82.12

Q. 63. Wich gland.s produce ad,renaline?Ans. Adrenal glands produce adrenaline.

C BSE Science Self -Tutor*X

fub*1@ny is the supply of blood, to the d,igestiue system and. skin reduced. d.uring emergencyI ' situation?Ans. The blood is diverted to muscles which need excess biood to act in such situations.

&{.Vhat effect does ad,renaline haue on heo,rt?

Ans" It makes the heartbeats faster which results in more supply of oxygen to muscles.

^Q.

00. Wat is the effect of ad,renaline on the respiratory system?' Ans. The muscles of the diaphragm and the rib muscles contract, so that the rate of

breathing increases for supply of more oxygen.

Q. 67. What happens when the groutth hormone is'produced in less quantity in chitdhoo:d?Ans. It affects the growth of the child and the child remains a dwarf. This condition is

llled dwarfisrn.qXia" Which part of the brain is associated with sensati.on of hunger?Ans. The forebrain is associated with the sensation of hunger.

Q. l. What are the conlponerlts of the hum.an neruous system?

Ans. The components of human nervous system are:(i) Central nervous system consisting ofthe brain and the spinal cord.(il) Peripheral nervous system consisting of cranial, spinal and visceral nerves.

Q. 2. Are the rnouements like ru,nning, playing and, chewing of cud by the buffaloes differentfrom the ntouement shown by a seed, growing into a seedling?

Ans. The two types of movements are different. Growth movemenis occur due tp cellenlargement in the seedling, but the movements like running, playing and chewingare due to the stimulus generated in the environment.

u4 S. Mention the receptors for tastland. smell in animals.Ans. Gustatory receptors for taste.'

^ Olfactory receptors for smell.6 e. 4. Why does impuLse mot)e in one direction in a nerue?

Ans. The ends of dendrites of a neuron receive the impulse from the receptor and passit to the cell body and then it reaches the axon. Axon passes the impulse to thedendrites of the next neuron through syrlapse, thus making the movement of theimpulse unidirectional.

Q" 5. Mahe a labelled diagram of aAns.

junction

Muscle libre

Mitochondrion

neura m,u.sctt lar j unctio n.Neuromuscular

Fig.2.3

C o ntro I and C oo r dination 82.18

({ e. 6. Differentiate between, cerebrum and. cerebellum.

Ans. Cerebrum

Cerebrura is a part of the forebrainand is also the largest part of thebrain.

It is the seat for memory, learningand intelligence and has sensory,associated and motor areas.

(,)

(r,)

Cerebellum is a part of the hindbrainand is smaller than the cerebrun.

It maintains the body posture andequilibrium.

Q. e.

Ans.

Q. 10"

-{ns.

Q. 7 " W.at are plant h.ormones? Giue the funetion of cytokinins.Ans. Plant hormones are naturally occurring chemical substance

control" and coordination in them.

The function of cytokinins is to promote cell division.

Q.8. Name the constituent parts of the peripheral neruou,s systern.

.{ns. (i) Cranial nerves (12 pairs) from the brain.(ii) Spinal nerves (31 pairs) from the spinal cord.

Name the h,ormone produced by the pancreas. Write the function of that harmone.

Insulin, which is produced by the pancreas, changes excess glucose in blood to glycogen,

thus maintaining the glucose level in the blood. If it is not produced in sufficientamounts, the blood glucose level increases, causing diabetes.

Name the hormones produced at puberty in girls and boys.

(l) Estrogen is produced rn grrls at puberty.(ii) Testosterone is produced in boys at puberty.

What happens ta the information, generated due ta change in the enuirorurnent, csnce

it is receiued at the ends of the dendritic tips?

The dendritic tips receive the information through receptors which causes thegeneration of an electrical impulse, which is carried to the ceil body and then to thenerve endi.ngs of the axon. It is finaliy passed on to the next neuron. llltimately, theinformation will reach the respective qpntre in the brain.Which parts of the neruous system are inuolued, in the follau,irtg actiuities:

(i) Balan cing of the body posture, (ii) Saliuation and uomitin g, (iii) Reftex action,and (iu) Thinhin g.

