Biology For Class X - Chapter No. 3 - Coordination And Control - Short Question Answers

 

Biology For Class X - Chapter No. 3 - Coordination And Control - Short Question Answers

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CHAPTER 3: COORDINATION AND CONTROL
B. Short Questions Answers

i) What do you mean by feedback system?
Ans: Feed Back System:
The check and balance system in a body is called feed back system. The feed back system has the following steps:

1. Stimulus:
   It refers to any factor which cause change either in internal or external environment of the organism.
   
   
   
   
2. Receptors:
   The changes are detected by special cells or organs termed as receptors. For example, eyes are photoreceptors (sensitive to light), ears are sound receptors, receptors, nose is chemoreceptor for gases and tongue is chemoreceptor for solids or liquids.
3. Response:
   It is the activity performed by some living organism after analyzing stimulus or stimuli.
4. Effectors:
   The organs like muscles, glands etc are termed as effectors. They take part in particular action or exhibit response.

ii) Why the nervous coordination is faster than chemical coordination?
Ans: Nervous Coordination is faster than the chemical coordination because it is an advanced type of coordination in which neurons generate electrochemical signals. Since the signaling is in electric form so it is very rapid.

 
iii) Which of the two coordination types is better and why?
Ans: Nervous Coordination is better than the chemical coordination because it is an advanced type of coordination in which neurons generate electrochemical signals. Since the signaling is in electric form so it is very rapid.

iv) How reflex action works by a reflex-arc?
Ans: Reflex Action:
The automatic involuntary responses which occur either due to internal or external stimuli are called Reflex Action.

Parts of Reflex Action:
Reflex action consists of:

1. Receptor: (Skin) receive stimuli.
2. Sensory Neuron: It carries message from receptor to the Central Nervous System (CNS).
3. Motor Neuron: It carries message from Central Nervous System (CNS) to the effector.
4. Effector: (Muscle of gland) which perform action.

Reflex Arc:
The pathway of passage in impulse during a reflex action is called Reflex Arc.

Reflex Arc Function:
Reflex arc works as:

1. A receptor in the skin detects a stimulus (the change in temperature).
2. Sensory neurons send electrical impulses to relay neurons, which are located in the spinal cord.
3. Motor neurons send electrical impulses to an effector.
4. The effector produces a response (muscle contracts to move hand away).

v) Why driving license is not issued to a color blind person?
Ans: Colour blindness is a deficiency of vision in which one cannot distinguish certain colours such as blue and yellow or red and green. It is due to the defect in cones of retina. Driving license is not issued to a person suffering from colour blindness because of their inability to distinguish red and green traffic lights.

 

  vi) Why thyroid gland swell up and give the name of the disease?
Ans: Thyroid Gland:
Thyroid gland is located in the neck region in front of trachea. It consists of two lobes, one on either side of trachea. It is butterfly in shape. Secretions:
It secretes three main hormones.

1. Thyroxine or T4 (Tetra lodo Thyroxine)
2. T3 (Tri lodo Thyroxine)
3. Calcitonin

Disease Goiter:
When there is a deficiency of iodine in diet it results in decreased level of thyroxin hormones (T3 and T4). Thyroid gland works more than normal to produce more thyroxin. As a result of which they become swollen and enlarged. This disease is called Goiter.

vii) What is the role of Islet's of Langerhans cells?
Ans: Pancreas:
Pancreas is a gland which acts as both exocrine and endocrine gland. It is located in abdominal cavity below the liver.

Islets of Langerhans:
The cells of pancreas are called Islets of Langerhans. They perform the function of endocrine gland. They are involved in regulating glucose metabolism .
The islets of Langerhans are of two distinct types.

1. Alpha Cells (α-cells):
   Alpha cells secrete hormone called Glucagon. When the level of blood glucose is low, Alpha cells secretes glucagon which increases the glucose level up to normal.
2. Beta Cells (β-cells):
   Beta cells secrete hormone called Insulin. When the level of glucose is high, Beta cells secretes Insulin which helps in decreasing the blood glucose levels.

viii) What is "emergency hormone" and why it is named so?
Ans: The inner layer of adrenal gland is called Adrenal Medulla. Adrenal medulla works under the influence of sympathetic nervous system. Adrenal Medulla produces many hormones which are collectively called Emergency Hormones. They are called emergency hormones because they are secreted in stress situation.

The important emergency hormones are:

1. Adrenaline OR Epinephrin:
   It increase heart rate, amount of glucose in blood, rapid respiration and metabolism during emotions and emergency.
   It also takes part in the contraction of blood vessels in intestine and dilation of blood vessels in muscles.
2. Non-Adrenaline Or Nor-Epinephrine:
   It also functions like epinephrine, but its main function is control of blood pressure during fight and flight.
   The over secretion of both these hormones causes high blood pressure.

ix) What are the possible reasons of paralysis?
Ans: Paralysis:
The partial or complete loss of controlled movement caused by the inability to contract one or more muscles accompanied by loss of sensation is called Paralysis.

Causes:

1. Bleeding (hemorrhage) or blood clot in the specific part of brain.
2. Injury to brain, spinal cord or nerves.

x) What is Epilepsy?
Ans: Epilepsy:
It is a brain disorder in which there is temporary alteration in one or more function or recurrent seizures.

Causes:

1. Abnormal electrical activity in brain.
2. Stimulus like sudden flash light on eyes.

Symptoms:

1. Unconsciousness
2. Stiffness of the body
3. Uncontrollable twitches or jerks

xi) Differentiate between Nervous and chemical coordination .
Ans: Difference Between Nervous and Chemical Coordination

S.NO.	NERVOUS COORDINATION	CHEMICAL COORDINATION
1.	Activity of Neurons.	Activity of special secretory cells.
2.	Signal type is electro-chemical.	Signal type is purely chemical.
3.	Rapid in action.	Slower in action.
4.	Response is shorter duration.	Response is longer duration.
5.	Advance type of coordination.	Primitive type of coordination.
6.	Exclusively related to animals.	Related to all organisms.
7.	Involves neurotransmitters.	Involves other signaling molecules such as hormones.

xii) Define coordination?
Ans: Coordination:
coordination is defined as the process where different units of a system work together to perform a meaningful function.

xiii) Define Coordination in lower organisms and plants?
Ans: Coordination in lower organisms and plants:
Lower organisms like prokaryotes, protozoa, algae, fungi and plants have chemical coordination through signaling molecules released usually in the form of hormones to regulate their movements, growth, metabolism, reproduction, etc.
Other responses like growth, reproduction are due to the secretion of hormones by secretory cells and carried via the transport media to their respective target organs.

For example:

1. Leaves of the “touch me not” are closed when touched.
2. Turning towards the direction of sun in “sun flower” plants.

xiv) Give at least one reason why leaves of “touch me not” fold or closed when touched?
Ans: Leaves of the “touch me not” are closed when touched. After a short while, they restore their original open position. The pressure or touch serves as stimulus while closing down of leaves is the response.

xv) Give at least one reason why the sunflower turns towards the direction of sun?
Ans: A fascinating movement is the turning towards the direction of sun in “sun flower” plants. It's a bit slower movement which is believed to be caused by phytohormones called Auxins. It causes rapid cell growth in shaded regions of the plant.

xvi): Why do we see lightning before hearing thunder?
Ans: Light and Sound in a thunderstorm:
In a thunderstorm, the lighting and its acoustic effect on ground appear with interval. Since the light travels much faster than sound, the lighting appears first and the sound of thunder is heard after a short while.