A abampere (aA) The unit of electric current in the CGSeniu system, defined as that current that, if flowing through two parallel conductors of negligible cross section and infinite length, placed 1 cm apart in vacuo, would produce on each conductor a force of 1 dyne per centimeter of length. 1 abampere = 1 abcoulomb/s = r statampere (where c = speed of light in cm/s) = 10 ampere. aberration Imperfect image formation due to geometric imperfections in the optical elements of a system ablation 1 . The wasting of glacier ice by any process (calving, melting, evaporation, etc.). 2. The shedding of molten material from the outer sur- face of a meteorite or tektite during its flight through the atmosphere. absolute age The age of a natural substance, of a fossil or living organism, or of an artifact, obtained by means of an absolute dating method. See absolute dating method. absolute density Density in kg/m' or, more commonly, in g/cm\ both at STP. Cf. density, relative density abso
Control and coordination class 10 NCERT biology MCQ & SAQ
Control and coordination class 10 NCERT biology NCERT SOLUTION:
1. What is the difference between reflex action and walking?
Reflex action is involuntary action which means it is not under control of the brain , it only involves the spinal cord, it is rapid, thus giving instant response to the stimulus and not affected by our thinking.
But walking is a voluntary action controlled by the brain that involves the central nervous system and spinal cord both and is affected by our thinking.
2. What happens at the synapse between two neurons?
The synapse is the tiny gap (not seen by naked eyes) between two adjacent neurons. 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 the process of how nervous impulses travel in the body. Similar synapse finally allows delivery of such impulses from neurons to other cells, such as muscle cells or glands.
3. Which part of the brain maintains posture and equilibrium of the body?
Cerebellum
4. How do we detect the smell of an agarbatti (incense stick)?
When agarbatti burns, it produces a pleasant smell, which is detected by the olfactory receptor present inside the nose. The action of smell generates the electrical impulse. These impulses are carried to the sensory area of the brain(forebrain-cerebrum). Thus we detect the smell of agarbatti.
All information from our environment is detected by the specialized tips of some nerve cells. These 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.
5. What is the role of the brain in reflex action?
Reflex action occurs in the spinal cord. The brain and spinal cord constitute the central nervous system. They receive information from all parts of the body and integrate it.
1. What are plant hormones?
The chemical substances produced in plants which control growth, development and responses in plants, are called plant plant hormones.
For example: Auxins, Gibberellins, Cytokinins and Abscisic acid.
2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
The main differences between the movement of the leaves of a sensitive plant and the movement of a shoot towards light are as follows:
3. Give an example of a plant hormone that promotes growth.
Auxin
4. How do auxins promote the growth of a tendril around a support?
Auxin is a plant growth hormone. When the tip of the tendril touches a support, then the auxins present on its tip moves to the side of the tip which is away from the support, so, due to more auxins in its tendrils away from the support grows faster.
5. Design an experiment to demonstrate hydrotropism.
Hydro’ means water. Hydrotropism means growth towards water.
Materials Required: Seed, A big container, Porous water pot, water and Sand.
Procedure:
• The tray should be big enough to accommodate the porous pot.
• Fill the tray with sand and insert some seeds in it.
• Make a pit in the sand and insert the porous pot in it.
• Fill the porous pot with water. • Leave the set up for about a week.
Observation:
After a week when seeds are taken out, it is observed that roots grow in the direction of the porous pot. This shows hydrotropic movement in roots.
1. How does chemical coordination take place in animals?
The chemical coordination in animals takes place by the action of chemicals called hormones. They are produced in certain glands in the body in very small amounts and poured directly into the blood. They are target based means work on particular organs and these organs are called target organs. The hormones control and coordinate various functions of the body such as development, growth, sexual changes etc.
2. Why is the use of iodised salt advisable?
Iodine is necessary for the thyroid gland to make thyroxine hormone. Thyroxine regulates carbohydrate, protein and fat metabolism in the body so as to provide the best balance for growth. Iodine is essential for the synthesis of thyroxine. In case iodine is deficient in our diet, there is a possibility that we might suffer from goiter. One of the symptoms in this disease is a swollen neck.
