Short Question Answers – Co-Ordination and Control | HSC Part-II – Biology Notes

Chapter 3

Short Question Answers – Co-Ordination and Control

Q.1. What is neuron?

Ans. The neurons are functional and structural units of nervous system. These are specialized cells which carry out the transmission of nerve signals.

Q.2. How many parts are there in the neuron?

Ans. A neuron consists of cell body, dendrites and axon.

Cell body has a nucleus, cytoplasm, rich in granules like Nissl Bodies, mitochondria and golgi bodies.

Dendrites are branched extensions of cytoplasm, originate from cell body. These dendrites make synapses with the axon terminals of another neuron and receive nerve signals.

Axon is only one number. Sometimes it is very long in length and termination branches whose ends are swollen called Synapse Cleft.

Q.3. What is the function of sensory neutron?

Ans. Sensory or Afferent Neuron are connected with some organs or receptors and conduct nerve signals to the CNS.

Q.4. What is the function of motor neuron?

Ans. Motor or Efferent Neuron are connected with muscles and conduct nerve signals from CNS to the muscles.

Q.5. Define nerve impulse.

Ans. Travelling of messages in the form of electric current through a neuron is called nerve impulse.

Q.6. What Synapse?

Ans. The region from where the nerve impulse move from one neuron to another neuron is called Synapse.

Q.7. Give the anatomical arrangement of Synapse?

Ans. The synapse consists of three components.

A pre-synaptic membrane (The Axon Terminal)

A narrow space called Synaptic Cleft

Post-synaptic Membrane (Dendrite of other neurons)

Q.8. How a nerve impulse is transmitted from one neuron to another neuron?

Ans. Synaptic Knob of axon terminals containing synaptic vesicles. The synaptic vesicles are filled with neurotransmitter, on the arrival of nerve impulse at axon terminal these neurotransmitters are released in the synaptic cleft and that neurotransmitter bind at the receptors of post synaptic membrane. In this way action potential is generated in post-synaptic membrane.

Q.9. What is reflex action?

Ans. The reflex action is automatic, involuntary and sudden response; occur due to internal or external stimuli. For example knee jerk, blinking of eyes.

Q.10. How many neurons are involved in the reflex arc?

Ans. A reflex involves only two neurons.

1. A Sensory Neuron

2. A Motor Neuron

Q.11. What is reflex arc?

Ans. The arrangement of sensory neurons and motor neurons is called reflex arc.

Q.12. How many types of reflexes are there? Explain.

Ans. There are two types of reflexes.

i. Monosynaptic reflexes: If only one synapse is found in the reflex arc is called Monosynaptic Reflexes. For example, Knee Jerk.

ii. Polysynaptic Reflexes: If reflex arc consists of two or more synapse is called Polysynaptic Reflexes. In this path way two or more inter neuron are found in between sensory and motor neurons.

Q.13. What is polarization and resting membrane potential and what is the distribution of different ions across the neurolemma?

Ans.

i. Cell membrane of neurons has unequal distribution of positive and negative ions inside and outside the membrane.

ii. Sodium ions are in greater concentration outside membrane while chlorine ions and negative charge proteins are in low concentration due to positive charge develops outside membrane.

iii. Potassium ions are in higher concentration on inside the membrane then outside the membrane. Chlorine ions and negative charge proteins are in higher concentration then potassium ions inside the membrane due to which membrane is negatively charged from inside.

This condition is called Polarization and Resting Membrane Potential (RMP). The RMP is about 70mv to 90mv.

Q.14. For which ions the cell membrane of neuron is permeable and how their concentrations are regulated across the cell membrane?

Ans. Cell membrane is permeable for both Na+ and K+ ions and these ions can move freely across the membrane but their concentrations are regulated by Na-K Pumps located in the cell membrane.

Q.15. What is repolarization or action potential and how an when nerve impulse is generated?

Ans. Due to the arrival of any signal, permeability of cell membrane to sodium ions suddenly increases. Sodium ions diffuse inside the membrane, after very short time potassium ions move outside the membrane.
Membrane is now positively charged from inside and negatively charged from outside the membrane due to the shifting of sodium ions inside the membrane. This condition is called Depolarization. It value is +30mv.
When this signal is shifted to another position on neuron, sodium ions move outside and potassium ions move inside by Na-K Pump. Membrane again positively charged from outside and negatively charged from inside. This condition is called Repolarization or Action Potential.

In this way the nerve impulse travels along the whole length of neuron.

Q.16. What is the path for the propagation of nerve impulse?

Ans. Propogation of Nerve Impulse. Action potential develops locally spread along the entire neurolemma is called propagation of nerve impulse.

Q.17. What is the basic structure of thalamus and how it works?

