Selina Concise Class 10 Biology Chapter 11 Sense Organs Solutions
1) Solution:-
i) Ans: Eyelids protect the outer surface of the eyes and can shut out light.
ii) Ans: Eyelashes helps to prevent falling of larger particles into the eye.
iii) Ans: Tears are use to keep the front surface of eye clean by washing away dust particles.
iv) Ans: Iris consist of radial muscles which helps to widen the pupil and circular muscles to constrict the pupil.
v) Ans: Function of ciliary muscle is to change the focal length of the eye lens.
2) Ans: the correct sequence is as follows:
Conjunctiva – cornea – aqueoushumour – lens – vitreous humour.
3) Name the following:
i) Ans: Yellow spot is the place of best vision in the retina.
ii) Ans: Place of no vision in the retina is blind spot.
iii) Ans: Rods are sensitive to dim light.
iv) Ans: Pupil is the circular opening enclosed by iris.
v) Ans: Ciliary muscles collectively hold the lens in position.
vi) Ans: Capacity or the eye to focus on different distances is called as power of accommodation.
vii) Ans: Concave lenses are required to correct near sightedness.
viii) Ans: Retina corresponds to black lining of the box of a camera.
4) Solution:-
i) Ans: The medicines dropped into the eye glow down into the nose, because an nasolacrimal duct conducts the secretion into the nasal cavity.
ii) Ans: A person from bright sunlight outside enters a poorly lit room and feels blinded for a short while because when he standing in light, muscles of iris contract and the pupil constricts and hence less light can pass into the eye. Therefore for the duration when muscles are trying to adjust the eyes, he feels blinded.
Progress Check
Solution:-
1) Ans:
External ear |
Middle ear |
Internal ear |
Ear drum | Hammer | Cochlea |
Pinna | Anvil | Semi-circular canals |
Tympanum | Stirrup | |
Eustachian tube | ||
Oval window |
2) Solution:-
i) Ans: Semi circular canals are small tubes which are filled with the fluid which keeps the body balance.
ii) Ans: It transforms the vibration of the associated structures into neural signals.
iii) Ans: Auditory nerve helps in hearing process.
3) Solution:-
Ans: It is false statement because human ear is concerned with hearing as well as body balance.
ii) Ans: Given statement is false because auditory nerve directs sound waves towards tympanum.
Review Questions
a) MULTIPLE CHOICE TYPE Solution-
1) Ans: b) cornea
Cornea is the part of the eye is grafted in a needy patient from a donated eye.
2) Ans: b) Cochlea
Cochlea is the part of our eye which is shaped like a snail shell.
3) Ans: a)
Option(a) Cochlea, ear ossicles and tympanum are The three parts of the human ear contributing in hearing.
4) Ans: a) retina
Retina is the region in the eye where the rods and cones are located.
VERY SHORT ANSWER TYPE:
1) Solution:-
a) Ans: Rhodopsin is the photosensitive pigment which is present in the rods of the retina.
b) Ans: Eustachian tube equalises the air pressure in the middle and external ear.
c) Ans: The ear ossicle attached to the tympanum is hammer.
d) Ans: Eustachian tube connects the cavity of the middle ear with the throat.
f) Ans: Auditory nerves helps to transmit impulse from ear to the brain.
g) Ans: Photoreceptors found in the retina of the eye are cones and rods.
h) Ans: Hypermetropia is caused due to shortening of the eye ball from front to back.
2) Solution:-
a) Ans: Cones : Iodopsim:: Rods :Rhodopsin
b) Ans: Sound : Ear drum :: Dynamic balance : Semi-circular canals
3) Ans:
Column I |
Column II |
i) The blind spot | e) No sensory cell |
ii) yellow spot | d) maximum Sensory cells |
iii)Ciliary muscle | b) Shape of the lens.
|
iv)Iris | a) colour of the eye. |
v)Pupil | c)entering the eye entering the eye. |
SHORT ANSWER TYPE
1) Solution:-
a) Ans: The given statement is The correct statement should be, ‘Deafness is caused due to rupturing of tympanic membranei.e. ear drum.’
b) Ans: Given statement is The correct statement will be, ‘Semi-circular canals are concerned with dynamic balance.’
2)
a) Ans: The oval shaped yellow spot (macula) is located near the centre of the retina in human eye. Yellow spot helps to see the things with highest clarity.
b) Ans: The location of the lacrimal gland is within the orbit above the lateral end of the eye. The main function of lacrimal gland is to release fluid which protects the surface of the eye as well as it moistens the eye.
c) Ans: Organ of corti is located in the mammalian cochlea. Organ of corti is the receptor organ which helps in hearing process.
d) Ans: Semi-circular canal are the three smalltubes which are filled with fluids which are located in the inner ear. The main function of semi-circular canal is to keep body balance. It forms an ampulla which contains sensory cells for dynamic balance.
e) Ans: The location of the oval window is in the middle ear. It’s function is to settle the fluid in the cochlear canals into vibration.
f) Ans: Location of utriculus is in the inner ear. It maintains static balance of body and joins semi-circular canals to cochlea.