3. How does our body respond when adrenaline is secreted into the blood?
Adrenaline is secreted directly into the blood and carried to different parts of the body. The target organs or the specific tissues on which it acts include the heart. As a result, the heart beats faster, resulting in a supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs. This diverts the blood to our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles. All these responses together enable the animal body to be ready to deal with the situation. Such animal hormones are part of the endocrine system which constitutes a second way of control and coordination in our body.
4. Why are some patients of diabetes treated by giving injections of insulin?
Diabetes patients as a treatment, they might be taking injections of insulin. This is a hormone which is produced by the pancreas and helps in regulating blood sugar levels. If it is not secreted in proper amounts, the sugar level in the blood rises causing many harmful effects.
1. Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Estrogen
(d) Cytokinin
Answer
(d) Cytokinin
2. The gap between two neurons is called a
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.
Answer
(b) synapse.
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3. The brain is responsible for
(a) thinking.
(b) regulating the heartbeat.
(c) balancing the body.
(d) all of the above.
Answer
(d) all of the above.
4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
All information from our environment is detected by the specialized tips of some nerve cells. These 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. We detect that we are touching a hot object by the action of receptors present on various organs or tissues.
If the olfactory receptor does not work properly then we are not able to smell things like agarbatti, perfumes, or the flavor of food.
5. Draw the structure of a neuron and explain its function.
A neurons consists of three parts;
(i) Cell body: It is a typical animal cell which contains cytoplasm and a nucleus.
(ii) Dendrites: A number of long and thin fibers come out from the cell body of the neurons, they are nerve fibers. The shorter fibers on the cell body of neurons are called dendrites.
(iii) Axon: The longest fiber on the cell body of neurons is called axon. It has an insulating and protective sheath (or cover)of myelin around it.
Function:
The 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 muscle cells or glands.
It is thus no surprise that nervous tissue is made up of an organized network of nerve cells or neurons, and is specialized for conducting information via electrical impulses from one part of the body to another.
6. How does phototropism occur in plants?
Photo means light. The response of plants towards the environmental triggers, light which change the directions that plant parts grow in is called phototropism.
The directional, or tropic, movements can be either towards the light, or away from it. So, in two different kinds of phototropic movement, shoots respond by bending towards light while roots respond by bending away from it.
For example: Sunlight bends towards the sun from where the light is coming. This is the response of the sunflower towards the plants.
7. Which signals will get disrupted in case of a spinal cord injury?
Reflex actions are involuntary actions and controlled by the spinal cord thus, get disrupted in case of spinal cord injury.
8. How does chemical coordination occur in plants?
Plants do not have nervous system but still sense the things because of stimulus such as gravity, light, chemicals(hormones), water, touch (touch -me -not plant).Hormones are responsible for the chemical coordination of plants by integrating their behavior by affecting growth of a plant resulting in movement of that plant part in response to a stimulus. When sunlight falls on the shoot from one side, the auxins hormone causes the shady side of the shoot to grow faster, making the shoot bend towards sunlight.
9. What is the need for a system of control and coordination in an organism?
Controlled movement must be connected to the recognition of various events in the environment, followed by only the correct movement in response. In other words, living organisms must use systems providing control and coordination. In keeping with the general principles of body organization in Multicellular organisms, specialized tissues are used to provide these control and coordination activities.
(i) Coordination is needed for all human activities like, thinking and behavior. Our breathing process, heart beats, we dance, read, write by the action of our nervous system. Our nervous system gets information from surroundings and processes it and then responds according to it. The endocrine system (hormonal system) helps in integrating various metabolic activities like reproduction, development, and all reflex actions (cope up with various give up situations).
(ii)The hormonal system in plants helps in the process of photosynthesis; they need carbon dioxide, water and sunlight. The stomatal opening in leaves opens up to allow in carbon dioxide gas, the roots bend towards water and the stem grows towards sunlight, the tendrils in climbing pants are supported by the hormonal system of the plant body.
Thus, we have a need for a control and coordination system in organisms.
10. How are involuntary actions and reflex actions different from each other?
involuntary actions are not controlled by us. They are independent processes meaning there is no stimulus involved in these actions but reflex action is also involuntary in nature but they involve stimulus means functions or respond according to it.
For example;
Involuntary actions: heart beat, breathing process; etc.
Reflex actions: stepping out in bright light, changes in size of pupil of eyes.