(l) Cerebellum, (ii) Medulla oblongata, (iir) Spinal cord and (ir,) Cerebrum.

Vrh,ere is cerebellum situated in the brain? What function does it perform?

Cerebellum ts situated postcrior to the cerebrum and is a part ofthe hindbrarn" ltmaintains the posture and equilibrium of the body during movements.

Where is pons present in the brain? Which actiuity it controls?

Pons is situated helow the cerebellum and above the medulla oblongata in the hmdbrain.It is responsible for regulating the respiratory activity.

$e.,r.

Q. 12.

-\ns.q. 13.

-\ls.

Q i4.

-{ns.

-{:es.

q 15. Differentiate betweeru sensory nerue and motor nerue.

)

Wh.at are plant h.ormones? Giue the funetion of cytokinins.

Plant hormones are naturally occurring chemical substances which bring about

82.14

Ans. Sensory Nerue

(l) Carries the impulse from thereceptor to the central nervoussystem.

(ii) Sensory area present in thenervous system receives the

C BSE Science Self -Tutor-X

Motor Nerue

Carries the impulse from the centralnervous system to the effectors.

centralimpulse

Motor rlerve receivesfrom the motor areanervous svsf,em.

the irnpulseof the central

throuEh sensorv nerve.

{* e. LG. Which hormone helps in the d.euelopment of borues s.nd. muscles? Which endacrinzgland produees it?

Ans. Growth hormone prod.uced by the pituitary gland helps in the development of

bones and muscles.

Q. 17. Testes in males produce a hormane. Name it. What function does it perform?

Ans. Testosterone is produced by the testes in males. It helps in the formation of the

sperms. This hormone also iegulates the development and growth of a boy into an

adult. It brings about the development of new characters like beard.

# e. lB. What witl be the effect of low and, excess secretion of the growth hormone from th.e

pituitary gland?

Ans. When the growth hormone is secreted in low quantity in the childhood, the growth

will be retarded and chilil will grow into a dwarf, exhibiting dwarfisrn. When the

hormone is secreted in excess during childhood, the person u'ill grow into a giant.

exhibiting gigantisrn.

Q. 19. hfention, names of uarious plunt hormones.

Ans. Auxins, gibberellins, cytokinins and abscisic acid.

Q. 20. Define reflex action. Giue a suitable example.

Ans. A reflex action is a spontaneous, automatic, mechanical response to a stimulus. Itis brought by the sensory n€rves, from the receptors to the spinal cord, and then

carriefl by ,ooto" nerves, from the spinal cord to the effector organs. An example of

a reflex action is btrinking of eyes on exposure to bright light'

Q. 21. Narne the hormone secreted, by the th,yroid g'!,and. and th.e po'llcrects.

Ans. Hormone secreted by the thyroid gland is thyroxine. Fancreas secretes the hormone

insulin. i

q,. 22. Name the sense orgarus which perceiue changes in the enuironntent.

Ans. The sense organs are the internalear, the retina of the eye, nose lining, tongue and skin-

Q. 23. lWat is an axon? ExPlain.

Ans. Axon is the long fibre of the neuron. Through axon, the nerve impuise moves awa5i

from the cell Uoay. ffre impulse from the axon is passed to dendrites of the next

neuron through sYnaPSe.

e. 24" How d,o the horm"ones prod.uced. by the end,ocrine glaruds reaclt' the target organs?

Ans. Refer Q. 53 on Page B2.11.

Q. 25. What will be the sequetuce of th,e following d.uring a reflex act'ion:

(i\ Effector orgafL, (ii) Receptar organ, (iii) spinal cord,, (iu) senstsry nerue'

(u) Mator nerue anvd (ui) Stimulus.

Ans. Stimulus -)

Receptor organ --> Sensory nerve ----> Spina1 cordT

Motor nerr/eEffector: organ +_--

Con tro| and, C oordinat ion,

Q. 26" Giue ane word, for the following:(i) tsending of th.e shoot of a plant towards light.(ii) Atlouentent ol an ttquatic plant towrtrd,s water.