Ans. The thalamus consists of two masses of nerve cells situated within the cerebral hemisphere just below the corpus callosum. Sensory input from skin, visceral organs and sense organs are transmitted to thalamus before redistribution to the cerebrum.

Q.18. Where hypothalamus is located. Which glans is associated with hypothalamus and what is its function?

Ans. Hypothalamus is located below thalamus. Pituitary gland also connects with hypothalamus. Hypothalamus controls body temperature blood pressure hunger thirst and secretion of hormones.

Q.19. Give general features of brain.

Ans. Brain is the main part of central nervous system (CNS). It is 1/5 of the total body weight. It is located in cranial cavity of skill and covered with meninges. Between meninges cerebrospinal fluid is failed.

Q.20. What is the basic structure of cerebrum?

Ans. Cerebrum consists of two cerebral hemispheres which are connected together by corpus collosum. Cerebrum has many infoldings or narrows or gyrl which are separated by sucli or fissures. The outer most surface of cerebrum is called cerebral cortex which is rich in neurons.

Q.21. Give the physiological significance of cerebrum.

Ans. Physiological significance of cerebrum

i. Mental activities involved in memory intelligence, sense of responsibility, thinking reasoning and learning.

ii. Sensory perception including pain, temperature touch, sight, hearing, taste and smell.

iii. Initiation and control of voluntary muscle contraction.

Q.22. Into how many lobes the cerebrum can be divided?

Ans. Cerebrum is divided into following lobes.

i. Frontal lobe: It controls smell and power of speech.

ii. Parietal lobe: It controls pain, pressure, thinking memory and learning.

iii. Temporal lobe: It concentrated with hearing

iv. Occipital lobe: It is concerned with vision

Q.23. From here the medulla oblongata extends and what is its importance?

Ans. Medulla oblongata extends from the pons verollii and continuous with the spinal cord. Some vital centers are located in it..

i. Cardiac center

ii. Respiratory center

iii. Reflex centers of vomiting, coughing, sneezing and swallowing

Q.24. What is spinal cord? Describe its structure?

Ans. Spinal cord is tubular structure which runs poster only with in the neural canal of verteral column. Spinal cord is also covered with meninges. The center of spinal cor is butterfly shape mass of grey matter surrounding it is the white matter in which the axons of neurons are located. from spinal cord spinal nrve arise which connect different parts of body with spinal cord serves as the pathway of nerve impulses from brain to various parts of the body and also control reflex action.

Q.25. What is hormone?

Ans. The hormone is a secretary product of ductless gland which release directly into blood and transported into the body, where it affects the particular target site.

Q.26. How many types of hormone are there on the basis of the chemical nature?

Ans. Types of Hormones on the Basis of Chemical Nature

Hormone are classified into three group on the basis of chemical compostion.

i. Petide Harmone: They consist of short chain amino acids and long chain amino acids. Glucagon, ADH and oxytocin are the example of short chain and insulin and prolactine are the example of long chain amino acids.

ii. Modified Amino Acid Harmones: These hormones consist consist of modified amino acids e.g., Thyroxin, epinephrine.

iii. Steroid Hormone: These hormones are lipid in nature e.g., progesterone, testosterone.

Q.27. What the first model of hormones says about the functions of hormones and to which types of hormone it is related?

Ans. First Model of Hormones Action

This model is related with peptide hormone. According to this model receptor of hormones is linked with an enzyme adenylate cyclase on the innr side of plasma membrane. Bindin of hormone with receptor activates adenylate cyclase, which converts into cyclic adenocine monophosphate (cyclic AMP) in the cytoplasm. This cyclic AMP activates specific enzymes which bring about appropriate response with n the cell.

Q.28. What is the second model of hormones says about the function of hormones and to which types of hormones it is related?

Ans. Second Model of Hormones Action

This model is related with steroid hormones. These hormones directly diffuse through plasma membrane into the cell. In the cytoplasm they find specific receptor which carry them into the nucleus where hormone receptor complex directly activates the appropriate genes. Thus under the instruction of genes, enzymes are synthesized to bring about specific response.

Q.29. How hypothalamus secrets it hormones and where they are stored?

Ans. Hypothalamus is the part of the fore brain. Its neuro-secretory cells produce both releasing hormones and inhibiting hormones. Some of its cells secrete Antidiurertic hormones (ADH) and Oxytocin which are stored in their nerve ending located in posterror lobe of pituitary gland.

Q.30. What is the size of pituitary gland? Where it is situated and into how many lobe sit can be divided?

Ans. Pituitary gland (hypophysis) is small pea size glands hangs from the base of hypothalamus. Pituitary gland consists of following lobes.

i. Anterior lobe

ii. Median lobe

iii. Posterior lobe

Q.31. Which hormones are secreted from the anterior lobe of hypophysis and what are their physiological effects?

