Class 12 biology chapter 9 Control and Coordination Textbook solution


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Q. 1 Multiple choice questions.
1. The nervous system of mammals uses 
both electrical and chemical means to 
send signals via neurons. Which part of 
the neuron receives impulse?
a. Axon
b. Dendron
c. Nodes of Ranvier
d. Neurilemma

2. ___________ is a neurotransmitter.
a. ADH
b. Acetyl CoA
c. Acetyl choline
d. Inositol

3. The supporting cells that produce myelin sheath in the PNS are _________.
 a. Oligodendrocytes
 b. Satellite cells
 c. Astrocytes
 d. Schwann cells

4. A collection of neuron cell bodies located outside the CNS is called _________.
a. Tract
b. Nucleus
c. Nerve
d. Ganglionl

5. Receptors for protein hormones are 
located
a. in cytoplasm
b. on cell surface
c. in nucleus
d. on Golgi complex

6. If parathyroid gland of man are removed, the specific result will be
 a. onset of aging
 b. disturbance of Ca++
 c. onset of myxoedema
 d. elevation of blood pressure

7. Hormone thyroxine, adrenaline and non-adrenaline are formed from ----------
a. Glycine
b. Arginine
c. Ornithine
d. Tyrosine

8. Pheromones are chemical messengers 
produced by animals and released outside the body. The odour of these substance affects
a. skin colour
b. excretion
c. digestion
d. behaviour

9. Which one of the following is a set of 
discrete endocrine gland
 a. Salivary, thyroid, adrenal, ovary
 b. Adrenal, testis, ovary, liver
 c. Pituitary, thyroid, adrenal, thymus
 d. pituitary, pancreas, adrenal, thymus

10. After ovulation, Graafian follicle 
changes into
 a. Corpus luteum 
 b. Corpus albicans
 c. Corpus spongiosum
 d. Corpus callosum

11. Which one of the following pair correctly matches a hormone with a disease resulting from its deficiency?
a. Parathyroid hormone - Diabetes insipidus
b. Leutinising hormone - Diabetes mellitus
c. Insulin Hyperglycemia
d. Thyroxine - Tetany

12. ___________ is in direct contact of brain in human
a. Cranium
b. Duramater
c. Arachnoid
d. Piamater


Q. 2 Very very short answer questions.
1. What is the function of red nucleus?
Answer : The red nucleus functions as a motor control pathway, sending movement commands towards the body via axon.

2. What is the importance of Corpora 
quadrigemina?
Answer : In the brain, the corpora quadrigemina (Latin for "quadruplet bodies") are the four colliculi—two inferior, two superior—located on the tectum of the dorsal aspect of the midbrain. They are respectively named the inferior and superior colliculus. The corpora quadrigemina are reflex centers involving vision and hearing.

3. What does the cerebellum of brain 
control?
Answer : Most body movements require the coordination of multiple muscle groups. The cerebellum times muscle actions so that the body can move smoothly. Vision: The cerebellum coordinates eye movements. Motor learning: The cerebellum helps the body to learn movements that require practice and fine-tuning.

4. Name the three ossicles of the middle 
ear.
Answer : The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively.

5. Name the hormone which is anti abortion hormone
Answer : Progesterone is a steroid hormone belonging to a class of hormones called progestogens.

6. Name an organ which acts as temporary endocrine gland
Answer : Placenta. The placenta is a temporary endocrine organ formed during pregnancy, which produces hormones important in the maintenance of a healthy pregnancy and in preparation for labour and breastfeeding.

7. Name the type of hormones binding to 
DNA and alter gene expression.
Answer : Hormones that Affect Gene Activity. Lipid‐soluble hormones act usually by gene activation/deactivation. Examples of these hormones include steroids, thyroid hormone, and vitamin A (retinoic acid). ... The receptor‐hormone complex binds DNA tightly and thereby activates or inactivates the synthesis of mRNA from these genes.

8. What is the cause of abnormal elongation of long bones of arms and legs and of lower jaw.
Answer :
Acromegaly occurs when your body produces too much growth hormone. This causes your tissues to enlarge, including your lower jaw.

9. Name the hormone secreted by the 
pineal gland.
Answer : It produces and secretes the hormone melatonin, which is a hormone that helps regulate biological rhythms such as sleep and wake cycles.