3) Solution:
a) Ans: Correct sequence is, Auditory canal, tympanum, ear ossicles, oval window, cochlea.
b) Ans: Correct sequence is, Conjunctiva, cornea, lens, retina, optic nerve.
4) Solution:
a) Ans: Cochlea helps to transmit impulses to the brain via auditory nerve.
b) Ans: Special functional activity of auditory nerve is to convey neuronal activity generated by cells in the hair to the specialised nucleus of the thalamus.
c) Ans: Special functional activity of the retina is to receive light which is focussed by the lens, convert that light into neural signals and send those signals to the brain to visualise image in front of the eye.
d) Ans: Special functional activity of choroid which is the part of middle ear is to bring oxygen and nutrients to the eye.
e) Ans: Sacculus containsa region of hair cells which send signals to the brain and concerns to the orientation of the brain.
5) Ans:
Structure |
Function |
Auditory nerve |
I) Transfers impulse from ear to brain. |
Ciliary muscle |
ii) Helps to change the focal length of eye lens. |
Semicircular canals | iii) Dynamic equilibrium |
6) Name the following.
a) Ans: Two pigments of sensory cells are rods and cones.
b) Ans: Two types of adaptations are,
i)Light adaptation ii) Dark adaptation
c) Ans: Two kinds of accommodations are,
i) Near accommodation & ii) Distant accommodation
d) Ans: Three layers of the eyeball are,
- Outer sclerotic
- Middle choroid
- Inner retina
7) Ans:
Cause
a) Lens turns opaque |
Eye defect
– Cataract |
b) Uneven curvature of the cornea – | Astigmatism |
c) Deficiency of vitamin A | – Dryeyes |
d) Lens losses it’s flexibility | Presbyopia |
e) Eye ball lengthens from front to back | – Myopia |
f) Lens becomes too flat | Hypermetropia |
D) DESCRIPTIVE TYPE
Solution:
a) Ans: Conjunctiva is the thin membrane covering the entire front part of the eye.
b) Ans: A particular spot lies at the back of the eye almost at the centre of the horizontal axis of the eyeball and contains maximum number of sensory cells is called as macula lutea.
c) Ans: When we pass from brightly lighted area to the dark room or vice versa we experience difficulty in seeing objects for short while. Slowly our vision is improved. This improvement is called as adaptation. There are two types of adaptations such as dark adaptation and light adaptation.
d) Ans: Ampulla is composition of nerve fibres which contains sensory cells for dynamic balance while the body is in motion and nerve fibres from them join the auditory nerve.
2) Differentiate between members of each of the following pairs with reference to what is asked in brackets.
a) Ans:
Myopia | Hyperopia |
Curved lens are used for correction of myopia. | Flat lens are used for correction of Hyperopia. |
b) Ans:
Rods | Cones |
Rods is the type of pigment which is sensitive to dim light. | Cones is the type of pigment which is sensitive to bright light. |
c) Ans:
Aqueous humour | Vitreous humour |
Aqueous humour is located in front chamber between cornea and lens. | Vitreous humour is located in between lens and retina. |
d) Ans:
Near accommodation | Distant accommodation |
In near accommodation, the shape of the lens used is more convex and rounded. | In distant accommodation, the shape of the lens is thinner or more flattened. |
e) Ans:
Dark adaptation | Light adaptation |
In dark adaptation there is regeneration of rhodopsin, the pigment of the rods. | In light adaptation, the visual purple of the rods is bleached. |
f) Ans:
Night blindness | Colour blindness |
Night blindness caused due to non-formation of the pigment visual purple of the rods and deficiency of vitamin A. | Colour blindness is caused mainly due to generic effect. |
Give reason:
a) Ans: a nasolacrimal duct conducts the secretion into the nasal cavity thus when medicines dropped into the eye come up to the nose and throat.
c) Ans: At the location of blind spot, there is no sensory cells and therefore it is considered as ‘area of no vision’.
4) Answer the following.
a) Ans: The process of focussing the eye to see objects at various positions and distances is called power of accommodation of the eye. Ciliary muscles are responsible for power of accommodation since it changes the focal length of eye lens.
b) Ans:Characteristics of the image that falls on the retina are as follows,
i) The image falls on the retina is real image.
ii) The image on retina is inverted in nature.
5) Ans: The mechanism is as follows, When we look at distant object, the lens will be more flattened or thinner. Ciliary muscles are use to change the shape of the lens. Normally ciliary muscles are relaxed and lens are stretched by suspensory ligament and as shown in fig. (a). But when we look at nearby objects, ciliary muscles are contract and lens becomes thicker, rounded and more convex as shown in fig. (b).
