the plant bending towards light due to the directional growth or movement of a plant organ in response to an external stimulus known as phototropism.

“There is a need for a system of control and coordination in an organism” Justify the statement. [CBSE 2008]

A change in the environment of a living organism evolves an appreciate movement in response. The movement to be made depend on the event that’s why triggering it. Such control movement must be connected to various events in the environment. Thus living organism must use system providing control and coordination.

Name the three major regions of the human brain. Which part of the brain maintains posture and equilibrium of the body? [CBSE 2008]

The three major regions or parts of the human brain are Fore brain, Mid brain and Hind brain. A part of the hind brain called the cerebellum maintains posture equilibrium of the body.

(a) Distinguish between voluntary and involuntary actions of our body. (b) Choose involuntary actions from amongst the following: Reading, breathing of heart, Salivation in the mouth of viewing a tasty food, talking. [CBSE 2008]

(a) Voluntary actions are the actions which need thinking and are performed knowingly that’s why are controlled by conscious though.
Example Speaking to a friend, writing a letter, etc.
Involuntary actions are not under the control of the will of an individual and are automatic response to a stimulus which is not under the voluntary control of the brain. Examples. Touching a hot plate unknowingly

(b) Involuntary actions: Beating of heart, salivation in the mouth on viewing a tasty food.



10th Science Chapter 7 Board Questions Set – 8 (3 Marks)
Smita’s father has been advised by a doctor to reduce his sugar intake. (i) Name the disease he is suffering from and name the hormone whose deficiency causes it. (ii) Identify the gland that secretes it and mention the function of this hormone. (iii) Explain how the time and amount of secretion of this hormone is regulated in human system. [CBSE 2012]

(i) He is suffering from diabetes. Deficiency of insulin causes diabetes.
(ii) Pancreas secretes insulin. Insulin helps in regulating blood sugar.
(iii) When the sugar level in blood increases it is detected by the cells of pancreas which responds by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

(a) How is brain protected from injury and shock? (b) Name two main parts of hind brain and state the function of each. [CBSE 2012]

(a) The brain sits inside a bony box. Inside the box the brain is contained in a fluid filled balloon which provides further shock absorption.
(b) Two main parts of hind brain are Medulla and cerebellum.
There functions are:
Medulla: Involuntary actions such as blood pressure, salivation and vomiting are controlled by medulla.
Cerebellum: It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.

(a) Which plant hormone is present in greater concentration in the areas of rapid cell division? (b) Give one example of a plant growth promoter and a plant growth inhibition. [CBSE 2012, 2011]

(a) Cytokinin is present in greater concentration in the area of rapid cell division.
(b) An example of a plant growth promoter is gibberellins and example of a plant growth inhibition is Abscisic acid.

Which organ secretes a hormone when blood sugar rises in our body? Name the hormone and name one enzyme released by this organ. [CBSE 2011]

Pancreas secretes a hormone when blood sugar rises in our body. Insulin is the hormone released by this organ and the name of the enzyme is pancreatic juice.

Explain how auxin help in bending of plant stem toward light. [CBSE 2011]

When a growing plant detects light auxin, synthesises at the shoot tip to help the cells to grow longer. When light comes from one side, auxin diffuses toward the shady side of shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from the light and the plant appears to bend towards light.

Auxin

Auxin are the group of plant hormones synthesized at the shoot-tip of the plant body. It promotes cell elongation, root formation, cell division, respiration and other physiological processes like protein synthesis, water uptake and protoplasmic permeability. Auxin also plays an important role in the development of seedless fruits.

10th Science Chapter 7 Board Questions Set – 9 (3 Marks)
What causes a tendril to encircle or coil around the object in contact with it is. Explain the process involved. [CBSE 2011]

When a tendril comes in contact with any support the part of the tendril in contact with the object does not grow as rapidly as the part away from the object. These cause the tendril to circle around the object and thus cling to it.

Name the hormone synthesised at the shoot tips. How does it help the plant to response to light? [CBSE 2011]

A hormone called auxin is synthesised at the shoot tip. When a growing plant detects light, auxin synthesis at the shoot tip to help the cells to grow longer. When light comes from one side, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light and the plant appears to bend towards light.