10. Which endocrine gland plays important, role in improving immunity?
Answer : The thymus gland is a small organ behind the breastbone that plays an important function both in the immune system and endocrine system.


Q. 3 Match the organism with the type of 
 nervous system found in them.
1. Neurons.           a. Earthworm
2. Ladder type.     b. Hydra
3. Ganglion.           c. Flatworm
4. Nerve net.         d. Human
Answer :
1. Nerons - human
2. Ladder type - flatworm
3. Ganglion - Earthworm
4. Nerve Net - hydra


Q. 4 Very short answer questions.
1. Describe the endocrine role of islets of 
Langerhans.
Answer : The islets of Langerhans are responsible for the endocrine function of the pancreas. Each islet contains beta, alpha, and delta cells that are responsible for the secretion of pancreatic hormones

2. Mention the function of testosterone?
Answer : Testosterone is the primary male sex hormone and anabolic steroid. In male humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.

3. Give symptoms of the disease caused by hyposecretion of ADH.
Answer : Central diabetes insipidus is marked by a decrease in either the production of ADH by your hypothalamus or the release of ADH from your pituitary gland. Common symptoms include excessive urination, which is called polyuria, followed by extreme thirst, which is called polydipsia.


Q. 5 Short answer questions
1. Rakesh got hurt on his head when he fell down from his motorbike. Which inner membranes must have protected his brain? What other roles do they have to play?
Answer : The meninges and CSF act as a shock absorber and protect the brain and spinal cord from mechanical injuries.

2. Give reason - Injury to medulla oblongata may prove fatal.
Answer : The medulla oblongata controls involuntary functions such as heart beat, rate of respiration, secretion of saliva, gut peristalsis etc. Injury to the medulla oblongata may stop important activities such as heart beat, respiration etc

3. Distinguish between the sympathetic and parasympathetic nervous system on the basis of the effect they have on: 
a. Heart beat 
b. Urinary Bladder 
Answer :
The sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. The parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.

  1. Involved in the fight or flight response. Involved in maintaining homeostasis and also, permits the rest and digest response.
  2. The sympathetic system prepares the body for any potential danger. The parasympathetic system aims to bring the body to a state of calm.
  3. Sympathetic system has shorter neuron pathways, hence a faster response time. Has comparatively longer neuron pathways, hence a slower response time.
  4. Increases heartbeat, muscles tense up. Reduces heartbeat, muscles relaxes.
  5. The pupil dilates to let in more light. The pupil contracts.
  6. Saliva secretion is inhibited. Saliva secretion increases, digestion increases.


4. While holding a tea cup Mr. Kothari’s 
hands rattle. Which disorder he may be 
suffering from and what is the reason for this?
Answer : Dupuytren's contracture typically progresses slowly, over years. The condition usually begins as a thickening of the skin on the palm of your hand.

5. List the properties of the nerve fibres.
Answer : nerve fibres are highly excitable tissue
› respond to various stimuli
› Capable of generating electrical impulse
› action potential is generated in the nerve fibre,

6. How does tongue detect the sensation of taste?
Answer : Digestive enzymes in saliva begin to dissolve food into base chemicals that are washed over the papillae and detected as tastes by the taste buds. The tongue is covered with thousands of small bumps called papillae, which are visible to the naked eye. Within each papilla are hundreds of taste buds.

7. State the site of production and function of Secretin, Gastrin and Cholecystokinin.
Answer : The digestive system is the primary site of action for most GI hormones and related polypeptides. The stomach is the primary site of gastrin production with some D-cells also populating the duodenum.

9. Where is the pituitary gland located? Enlist the hormones secreted by anterior pituitary.
Answer : The pituitary gland is a pea-sized endocrine gland that is situated in the middle of the skull base and kept protected within a bony cavity called the sella turcica. It plays an essential role in regulating the functions of various other endocrine glands and maintaining overall hormone levels in the blood.

10. Explain how the adrenal medulla and 
sympathetic nervous system function as 
a closely integrated system.
Answer : The inner medulla is closely involved with the autonomic nervous system, whereas the outer cortex is more exclusively glandular. The adrenal medulla is actually a glandular extension of the sympathetic division of the autonomic nervous system.

11. Name the secretion of alpha, beta and delta cells of islets of langerhans. 
Explain their role
Answer : The alpha cells of the islets of Langerhans produce an opposing hormone, glucagon, which releases glucose from the liver and fatty acids from fat tissue. ... The delta cells produce somatostatin, a strong inhibitor of somatotropin, insulin, and glucagon; its role in metabolic regulation is not yet clear.

