Control and Coordination - Lakhmir Singh Manjit Kaur Solutions Pg No. 117 Class 10 Biology

Solutions of Control and Coordination Lakhmir Singh Manjit Kaur LAQ, HOTS and MCQ Pg No. 117 Class 10 Biology

Solutions of Control and Coordination Lakhmir Singh Manjit Kaur LAQ, HOTS and MCQ Pg No. 117 Class 10 Biology

Long Answer Type Questions-Pg-117

53A. Name the structural and functional unit of nervous system.

Answer

→ A neuron is the structural and functional unit of nervous system.

53B. Draw a flow chart to show the classification of nervous system into various parts.

Answer

→ The below flow chart depicts the classification of nervous system into various parts.
Example: A student who is getting late for school suddenly sees his watch then starts walking fast autonomously. Here, when the eyes see the time they send the information to brain through the sensory nerves. After which the brain receives the information, analyses them and sends the instructions to walk faster to muscle of our legs through the motor nerves. Then, the muscle of the legs act simultaneously by which student walks faster.

53C. What is autonomic nervous system? What is its function?

Answer

→ Autonomic nervous system is self-governing nervous system which controls and regulates the functions of the internal organs of our body involuntarily.

53D. What is voluntary nervous system? Explain the working of voluntary nervous system with an example.

Answer

→ The voluntary nervous system helps us to take voluntary actions which are under the conscious control of the brain.
Example: A student who is getting late for school suddenly sees his watch then starts walking fast autonomously. Here, when the eyes see the time they send the information to brain through the sensory nerves. After which the brain receives the information, analyses them and sends the instructions to walk faster to muscle of our legs through the motor nerves. Then, the muscle of the legs act simultaneously by which student walks faster.

54A. What is a reflex action? Explain with the help of an example.

Answer

→ A reflex action is an involuntary, rapid response in the body to a stimulus.
Example: Moving our hand away on touching a hot bowl.

54B. Define reflex arc. Give the flow chart of a spinal reflex arc.

Answer

→ Reflex arc is the pathway taken by the nerve impulses in the reflex actions.

54C. How are involuntary actions and reflex actions different from each other?

Answer

→ All reflex actions are involuntary in nature but all involuntary actions are not reflexes. A reflex action is a rapid and autonomic response to a stimulus which is not under the voluntary control of the brain. Involuntary actions do not need thinking and also not performed by us knowingly. Sneezing and coughing are the examples of reflex actions whereas digestion and respiration are involuntary actions.

55A. What is the function of our nervous system?

Answer

→ The nervous system consists of the brain, spinal cord, sensory organs and all of the nerves that connect these organs with the rest of the body. Its main function is to establish the communication system between the organs of our body. It receives information from the surroundings, processes it, interprets it and then responds accordingly.

55B. What are the main organs of the human nervous system? Draw a labelled diagram to show the main organs of the human nervous system.

Answer

→ Brain, spinal cord and nerves are the main organs of the nervous system.
55C. How does the human nervous system work? Explain.

Answer

→ After affecting, the sense organ in our body sends the message (in the form of electrical impulses) to brain through the sensory neurons. The brain reads the signals and decides the necessary action to be taken out. Then, brain sends out the instructions through motor nerves to the body muscles of concerned part and then this part acts accordingly.

56A. What is a neuron? Draw a labelled diagram of a neuron.

Answer

→ A neuron, also known as nerve cell, is a cell that carries message between the brain and other body parts. It is the basic unit of the nervous system.

56B. What is a synapse? What happens at the synapse between two neurons? How are the messages carried across a synapse? Explain with the help of a labelled diagram.

Answer

→ In the nervous system, the synapse is a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter. Synapse between two neurons allows electrical impulses to pass in one direction only. The process is as follows: When the receptor sends an electrical impulse, it reaches at the end of the axon of sensory neuron. Then this electrical impulse releases a chemical, known as neurotransmitter, in very small amount into the synapse between two adjacent neurons. Neurotransmitter crosses the synapse and starts a similar electrical impulse in the dendrite of the next neuron. By this way, the electrical impulse passes from one neuron to the next across the synapse.

57A. Name two systems which taken together perform the functions of control and coordination in human beings.

Answer

→ Both nervous system and endocrine system are two systems which taken together perform the functions of control and coordination in human beings.