11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Difference between nervous and hormonal mechanism:
12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
The movement of sensitive plant leaves takes place due to the sudden loss of water in the pad-like swelling (called pulvini) at the base of all the leaves. Pulvini limp gets drooped and folded due to the loss of water. On the other hand, the movement of our legs takes place due to pulling in the muscles of the legs on the leg bones.
Control and coordination class 10 NCERT biology MCQ :
1. The brain is lodged inside the cavity of skull known as :
a) Pia Mater
b) Dura Mater
c) Cranium
d) Meninges
► c) Cranium
2. Roots of plants are:
(a) positively geotropic
(b) negatively geotropic
(c) positively phototropic
(d) None of these
► (a) positively geotropic
3. Which plant hormone promotes cell division?
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscisic acid
► (c) Cytokinin
4. Which plant hormone promotes dormancy in seeds and buds?
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscisic acid
► (d) Abscisic acid
5. When a person is suffering from severe cold, he or she cannot –
a) Differentiate the taste of an apple from that of an ice – cream.
b) Differentiate red light from green light.
c) Differentiate a hot object from a cold object.
d) Differentiate the smell of a perfume from that of an agarbatti
► (d) Differentiate the smell of a perfume from that of an agarbatti.
6. Response of plant roots towards water is called:
(a) Chemotropism
(b) Phototropism
(c) Hydrotropism
(d) Geotropism
► (c) Hydrotropism
7. Fall of mature leaves and fruits from plants is triggered by which of the following substances?
(a) Auxin
(b) Cytokinin
(c) Gibberellin
(d) Abscisic acid
► (d) Abscisic acid
8. Movement of sunflower in accordance with the path of Sun is due to
(a) Chemotropism
(b) Geotropism
(c) Phototropism
(d) Hydrotropism
► (c) Phototropism
9. Junctions of two neurons are called.
a) Synapse
b) Synapsis
c) Joint
d) Junction
► a) Synapse
10. The main function of abscisic acid in plants is
(a) to promote cell division.
(b) to inhibit growth.
(c) to promote growth of the stem.
(d) to increase the length of cells.
► (b) to inhibit growth.
11. Which gland secretes the growth hormone?
(a) Pituitary gland
(b) Thyroid
(c) Hypothalamus
(d) Adrenal
► (a) Pituitary gland
12. Which of the following acts as both endocrine and exocrine gland?
(a) Pancreas
(b) Thyroid
(c) Adrenal
(d) Liver
► (a) Pancreas
13. Which of the following is a plant hormone?
a) Insulin
b) Thyroxin
c) Estrogen
d) Cytokinin
►d) Cytokinin
14. Breathing is controlled by which part of the brain?
(a) Cerebrum
(b) Cerebellum
(c) Hypothalamus
(d) Medulla oblongata
► (d) Medulla oblongata
15. Main function of cerebrum is
(a) thinking
(b) hearing
(c) memory
(d) balancing
► (a) thinking
16. Which nerves transmit impulses from the central nervous system towards muscle cells?
(a) Sensory nerves
(b) Motor nerves
(c) Relay nerves
(d) Cranial nerves
► (b) Motor nerves
17. The neurons that carry nerve impulse from spinal cord to effectors are called:
a) Sensory neurons
b) motor neurons
c) Interneurons
d) spinal neurons
► b) motor neurons.
18. The substance that result into the fall of mature leave and fruits from plants is due to :
a) auxin
b) gibberellin
c) ABA
d) cytokinin
► b) gibberellin
19. Visceral nervous system controls and integrates the function of –
a) Urinary bladder
b) Blood vessels
c) Heart
d) All of the above
► d) All of the above
20. A part of the body which responds to the in-structions sent from nervous system is called
(a) receptor
(b) effector
(c) nerves
(d) muscles
► (b) effector
21. Identify which of the following statements about thyroxine is incorrect?
(a) Thyroid gland requires iodine to synthesize thyroxine.
(b) Thyroxine is also called thyroid hormone.
(c) It regulates protein, carbohydrates and fat metabolism in the body.
(d) Iron is essential for the synthesis of thyroxine.
► (d) Iron is essential for the synthesis of thyroxine.