Ans. (i) Phototropism"(il) Hy,Jrotroprsm.

q". 27. What com,ponents are inualued in reflex action?Ans. The components involved in reflex action are:

(i) Sensorv receptors, (ij) Sensory nerves, (iii) Spinal cord, (iu) Motor nerves and(u) Effector organs like muscles and glands.

Q, 2E" \\\to,t constitutes peripheral neruous system?

Ans. Peripheral nervous system consists of cranialspinal nerves arising frorn the spmal cord"

nerves arlsing from the brain and

Q. 29. Do yow th,ink anintals need, orgarL systems to bring about q, corcect and, coord,irtated,mouentent in response to a stimulusT No,me the systerns inuoltted,.

Ans. Animals need organ systems to bring about the correct and coordinated movernentsin response to a stimulus. The two systems involved are:(i) Nervous systern and (ii) Muscular system.

Q. 30. How does the brain act'!

Ans" The hrain receives informatron from sensory receptors ttrrough sensory nerves andthe splnal cord" It already has pre'n ious information. Brain analyses the vaLrousinformation, decides and executes the decision through motor nervers by strmulatrng

. the concerned muscles or the glands.

* q. ,, " Is the rnuemen t shawn by the tend,ril sanle as tho,t showrr, by leaues of a touch-nte-n,ot

Q. 33"

plant?The movement shorvn by the tenctrii in response to the contact is slow anddirectional, whereas the movement shown by a touch-rne-not plant, cau.serl inl'esponse to touch, is very fast and non-directional"lhut q,re directianal mouements in plant, parts?The tropic movements or directionatr movuments caused by light, gravity. waterand cheuricals may be towards the stimulus, as shown by the stem rnoving towardslight or as showrr by the roots rnoving away from light but towards gravity. Thestem moves upwzrrds towards light but au,ay frorn gravity.Giuert belau.; is a lcr,belled, d,iagram of a, n earon,. Laak at the diagram and, a,n,swer th,e

followin g:{i) Wh,ere i,s in,formation acquired?{ii) How d,aes inforntation truuel as an el,eetric intpulse?(iii) I{aw th,e im.pu,l,se. posses from ane rleuran, to the next neuron?

82.r5

Aras"

6q.*r.Ans,

Nerve endings

82.16 CBSE Science Self'Tutot-X

Ans. (i) The information is acquired at the ends of the dendritic tips of the neuron-

(ii) The informatiou, &om the cyton (cellbody), travels through axon as an electric

rmpulse.(iii) The nerve endings of the axon pass the impulse to the dendritic tips of the nexl

ne\rron through sYnaPSe.

Q. 34. What are the functions of the cerebellum?

Ans" It is responsible for precision of voluntary actions and for maintaining the postrur

and balance ofthe bodY"

& e. Bd. How d,oes the thinhing part of the brairu receiue information and. send its ntessa,ge tr

effector cells?

Ans. Thinking part of the brain is connected by sensory nerves all over the body. Th'

information picked up by receptors is transmitted through sensory nerves to ththinking prri of the brain, where it is changed into a message and is sent back tthe effectors, through motor nerves.

Q. 36. wat is the second. pathway, other than the reflex arc, through which the neruou

systern cornmunicates with the rnuscles?

Ans. Brain facilitated by the peripheral nervoua system, consisting of cranial nerve

from the brain and spinal nerves from spinal cord, forms the second pathway t

communicate with muscles-

{b e. 87. How d.o the aisociation areas present in cerebrum af the forebrain function?

Ans. Association areas interpret the sensory information by putting all the informatior

received from various receptors and the information already stored in it. Afttrnterpretation, information is eent to the motor areas to make the muscles ar

accordingly"

e. 88. Wh,e.re are the areas for thinhing processes and motor resporuses located in the brair

Ans. The sensory regions or the thinking processes like sight, smell and hearing ar

present separatlly in the forebrain, i.e., inthe cerebrum. Separate areas, for motr

activities are also located in the cerebrum of the brain'

Q.gg. Which iruuoluntary actiuities are associated with the medulla oblongata of tl

^r". f;,-*q:l"i1r.* r.ur"rueat, hreathing process, salivation, vomiting and blood pressu

. are associated with the medulla oblongata of the hindbrain'

$ e. 4O. In what form d.oes th,e thinking tiss.ue in our bocly occur? Where is it situated. in t)

brain?

