SELINA Solutions for Class 10 Biology Chapter 11 - Sense Organs

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Chapter 11 - Sense Organs Exercise Ex. 1

Question A.1
Which part of the eye is grafted in a needy patient from a donated eye?

(a) Conjunctiva

(b) Cornea

(c) Choroid

(d) Ciliary muscles
Solution A.1
(b) Cornea
Question A.2
Which part of our ear is shaped like a snail shell?

(a) Semi-circular canals

(b) Cochlea

(c) Stapes

(d) Eustachian tube
Solution A.2
(b) Cochlea
Question A.3
The three parts of human ear contributing in hearing are:-

(a) Cochlea, ear ossicles and tympanum

(b) Semi-circular canals, utriculus and sacculus

(c) Eustachian tube, tympanum and utriculus

(d) Perilymph, ear ossicles and semi-circular canals
Solution A.3
(c) Eustachian tube, tympanum and utriculus
Question A.4
The region in the eye where the rods and cones are located is the

(a) Retina

(b) Cornea

(c) Choroid

(d) Sclera
Solution A.4
(a) Retina
Question B.1

Name the following:

(a) The photosensitive pigment present in the rods of the retina.

(b) The part which equalizes the air pressure in the middle and external ear.

(c) The ear ossicle attached to the tympanum.

(d) The tube which connects the cavity of the middle ear with the throat.

(e) The part of the eye responsible for its shape.

(f) The nerves which transmit impulse from ear to the brain.

(g) The photoreceptors found in the retina of the eye.

(h) The eye defect caused due to shortening of the eye ball from front to back.

Solution B.1

(a) Rhodopsin

(b) Eustachian tube

(c) Hammer

(d) Eustachian tube

(e) Cornea

(f) Auditory nerves

(g) Rods and cones

(h) Hypermetropia

Question B.2
Note the relationship between the first two words and suggest the suitable word/words for the fourth place.

(a) Cones: Iodopsin:: rods: ________.

(b) Sound: ear drum:: dynamic balance: __________.
Solution B.2
(a) Cones: Iodopsin:: rods: rhodopsin

(b) Sound: ear drum:: dynamic balance: semi-circular canals
Question B.3

Which one or more of the expressions in column II are appropriate for the items listed in column I? Match the correct pairs:

Column I 

Column II 

(i) The blind spot 

(a) colour of the eye 

(ii) The yellow spot 

(b) shape of the lens 

(iii) Ciliary muscle 

(c) amount of light entering the eye 

(iv) Iris 

(d) maximum sensory cells 

(v) Pupil 

(e) no sensory cells 

 

Solution B.3

Column I 

Column II 

(i) The blind spot 

(e) no sensory cells  

(ii) The yellow spot 

(d) maximum sensory cells 

(iii) Ciliary muscle 

(b) shape of the lens  

(iv) Iris 

(a) colour of the eye  

(v) Pupil 

(c) amount of light entering the eye 

 

Question C.1

State whether the following statements are true (T) or false (F). If false, correct it by changing any one single word.

(a) Deafness is caused due to rupturing of the pinna.(T/F)

(b) Semicircular canals are concerned with static (positional) balance. (T/F)

Solution C.1

(a) False

Correct statement: Deafness is caused due to rupturing of the eardrum.

(b) False

Correct statement: Semicircular canals are concerned with dynamic balance.

Question C.2

Where are the following located? State their main functions:

(a) Yellow spot

(b) Lacrimal gland

(c) Organ of Corti

(d) Semicircular canal

(e) Oval window

(f) Utriculus

Solution C.2

(a) Yellow spot lies at the back of the eye almost at the centre on the horizontal axis of the eyeball. It is the region of brightest vision and also of colour vision.

 

(b) Lacrimal glands are located at the upper sideward portion of the eye orbit. They pour the secretion in the form of tears which serves as a lubricant, antiseptic and even washes away dust particles from the eyes.

 

(c) Organ of Corti is present in the middle cochlear canal of the ear. It helps in hearing.

 

(d) Semicircular canals are located in the inner ear. These help in maintaining the dynamic equilibrium of the body.

 

(e) Oval window is located in the middle ear. It helps in setting the fluid in the cochlear canals into vibration.

 

(f) Utriculus is located in the inner ear. It joins the semi-circular canals to cochlea. It also helps in maintaining static balance of the body.

Question C.3

Given below are two sets (a) and (b) of five parts in each. Rewrite them in correct sequence.