Name any three endocrine glands in human body and briefly write the function of each of them. [CBSE 2011]

Three endocrine glands with their function in human body are as follows:
(i) Thyroid gland
Function: It secretes a hormone called thyroxine which regulates the metabolism of carbohydrates, fats and proteins in the body and so provide the best balance for growth.
(ii) Adrenal glands
Function: It secretes two hormone adrenalin and corticoid hormones which regulates blood pressure, heart beat, breathing rate, carbohydrates metabolism and mineral balance.
(iii) Pancreas
Function: It secretes two hormone insulin and glucagon. Insulin hormone lower the blood glucose. Glucagon hormone increases the blood glucose.

Which part of brain controls involuntary actions. Write the function of any two regions of it. [CBSE 2011]

Hind brain controls the involuntary actions.
Cerebellum controls the coordination of body movement and posture.
Medulla oblongata regulates center for swallowing, coughing, sneezing and vomiting.

What is chemotropism? Give open example. Name any two plant hormones and mention their functions. [CBSE 2011]

Chemotropism is the movement of a part of the plant in response to a chemical stimulus. It can positive chemotropism and negative chemotropism.
Example: The growth of the pollen tube towards a chemical which is produced by an ovule during the process of fertilisation in a flower.
Two plant hormones with their functions are as follows:
Auxins promote cell elongation, root formation, cell division, respiration and other physiological process like protein synthesis, etc.
Gibberellins stimulates stem elongation, seed germination and flowering.

Gibberellins

Gibberellins stimulate stem elongation, seed germination and flowering. The maximum concentration of gibberellins is found in fruits and seeds.

10th Science Chapter 7 Board Questions Set – 10 (3 Marks)
State the functions of any three of the structural and functional unit of nervous system. [CBSE 2011]

The structural and functional unit of nervous system i.e. neuron with their functions are as follows:
(i) Cell body: Stimulus received from dendrite is changes into impulse in the cyton.
(ii) Dendrites: They receive sensation or stimulus which may be physical, chemical, mechanical or electrical. They pass the stimulus to the cyton.
(iii) Axon: It conduct impulse away from the cell body.

What is phototropism? How does it occur in plants? Describe an activity to demonstrate phototropism. [CBSE 2010, 2009]

Phototropism is the directional growth movement of curvature of plant organs in response to unidirectional exposure to light.
Phototropism in plants:
Plants bend toward light when they are exposed to it. The aerial shoots usually grow toward light while some aerial roots grow away from light. This response to controlled by the differential distribution of the plant growth substance auxin in the illuminated part which cause differential growth of the root and shoot.
Activity to demonstrate phototropism:
A conical flask with water is taken and neck of which is covered by a wire mesh 2 or 3 freshly germinated bean seeds, are kept on the wire mesh. A cardboard box so that open side of the box receives light from a window. After 2-3 days it will be seen that shoots bend toward light and roots away from light.

What is hydrotropism? Describe an experiment to demonstrate hydrotropism? [CBSE 20019 2011, 2015]

Hydrotropism is the directional growth of a plant part is response to water.
Example root shows hydrotropism as they grow towards water in the soil and are positively hydrotropic.
An experiment to demonstrate hydrotropism are as follows:
(i) A porous pot filled with water is taken and is inserted in a tub filled with dry sand.
(ii) A freshly germinated pea seedling is sowed in a sand.
(iii) As water is not available in sand the root growing will bend towards the porous pot filled with dry sand.
(iv) A hydrotropic curvature of the root is observed as it grows towards water.
(v) This bending of roots shows the movement in response toward water.

What are hormones? State one function of each of the following hormones: (i) Thyroxine (ii) Insulin [CBSE 2009, 2011]

Hormone are the chemical substances which coordinate and control the activities of living organism and also their growth. The term hormone was introduced by Bayliss and Startling function
(i) Thyroxine hormone regulates the metabolism of carbohydrates, fats and protein in the body so as to provide the best growth balance.
(ii) Insulin hormone helps in regulating sugar level in blood.

(a) Name the two main constituents of the Central Nervous System in human being. (b) What is the need for a system of control and coordination in human being? [CBSE 2009]

(a) Two main constituent of the Central Nervous System in human beings are the brain and spinal cord.
(b) The different organs of our body work in coordination when we perform any activity. For example, when we are taking food, our eyes help in locating the food, our nose detect the smell, our hand brings the food, the teeth and jaw muscles chew the food and saliva starts the digestion process.
So, control and coordination is essential in maintaining a state of stability and a steady state between the internal condition of an organism and the external environment.