Ans. Hormones of Anterior Lobe of Pituitary Gland

This lobe secretes following hormones.

i. Somatotropin – This hormones increases metabolism or many tissues and influences the growth of bones and soft tissues.

ii. Thyroid Stimulating Hormones – This hormone regulates the secretions of thyroid gland.

iii. Follicile Stimulating Hormones - This hormone starts the formation of gametes in gonads.

iv. Adrenocorticotropic Hormones – This hormones controls the functioning of cortex of adrenal gland.

v. Prolactin – It stimulates mammary gland to secrete milk.

Q.32. Which hormones are secreted from the posterior lobe of hypophysis and what are their physiological effects?

Ans. Hormone of Median Lobe of Pituitary Gland

In many vertebrate this lobe secretes Melanocyte Stimulating Hormones (MSH) which controls darkening of skin. In man MSH secretes by anterior lobe with uncertain function.

Q.33. Which hormones are secreted from the posterior lobe of hypophysis and what are their physiological effects?

Ans. Hormone of Posterior Lobe of Pituitary Gland

i. Antidiuretic Hormone – This hormone increases reabsorption of water from kidney hence decrease with output.

ii. Oxytocin – This hormone contracts uterus during child birth and release of milk from mammary gland.

Q.34. What types of abnormalities are produced by hyper secretion and hypo secretion of pituitary gland?

Ans. Abnormalities of Pituitary Gland

i. Gigantism – In this condition person attain enormous height due to over secretion of growth hormone.

ii. Dwarfism – In this condition height of person remain very short due to low secretes of growth hormones.

iii. Acromegaly – It is the enlargement of bones of hands, feet and face. This condition appears due over secretion of growth hormone during adult hood.

Q.35. Where thyroid gland is located? How any types of hormones are secreted by the thyroid gland and what are their metabolic effects.

Ans. This gland is located below the neck. It is the shape of letter “W”. It secretes two hormones.

i. Thyroxin Hormone – It is of two types. Trixiodo Thyronine (T3) and Thyroxin (T4) hormones. It stimulates the metabolism of the body and important for physical and mental development.

ii. Calcitonin – This hormone decrease the level of calcium in blood after depositing excess calcium in bones.

Q.36. What type of pathological conditions appears due to hybo secretion of thyroxin hormone in adult and childrens?

Ans.

i. Goiter – it is abnormal enlargement of thyroid gland due to deficiency of iodine in diet.

ii. Myxedema – In adult hood low secretion of thyroixin causes over weight, sluggish, dry, skin, hair loss, intolerant to cold, confused and depressed individual.

iii. Cretinism – In children low secretion of thyroxin causes stunted growth, mental retardation and coarse facial features.

Q.37. Where parathyroid gland is located and which hormone is secreted from it and what is its significance?

Ans. Parathyroid Gland are four in number and are located behind the thyroid gland. This gland secret one hormone called parathormone. It increases reabsorption of calcium from the kidneys and also induces release of calcium from bones.

Q.38. What is the name of the dual nature gland? Where beta and alpha cells and what are their secretions? How their secretions effect the blood glucose level and metabolism of the body?

Ans. Pancreas acts as both endocrine and exocrine glands. The endocrine portion of the gland is called Islet of Langerhans. It secret two hormones.

i. Insulin – It is secreted from the beta cells of Islet of Langerhans. It decreases blood glucose level after stimulating liver, muscles and adipose tissues. It also promotes synthesis and conversion of glucose unto glycogen.

ii. Glucogen – It is secreted from the alpha cells of the Islet of Langerhans. It is secreted in response of deficiency of glucose. It increases glucose level after converting glycogen into glucose.

Q.39. What is diabetes mellitus? What are its sign and symptoms?

Ans. DIABETES MELLITUS – It is due to the deficiency of insulin hormone. In this there is persistent rise in blood glucose level. In this disease frequent urination, weight loss, formation of ketone bodies and imbalance function of brain are the symptoms.

Q.40. Where adrenal glands are situated and what are their roles in the maintenance of body physiology?

Ans. Adrenal glands are two in number and are located on the top of each kidney. Each adrenal gland has two parts.

(A) Adrenal Cortex – It is regulated by Adreno Cortico Tropic Hormone (ACTH) of the pituitary gland. It three hormones.

(i) Cortisoe – It promotes metabolism of glucose. It also promotes the conversion of protein into glucose.

(ii) Aldosterone – It increases the metabolism of Na+ and Cl- ions by the kidneys.

(iii) Androgen – Secretion of androgen in male causes growth of facial hairs, deepening of voice and increase in muscle. Excessive secretion of androgen in females cause masculinzation and appearance of beard.

