12th Class Biology Chapter 3 Short Questions with Answers Solved

Question: 1

Give two commercial application of ethane.

Answer: 1

1-70

It is used to increase the speed of lates flow in rubber plant.it is also used for artificial ripening of fruits and to induce flowering in pineapple.

Question: 2

What are calluses?

Answer: 2

2-70

These are the mass of undifferentiated cells produced in response to injury on plant body by mitotic cell division.

Question: 3

What is circannual rhythm?

Answer: 3

3-70

The rhythmic activities of organisms which are performed annually or after 365 days is called circannual rhythm.

Question: 4

What is chlorosis? How it is caused/

Answer: 4

4-70

Yellowing of plant leaves due to deficiency of chlorophyll is called chlorosis it is caused due to the deficiency of magnesium.

Question: 5

What is chlorosis?

Answer: 5

5-70

Yellowing Of plant leaves due to deficiency of chlorophyll is called chlorosis.It may be due to deficiency of nitrogen, magnesium or when plant is kept in dark for long time.

Question: 6

What is meant by division of labour ?

Answer: 6

6-70

Division of labour means a specific type of cells can perform a specific type of function.Like muscle cells contract and relax,glandular cells produce secretions, phloem can transport food.

Question: 7

What are biorhythms and diurnal rhythms?

Answer: 7

7-70

Biorhythms are the biological activities of living organisms which are performed at regular intervals are called biorhythms.

Diurnal rhythms are the biological activities of organisms which are performed during one day 0r 24 hours.

Question: 8

Name the synthetic auxin used as selective weed killer.

Answer: 8

8-70

2-4D (2,4 Dichlorophenoxy acetic acid)is selective weed killer.

Question: 9

Write down the commercial application of gibberellins.

Answer: 9

9-70

Gibberellin is commercially used in brewing industry to produce alcohol by malting process of barley.

It delay and improve storage life of the banana and grape fruits.

It also promotes fruit setting.

Question: 10

What are the commercial applications of cytokinins?

Answer: 10

10-70

It is used to delay age of fresh leaf crops and keep flowers fresh.It can also be used to break dormancy of seeds of some plants.

Question: 11

Define biorhythms and gives its types.

Answer: 11

11-70

In living organisms the behavioral activities occur at regular intervals which are called biorhythms.

Circannual rhythms (365 days)
Diurnal rhythms (24 hours)

Question: 12

Give two functions of cytokinin hormone.

Answer: 12

12-70

It inhibits primary root growth and promote opening of stomata.

Question: 13

What are effectors?Give example.

Answer: 13

13-70

Effectors are the organs which show response after receiving message from the associative neurons via motor neurons.For example muscles and glands.

Question: 14

What are commercial applications of abscisic acid?

Answer: 14

14-70

Abscisic acid can be sprayed on tree crops to regulate fruit drop at the end of the season.This removes the need for picking over a long time span.

Question: 15

Mention the relative abundance and distribution of receptors in human skin.

Answer: 15

15-70

The relative abundance of various types of receptors differs greatly for example pain receptors are nearly 27 times more abundant than cold receptors.The cold receptors are nearly 10 times more abundant than heat or temperature receptors.

Question: 16

Compare photoreceptors with chemoreceports.

Answer: 16

16-70

Chemoreceptors These are sensitive for chemical changes.These are for smell,taste and for blood carbon dioxide and oxygen,glucose,amino acids and fatty acids(receptors in hypothalamus)

Question: 17

Write four important roles of ethylene.

Answer: 17

17-70

Ethene inhibits root growth.

Question: 18

Write down four functions of auxin.

Answer: 18

18-70

Function of auxin are

Question: 19

Differentiate between chemoreceptors and mechanoreceptors.

Answer: 19

19-70

Chemoreceptors These are sensitive for chemical changes.These are for smell,taste and for blood carbon dioxide and oxygen,glucose,amino acids and fatty acids(receptors in hypothalamus)

Question: 20

Define Nissl's Granules.

Answer: 20

20-70

^{Nissl's granules which are groups of ribosomes associated with rough endoplasmic reticulum and glogi apparatus for protein synthesis,present in cell body of neuron.}

Question: 21

What are meissner's corpuscles?

Answer: 21

21-70

Meissner's corpuscles (encapsulated endings) which lie in papillae which extend into the ridges of the finger tips.The corpuscles consists of spiral and much twisted endings,each of which ends in knob.These are touch receptors.

Question: 22

What is neurogila?Give its role.

Answer: 22

22-70

In higher animals half of the nervous system consists of neurogila cells.It plays a vital role in the nutrition of neurons and their protection by myelin sheath.

Question: 23

What are pacinian corpuscles?

Answer: 23

23-70

Pacinian corpuscles situated deep in the body.These are also encapsulated neuron endings and receive the deep pressure stimulus.Those located in the limbs probably from a basis for vibration sense.

Question: 24

Define receptors.Give their types.