57B. What does the central nervous system in humans consist of? What is the job of the central nervous system?

Answer

→ The Central Nervous System (CNS) is made up of brain and spinal cord. The CNS is the main control center of the body. It takes in sensory information, organizes and synthesizes this input, then provides instructions for motor output to the rest of the body. In other words, it functions as the transmitter and receiver as well as the pathway for information flow and determines how the body responds to changes in its internal and external environment.

57C. Give the various functions of brain.

Answer

→ Functions of the brain: The brain is the command centre for the nervous system. It receives input from the sensory organs and sends output to the muscles. Intelligence, creativity, emotions, and memory are a few of the many things governed by the brain. It also controls the thoughts, memory and speech, movement of the arms and legs, and the function of many organs within the body.

58A. Write the names of five endocrine glands found in the human body. Name the hormones secreted by each gland.

Answer

→ (i) Pituitary gland secretes growth hormone.
(ii) Thyroid gland secretes thyroxine hormone.
(iii) Pancreas secreted insulin hormone.
(iv) Adrenal gland secretes adrenaline hormone.
(v) Testes secrete testosterone hormone.

58B. How do hormones reach the organs they control?

Answer

→ The endocrine glands are ductless glands which secrete their products as hormones. They release hormones directly into the blood stream. These hormones reach the target body part through the blood and then act on it.

58C. Name the gland which controls the secretion of hormones from the pituitary.

Answer

→ Hypothalamus gland controls the secretion of hormones from the pituitary.

58D. How does our body respond when adrenaline is secreted in large amounts into the blood?

Answer

→ The adrenaline hormone is secreted by adrenal gland, a gland present on top of the kidney. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency. It increases blood flow into muscles, breathing and heart rate and causes liver to put more stored glucose into our blood which causes production of high energy. Thus, if adrenaline is secreted in large amounts then it prepares our body for action.

58E. Name the disease which occurs in adults due to the deficiency of iodine in the diet. What is the main symptom of this disease?

Answer

→ The Goitre disease occurs in adults due to deficiency of iodine in the diet. In this disease, the neck of the person gets swollen due to the enlargement of thyroid gland.

Multiple Choice Questions (MCQs)-Pg-117

59. A cell (or group of cells) in a sense organ which is sensitive to a particular type of stimulus is called:
A. interceptor
B. effector
C. receptor
D. acceptor

Answer

→ A receptor is an organ or cell able to respond to heat, light or other external stimulus and transmit a signal to a sensory nerve. Example: Photoreceptor (a receptor which detects light) and phonoreceptor (a receptor which detects sound).

60. Which of the following cannot be considered a receptor?
A. ear
B. nose
C. muscle
D. eye

Answer

→ Muscle is not a receptor.

61. One of the following acts as an endocrine gland as well as an exocrine gland. This one is:
A. salivary gland
B. pancreas
C. pituitary
D. parathyroid

Answer

→ Pancreas gland acts as an endocrine gland as well as an exocrine gland.

62. Which of the following helps in maintaining posture and balance of the human body?
A. cerebellum
B. cerebrum
C. medulla
D. pons

Answer

→ The cerebellum is the area of the hindbrain that controls motor movement, coordination, balance, equilibrium and muscle tone.

63. The number of pairs of nerves which arises from the spinal cord is:
A. 21
B. 31
C. 41
D. 51

Answer

→ There are total 31 pairs of nerves arise from the spinal cord.

64. Cerbellum, medulla and pons are the parts of:
A. mid-brain
B. hind-brain
C. forebrain
D. spinal cord

Answer

→ Hindbrain consists of cerebellum, medulla and pons.

65. Which of the following are cerebral reflexes?
(i) A person pulls away his hand on touching a hot object.
(ii) A person spits out immediately when a fly enters his mouth while talking.
(iii) A person walking bare foot lifts his foot at once on stepping on to a nail
(iv) A person's pupil contracts at once in the presence of bright light.
A. (i) and (ii)
B. (ii) and (iii)
C. (iii) and (iv)
D. (ii) and (iv)

Answer

→ A person spits out immediately when a fly enters his mouth while talking and a person's pupil contracts at once in the presence of bright light are cerebral reflexes.

66. Iodine is necessary for the synthesis of which of the following hormone?
A. adrenaline
B. auxin
C. thyroxine
D. insulin

Answer

→ Iodine is necessary for the synthesis of thyroxin hormone which is released by the thyroid gland and prevents from goiter disease.