(B) Adrenal Medulla – It secretes two hormones.

(i) Adrenaline OR Epinephrine – Adrenaline increases heart beat, blood glucose level, breathing rate and metabolic are

(ii) Nor-Adrenaline OR Epinephrine – It sustain blood pressure.

Q.41. What are hypo and hyper effects of the secretions of adrenal glands?

Ans.

(i) Cushing’s Syndrome – It occurs due to over production of cortisol, characterized by obesity, muscle wasting, hypertension and diabetes.

(ii) Addison’s Disease – It occurs due to deficiency of the hormones of adrenal gland. Deficiency of hormones occur due to destruction of adrenal gland. It is characterized by weakness, weight loss, low blood sugar and reduced blood pressure.

Q.42. Where thymus gland is located and what is the significance of its secretion in immune system?

Ans. Thymus gland is located in the chest behind the sternum. It consists of two lobes. It secretes number of hormones including Thymosin, which stimulates the development and differentiation of T-lymphocytes.

Q.43. What is the function of pineal gland?

Ans. Pineal gland is a cone shaped body in the brain. It secretes melatonin at might. Melatonin helps in the growth and development of gonads.

Q.44. Name the hormones secreted by the ovary and what their physiological roles in the female body?

Ans. Ovary secretes two hormones.

i. Estrogen – it produces female secondary sexual characters.

ii. Progesteron – It helps in the preparation and maintenance of uterus for the development of embryo.

Q.45. What is animal behavior?

Ans. The response of an animal in relation to its internal or external environment is called animal behavior.

Q.46. What is ethology?

Ans. The scientific study of the nature of behavior is called ethology.

Q.47. Into how many types the behavior can be divided?

Ans. Behaviors are identified into two types

(i) Innate Behavior (Intensive Behavior) – Behaviors are automatic preprogrammed and genetically determined which do not involve any learning. Innate behavior can be categorized into following types.

(ii) Learning Behavior – The process that bring about adaptive changes in the behavior of an animal in response to a stimuli. It related to a specific experience in the animals life with that or a similar stimuli.

Q.48. What are Kinases? What type of behavior is showed by the wood lice during hot and humid conditions?

Ans. In this behavior animal shows random movements to a particular stimulates. This movement depends on the intensity of stimulates not the direction. For example wood lice move about quickly in dry condition but slow down and stop in humid areas.

Q.49. What is taxis? What type of behavior is showed by the moth for light?

Ans. In this behavior animal shows directional movement. The movement towards stimulus is positive taxis, while away from the stimulus is negative taxis. for example, Moth flies towards the light.

Q.50. What are reflexes?

Ans. These are short lived, rapid responded mediated by nervous system.

For example; Knee jerk, blinking of eye and withdrawal pf hand from hot objects.

Q.51. What is fixed action pattern?

Ans. This behavior is triggered or sign stimulus or releaser. For example; In stickle back fish one male attacks the other made which enters in its territory. It was found that releaser is the red belly of the intruder.

Q.52. What is latent learning? Explain.

Ans. A type of learning which is not associated with a particular stimulus and is not normally rewarded, but is utilized in a different situation at a later time is called latent learning. For example rate can easily find their way in experimental maze by their explaining nature. This habit makes them expert in recognizing their environment. This ability is not immediately rewarded but the knowledge of their barrows and different approaches is useful when a predator approaches them.

Q.53. What is operant condition? Explain.

Ans. Operant Condition – (Trial and error learning)

In this kind of learning and animal learns to associate its behavior to receive and award or punishment. B.F. Skinner kept hungary, pigeons or mice in skimmer box. Inside the box there was a lever which operated a food supply. When the lever was pressed by the animal a sample of food was delivered. After several accidental incidents of pressing the lever the animals learnt to get food.

Q.54. What is biological rhythm?

Ans. Some organisms do some activities at regular internals irrespective to the season or day length. This kind of behavior is called time biology or biological rhythm.

Q.55. How many types of biological rhythm are? What is there basis of classification?

Ans. Depending upon the external or internal regulating factors, the biological rhythm can be differentiated into exogenous or endogenous rhythm. The exogenous rhythms are controlled by external factors such as light and dark. Where as endogenous rhythm controlled by internal factors such as biochemical and physiological changes.

Q.56. Give some examples of biological rhythms.

Ans. Some examples of biological rhythm are as follows.

(i) Breeding Season – Some animals have particular breeding seasons because their feeding and rearing is possible in these season.

(ii) Biannual Migration – Salamons and eel fish migrate between sea and rivers more thanonce in their life cycle.

(iii) Animals are active for only part of the 24 hour cycle. For example diurnal, nocturnal and crepuscular animals.

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