Answer: 24

24-70

Receptors are the sensory organs which receive stimulus and transfer it to associative neurons via sensory neurons for further action e.g,eye,ear,nose,skin and tongue.

Question: 25

What are neurotransmitters?Give it example.

Answer: 25

25-70

Neurotransmitters are the chemicals which are secreted at neuron endings,which transfer nerve impluse from on neuron to another neuron e.g Acetylcholine,adrenaline,dopamine,serotonin.

Question: 26

Differentitae between reflex arc and reflex action.

Answer: 26

26-70

Reflex arc The path followed by the nerve impulse during the reflex action is called reflex arc.

Question: 27

What is meant by resting membrane potential?

Answer: 27

27-70

A typical neuron at rest is more positive outside than inside the cell membrane.This net difference in charge between the inner and outer surface of a non-conducting neuron is called resting membrane potential.

Question: 28

What do you Know about saltatory nerve?

Answer: 28

28-70

In myelinated neuron the nerve impulse jump from on node to another node (node of Ranvier).It is called salutatory nerve impulse.

Question: 29

Sketch and label sensory neuron.

Answer: 29

29-70

Differentiate between axons and dendrites.

Question: 30

Define reflex arc and give its components.

Answer: 30

30-70

The path followed by the nerve impulse during the reflex action is called reflex arc.Its components are receptors,sensory neurons,inter neuron.motor neuron and effectors.

Question: 31

Differentiate between nerve impulse and saltatory impluse.

Answer: 31

31-70

Nerve impulse Nerve impulse is a wave of electrochemical changes which travels along the length of the neuron involving chemical reactions and movement of ions across the cell membrane.

Question: 32

Define synapse.

Answer: 32

32-70

There are the microscopic gaps between the two neurons where neurotransmitters are secreted and nerve impluse is transferred from one neuron to next neuron.

Question: 33

Differentiate between resting membrane potential and active membrane potential.

Answer: 33

33-70

Resting membrane potential A typical neuron at rest is more positive outside than inside the cell membrane.This net difference in charge between the inner and outer surface of a non-conducting neuron is called resting membrane potential.

Question: 34

How brain is protected with various covers?

Answer: 34

34-70

Cranium protects the brain.Beneath the cranium brain is protected by triple layer of meninges.Between the meninges there is filled cerebrospinal fluid which act as shock absorber.

Question: 35

What is sodium potassium pump?

Answer: 35

35-70

These are the special proteins which are present on the neuron membrane and act as pump to move the K ions across the membrane during the transmissionof nerve impluse

Question: 36

Give the name of structural components of limbic system.

Answer: 36

36-70

Limbic system includes hypothalamus,hippocampus and amygdala.

Question: 37

What is epilepsy?

Answer: 37

37-70

it is one of the convulsive disorders of nerves which is characterized by abrupt transient symptoms of motor,sensory,psychic or autonomic nature,frequently associated with changes in consciousness.

Question: 38

What is cerebrospinal fluid?Give its function.

Answer: 38

38-70

Beneath the cranium,the brain and spinal cord are protected by triple layer of meninges.Between the layers of meninges the cerebrospinal fluid (CSF),similar in composition to blood plasma.

Question: 39

Differentiate between nerves and ganglia.

Answer: 39

39-70

Nerve The nerves are the bundles of axons or dendrites bounded by connective tissues.

Question: 40

What do you know about parasympathetic nervous system?

Answer: 40

40-70

A few cranial nerves including the vagus nerve together with the fibre from bottom portion of spinal cord from PNS.It promotes all the internal responses which are associated with the relaxes state i.e,contraction of pupil,promotes food digestion and retards heart beat.

Question: 41

Name various structural that protect our brain.

Answer: 41

41-70

Following are the structures which protect our brain

Question: 42

Differentiate between CNS and PNS

Answer: 42

42-70

CNS Central nervous system consists of brain and spinal cord.

Question: 43

Compare sympathetic nervous system with parasympthetic nervous system.

Answer: 43

43-70

Parasympathetic nervous system A few cranial nerves including the vagus nerve together with the fibre from bottom portion of spinal cord from PNS.it promotes all the internal responses which are associated with the relaxed state i.e,contraction of pupil,promotes food digestion and retards heart beat.

Question: 44

What is action of nicotine on coordination?

Answer: 44

44-70

Nicotine affects post synaptic membrane in CNS and PNS.It minimizes the action of acytylcholine on the nicotine receptors.So it is sitmulant of nerve impluse. It increases the heart beat rate,blood pressure and digestive tract mobility. Nicotine may cause vomiting,diarrhoea and even cause water retention relation by the kidneys.

Question: 45

Write a note on Alzheimer's disease.

Answer: 45

45-70

It is characterized by decline in brain function.Its symptoms are similar to those of dememntia(memory loss).There is genetic predeposition to the disease in some people.So it runs in families.

Question: 46

Give two characteristics of hormones.

Answer: 46

46-70

hormones are porteins in nature.

Question: 47

Give effects of nicotine on blood vascular system and digestive system in man.