Cytokinin

Cytokinin are produced in dividing cells throughout the plant. In mature plant, Cytokinin are produced in the root tips and are transported to the shoots. Cytokinin promote cell division and also helps in breaking the dormancy of seeds and buds and regulate the phloem transport. Cytokinin delay the ageing in leaves and promote the opening of stomata.

10th Science Chapter 7 Board Questions Set – 11 (3 Marks)
What is a reflex action? Describe the step involved in a reflex action. [CBSE 2009, 2010]

Reflex action: It is defined as an unconscious automatic and involuntary response of effectors i.e. muscles and glands to stimulus which is control through the spinal cord.
Mechanism of Reflex action. It involves the following steps:
(i) Receptors organ like skin perceive the stimulus and activates a nerve impulse.
(ii) Sensory organ carries message in the form of sensory impulse to the spinal cord.
(iii) The spinal cord act as modulator. The neurons of spinal cord transmit the sensory nerve impulse to motor neuron.
(iv) Motor nerve conducts these impulses to the effectors like leg muscles which responds by pulling back the organ away from the harmful stimulus.

Define hormones Name the hormone secreted by thyroid. Write its function. Why is the use of iodised salt advised to us? [CBSE 2010, 2008]

Hormones are the chemical substance which coordinates and control the activities of living organism and also their growth. The hormone secreted by thyroid is thyroxine. Its function is to regulate the metabolism of carbohydrates, fast and protein in the body so as to provide the best balance for growth. The use of iodised salt is advised to us because iodine is necessary for the thyroid gland to produce thyroxine hormone. Thyroxine regulates carbohydrates, protein and fat metabolism which is required for growth. Deficiency of iodine in the body causes disorder like swollen neck and disease called Goitre.

Which animal or plant hormone is associated with the following? (i) Increased sugar level in blood. (ii) Changes at puberty in boys. (iii) Inhibits growth of plants (iv) Rapid development of fruits (v) Dwarfism (vi) Goitre [CBSE 2008]

The animal or plant hormone which is associated with the following are as follow:
(i) Increased sugar level in blood- Insulin hormone
(ii) Changes at puberty in boys- Testosterone hormone
(iii) Inhibits growth of plants- Abscisic Acid
(iv) Rapid development of fruits- Cytokinin
(v) Dwarfism- Growth hormone
(vi) Goitre- Thyroxine hormone

As the blood sugar level in our body falls insulin secretion is reduced. Justify this statement in the reference of feedback mechanism that regulate timing and amount of hormone released. [CBSE 2015]

Insulin is a hormone that regulates our blood sugar level by converting it into glycogen which can be stored. Hence of there is more levels of sugar in blood then more insulin is produced and if the sugar level is less than insulin production is also reduced. This is because of feedback mechanism where the blood sugar itself acts as a feedback for more or reduced insulin synthesis.

How does feedback mechanism regulate the hormone secretion? Explain with the help of an example. [CBSE 2017, 2018]

Feedback system is a regulatory mechanism in which presence of certain level of hormone promotes or inhibits its further formation.
Regulation of thyroxine production by its concentration in blood is an example of hormonal feedback system. If the level of thyroxine is more in the blood, this is detected by hypothalamus, which stops producing thyroid stimulating hormone. Non availability of TSH results in failure of thyroid to produce thyroxine in blood. But if concentration is low in the blood, hypothalamus produce TSH which then passes into circulatory system and reaches thyroid gland. Thyroid now begins to secrete more thyroxine.

State the source of secretion and function of the following hormones:
(i) Thyroxin
(ii) Insulin
(iii) Growth hormone [CBSE 2016, 2017, 2018]

HormoneSourceFunction
(i) ThyroxineThyroid glandRegulates metabolism of carbohydrates, fats and proteins.
(ii) InsulinPancreasPromotes sugar absorption from blood thereby regulating blood sugar level.
(iii) Growth hormonePituitary glandRegulates overall growth of the body.



10th Science Chapter 7 Board Questions Set – 12 (3 Marks)
In the absence of muscles cells, how do plant cells show movements? [CBSE 2016]

Plants do not have nervous system and muscles. Even then they exhibit well-coordinated and controlled movements. Plants possess chemical coordination. They respond to stimuli by secreting chemical substance called as plant growth regulators. They either stimulate or retard growth. Five major type of plant growth hormone are auxin, gibberellins, Cytokinin, Abscisic acid and ethylene. Certain changes in the orientation of plant parts in relation to other parts caused by intrinsic or external stimuli are non-directional, growth independent movements. They are referred as nastic movements. Thus, plants show movements due to growth or change in turgor pressure.