22. Which part of the nervous system controls the reflex activities of the body?
(a) Brain
(b) Spinal cord
(c) Cerebrum
(d) Cerebellum
► (b) Spinal cord
23. Select the mismatched pair
a) Adrenaline – Pituitary gland
b) Testosterone – Testes
c) Estrogen – Ovary
d) Thyroxine – Thyroid gland.
► a) Adrenaline – Pituitary gland
24. Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Estrogen
(d) Cytokinins
► (d) Cytokinins
25. Posture and balance of the body is controlled by
(a) Pons
(b) Medulla oblongata
(c) Cerebellum
(d) Cerebrum
► (c) Cerebellum
26. The highest coordinating center in the human body is
(a) spinal cord
(b) heart
(c) brain
(d) kidney
► (c) brain
27. The longest fiber on the cell body of a neuron is called
(a) sheath
(b) cytoplasm
(c) axon
(d) dendrites
► (c) axon
28. Any change in the environment to which an organism responds is called
(a) stimulus
(b) coordination
(c) response
(d) hormone
► (a) stimulus
29. Which of the following tissues provide control and coordination in animals?
(a) Nervous and Skeletal
(b) Muscular and Skeletal
(c) Muscular and Transport
(d) Nervous and Muscular
► (d) Nervous and Muscular
30. How many pairs of cranial nerves are present in man?
(a) 12
(b) 21
(c) 31
(d) 41
► (a) 12
31. The hormone that is used to keep flowers fresh is
(a) cytokinin
(b) gibberellins
(c) auxin
(d) abscisic acid
► (a) cytokinin
32. Reflex actions are mediated through
(a) brain
(b) effectors
(c) spinal cord
(d) receptors
► (c) spinal cord
33. Which statement is incorrect about auxins?
(a) They promote the growth of root
(b) They promote the growth of shoot
(c) They influence the formation of flower and ripening of fruit
(d) They inhibit the growth of root
► (a) They promote the growth of root
34. The main effect of cytokinin in plants is to
(a) improve the quality of fruits
(b) prevent the growth of lateral buds
(c) regulate opening and closing of stomata
(d) stimulate cell division
► (d) stimulate cell division
35. Aging in human beings is caused by disappearance of which of the following glands?
(a) Adrenal
(b) Pituitary
(c) Thyroid
(d) Thymus
► (d) Thymus
36. Which hormone regulates the ionic balance in the body?
(a) Glucagon
(b) Thyroxine
(c) Testosterone
(d) Vasopressin
► (d) Vasopressin
37. Which endocrine gland is also known as ‘master gland’?
(a) Pancreas
(b) Adrenal
(c) Pituitary
(d) Hypothalamus
► (c) Pituitary
38. Which of the following is not associated with plant growth?
(a) Auxin
(b) Gibberellins
(c) Cytokinins
(d) Abscisic acid
► (d) Abscisic acid
39. Which of the following is not a ductless gland?
(a) Adrenal
(b) Liver
(c) Thyroid
(d) Pituitary
► (b) Liver
40. Which of the following acts as both endocrine and exocrine glands?
(a) Adrenal
(b) Pituitary
(c) Ovaries
(d) Pancreas
► (d) Pancreas
41. Assertion: Impulse travels from dendrite to cell body and then along the axon to its end.
Reason: Information acquired at the end of the dendrite tip of a nerve cell sets off an electric impulse.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.
► (a) Both A and R are true and R is the correct explanation of A.
42. Assertion: Reflex Arc works faster than the thinking process of the brain.
Reason: Reflex Arc works in the case of those animals who don't have a thinking process.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.
► (c) A is true but R is false.
43. Assertion: On attaining puberty, breast size increases and reproductive organs develop in females.
Reason: Ovaries release hormone proges-terone in females.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.
► (b) Both A and R are true but R is not the correct explanation of A.
44. Assertion: Brain is a delicate organ which is protected from injury.
Reason: The bony box protects the brain from any shock.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.
► (c) A is true but R is false.
45. Assertion: Plants do have a nervous system for control and coordination.
Reason: Plants use electro chemical means to convey information from cell to cell.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.
► (d) A is false but R is true.
Control and coordination class 10 NCERT biology SAQ:
Q1. What is the feedback mechanism of hormone regulation? Take the example of insulin to explain this phenomenon. [Delhi 2019]
Hormones are secreted in extremely less quantity. Excess or deficiency of such hormones can have harmful effects on our body. A feedback mechanism controls the timing and secretion of hormones released by various glands.