Answer: 47

47-70

It increases the heart beat rate,blood pressure and digestive tract mobility Nicotine may induce vomiting and diarrhoea and even may cause water retention relation by kidneys.

Question: 48

What are the functions of oxytocin hormone?

Answer: 48

48-70

It cause distention of cervix,its primary function is on smooth muscles,particularly on uterus during child birth and also cause milk ejection.

Question: 49

What is cushing's disease? Give its symptoms.

Answer: 49

49-70

In cushing's disease too much cortical hormones are produced. Symptoms include an excessive protein breakdown resulting muscular and bone weakness.

Question: 50

Which Hormones are secreted by posterior lobe of pituitary gland?

Answer: 50

50-70

Antidiuretic hormone and oxytocin are secreted by the posterior lobe of pituitary gland.

Question: 51

What are the function of parathyroid glands? Or What are two functions of parathyroid gland?

Answer: 51

51-70

Parathyroid gland produces paratharmone which control calcium level in the blood.Its over activity cause demineralization of bones while under activity cause muscular tetany.

Question: 52

What is cretinism?

Answer: 52

52-70

If congenitally thyroxin production is low,it may cause cretinism,where the individual fails to develop normally.These are small,have coarse scanty hairs,thick yellowish scaly skin and mentally retarded.

Question: 53

Write down the role of hypothalamus in chemical coordination.

Answer: 53

53-70

It is a part of fore brain.It is here that many of the sensory stimuli of nervous system are converted into hormonal responses.It is believed that oxytocin and ADH are produced in hypothalamus.

Question: 54

What is the role of anti diuretic hormone(ADH)?

Answer: 54

54-70

ADH secretion cause decrease in blood pressure,blood volume and osmotic pressure of the blood detected by osmoreceptors in the hypothalamus.It is mainly control the concentration of urine.

Question: 55

How ca++concentration in human blood is regulated?

Answer: 55

55-70

Calcium level in human is controlled by the paratharmone. Low level of calcium ions in the blood stimulate parathyroid directly to increase the parathormone production whereas high level of calcium ions in the blood suppresses its release.

Question: 56

Name hormones secreted by Islets of langerhans and their role.

Answer: 56

56-70

Islets of langerhans produce Insuline and glucagon. They maintain blood glucose level.

Question: 57

Name hormones released by adrenal gland.

Answer: 57

57-70

It produces adrenaline and nor adrenaline by adrenal medulla.
Adrenal cortex produces aldosterone and androgenic hormones.

Question: 58

Give the functions of androgens.

Answer: 58

58-70

In human males androgens cause the development of secondary male characteristics. In females its excess secretion may cause the development of male characters.

Question: 59

Give the role of insulin and glucagon.

Answer: 59

59-70

Insulin controls the blood sugar level by different ways.It may be as

Question: 60

Discuss the role of two hormones produced by gut.

Answer: 60

60-70

Gastrin produced from mucosa of pyloric region of stomach. It stimulates the production of gastric juice.

Question: 61

Define habituation. Give its example.

Answer: 61

61-70

It is the simplest from of learning and involves modification of behavior through decrease in response due to repeated stimuli e.g Rodents respond to alarm cells by others in their groups,if these calls are continued and no danger is confirmed further calls may be ignored.

Question: 62

What is leutinnizing hormone(LH). Write its role

Answer: 62

62-70

LH works with FSH to stimulate oestrogen secretion and rupture mature follicles to release ovum. It also causes leutinization of follicle after ovulation and along with prolactin maintains corpus leuteum.

Question: 63

Differentiate between kineses and taxes.

Answer: 63

63-70

Kineses: kineses is a behavior in which an organism changes the speed of random movement which helps them to survive in the environment.

Question: 64

Write four similarities of nervous and chemical coordination.

Answer: 64

64-70

Similarities are as follow

Question: 65

Give role of human gut as endocrine tissue.

Answer: 65

65-70

Human gut act as endocrine gland. Important hormones produced by gut are Gastrin: This hormone is produced by mucosa of pyloric region of the stomach. It stimulates the production of gastric juice. It produced under the influence of protein in the food.

Question: 66

Define feedback machanism.

Answer: 66

66-70

It is a type of interaction in which a controlling mechanism is itself controlled by the products of the reaction it is controlling.

Question: 67

Define latent learning.

Answer: 67

67-70

It is the association of different stimuli or situations without any patent or patent reward.

Question: 68

Explain imprinting.

Answer: 68

68-70

young birds after hatching have a tendency to follow moving objects in their surroundings and show a brief period of sensitivity during which shape of object can be imprinted with the result that the young birds follow them.

Question: 69

What is reflex action?

Answer: 69

69-70

Reflex action is a type of involuntary action.The direction of stimulus is from receptors to sensory neuron to associative neuron and then through motor neuron to the effectors.

Question: 70

Enlist any four types of learning behavior.

Answer: 70

70-70

Four types of learning behavior are

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