67. Which of the following is a mis-matched pair?
A. adrenaline : pituitary gland
B. estrogen: ovary
C. pancreas : insulin
D. progesterone : ovary

Answer

→ Adrenaline hormone is released from adrenal gland.

68. One of the following is an incorrect statement about insulin. This is:
A. it is produced in pancreas
B. it regulates growth and development of the body
C. it regulates blood glucose level in the blood
D. its deficiency in the body will cause diabetes

Answer

→ Insulin does not regulate growth and development of the body.

69. The spinal cord originates from:
A. cerebrum
B. cerebellum
C. medulla
D. pons

Answer

→ The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata.

70. The involuntary actions in the body are controlled by:
A. medulla in forebrain
B. medulla in hindbrain
C. medulla in spinal cord
D. medulla in midbrain

Answer

→ The involuntary actions in the body are controlled by medulla which is located in hindbrain.

71. Which of the following is not an involuntary action?
A. vomiting
B. chewing
C. heart beat
D. salivation

Answer

→ Chewing is a voluntary action.

72. Which of the following hormone prepares our body for action in emergency situations?
A. testosterone
B. growth hormone
C. adrenaline
D. insulin

Answer

→ The adrenaline hormone is secreted by adrenal gland, a gland present on top of the kidney. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency.

73. One of the following controls the peristaltic movements of alimentary canal. This one is:
A. cerebrum
B. cerebellum
C. pons
D. medulla

Answer

→ The involuntary actions like peristaltic movements of alimentary canal in the body are controlled by medulla which is located in hindbrain.

74. The hormone which is associated with male puberty is called:
A. oestrogen
B. adrenaline
C. testosterone
D. progesterone

Answer

→ Testosterone hormone is secreted by testes and responsible for male puberty and other secondary sexual characters.

75. Which of the following endocrine gland does not occur as a pair in the human body?
A. adrenal
B. pituitary
C. testis
D. ovary

Answer

→ Pituitary gland does not occur as a pair in the human body. It has 2 lobes: anterior lobe and posterior lobe.

76. The junction between two adjacent neurons is called:
A. nerve junction
B. sensory junction
C. synapse
D. neuro-muscular joint

Answer

→ In the nervous system, the synapse is a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

77. The life processes in humans are controlled and regulated by:
A. reproductive and endocrine systems
B. respiratory and nervous systems
C. endocrine and digestive systems
D. nervous and endocrine systems

Answer

→ Nervous system and endocrine system are the two systems of control and coordination in higher animals like human.

78. A doctor advised a person to take injection of insulin because:
A. his blood pressure was high
B. his heart beat was high
C. his blood sugar was high
D. his thyroxine level in blood was high

Answer

→ Insulin hormone decreases the blood sugar level.

79. All the voluntary actions of our body are controlled by:
A. cerebrum
B. cerebellum
C. pons
D. medulla

Answer

→ The part of the brain that controls voluntary actions is cerebrum, the largest part of the brain.

80. One of the following statements is not true about thyroxine. This is:
A. Thyroid gland requires iron to synthesise thyroxine
B. It regulates carbohydrate, protein and fat metabolism
C. Iodine is essential for the synthesis of thyroxine
D. Thyroid gland can enlarge due to lack of thyroxine

Answer

→ Thyroid gland requires iodine to synthesise thyroxine hormone.

81. Which of the following does not act as an endocrine gland as well as an exocrine gland?
A. testis
B. ovary
C. pituitary
D. pancreas

Answer

→ Pituitary gland does not act as an endocrine gland as well as an exocrine gland.

82. The part of brain which controls the involuntary actions such as heart beat, breathing, blood pressure, etc. is:
A. pons
B. medulla
C. cerebrum
D. cerebellum

Answer

→ The medulla oblongata connects the brain to the spinal cord and controls involuntary actions.

83. Dwarfism results due to:
A. excessive secretion of thyroxine hormone
B. excessive secretion of growth hormone
C. less secretion of adrenaline hormone
D. less secretion of growth hormone

Answer

→ Growth hormone (GH) is responsible for growth and development in human. Less secretion of this hormone results dwarfism.