Ans. Thinking tissue in our body consists of a dense network of intricately arrangr

neurons- This tissue is present in front part of the brain. It receives informationsignals from all or"" th" body, through receptors. This region consists of tlsensory areas, associated areas and motor areas.

Q. 4tr; I{ow d,oes the sensory tissue (thinking tissue) recognise the signals from all partsthe body?

Ans. To receive the signals, the sensory tissue consisting of the sensory areas and tassociated areas, connect to various parts of the body by nerves which briinformation to it.

Control and Coordination B.2.r7

q.42"

Ans.

Q;43.Ans.

How does the sensory tissue or thinking tissue send, its message to m,uscles or gla,rLd,sta elicit a, response, which it interprets accord,ing to the sigials receiued.?The sensory tissue or thinking tissue sends its message through nerves to themuscles or glands, so that a proper response is given uy ttre organs. For example,when we take food in the mouth, the salivary glands

"ui"r." mo""e "alirra ";;;rldraises his hands to catch a ball in the air.

Do animal hormones cause d,irectional growth?Hormones in animals do not cause directional growth. But hormones bring aboutcontrolled growth of different parts of the body. Even in children, durin-g theirgrowth, the design of the body is carefully maintained.

Q' 44. Wy is endocrine system considered.the second. controlling and, coord,inating systemin our body?

Ans. The responses generated by the nerves produce electrical impulses which arelimited. A chemical signal in the form of hormones brings about widespread.changes all cells ofthe body receive the hormones. Therefor", th" endocrine systemis considered the second controlling and coordinating system in our body.

-

Q.L. DescrftetherW-{ns. A neuron is the structural and functional unit of the nervous system. Each neuron

is made up of three parts: (i) Cell body, (ir) Dend.rites, and (zzriAxon. It consists ofa cell body with small branches knows as dendrites and a long fibre the axon.The axon takes the nerve impulse away from the cell body and paJses it to the nextneuron through the synapse.

9.2. Wy is there a need for chentical communication?Ans. Electrical impulses generated in the nervous tissue are very fast, but their effect is

seen only in those cells which are connected to the nerves which are stimulated. So,response is in limited area. I\{oreover, second impulse cannot be generated as ittakes time for the nerve fibre to recover from the first impul.". C"ll* cannotgenerate electric impulse continuously. For widespread, Iong-tasting response,chemical communication is needed.

* t. l\'hy is it necessary that the hormones should be prod.uced, and. secreted, in precisequantity and only when required?

'frc. Energy is needed for the production of hormones, and for their secretion and theiractivity. They cannot be stored as they require space and energy. To avoid wastage ofenergy and to save space, the hormones should be produced in precise quantity andonly when needed by the body.

| * How does the brain resporud to the stimuli?'L' Brain responds to involuntary actions, reflex actions and voluntary actions. The

strmulus brings information, received through the peripheral nervous system by,the cranial nerves arising from the brain, and spinai r"ru" arising from ihe spinal;ord. The process of thinking, i.e., analysing starts after the information reaches'$.e respective centres of the brain. The difierent inputs and. outputs from thesecentres ofthe brain are integrated and a response is given accordingly.

CBSE Science Self'Tutor-X

q. S.)run"tion the d.ifferent types of receptors fou,nd in human body and the sensatiorus

they perceiue.

irs. The different types ofreceptors are:(i) Photoreceptors: Perceive light, e.g., eyes.

(ii) Phonoreceptors: Perceive sound waves. e.g.' eats'(iii) Olfactory receptors Perceive sense of smeIl, e.gl', nose'

(iu) Gustatory receptor"s.' Perceive sense of taste, e.g', tongue'(u) Skin: Sense ofhotness, coldness, pressure and touch'

Q. 6. Which are the two types of neruous systems operating in our body? Wich functionsdo they control and, coordinate?

Ans. Two types of nervous systems operating in our body are:

(i) Central neruous system: Central nervous system consists of brain and spinal

cord.. Brain controls and coordinates information from the receptors and

sends impulse to the effectors for action. Reflex actions are governed by the

spinal cord and the information is perceived by the brain'(ii) Peripheral neruous system: Peripheral nervous system consists of cranial

nerves arising from tle brain, and the spinatr nerves arising from the spinal

cord" Cra.nial nerves bring impulses to sensory centres in the brain and carry

the response from motor centre to the organ or eff"ectors concerned" Spinal

nerves conduct nerve inopulses to hring about reflex action'

ifferentiate behteen geottopisnt, an'd, ph,ototropism in' plants'

ototropi,sm

(,) It is a phenomenon brought about inthe direction oflight.