(a) Cochlea, tympanum, auditory canal, ear ossicles, oval window

(b) Conjunctiva, retina, cornea, optic nerve, lens

Solution C.3

(a) Auditory canal, tympanum, ear ossicles, oval window, cochlea

(b) Conjunctiva, cornea, lens, retina, optic nerve

Question C.4

Given below are certain structures. Write against each their specific functional activity.

(a) Cochlea

(b) Auditory nerve

(c) Retina

(d) Choroid

(e) Sacculus

Solution C.4

(a) Cochlea: Cochlea contains organ of Corti which contains sensory cells for hearing. They transmit sound impulses to the brain through auditory nerve.

 

(b) Auditory nerve: It is the main nerve formed by nerve fibres arising from the sensory cells present in cochlea. This nerve carries sound impulses from inner ear to the brain.

 

(c) Retina: It is the innermost layer of eye which is sensitive to light. Retina forms the image of an object seen by the eyes.

 

(d) Choroid: It is middle vascular layer of the eyeball. Choroid provides nourishment to the eye.

 

(e) Sacculus: It is a part of semicircular canals of the inner ear. It contains sensory cells called macula which help in static balance of the body when it is a stationary position. 

Question C.5

Complete the following table by filling in the blank spaces.

Structure 

Function 

…………………………… 

Transfers impulse from inner ear to brain 

…………………………… 

Helps to change the focal length of the eye lens 

…………………………… 

Dynamic equilibrium 

 

Solution C.5

Structure 

Function 

Auditory nerve 

Transfers impulse from inner ear to brain 

Ciliary muscle 

Helps to change the focal length of the eye lens 

Semicircular canals 

Dynamic equilibrium 

 

Question C.6

Name the following:

(a) Two pigments of the sensory cells.

(b) Two types of adaptations.

(c) Two kinds of accommodations.

(d) Three layers of the eyeball.

Solution C.6

(a) Rhodopsin and iodopsin.

(b) Dark adaptation and light adaptation.

(c) Distant vision accommodation and near vision accommodation.

(d) Sclera, choroid and retina. 

Question C.7

Name the eye defects caused due to each of the following:

Cause

Eye defect

(a) Lens turns opaque

………………………..

(b) Uneven curvature of the cornea

………………………..

(c) Deficiency of vitamin A

………………………..

(d) Lens loses its flexibility

………………………..

(e) Eye ball lengthens from front to back

………………………..

(f) Lens becomes too flat

………………………..

 

Solution C.7

Cause

Eye defect

(a) Lens turns opaque

Cataract

(b) Uneven curvature of the cornea

Astigmatism

(c) Deficiency of vitamin A

Night blindness

(d) Lens loses its flexibility

Presbyopia

(e) Eye ball lengthens from front to back

Myopia

(f) Lens becomes too flat

Hyperopia

 

Question D.1

Define the following terms:

(a) Conjunctiva

(b) Macula lutea

(c) Adaptation

(d) Ampulla

Solution D.1

(a) Conjunctiva: A thin membrane covering the front part of the eye is called conjunctiva.

 

(b) Macula lutea: Macula lutea or yellow spot is a point in the centre of the retina where rods and cones are highly concentrated which offers brightest vision.

 

(c) Adaptation: Adaptation is the ability to adjust vision in bright and dark areas.

 

(d) Ampulla: Ampulla is the swollen wide part of each semicircular canal which contains sensory cells called cristae which help in dynamic equilibrium or dynamic balance of the body when it is motion. 

Question D.2

Differentiate between members of each of the following pairs with reference to what is asked in brackets.

(a) Myopia and hyperopia (type of lens used for correction)

(b) Rods and cones (sensitivity)

(c) Aqueous humour and vitreous humour (location)

(d) Near and distant accommodation (shape of lens)

(e) Dark and light adaptation (pigments which will be regenerated)

(f) Night blindness and colour blindness (sensory cells which cannot function properly)

Solution D.2

(a) Differences between myopia and hyperopia (type of lens used for correction):

Myopia

Hyperopia

Myopia can be corrected by suitable concave (diverging) lens.

Hyperopia can be corrected by suitable convex (converging) lens.

 

(b) Differences between rods and cones (sensitivity):

Rods

Cones

Rods are sensitive to dim light but do not respond to colour.

Cones are sensitive to bright light and are responsible for colour vision.

 

(c) Differences between aqueous humour and vitreous humour (location):

Aqueous humour

Vitreous humour

Aqueous humour is the front chamber between the lens and the cornea.