84. The dramatic changes in body features associated with puberty are mainly because of the secretions of:
A. estrogen from testes and testosterone from ovary
B. estrogen from adrenal gland and testosterone from pituitary gland
C. testosterone from testes and estrogen from ovary
D. testosterone from thyroid gland and estrogen from pituitary gland

Answer

→ Testosterone hormone, also known as male sex hormone, is secreted by testes. Oestrogen and progesterone hormones are released by ovaries. Both testosterone and oesterogen are responsible for puberty in males and females respectively.

85. Which of the following statements is correct about receptors?
A. gustatory receptors detect taste while olfactory receptors detect smell
B. both gustatory and olfactory receptors detect smell
C. auditory receptors detect smell and olfactory receptors detect taste
D. olfactory receptors detect taste and gustatory receptors detect smell

Answer

→ Gustatory receptors are present in the tongue and are responsible for detecting taste. Olfactory receptors are present in the nose and responsible for detecting smell.

86. The part of brain which takes part in regulating respiration in the human body is:
A. medulla
B. pons
C. cerebellum
D. cerebrum

Answer

→ Pons of the human brain takes part in regulating respiration in the human body.

87. Electrical impulse travels in a neuron from:
A. dendriteaxon axon end Cell body
B. cell body dendriteaxon axon end
C. dendritecell body axonaxon end
D. axon endaxoncell body dendrite

Answer

→ The electrical impulse travels in a neuron from dendrite to cell body to axon to axon end.

88. In a synapse, chemical signal is transmitted from:
A. axon to cell body of the same neuron
B. cell body to axon end of the same neuron
C. dendrite end of one neuron to axon end of adjacent neuron
D. axon end of one neuron to dendrite end of adjacent neuron

Answer

→ In a synapse, chemical signal is transmitted from axon end of one neuron to dendrite end of adjacent neuron.

89. In a neuron, the conversion of electrical signal to a chemical signal occurs at/in:
A. dendrite end
B. cell body
C. axon end
D. myelin sheath

Answer

→ The conversion of electrical signal to a chemical signal occurs at axon end in a neuron.

90. One of the following gives the correct sequence of the components in a reflex arc. This is:
A. ReceptorMuscle sensory neuron Motor neuron Spinal cord
B. Receptors Motor neuron Spinal cord Sensory neuronMuscle
C. ReceptorsSpinal cord Sensory neuron Motor neuronMuscle
D. ReceptorsSensory neuronSpinal cord Motor neuronMuscle

Answer

→ The correct sequence of the components in a reflex arc is as follows:
ReceptorsSensory neuronSpinal cord Motor neuronMuscle

91. Which of the following statements are true?
(i) sudden action in response to something in the environment is called reflex action
(ii) sensory neurons carry electrical signals from spinal cord to muscles in a reflex action
(iii) motor neurons carry signals from receptors to spinal cord in a reflex action
(iv) the pathway of transmitting signals from a receptor to a muscle is a reflex action
A. (i) and (ii)
B. (i) and (iii)
C. (i) and (iv)
D. (i), (ii) and (iii)

Answer

→ Both statements (i) and (iv) are true.

92. The gustatory receptors of our body are in one of the following organs. This organ is:
A. ear
B. nose
C. tongue
D. skin

Answer

→ The gustatory receptors of our body are responsible for taste.

93. The olfactory receptors in humans are located in:
A. eyes
B. tongue
C. ears
D. nose

Answer

→ The olfactory receptors of our body are responsible for smell.

94. The contraction of pupil of the eye in the presence of bright light is an example of:
A. Voluntary reflex
B. Spinal reflex
C. Cerebral reflex
D. Adrenal reflex

Answer

→ The contraction of pupil of the eye in the presence of bright light is an example of cerebral reflex.

95. The faulty functioning of an endocrine gland can make a person very short or very tall. This gland is:
A. thyroid
B. pineal
C. adrenal
D. pituitary

Answer

→ The Growth hormone (GH) is secreted by pituitary gland. This hormone is responsible for controlling the growth and development in humans.

96. The underactive endocrine gland which causes goitre is:
A. pancreas
B. thyroid
C. adrenal
D. pituitary

Answer

→ The thyroxine hormone is secreted by thyroid gland. The lack of this hormone causes goiter in humans.

97. The endocrine gland whose malfunctioning causes diabetes disease is:
A. pituitary
B. pineal
C. parathyroid
D. pancreas

Answer

→ Pancreas gland secretes the insulin hormone which controls the blood sugar level and prevents from diabetes disease.