(,,)

(iii)

The stimulus is perceived bY thehormone auxins, present at shoot trps'

It causes the shoot to come uP above

the soil and bends the plant torn'ards

1i

Na.nte the parts of the hindbrain. Mention the functirsns perfornted by them,.

The hindbrain consists of the following parts:

(i) Cerebetl,unt: It,is situated on the posterior si.de of the forebrain. It controls the

voluntary actions with precisron iike maintaining the posture and baiance of

the body.(ii) Pons: It is present below the cerebellum and above the medulla ohlongata. [t

is the centre of controlling respiratory activities.(iii) Med.utla oblongato.; It is present below the pons" It controls involuntar-r

activities }i}.e vomiting, blood pressure and salivabion"

Nam.e the phenomenon, occut'ring irt, plants which are

u) d,ter an d ch,ent iculs.

Ph.ototropisrru; Bending of plants towards light.

under the control af li

Hyd,rotropisrn.' Movement of plant parts towards rvater as seen in aquatic planrs'

Chernotrapi.srn." Movement of plant parts in response to a chernical as seen

germinating pollen tube moving towards egg in the ovule of a flower"

lt is a phenomenon brought aboutas a response to gravitY.The stimulus is perceived bY theroot tips"

It makes the root to Penetrate thesoil"

Q. e.

Ans.

Ans.

Q. 10.

Ans.

t q. rr.Ans.

Control an d Coordination 82.19

How does cltendco,l contmunication occur in ntu,lticellular organisms?. On stimulation, the cells of the endocrine glands release the chemrcal substance,

Le.. hcirmone". Specific cells recognise a particular hormone. The hormone then diffuse rnto

these cells and into the rest of the body.. These chemical substances or horrnones, show- great diversity in their actions.

IIou: do attxins cause bendin.g of plunts toutards light?. Shoot apex produce, hormones known as auxins which help in the enlargement

of cells" Auxins rnove downwards in the shoot., When the plant is exposed to unilateral light, auxins diffuse from the lighted

side to the side of the stern which is not exposed to light.. On the darkened side of the shoot, cells elongate, whereas on the lighted side

elongation of cells does not occur, as no auxins are present" This makes theshoot bend towards light.

Mentiaru the functions of the folloui,n,g pl,ant horm.orues:

(i) Gibberellins, (ii) Cytokinins ond (iii) Abscisic acid,.

(i) Gibberel.lins : Promote grou,th of the stem.(ii) Cytokinins Promote cell divisron and are found in concentrated amounts

where active cell division is occurring, such as in youngfruits and seeds.

Since plants need to stop certain activities ofgrowth, abscisicacid is the hormone which inhibits growth. It also causes

(iii) Abscisic acid :

I e. ,r. How is the retease "r;::Xr,:r,)ir),lriro,

-{ns. The timing and the amount of hormone released are regulated by the feedbackmechanism. If more hormone is released, the information is picked up byrespective orBan which controls the release of hormone. Same mechanism occurswhen hormone is being released in less quantity.Excess of glucose * more insulin

-> Maintains glucose level in blood

fPancreas

J

Less glucose * less insulin --+ Maintains glucose level in blood

Q 14. IIow do muscles act?

-{.ns. The order or message given by the brain is finally executed by the muscles. Musclesare made up of muscle fibres. Each muscle fibre is made up of specific proteins(myosin and actin) which are arranged in a definite pattern. When the impulse

ff "eaches the muscles, the proteins change their shape and also their arrangement,

causing change in shape of the muscle fibre.(& 15. Are all mouements, in organisms, connected to growth? Wy do mouements, oth,er

than, growth, occur?