(a) State the role performed by plant hormones. Name a plant hormone which is essential for cell division. (b) Name and explain the role of plant hormone involved in phototropism. [CBSE 2017, 2018]

(a) Role of plant hormones:
Chemical control in the plant is performed through plant hormones. They help to coordinate growth development and responses to the environment.
Plant hormones auxin and Cytokinin helps in cell division.
(b) When growing plants detect light a hormone called auxin, synthesised at the shoot tip helps the cells to grow longer. When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of shoot which is away from light.

(a) Name the gland the secrete: (i) Insulin (ii) thyroxine (b) Explain with an example how the timing and amount of hormone secreted are regulated in a human body. [CBSE 2017, 2018]

(a) Gland that secretes:
(i) Insulin- Pancreas
(ii) Thyroxine- Thyroid gland
(b) The timing and amount of hormone secreted are regulated by the Feedback mechanisms. For example:
(i) High glucose level in blood induces the pancreatic cells to produce more insulin which converts glucose to glycogen.
(ii) Low glucose level in the blood does not induce the pancreatic cells to produce insulin so that less conversion of glucose to glycogen occurs.

(a) Name the part of human brain which controls: (i) voluntary actions (ii) involuntary actions. (b) State the significances of peripheral nervous system. Name the components of this nervous system and distinguish between their origins. [CBSE 2008, 2017, 2018]

(a) (i) Voluntary actions are controlled by cerebellum.
(ii) Involuntary actions are controlled by mid-brain.
(b) Peripheral nervous system facilitates the communication between central nervous system and other body parts.
Components of peripheral nervous system are:
(i) Cranial Nerve: Originating from brain.
(ii) Spinal Nerve: Originating from spinal cord.

What is synapse? In a neuron cell how is an electrical impulse created and what is the role of synapse in this context? [CBSE 2015]

Synapse is the gap/junction between two successive neurons. All information from the environment is detect by the specialized tips the dendrites of some nerve cells present in tissues and organs. These are called receptors. They are located in our sense organ like, nose, tongue, skin, eye, and inner ear.
Sensory receptors are of different types. Photoreceptors, phonoreceptors, olfactoreceptors, gustatoreceptors, thermoreceptors and so on. They detect light, sound, smell, taste, heat, and cold respectively.
The above mentioned receptors initiate electrical impulses to be picked up by sensory nerves. This impulse travels from the dendrite to the cell body, and then along the axon to its end. Axon ending of one neuron are placed close to dendrites of the next neuron. This junction is called synapse or gap. As soon as the impulse reaches the end of neuron it sets off release of some chemicals. These chemicals cross the gap or synapse and start a similar electrical impulse in dendrites of neuron. Finally, the 9impulses reaches a muscle or a gland.

Write two points of difference between enzymes and hormones. Name one endocrinal gland in our body which performs dual function. Write the function. [CBSE 2016]

EnzymesHormones
1. Are produced by exocrine glands.1. Are produced by endocrine glands.
2. Sits of secretion and action is same.2. Sits of secretion and actions is different.

Pancreas perform dual function. It produced enzymes like Trypsin, Lipase etc., which aid in digestion. It also produces insulin hormone which regulates blood-sugar level.

10th Science Chapter 7 Board Questions Set – 16 (5 Marks)
Name the two components of central nervous system. How are they protected? Name the component which is considered as highest coordinating centre of the body. Describe its three regions. [CBSE 2016]

Brain and spinal cord are the two components of central nervous system. Human brain is protected by a bony skull, also called as cranium. Internal to the skull it is covered from outside by three membranes called meninges there is a fluid called as cerebrospinal fluid. Beneath the membrane brain is divided into three major parts namely fore-brain, midbrain and hind brain.
Brain is considered as highest coordinating center of the body.
Its three region are given below:
(a) Fore brain is the main thinking part of the brain. It has different regions or areas such as:
(i) Sensory area: It receives sensory impulses from various receptors.
(ii) Auditory area: It is concerned with hearing.
(iii) Olfactory area: It is concerned with smell.
(iv) Gustatory area: It is concerned with taste.
(v) Optic area: It is concerned with sight.
(vi) Association area: This area interprets various sensory information and makes decision how to respond.
(vii) Motor area: Decision made by association area are passed on to this area which control the movement of voluntary muscles.
(b) Mid brain comprises of four lobes. So it is also known as copra quadrigemina. Actions of involuntary muscles are controlled by the midbrain and hind brain.
(c) Hind brain comprises of cerebellum, pons varolii and medulla oblongata. Cerebellum is the second largest part of the brain that coordinate muscles activity of the body as well as maintains body equilibrium or posture. Pons connects cerebellum and medulla oblongata and function as a reply centre among different parts of brain. Medulla oblongata lies below cerebellum and continuous behind spinal cord. Involuntary actions like blood pressure, salivation and vomiting are controlled by the medulla in the hind brain.