98. The use of iodized salt is recommended to prevent:
A. diabetes
B. gonorrhoea
C. dysentery
D. goitre

Answer

→ Goitre disease is caused to lack of iodine in the diet.

99. Which of the following are often called glands of emergency?
A. thyroid
B. pituitary
C. adrenal
D. pancreas

Answer

→ Adrenaline hormone, a hormone is released from adrenal gland, is also known as emergency hormone. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency.

Questions Based on High Order Thinking Skills (HOTS)-Pg-120

100. P is a cell (or group of cells) in the human body which is sensitive to a particular type of stimulus and conveys the messages to CNS through nerves Q. On the other hand, R is a part of the human body which can respond to a stimulus according to the instructions sent from the CNS through nerves S.
(a) What is P? Name five organs which contain cells (or group of cells) like P.
(b) Name the nerves Q.
(c) What is R? Give two examples of R.
(d) Name nerves S.
(e) How do messages travel through the nerves Q and S?

Answer

→ (a) In above question, the P is a receptor. Eyes, ears, nose, tongue and skin contain cells like P (receptor).
(b) Nerves Q are sensory nerves.
(c) In above question, R is the effector. Muscles and glands are the examples of R (effectors).
(d) Nerves S are motor nerves.
(e) Messages travel through nerves Q (sensory nerves) and S (motor nerves) in the form of electrical impulses.

101. The human body contains a large number of cells A which are very long and branched, and look like electric wires. The longest branch of this cell is B whereas there are many small branches C. Any two A cells do not join to one another completely in the human body. There is a microscopic gap D between every pair of adjacent A cells through which electric impulses can pass by the release of a chemical substance.
(a) What are cells A?
(b) What is the name of (i) branch B, and (ii) branches C?
(c) What is the microscopic gap D known as?
(d) What is the function of cells like A in the human body?
(e) The cells A are of three types. Name the three types.

Answer

→ (a) In above question, cells A are neurons or nerve cells.
(b) (i) Branch B is axon and (ii) C branches are dendrites.
(c) The microscopic gap D is known as synapse.
(d) Cell A or Neurons transmit electrical signals or impulses to and from the central nervous system.
(e) Cell A or Neurons are of three types: Sensory neurons, motor neurons and relay neurons.

102. When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers an impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.
(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
(b) What is (i) neuron S, and (ii) neuron T?
(c) Name the tissue U.
(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
(e) Name the effector in this whole process.

Answer

→ (a) (i) In above question, the receptor P is thermoreceptor.
(ii) The neuron Q is a sensory neuron and
(iii) The organ R is spinal cord.
(b) (i) The neuron S is a relay neuron.
(ii) The neuron T is a motor neuron.
(c) The tissue U is a muscle.
(d) Reflex action is phenomenon in which hand is pulled away quickly from the hot plate.
(e) Muscle of arm is an effector in this process.

103. The gland X which is located just below the brain in the human head secretes a chemical substance Y which controls the development of bones and muscles in the body of a person. Secretion of too little of substance Y as well as the secretion of too much of substance Y by the gland X leads to abnormal development of the body of a person.
(a) Name the gland X.
(b) What is the chemical substance Y?
(c) What happens if too little of substance Y is secreted?
(d) What happens if too much of substance Y is secreted?
(e) Name the system of glands in the human body of which gland X is a part.

Answer

→ (a) In above question, the gland X is pituitary gland.
(b) The chemical substance Y is Human growth hormone.
(c) If too little of substance Y is secreted then the person becomes a dwarf (very short) because growth hormone is responsible for growth and development in humans.
(d) If too little of substance Y is secreted then the person becomes a giant (very tall) because growth hormone is responsible for growth and development in humans.
(e) Gland X (pituitary gland) is a part of the endocrine system.

104. A and B are the two systems of control and coordination in the human body. The messages in system A are transmitted in the form of chemical substances C which travel comparatively slowly through the blood stream. The substances C are made in tissues D present in the head and trunk of human body. The messages in system B are transmitted very quickly in the form of electrical impulses through fibres E. The effect of messages transmitted by system B usually lasts for a much shorter time as compared to those transmitted by system A.
(a) Name the system A. What does system A consist of?
(b) Name the chemical substance C.
(c) What is tissue D? Name any five such tissues in the human body.
(d) Name the system B. What does system B consist of?
(e) Name the fibres E.
(f) State whether system A controls the working of system B or system B controls the working of system A.