1)

B2.20 CBSE Science Self-Tutnr-)

Ans. AII movements are not connected to growth, like a cat running, a child cycling albuffaloes chewing cud. Such movements occur due to the following reasons:

. Movements occur in response to a change in environment.

. Movements in living organisms occur as they want to get benefit from thchanges occurring in the environment. For example, a plant grows towards thsun to get enough sunlight and buffaloes chew cud to break food into smallcparticles for better digestion.

. Organisms move away from dangerous situations to protect themselves.

Q. 16. Does spiructl cord, perfornt. only the reflex actions? What other function, inuoluing rtbrain, is carried out by the spinal cord,?

Ans. The spinal cord, besides performing reflex actions, also sends information to tisensory or the thinking area of the brain to bring a response. Thinking involrtcomplex mechanisms and neural connections which are present in the brain. Thuthe brain and spinal cord together help in the thinking process and form the cenErnervous system.

Q. 17. What is a reflex arc? How does i.t. fwnction?Ans. Reflex arc consists of a sensory nerve which carries information or input from O

receptors to the spinal cord. The speciai nerve cells interpret the information arsend the message for output through nerves to the effectors such as muscles el

- glands. The response isvery fastandwithoutevenrecognisingthe response we rarto the rnformational input. Simultaneously, the informational input is also sent I

, the brain. r

$ e. 18. What reactions occur in atl enlergency situation? How d,oes an organism cope u'ilthis situation?

Ans. In an emergency situation, the organism prepares itself for either running or frghtiqThese processes require a large amount of energy, which is released in a controllmanner. Fighting or running will require functions of many different types of tissrrin an integrated manner. To meet such energy requirements, the body releaseschemical signal which reaches to all the cells of the body, to get widespreeresponses. The chemical signal thus released is the hormone adrenali.ne producrby the adrenal glands.

Q.1. Describe an experiment to d,emonstrate that shoot grous toward.s light a.nd rdtowards grauity.

lm. , (i) T,ake a conical flask containing water(ii) Put a wire mesh over the flask and place 3 to 4 germinating seeds on tl

mesh.(iii) Place the flask in a cardboard box open on one side.(iu) Keep the experimental setup in such a way that the open side of the box fad

the light from the window, as shown in the figure.

Control and Coordination B2"21

Shoot (negatively geotropic)

Roots (positively geotropic)

Shoot grows towards light Rootrs grow towards gravity

Flg.2.,l(u) Keep the experimental setup for 3 to 4 days in the same position till the

germinating seeds produce small shoots.(ui) You will observe that the shoot has bent towards the light and roots have moved

downwards, ri.e., towards gravity.(uri) Now put the shoot horizontally in euch a way th.at the shoot is away from light

and the roots are faced towarde the light.(urzi) Observe after B to 4 days.(ir) You will observe that the shoot ie again moving towards light and roots are

moving towards gravity.(r) This shows that the shoot is poeitiveiy phototropic and negatively geotropic,

whereas the roots are negatively phototropie and positively geotropic.

ft e. 2. Explain the fottowing:How does insulin lower the blood, glucose leuel?

Why do body changes ocatr in boys and girls at puberty?How is the leuel of hormones maintained, in, the btood,?

l\hat is the best wajt of tahing iadine in the diet?IIow does pituitary gland, affect the growth of a chitd?Excess of glucose is controlled by insulin as it changes excess glucose intoglycogen.

Testosterone released by testes in h.oys and estrogen released by ovaries ingirls bring about body changes at puberty.If the amount of a hormone is more or less in the blood, the feedback mechanismmakes the gland secrete less or more hormone in the blood.Best way of taking iodine in the diet is in form of iodised salt.Pituitary gland produces the growth hormone which causes controlledgrowth. If the hormone is produced in less quantity in childhood, then thegrowth is retarded and the child grows into a dwarf and, if produced in large

" quantity, a child grows into a giant.

0 e 3. Make a Labelled, d,iagram of the reflex arc. Mention the salient features of the reflexaction.