6) Ans: After looking at the bright object if we close our eyes, the sensation of light remains or persist for a short period of time which is known as persistence image or after image. This period lasts for one-tenth of the second. Therefore by closing the eyes and gently pressing them by our palms, we may see some specks of brilliant light.
7) Ans: The three bones which are collectively known as ear ossicles areMalleus (hammer), Incus (anvil) and Stapes (Stirrup). The ear ossicle named ‘stapes’ vibrates and transmits the vibration to the oval window. Whereas other two ear ossciles magnify the vibration of stapes as a result of their lever like action.
STRUCTURED/APPLICATION/SKILL TYPE
1) Soluition-
a) Ans: (1) Shape of the lens during near vision or near accommodation is more convex and rounded.
(2) Shape of the lens during distant vision or distant accommodation is more flattened or thinner.
b) Ans: The structures in the eye responsible for bringing about the change in the shape of the lens are,
Ciliary muscles
Suspensory ligament
c) Ans:(1) In the dark, the rod cells of the retina and their pigment rhodopsin get activated.
(2) Where in the light, cone cells of the retina with pigment iodopsin get activated.
2) Solution-
a) Ans: The inner ear has three parts as follows,
Cochlea – It is spiral shaped and looks like a snail shell.
Semi-circular canals – Arranged at right angles to each other in three different planes.
- Vestibule –It is the short stem joining the bases of semi-circular canals to the cochlea. Utriculus and sacculus collectively known as vestibule.
b) Ans:(1) Parts of the ear associated with static balance are utriculus and sacculus.
(2) Internal ear is the part of ear associated with hearing.
(3) Part of the ear associated with dynamic balance is semi-circular canal.
c) Ans: Auditory nerve transmits messages from the ear to the brain.
3)
a) Ans: Labelled guidelines in the fig. are as follows,
1 – Humour
2 – Lens
3 – Ciliary muscle
4 – Cornea
5 – Conjunctiva
6 –Sclera
7 –Choroid
8 – Retina
9 –
10 – Optic nerve
b) Ans: Part 3: Ciliary muscle – The role of ciliary muscle is to control accommodation for viewing objects.
Part 7 : Choroid –The role of choroid is to maintain temperature and volume of the eye.
d) Ans: Part 6 is sclera and part 8 is Retina. Retina is located at the back of the eyeball where sclera is tough outer coat layer of the eye. Retina converts light into neural signal and sent it to the brain whereas sclera covers the eyeball except cornea.
4) Solution:-
(a) Ans: The defect shown in given diagram is myopia.
(b) Ans: Reasons for the myopia are,
I) Eye lens becomes curved or convex.
ii) There is more depth of eyeball i.e. eyeball lengthens from front to back.
(c) Ans: Part 1 – Vitreous humour
Part 2 –Blind spot
Part 3 –Lens
Part 4 –Pupil
(d) Ans: To correct the eye defect like myopia, concave lens are used.
5) Ans:-
I) Ans: Given sense organ is ear.
ii) Ans: Part “m” is malleus, part “i” is incus and part “s” shows stapes. And three parts collectively called as ear ossicle.
iii) Ans: The part shown in the form of spiral is cochlea.
Cochlea transform the vibrations of fluid into neural signal and transfers it to the brain using auditory nerve.
iv) Ans: The part labelled as “tm” is tympanic membrane. In the process of hearing tympanic membrane vibrates and then sets the ear ossicles into vibration.
6) Ans:-
i) Ans: The collective biological term for malleus, incus and stapes is ‘Ear osscicle’.
ii) Ans: Part A –Cochlea
Part B –Semi-circular canals
Part C –Ear ossciles
iii) Ans: The function of part-A i.e. Cochlea is to transform the vibrations of the cochlean fluid into neural signal and transfer it to the brain using auditory nerve. The function of semi-circular canal is to form an ampulla which contains sensory cells for dynamic balance.
iv) Ans: Audio receptor region present in part-A is organ of corti.
v) Ans: Cochlea is responsible for static balance in human beings.
8)
a) Ans: A girl facing a problem of myopia.
b) Ans: The normal condition is shown in section A and section B is applicable to myopia.
c) Ans: She needs reading glasses with concave lens.
9)
a) Ans: Part 1–Pinna
Part 2 –Tympanic membrane
Part 3 –Auditory canal
Part 4 –Malleus and stapes
Part 5 –Semi-circular canal
Part 6 –Cochlea
Part 7 –Auditory nerves
Part 8 – Eustachian tube
b) Ans: The role of part 6- cochlea is to transform vibrations of the cochlean fluid into neural signal and send it to the brain though auditory nerve.
Part 7- auditory nerve is used for the purpose of hearing.
Part 8 –Eustachian tube is used to aerates middle war system and it clears mucous from the middle ear.
c) Ans: Sharp objects may burst the ear drum which leads to deafness. Therefore it is harmful to use sharp object to remove ear wax. Part involved in this process is
part 2 – tympanic membrane.
Here is your solution of Selina Concise Class 10 Biology Chapter 11 Sense Organs
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