For example: On the rise of blood glucose level, information is sent to pancreas to release insulin. When the appropriate amount of glucose level is obtained in the blood, the release of insulin is stopped.
Q2. (a) Name the part of human brain which controls: [CBSE 2017-18 C]
(i) voluntary actions (ii) involuntary actions.
(b) State the significance of the peripheral nervous system. Name the components of this nervous system and distinguish between their origins.
(a) (i) Voluntary actions are controlled by Cerebellum (hindbrain).
(ii) Involuntary actions are controlled by midbrain.
(b) Peripheral nervous system facilitates the communication between central nervous system and other body parts.
Components of peripheral nervous system are:
(i) Cranial Nerves: Originating from the brain.
(ii) Spinal Nerves: Originating from the spinal cord.
Q3. (a) Name the gland that secrete:
(i) insulin, (ii) thyroxin.
(b) Explain with an example how the timing and amount of hormones secreted are regulated in a human body. [CBSE 2017-18 C]
(a) Gland that secretes:
(i) Insulin - Pancreas
(ii) Thyroxine - Thyroid gland
(b) The timing and amount of hormones 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.
Q4. (a) State the role performed b y plant hormones. Name a plant hormone which is essential for cell division.
(b) Name and explain the role of plant hormones involved in phototropism. [CBSE 2017-18 C]
(a) Role of plant hormones:
Chemical control in the plants is performed through plant hormones. They help to coordinate growth, development and responses to the environment.
Plant hormones auxin and cytokinin help in cell division.
(b) When growing plants detect light, a hormone called auxin, synthesized 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 the shoot which is away from light.
Q5. What is geotropism? Draw a labeled diagram of a potted plant showing positive geotropism and negative geotropism. [CBSE 2017-18 C]
The downward growth of roots due to attraction by earth’s gravity and upward growth of shoots against it, is geotropism.
Q6. How does the feedback mechanism regulate hormone secretion? Explain with the help of an example. [CBSE 2017-18 C]
Feedback system is a regulatory mechanism in which the presence of a certain level of hormone promotes or inhibits its further formation.
Regulation of thyroxine production by its concentration in blood is an example of a hormonal feedback system. If the level of thyroxine is more in the blood, this is detected by hypothalamus, which stops producing thyroid-stimulating hormone (TSH). Non-availability of TSH results in failure of thyroid to produce thyroxine. This automatically results in reduction of thyroxine in blood.
But if concentration of thyroxine is low in the blood, hypothalamus produces TSH which then passes into circulatory system and reaches thyroid gland. Thyroid now begins to secrete more thyroxine.
Q7. State the source of secretion and function of the following hormones: [CBSE 2016,2017-18 C]
(i) Thyroxin (ii) Insulin (iii) Growth hormone.
Q8. What are trophic levels? Make a food chain of four trophic levels. [CBSE 2017-18 C]
Each step/level of the food chain where energy transfer takes place is called a trophic level.
Example: (i) Plants → Grasshopper Frog → Snake
(ii) Plants Deer → Hyena Tiger
Q9. Different parts of the brain are associated with specific functions. Name the part of human brain which perform the following functions: [CBSE 2017-18 C]
(a) Sensation of feeling full
(b) Vomiting
(c) Picking up a pencil
(d) Riding a bicycle.
(a) Cerebrum - Forebrain
(b) Medulla - Hindbrain
(c) Cerebellum - Hindbrain
(d) Cerebellum - Hindbrain
Q10. (a) What are sensory and motor neurons? Write their function. [CBSE 2018C]
(b) Different parts of the brain are associated with specific functions. Name the part of human brain which perform the following functions:
(i) Sensation of feeling full
(ii) Vomiting
(a) Two types of neurons are:
(i) Sensory neurons - They transmit information from the receptors to the central nervous system.
(ii) Motor neurons - They transmit information from the brain to the effector organs.
(b)
(i) Forebrain (a center for hunger)
(ii) Hindbrain (medulla)
Q11. Name the plant growth hormone which is synthesized at shoot tip. Explain with the help of a diagram why a plant bends towards light during growth. [CBSE 2016]
(i) Auxin is a phytohormone which is synthesized at shoot tip.