(,)

(ii)(iii)(iu)

(u)

Ans" (r)

(ii)

(;ii)

(iu)

(u)

a

B,2.22 CBSE Sci.ence Self'Tutor-1

Ans. Spinal cord (CNS)

Relay neuron

Fig.2.5

Salient features of reflex action:r Reflexactionisanim.oluntary,suddenreqronsetoastimulusperceivedbythereceptmso Sensory nerve carr:ies the message from the receptors to the spinal cord.

o The *"..*g* is changed into a response in the spinal cord, which is sent through

the motor nerve to the effectors.o Effectors, i.e., muscles or glands show an involuntary response to the stimuluso Spinal cord sends information to the brain also'

Q.4. Mention fioe churacteristics of horm.on'es.

Ans. The five characteristics of hormones are:(i) They are pioduced by endocrine or ductless glands'

(ii) They are organic compounds of various types'(iii) Being specific in nature, they act on specific target organs or tissues.

(ju) They are produced in very minute quantities and are pour:ed directly into the

venous blood.(u) They bring about control and soordination of the botty activities such as growth

and develtlprrrent.

Draut an oatline of the hunran body and show the position of endocrine glan'ds in it-Q. 5.

Ans.Pineal gland

Hypothalamus

Pituitary gland

Thyroid gland

Kidney

Pancreas

Ovarv (in female)

Testis (in male)

Parathyroid glands

Adrenal gland

Control and Coordination 82.23

Q.6. What are plant hormones? Mention the functions regulated by them in the plants.Ans. Plant hormones are the chemical messengers of diverse nature, produced naturally

by the parts of the plant and they regulate many functions in plants, such as:. growth of roots, stem and leaves, and flowering in plants.o phototropism exhibited by the shoots and geotropism exhibited by the roots.. nastic movements and stomatal opening and closing.

Q. 7, Giuen below is a diagram of the brain of man. Labei the following parts in it:(i) Cerebrum, (ii) Cerebellum, (iii) Medulla oblongata, (iu) Pons, (u) Craniurn

(Skull), (ui) Midbrain, (uii) Hypothalamus, (uiii) Pituitary gland, (ix) Hindbrainand, (x) Forebrain.

Ans. Cranium(Skull)

Forebrain

Pituitary gland

Hind brain

What are receptors and effectors? Name three receptors which you haue studied endthe type of stimulus they perceiue.

Receptors: Receptors respond to specific stimuli and pass the information to thesensory nerves. They are cells present in the sensory organs like skin, eye, ear,tongue and nose.

Effectors: These are either muscles or glands which receive the informationbrought by motor neryes from the brain.The three receptors are:

(i) Photoreceptors: These respond to light.(ii) Gustatory receptors.'These respond to taste.

_ Qii) Olfactory receptors: These respond to smell.O g. 9. Mention the components of the central nen)ous system. List the general features of

the brain. Describe the parts of forebrain, midbrain and hindbrain.Ans. Components of the central neryous system are the brain and the spinal cord.

Brain:The brain is lodged and protected by a bony box called cranium, which is present inthe skull. The brain is lodged in the fluid filled space which provides shock absorption.

Q.8.

Ans.

1)

82.24 CBSE Sci,ence Self-Tutor-)

The fluid is known as cerebrospinal fluid. The brain is divided into three parts whiclare:

(i) Forebraln; It includes cerebrum and hypothalamus. Separate areas such afor hearing, smell, sight and many other activities, are present in th,forebrain, i.e., the cerebrum. Cerebrirm conslsts of sensory areas, associaterareas and motor areas. The separate areas,.i.e.,.association areas, whersensory information are brought to it, where it is analysis along with thinformation already stored in the brain. Based on these information,decision is made about the response which is the sent to the effective orgalike muscles of legs, organs, etc. Hypothalamus is a link between nervousystem and endocrine system.

(ii) Mid.brazn.' It consists of brainstem through which sensory and motor nerveenter and leave the cerebral hemispheres to provide information

(iii) Hinclbrain: Itconsists of cerebrum which is the centre of maintaining posturand balance of the body. Pons relays information from the spinal cord Ibrain to spinal cord and from spinal cord to brain" It relays information to thtwo lobes of concentration and medulla oblongata is the centre for regulatin"blood pressure, salivation vomiting, respiration, coughing and speaking.

Spinat Cord,:

(i) It is responsible for reflex actions.