With the help of suitable examples explain the term phototropism, geotropism and chemotropism. [CBSE 2016]

The stimulus oriented movement of plant or plant part is called tropism. The direction of movement is related to the direction of stimulus. These movements are always growth orientated movements. They are different types namely phototropism, hydrotropism, geotropism, thigmotropism and chemotropism.
(i) Phototropism is a directional growth movement which occurs in response to unidirectional exposure to light. The region of photoreception is shoot apex where auxin is produced. Auxin moves from illuminated region to the shaded region. This causes more growth on the dark side of stem causing it to bend towards the source of light. Movement of shoot toward light is called phototropism.
(ii) Roots are positively geotropic and negatively phototropic. Shoots are positively phototropic and negatively geotropic.
(iii) Growth of pollen tube inside the style, ovary and ovule in response to the chemicals produced by them is an example of chemotropism.

(a) Define hormone. Write four characteristic of hormones in humans. (b) Name the disorder caused by the following situations: (i) Under secretion of growth hormone. (ii) Over secretion of growth hormone. (iii) Under secretion of insulin. (iv) Deficiency of iodine. [CBSE 2016]

(a) Hormones are chemical information molecule that are required in minute quantities and are directly poured in the blood stream by the gland. They act on a specific organ called target organ. So their site of production varies from site of action.
Their characteristic are:
(i) They are poured into blood stream.
(ii) Are generally proteinaceous or steroid.
(iii) There secretion is regulated by feedback mechanism.
(iv) Their site of action and secretion is different.
(b) (i) Dwarfism
(ii) Gigantism.
(iii) Diabetes
(iv) Goitre

(a) Name the hormone which is released into the blood when its sugar level rises. Name the organ which produces this hormone and its effect on blood sugar level. Also mention the digestive enzymes secreted by this organ with one functions of each. (b) Explain the need of chemical communication in multicellular organisms. [CBSE 2016]

(a) When blood sugar level rises in blood, a hormone named insulin is produced by cells of islets of Langerhans in the organ Pancreas. Pancreas also produced pancreatic juice which contains pancreatic enzymes such as trypsin, pancreatic amylase and pancreatic lipase. Insulin promotes glucose absorption by individual cells and absorption and formation of glycogen in liver and muscles. This reduces glycose level in blood. As soon as the blood sugar comes to normal the pancreatic cells stops secretion of insulin.
Pancreas secretes slightly alkaline pancreatic juice which contains three major following enzymes:
(i) Trypsin which digests proteins.
(ii) Lipase which digests fats.
(iii) Amylase which digests carbohydrates.
(b) An organism has different organs which perform various functions. The survival of an organism depends on integrated and coordinated function of these organs. Nervous and endocrine system of an organism make them work together like parts of one machine to accomplish homeostasis or coordination.

What are phytohormones? List four type of phytohormones. Where are they synthesised. [CBSE 2016]

Plants possess chemical coordination. They respond to stimuli by secreting achemical substance called as plant growth relators. They either stimulate or retard growth. Five major types of plant growth hormone are auxin, gibberellins, cytokinins, abscisic acid and ethylene.
These plant are growth regulator also known as phytohormones.
They are synthesised at the shoot aspics, leave, developing embryos, root tips etc.

Write the names of the hormones secreted by pituitary gland and adrenal gland. State their functions in the body. [CBSE 2015]

Hormone secreted byFunctions
1. Pituitary gland: Growth HormoneRegulates growth and development of the body.
2. Adrenal gland: Adrenaline(i) Prepares the body for facing an emergency situation. (ii) Increases heart rate, resulting in more oxygen supply to muscles. (iii) Reduces blood supply to skin and digestive system. (iv) Increases breathing rate.



Abscisic Acid

Abscisic Acid is a growth inhibitor which reserves the growth promoting effects of auxins and gibberellins. Its effect includes writing of leaves. It causes democracy of seeds. It also promotes the closing of stomata.