(ii) When a plant is exposed to light coming from one side of the plant then auxin located at the shoot tip diffuses towards the shaded side of the shoot. High concentration of auxin in the shaded region stimulates the cells to grow longer in comparison to the region exposed to light. So the shoot tends to bend towards the light.
Q12. Name the hormone which regulates carbohydrate, protein and fat metabolism in our body. Which gland secretes this hormone? Why is it important for us to have iodised salt in our diet? [CBSE 2016]
Thyroxine regulates carbohydrates, protein and fat metabolism in our body.
Thyroxine is secreted from the thyroid gland. Deficiency of iodine in our food causes (goiter) where the thyroid gland enlarges as it needs to absorb more amount of iodine. Iodine is required to make thyroxine. Therefore, iodine is added to salt to supplement iodine requirement.
Q13. Name the two components of central nervous systems in humans. [CBSE 2012, 2016]
The two components of the Central Nervous System in humans are the brain and spinal cord.
Q14. In the absence of muscle cells, how do plant cells show movements? [CBSE 2016]
Plants do not have nervous systems and muscles. Even then they exhibit well coordinated and controlled movements. Plants possess chemical coordination. They respond to stimuli by secreting chemical substances called plant growth regulators. They either stimulate or retard growth. Five major types of plant growth hormones are auxins, gibberellins, cytokinins, 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 to as nastic movements. Thus, plants show movements due to growth or change in turgor pressure.
Q15. (a) Write two points of differences between enzymes and hormones. [CBSE 2016]
(b) Name one endocrine gland in our body which performs dual function. Write the functions.
(a) Differences between enzymes and hormones:
(b) Pancreas performs dual function. It produces enzymes like Trypsin, Lipase etc., which aid in digestion. It also produces insulin hormone which regulates blood-sugar levels.
Q16. Name the largest part of the hind-brain. [CBSE 2016]
Cerebellum.
Q17. Name the system which facilitates the communication between the central nervous system and the other body parts of the body. [CBSE 2016]
Peripheral nervous system.
Q18. 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 junction between two adjustment neuron or nerve cells, i.e. between the axon ending of one and the dendrite of the next.
Transmission of Nerve Impulse. The information acquired at the end of the dendritic tip of a neuron sets off a chemical reaction which creates an electrical impulse. This impulse travels from the dendrite to the cyton along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals, which cross the synapse and start a similar electrical impulse in a dendrite of the next neuron. In this way nerve impulses travel in the body.
Synapse helps in transmitting impulses from one neuron to another.
Q19. “As the blood sugar level in our body falls insulin secretion is reduced.” Justify this statement in the reference of a feedback mechanism that regulates the 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, if there are more levels of sugar in blood then more insulin is produced and if the sugar level is less then insulin production is also reduced.
This is because of the feedback mechanism where the blood sugar itself acts as a feedback for more or reduced insulin synthesis.
Q20. State the role played by ovaries in a human female. [CBSE 2015]
Roles of ovary:
Ovaries produce female gametes, ova.
It also produces a female sex hormone called estrogen. Estrogen is essential for development of secondary sex organs in female as well as secondary sexual characters like high pitch voice, development of mammary glands.
Draw the diagram of a neuron.
Solution:
Differentiate between tropic and nastic movements.
Solution:
Tropic movement:
The movement of a plant in the direction of stimulus.
Nastic movement:
The movements, which are neither towards or away from the stimulus
Draw a neat diagram of the nervous system in an insect.
Solution:
Define reflex action with suitable examples.
Solution:
When we suddenly withdraw our hands on pricking a pin, it is a reflex action. This type of sudden response to a stimulus is involuntary. A reflex action is defined as an unconscious and involuntary response of effectors to a stimulus. In reflex actions, a message from the receptors is relayed by sensory nerves to the spinal cord, which sends information for response via motor nerves to effectors. The pathway is called reflex arc. The simplest type of reflex action is knee-jerk reflex. In this case, while sitting with freely hanging legs, a strike below the knee cap kicks the leg forward. Other reflex actions are coughing, sneezing, yawning and blinking of eyes.
Name the hormones secreted by thyroid, parathyroid and pancreas.