12. Which are the 2 types of goitre? What 
are their causes?
Answer : Types of goiters

  1. Colloid goiter (endemic) A colloid goiter develops from the lack of iodine, a mineral essential to the production of thyroid hormones. 
  2. Nontoxic goiter (sporadic) The cause of a nontoxic goiter is usually unknown, though it may be caused by medications like lithium. 
  3. Toxic nodular or multinodular goiter.


13. Name the ovarian hormone and give 
their functions.
Answer : Ovaries produce and release two groups of sex hormones—progesterone and estrogen. There are actually three major estrogens, known as estradiol, estrone, and estriol. These substances work together to promote the healthy development of female sex characteristics during puberty and to ensure fertility.


Q. 7 Long answer questions.
1. Explain the process of conduction of 
nerve impulses upto development of 
action potential
Answer :
The nerve fibre is at resting phase when it is not stimulated by any impulse. They possess a potential difference along the membrane which is known as resting potential (-70mv). The membrane is negatively charged inside due to the lower concentration of potassium ions and positively charged outside due to the high concentration of sodium ions.
When an electrical stimulus is received by a nerve fibre, an action potential is generated. The membrane becomes permeable to sodium ions than to potassium ions. This results in a positive charge inside and negative charge outside the nerve fibre. Hence, the membrane is said to be depolarised.
The potential generated at this phase is known as the action potential. As the action potential reaches its maximum value, the membrane potential gets reversed and this state is known as repolarization. By sequential activity of the nerve conduction, it reaches the terminal end of the axon and stimulates the synaptic vesicles which release the neurotransmitters. The neurotransmitters cross the synaptic membrane and reach the dendrite of the next neuron.

2. Draw the neat labelled diagrams of.
a. Human ear


b. Sectional view of human eye


c. L. S. of human brain


d. Multipolar Neuron



3. Answer the questions after observing the diagram given below.


a. What do the synaptic vesicles contain?
Answer : Each vesicle contains many neurotransmitters that are essential for helping the neuron.

b. What process is used to release the neurotransmitter?
Answer : Calcium enters the axon terminal during an action potential, causing release of the neurotransmitter into the synaptic cleft. After its release, the transmitter binds to and activates a receptor in the postsynaptic membrane. Deactivation of the neurotransmitter.

c. What should be the reason for the next impulse to be conducted?
Answer : Neurons, or nerve cells that carry nerve impulses, are made up of the cell body, the axon, and several dendrites. Signals move across the synapse, the place where the axon of one neuron meets the dendrite of another, using chemicals called neurotransmitters.

d. Will the impulse be carried by post-
synaptic membrane carried even if one 
pre-synaptic neuron is there?
Answer : After release into the synaptic cleft, neurotransmitters interact with receptor proteins on the membrane of the postsynaptic cell, causing ionic channels on the membrane to either open or close. When these channels open, depolarization occurs, resulting in the initiation of another action potential.

e. Can you name the channel responsible 
for their transmission?
Answer : synaptic transmission

4. Explain the Reflex Pathway with the help of a neat labelled diagram.
Answer: The reflex arc typically consists of five components:
1. The receptor is present in the receptor organ.
2. The sensory neuron conducts the nerve impulses towards the central nervous system (CNS). The CNS is comprised of the brain and the spinal cord.
3. The information is transferred from one neuron to other.
4. A motor neuron conducts the response nerve from the CNS to the effector organ.
5. The effector organ shows response by contracting or secreting a product.
The instant movement performed by the individual in response to the stimulus is known as a reflex action.

5. Krishna was going to school and on 
the way he saw a major bus accident. 
His heart beat increased and hands and 
feet become cold. Name the part of the 
nervous system that had a role to play in 
this reaction. 
Answer : Medulla Oblongata

6. What will be the effect of thyroid gland atrophy on the human body?
Answer : The thyroid controls how your body's cells use energy from food, a process called metabolism. Among other things, your metabolism affects your body's temperature, your heartbeat, and how well you burn calories. If you don't have enough thyroid hormone, your body processes slow down.