Answer

→ (a) In above question, the system A is endocrine system. System A (Endocrine system) consists of glands.
(b) The chemical substance C is hormones.
(c) The tissue D is endocrine glands. Pineal, thyroid, pancreas, pituitary and ovaries are five such tissues in the human body.
(d) The system B is nervous system. The system B (nervous system) consists of brain, spinal cord and nerves.
(e) The fibre E is nerve fibres.
(f) The system B (nervous system) controls the functioning of system A (Endocrine system).

105. A cylindrical structure P in our body begins in continuation with medulla and extends downwards. It is enclosed in a bony cage Q and surrounded by membranes R. As many as x pairs of nerves arise from the structure P. The structure P is involved in the reflex actions of our body and conduction of nerve impulses to and from another organ S of our body with which it forms CNS.
(a) Name the structure P.
(b) Name (i) bony cage Q, and (ii) membranes R.
(c) How much is x?
(d) Name the organ S.
(e) What are the reflexes involving structure P only known as?

Answer

→ (a) In above question, the structure P is spinal cord.
(b) The bony cage Q is vertebral column and membranes R is meninges.
(c) The value of X is 31.
(d) The organ S is brain.
(e) The reflexes involving structure P (Spinal cord) only are known as spinal reflexes.

106. The pancreas is made up of two parts A and B. The part A secretes insulin whereas part B secretes pancreatic juice.
(a) Which part is functioning as an endocrine gland? Why?
(b) What is insulin and what effect does it have in the body?
(c) Name the disease which can be treated by giving insulin injections.
(d) What does pancreatic juice contain? Where does pancreatic juice go?
(e) Name the life process in which pancreatic juice is made use of.

Answer

→ (a) In above question, Part A is functioning as an endocrine gland because it secretes insulin hormone.
(b) Insulin is a hormone secreted by pancreas. It controls the blood sugar level and prevents from diabetes diseases.
(c) In diabetes, the patients are treated by injecting insulin injections.
(d) Digestive enzymes like pancreatic amylase, tryspin and lipase are present in the pancreatic juice. This pancreatic juice goes to small intestine.
(e) In digestion process, the pancreatic juice is made use of.

107. The gland A is attached to the wind pipe in the human body. The gland A makes and secretes a hormone B which controls the metabolism of carbohydrates, fats and proteins in the body. The non-metal element C is necessary for the formation of hormone B. The deficiency of C in the diet can cause a deficiency of hormone B in the body leading to a disease D in which the neck of a person appears to be swollen. People are advised to use salt E in cooking food so as to avoid disease D.
(a) Name (i) gland A, and (ii) hormone B
(b) What is the element C?
(c) Name one type of food which can provide sufficient C in the diet of a person.
(d) Name (i) disease D, and (ii) salt E.

Answer

→ (a) (i) In above question, the gland A is thyroid gland
(ii) The hormone B is thyroxine hormone which is released from the gland A (thyroid gland).
(b) The element C is iodine.
(c) Sea food like fish can provide sufficient element C (iodine) in the diet of a person.
(d) (i) The disease D is goiter.
(ii) The sale E is iodised salt.

108. A piece of thread was tied tightly around an animal's pancreatic duct. The animal subsequently had difficulty in digesting food but did not get diabetes. Explain.

Answer

→ After tying a piece of thread around the animal's pancreatic duct, it gets closed. By this, the digestive enzymes present in the pancreatic juice cannot reach into small intestine. Animals feel difficulty to digest the food in the absence of pancreatic juice. However, the pancreas secretes insulin hormone directly in the blood by which the animal does not get diabetes.

109. Which is the target organ of both adrenaline and insulin?
(a) heart
(b) kidney
(c) liver
(d) pancreas

Answer

→ Correct Answer: (c)
Both adrenaline and insulin act on liver in the body hence, the liver is the target organ for both these hormones.

110. A gland W is located just below the stomach in the human body. The gland W secretes a hormone X. The deficiency of hormone X in the body causes a disease Y in which the blood sugar level of a person rises too much. The person having high blood sugar is called Z.
(a) Name (i) gland W, and (ii) hormone X.
(b) What is the function of hormone X?
(c) Name (i) disease Y, and (ii) person Z.
(d) What advice would you like to give to a person who is suffering from disease Y due to faulty life-style?