Solution:
(i) Thyroid secretes thyroxine,
(ii) Parathyroid secretes calcitonin and
(iii) Pancreas secrete insulin and glucagons.
List the functions of testosterone and estrogen.
Solution:
The functions of testosterone are the regulation of male accessory sex organs and secondary sexual characters like moustache, beard and voice.
The functions of estrogen are the regulation of female accessory sex organs and secondary sexual characters like mammary glands, hair pattern and voice, and the maintenance of pregnancy.
What are phytohormones?
Solution:
A phytohormones can be defined as 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.
What are the meanings? What are their functions? Name the fluid, which is filled in between meanings.
Solution:
The brain is surrounded by three membranes called meanings, which help to protect the brain. The space between the meanings is filled with cerebrospinal fluid, which protects the brain from mechanical shocks.
name any growth inhibiting phytohormone.
Solution:
Abscisic acid is a growth inhibiting phytohormone
What makes a stem bend towards sunlight?
Solution:
The chemical substance called plant hormone or phytohormone makes a stem bend towards sunlight.
Control and coordination class 10 NCERT biology LONG QUESTION:
Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify the statement.
Solution:
In humans, the nervous system is the most important, rather essential, system for regulation, control and coordination of body functions. It makes possible a range of adaptive responses to changes in the environment in the interests of the individuals. This system helps the individual to respond in a coordinated manner to environmental changes, to control various movements and to prolong life by protecting the body against harmful stimuli. Coordination in humans is brought about by the secretions of endocrine glands. Endocrine glands are the ductless glands, which secrete the chemical substances called hormones directly into the blood. Any chemical substance, which is formed in the tissues of endocrine glands and are carried by the blood to other parts of the body for its specific actions is termed as a hormone. An organ, which responds to such a hormone, is known as the target organ. Hence, hormones and the nervous system together perform the function of control and coordination in human beings.
Q1. Draw a diagram of the cross-sectional view of human brain as given below on your answer sheet and label: [CBSE 2017-18 C]
(а) The part that helps in performing voluntary actions.
(b) The part that controls salivation and vomiting.
(c) The largest part of the forebrain.
(d) A fluid that protects the brain.
(e) Meninges.
(a) Cerebrum
(b) Medulla
(c) Cerebrum
(d) Cerebrospinal fluid
(e) Meninges or three membranes covering the brain.
Q2. Name the two components of the central nervous system. How are they protected? Name the component which is considered as the highest coordinating center of the body. Describe its three regions. [CBSE 2016]
Brain and spinal cord are the two components of the central nervous system.
Human brain is protected by a bony skull, also called a cranium. Internal to the skull it is covered from outside by three membranes called meninges. In between the meninges there is a fluid called cerebrospinal fluid. Beneath the membrane the brain is subdivided into three major parts namely fore-brain, midbrain and hindbrain.
Brain is considered the highest coordinating center of the body.
Its three regions are given below:
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 decisions on how to respond.
(vii) Motor area - Decisions made by association area are passed on to this area which control the movement of voluntary muscles.Midbrain comprises four lobes. So it is also known as corpora quadrigemina. Actions of involuntary muscles are controlled by the midbrain and hind-brain.
Hind-brain comprises cerebellum, pons varolii and medulla oblongata. Cerebellum is the second largest part of the brain that coordinates muscular activity of the body as well as maintains body equilibrium or posture. Pons connect cerebellum and medulla oblongata and function as a relay center among different parts of the brain. It possesses a pneumotaxic area of the respiratory center. Medulla oblongata lies below the cerebellum and continues behind the spinal cord. Involuntary actions like blood pressure, salivation and vomiting are controlled by the medulla in the hind-brain.
Q3. With the help of suitable examples explain the terms phototropism, geotropism and chemotropism. [CBSE 2016]
The stimulus oriented movement of the plant or plant part is called tropism. The direction of movement is related to the direction of stimulus. These movements are always growth oriented movements. They are of different types namely phototropism (growth movement in response to light), hydrotropism (water), geotropism (force of gravity), thigmotropism (contact) and chemotropism (chemicals).
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 the illuminated region to the shaded region. This causes more growth on the dark side of the stem causing it to bend towards the source of light. Movement of shoots towards light is called phototropism.
Roots are positively geotropic and negatively phototropic. Shoots are positively phototropic and negatively geotropic.