7. Write the names of hormones and the 
glands secreting them for the regulation 
of following functions.

a. Growth of thyroid and secretion of 
thyroxine.
Answer : The hypothalamus secretes thyrotropin-releasing hormone which, in turn, stimulates the pituitary gland to produce thyroid stimulating hormone. This hormone stimulates the production of the thyroid hormones, thyroxine and triiodothyronine, by the thyroid gland.

b. Helps in relaxing pubic ligaments to 
facilitate easy birth of young ones.
Answer : Oxytocin catalyses the final powerful uterine contractions at the end of an undisturbed birth, sometimes called the fetal ejection reflex, that birth the baby quickly and easily.

c. Stimulate intestinal glands to secrete 
interstinal juice.
Answer :
Cholecystokinin: A small intestinal hormone that stimulates secretion of pancreatic enzymes and bile. Secretin: Another hormone secreted from small intestinal epithelial cells; stimulates secretion of a bicarbonate-rich fluids from the pancreas and liver.

d. Controls calcium level in the blood
Answer : Blood calcium levels are regulated by parathyroid hormone (PTH), which is produced by the parathyroid glands.

e. Controls tubular absorption of water 
in kidneys.
Answer : This control is exerted directly by ADH and aldosterone, and indirectly by renin.

f. Urinary elimination of water.
Answer : Urinary elimination of water is regulated by ADH (Vasopressin). it is secreted by the hypothalamus and stored in the pituitary.

g. Sodium and potassium ion 
metabolism.
Answer : Sodium is reabsorbed from the renal filtrate, and potassium is excreted into the filtrate in the renal collecting tubule. The control of this exchange is governed principally by two hormones—aldosterone and angiotensin II.

h. Basal Metabolic rate.
Answer : The basal metabolic rate, which is the amount of calories required by the body at rest, is determined by two hormones produced by the thyroid gland: thyroxine, also known as tetraiodothyronine or T4, and triiodothyronine, also known as T3.

i. Uterine contraction.
Answer : Oxytocin stimulates the uterine muscles to contract and also increases production of prostaglandins, which increase the contractions further.

j. Heart beat and blood pressure.
Answer : Renin controls the production of two other hormones, angiotensin and aldosterone.

k. Secretion of growth hormone.
Answer : Growth hormone (GH), also called somatotropin or human growth hormone, peptide hormone secreted by the anterior lobe of the pituitary gland.

l. Maturation of Graafian follicle. 
Answer : FSH stimulates the growth and maturation of immature oocytes into mature (Graafian) follicles before ovulation

8. Explain the role of hypothalamus 
and pituitary as a coordinated unit in 
maintaining homeostasis?
Answer : The hypothalamus is a small region of the brain. It’s located at the base of the brain, near the pituitary gland.

While it’s very small, the hypothalamus plays a crucial role in many important functions, including:

  1. releasing hormones
  2. regulating body temperature
  3. maintaining daily physiological cycles
  4. controlling appetite
  5. managing of sexual behavior
  6. regulating emotional responses


9. What is adenohypophysis? Name the homones secreted by it?
Answer : Hormones secreted by the Anterior Pituitary Gland (Adenohypophysis) ... Thyrotropin Releasing Hormone (TRH causes the release of TSH;Thyroid Stimulating Hormone;Thyrotropin) Gonadotropin Releasing Hormone (GnRH releases LH and FSH.) Growth Hormone R.H. & Growth Hormone I.H. Prolactin R.H. & Prolactin I.H.

10. Describe in brief, an account of disorders of adrenal gland.
Answer : The main diseases of a hyperactive adrenal gland include: primary hyperaldosteronism (too much aldosterone), Cushing's syndrome (too much cortisol), and pheochromocytoma/paraganglioma (too much adrenaline).

11. Explain action of steroid hormones and proteinous hormones.
Answer : Steroid hormones are transported through the blood by being bound to carrier proteins—serum proteins that bind them and increase the hormones' solubility in water. Some examples are sex hormone-binding globulin (SHBG), corticosteroid-binding globulin, and albumin.


12. Describe in brief an account of disorders of the thyroid.
Answer : Thyroid disorders are conditions that affect the thyroid gland, a butterfly-shaped gland in the front of the neck. The thyroid has important roles to regulate numerous metabolic processes throughout the body. Different types of thyroid disorders affect either its structure or function.

There are specific kinds of thyroid disorders that includes:

  1. Hypothyroidism
  2. Hyperthyroidism
  3. Goiter
  4. Thyroid nodules
  5. Thyroid cancer