, (ii) It sends sensory rnformation to the brain for analysis.

dbe. fO. How are inuoluntary actions a.nd, reflex actions different from each other?

Ans. Inuoluntary Actions Reflex Acti.ons

(i) Nerves from medulla oblongata fromcause these actions.

(li) Internal stimulus causes thegeneration of nerve impulse.

(iii) An involuntary action is governedby medulla oblongata, but we canfeel the response.

(lu) Speed of response is slow"

(u) Response is generated in thesmooth muscles of vrsceral organslike diaphragm during breathingand peristaltic movements in ihealimentary canal.

These actions occur through nervesthe spinal cord.

Stimulus from environment causesgeneration of nerve impulse rn thesense organ.

It is an involuntary action that occurwithout its acknowledgement.

Speed of the response is very fast.

Response is generated mostly bystriated muscles and glandspresent in the senrJe organs"

&e.rr.Ans. Any change in the environment is received by receptors present all over our bod

Receptors send the stimulus through nerves to the seat of that sensation, in tlthinkrng tissue or the sensory area. After receiving the information or input, tlthinking tissue interprets it and sends the message again through the nerves to tleffectors like muscles or glands. This takes encugh time which may be harmfulrhe person. If reflex action, such as wrthdrawing hand on touching a hot objetwere to operate through the thinkrng tissue" our hand may get burnt. Retlex actitoccurs spontaneously through the reflex arcs"

Wty reflex action does not depend on the thinlzing tr.ssue in the broin?

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C o ntr o L and, C o o r dina,tio n 82"25

Q. 12. W,at are the effects of adrenaline on our body organs, so Gs to nrcet tl"te emergen.cvsituo.tion?

Ans. Adrenaline is directly secreted into the blood stream. and then carried to differentparts of the body and regulates the effects.

' it acts on the various target organs such as heart, which beats faster to give moreoxygen to the muscles.

Q.r3.-{ns.

and the digestive system is reduced due to thethe small arteries in these organs.which is diverted to the skeletal muscles.

the diaphragm also contract, whrch cause the

about together to meet the emergency situation.

it occur in plants? Describe o,n actiui,ty t,t't

{2009}

4. 1. What is 'plvototropism'? How doesde mo n s trate photo tr o pris m, "

-{rrs. Refer ro Q. X on Pages BZ.ZO andBL.Zl"

-d5.

What is 'ltydratropisnt,'? Descri,be an, experintent

Referto Q. 10 on Page 82.4.

Wh,at a.re horntones? State one functrcns of each(i) Thyroxin (ii) In sulin.

. the blood supply to the skincontraction of muscles around

. More blood is made available,

. Rib muscles and muscles ofbreathing rate to increase.

All these responses are broughtDescribe the hu.man forebrain.The anterior part of the brain forms the forebrain and consists of cerebrurn andhypothalamus. Cerebrum is the largest part of the brain and is also the thinkingpart of the brarn. Forebrain receives sensory information or impulses from thedifferent receptors such as photoreceptors, phonoreceptors, olfactory receptors andgustatory receptors. There are separate sensory areas for these sensatrons.Forebrain also contains association areas where the sensory information is analysedby putting together the infbrmation received from clifferent receptors andinformation already stored in the forebrain. After analysis, the decision is madewhich is passed on to the motor areas for the response. These motor areas are alsopresent in thLe forebrain and control the movement of voluntary muscles" Forebrarnalso contarns sensory areas for sensations lihe hunger etc. Hypothalamus bnngsabout coordination between nervous system and end.ocrine system.

.f, to de ntonstro,te l't4t droiropisnt, ^

(2009)

of the following horntones:(2A09\

to coordinate{:s. Hormones are chemrcal messenger produced. by endocrine glandsfr-rnctions like growth, metabolism and reproduction rn animals.

{i) Th'ytoxin.: Thyroid gland produces thyroxine. It regulates the metabolism iifcarbohydrates, fats and proteins and provides best balance for growth.

(.ii') Insulin': Pancreas secretes insulin. Insulin maintarns giucose level rn theblood by changing excess glucose into glycogen. When rt is not secr.etecl insufficient amount, the person suffers frorn diatretes"

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