Growth of pollen tube inside the style, ovary and ovule in response to the chemicals produced by them is an example of chemotropism.
Q4. (a) Define hormones. Write four characteristics 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 informational molecules that are required in minute quantities and are directly poured in the bloodstream by the glands. They act on a specific organ called target organ. So their site of production varies from site of action.
Their characteristics are:
They are poured into the blood stream.
Are generally proteinaceous or steroid.
Their secretion is regulated by a feedback mechanism.
Their site of action and secretion is different.
(b)
(i) Dwarfism
(ii) Gigantism
(iii) Diabetes
(iv) Goiter.
Q5. 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 function of each. [CBSE 2016]
When blood sugar level rises in blood, a hormone called ‘' is produced by β-cells of islets of Langerhans in the organ Pancreas. Pancreas also produces 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 glucose level in blood. As soon as the blood sugar comes to normal the pancreatic cells stop secretion of insulin.
Pancreas secretes slightly alkaline pancreatic juice which contains three major following enzymes:
Trypsin which digests proteins.
Lipase which digests fats.
Amylase which digests carbohydrates.
Q6. What are phytohormones? List four types of phytohormones. Where are these synthesized? [CBSE 2016]
Plants possess chemical coordination. They respond to stimuli by secreting chemical substances called plant growth regulators. They either stimulate or retard growth. Five major types of plant growth hormones are auxins, gibberellins, cytokinins, abscisic acid and ethylene.
These plant growth regulators are also known as phytohormones.
These are synthesized at shoot apices, leaves, developing embryos, root tips etc.
Q7. What is meant by reflex-action? With the help of a labeled diagram trace the sequence of events which occur when we touch a hot object. [CBSE 2015]
Reflex action is defined as an unconscious, automatic and involuntary response of effector, i.e. muscle and gland to a stimulus which is monitored through the spinal cord.
Sequence of events when we touch a hot object are:
Receptor organ skin receives the stimulus and activates a sensory nerve impulse.
Sensory neurons carry the message in the form of sensory impulse to the spinal cord.
The spinal cord acts as a modulator. The neurons of the spinal cord transmit the sensory nerve impulses to the motor neuron.
Motor nerve conducts these impulses to the effector organ hand which responds by pulling back the hand away from the hot object.
Q8. Write the names of the hormones secreted by the pituitary gland and adrenal gland. State their functions in the body. [CBSE 2015]
Describe the central nervous system in human beings.
Solution:
The central nervous system in human beings is highly developed. It consists of
(i) brain and (ii) spinal cord. Brain is the highest coordinating center in the body. It is protected by a bony box in the skull called the cranium. Brain is covered by three membranes, called meninges. The space between the membranes is filled by cerebrospinal fluid that protects the brain from mechanical shocks.
The brain is broadly divided into three regions
(i) Fore brain (ii) Midbrain and (iii) Hindbrain.
Each region of the brain consists of various centers. The forebrain includes cerebrum and olfactory lobes.The cerebrum is the most complex and specialized part of the brain. It consists of two cerebral hemispheres.The cerebrum has sensory areas where information is received from sense organs. Similarly, there is the motor area from where impulses are sent to the muscle or effectors organs. In the cerebrum, specific regions for each kind of stimulus and its response are located. Pairs of cranial nerves arise from the brain. The hindbrain consists of three centers, cerebellum, pons and medulla oblongata. Medulla oblongata is the regulating center for swallowing, coughing, sneezing and vomiting. The pons take part in regulation of respiration. Coordination and the adjustment of movement and posture are under the control of the cerebellum.
Spinal cord is a part of the central nervous system, which lies in the vertebral canal. It is a downward continuation of the medulla oblongata. In the spinal cord, the arrangement of white and gray matter is the reverse of that of the brain. The gray matter containing cytons is the inner region and white matter containing myelinated axons is the outer. In the center of the spinal cord runs a small central canal. This central canal, which runs the entire length of the spinal cord, is continuous with the ventricles of the brain. The spinal cord in the transverse section has an H-shaped structure because it has fissures on the ventral and the dorsal sides. The dorsal fissure almost reaches the gray matter while the anterior median fissure falls short of it. Spinal cord gives off 31 pairs of nerves.
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