Answer

→ (a) (i) In above question, the gland W is Pancreas.
(ii) The hormone X is insulin, secreted by gland W (pancreas).
(b) The hormone X (insulin) controls the blood sugar level and prevents from diabetes disease.
(c) (i) The disease Y is diabetes and (ii) the person Z is known as a diabetic person.
(d) In disease Y (diabetes), the patient should reduce his weight, take balance and control diet, avoid intake of more sugar in meal, do regular physical exercise and yoga, go for routine medical checkup and take medicines regularly.

111. There are two similar glands P which are located on the top of two similar organs Q in the human body. The glands P are often called glands of emergency and they secrete a hormone R into the blood stream. The hormone R is secreted in large amounts when a person is frightened. It brings about temporary changes in the body which allow a lot of substance S from the liver to go into blood so as to provide a lot of energy in a very short time. This helps the person concerned to fight back or run away from the frightening situation. What are P, Q, R and S?

Answer

→ (i) In above question, the gland P is adrenal glands.
(ii) The organ Q is kidneys.
(iii) The hormone R is adrenaline hormone
(iv) The substance S is glucose.

112. The two glands A and B which occur in pairs, are present in the endocrine system of humans. The pair of glands A is found only in females whereas the pair of glands B occurs only in males. The glands A make and secrete two hormones C and D whereas glands B make and secrete only one hormone E. In addition to hormones, glands A make gametes F whereas glands B make gametes G.
(a) What are glands A?
(b) What are hormones C and D?
(c) What are glands B? Name the hormone E.
(d) What are gametes (i) F, and (ii) G?
(e) Which event in the life of males and females is associated with the secretion of hormones C, D and E?

Answer

→ (a) In above question, the glands A are ovaries.
(b) The hormone C is oesterogen whereas hormone D is progesterone.
(c) The glands D are Testes. The hormone E is testosterone (a male sex hormone) released from gland D (testes).
(D) (i) The gametes F are ova or eggs.
(ii) The gametes G are sperms.
(e) In both males and females, puberty is associated with the secretion of hormones C (oesterogen), D (progesterone) and E (testosterone).

113. The organ A which is located inside the skull of our body is protected by a bony box Band it is surrounded by three membranes C. The space between the membranes is filled with a liquid D which protects the organ A from mechanical shocks. The organ A in combination with another organ E makes up the central nervous system.
(a) What is organ A?
(b) What are (i) B (ii) C, and (iii) D ?
(c) Name the organ E.
(d) While walking barefooted, if we happen to step on a sharp piece of stone, we immediately lift our foot up. Which of the two organs, A or E, is directly involved in this action?
(e) If we step out from a darkened room into bright sunshine, we close our eyes for a moment. Which of the two organs, A or E, is directly involved in this action?

Answer

→ (a) In above question, the organ A is brain.
(b) (i) The membrane B is cranium or skull.
(ii) The membrane C is Meninges.
(iii) The membrane D is cerebrospinal fluid.
(c) The organ E is spinal cord.
(d) The organ E (spinal cord) is directly involved in the action mentioned in the question.
(e) The organ A (brain) is directly involved in the action mentioned in the question.

114. Write down the following in the correct order for a simple reflex arc:
(a) impulse travels in motor fibre
(b) impulse travels in sensory fibre
(c) effector organ stimulated
(d) impulse crosses synapse

Answer

→ The pathway taken by nerve impulses in a reflex action is called a reflex arc. It is an automatic response to a stimulus. When a stimulus is given to a receptor, the receptors produce an impulse in the sensory fibre. The sensory fibre carries this message in the form of an electrical stimulus across the synapse. From the synapse, the impulse travels in the motor fibre and stimulates the effector organ to produce the desired response.
The correct order for a simple reflex arc is:
(b) →(d) → (a) → (c).

115. Explain why, the tongue may be considered to be both a receptor and an effector organ.

Answer

→ Tongue has taste buds hence, it is considered as a receptor. Taste buds act as receptors (gustatory receptor) for different kinds of taste. Tongue is a muscular organ having muscles which can respond to a stimulus hence, it is also considered to be an effector.

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