Vitreous humour is larger cavity of the eyeball behind the lens.

 

(d) Differences between near and distant accommodation (shape of lens):

Near accommodation

Distant accommodation

For near accommodation, the lens becomes more convex or rounded.

For distant accommodation, the lens is more flattened or thinner.

 

(e) Differences between dark and light adaptation (pigments which will be regenerated):

Dark adaptation

Light adaptation

For dark adaptation, visual purple or rhodopsin pigment will be regenerated.

For light adaptation, visual violet or iodopsin pigment will be regenerated.

 

(f) Differences between night blindness and colour blindness (sensory cells which cannot function properly):

Night blindness

Colour blindness

In night blindness, the rod cells cannot function properly.

In colour blindness, the cone cells cannot function properly.

 

Question D.3

Give reason:

(a) Sometimes medicines dropped into the eyes come into the nose and even throat.

(b) Three small bones of ear ossicles are advantageous as compared to one single bone for hearing.

(c) Blind spot is considered as 'area of no vision'.

Solution D.3

(a) Sometimes medicines dropped into the eyes come into the nose and even throat because the nasolacrimal duct conducts the secretion into the nasal cavity.

 

(b) Three small bones of ear ossicles transmit the vibrations received by the tympanum and amplify them. If these were replaced by a single bone, the vibrations received by the tympanum would not be amplified. Hence, three small bones of ear ossicles are advantageous as compared to one single bone for hearing.

 

(c) There are no sensory cells in the blind spot and therefore, this is considered as 'area of no vision' and image striking it cannot be perceived.

Question D.4

Answer the following:

(a) What is meant by power of accommodation of the eye? Name the muscles of the eye responsible for the same.

(b) Mention the characteristics of the image that falls on the retina of the eye.

Solution D.4

(a) The process of focusing the eye at different distances is called the power of accommodation. The ciliary muscles are responsible for the power of accommodation.

 

(b) The image formed on the retina is inverted and real.

Question D.5

Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.

Solution D.5

While reading a book, the lens is more convex or rounded due to contraction of ciliary muscles because the book is usually read from a short distance. When we raise our head and look at a distant object, the ciliary muscles relax to build the tension on the suspensory ligament so that they can stretch the lens. This change in the curvature of the lens makes us focus on distant object.

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

Question D.6

By closing the eyes and gently pressing them with your palms, you may see some specs of brilliant light. How do you get this sensation while there is no light entering your eyes?

Solution D.6

If we look at a bright object and then close our eyes, the sensation of light persists for a short period. This is known as persistence image or the after image. It lasts for one-tenth of a second. Therefore by closing the eyes and gently pressing them with your palms, you see some specs of brilliant light.

Question D.7
Name the three ear ossicles. How do they contribute in the mechanism of hearing?
Solution D.7
The three ear ossicles are: Malleus (hammer), Incus (anvil) and Stapes (stirr up).

The last ear ossicle, stapes, vibrates and transmits the vibration to the oval window.

The role of other two ear ossicles is to magnify the vibration of stapes as a result of their lever like action.
Question E.1

With reference to the functioning of the eye, answer the questions that follow:

a. What is the shape of the lens during (1) near vision (2) distant?

b. Name the two structures in the eye responsible for bringing about the change in the shape of the lens.

c. Name the cells of the retina and their respective pigments which get activated (1) in the dark and (2) in the light.

Solution E.1

a. Shape of the eye:

 Near vision - flattened

 Distant - rounded or more convex

 

b. Ciliary muscles and suspensory ligament

 

c. In the dark: Cells - rod cells, Pigment - rhodopsin

In the light: Cells - cone cells, Pigment - iodopsin

Question E.2

With reference to the human ear, answer the questions that follow:

a. Given the technical term for the structure found in the inner ear.

b. Name the part of the ear associated with (1) static balance (2) hearing (3) dynamic balance.

c. Name the nerve, which transmits messages from the ear to the brain.

Solution E.2

a. The middle ear or membranous labyrinth has two structures inside it, the cochlea and the semi-circular canals.

b. Static balance - Utriculus and sacculus (inner ear)

Hearing - Internal ear

Dynamic balance - Semi-circular canals (inner ear)

c. Collectively they are termed as ossicles.

Question E.3

The figure given below refers to the vertical section of the eye of a mammal. Study the figure carefully and answer the following questions.

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs 

(a) Label the guidelines shown as 1 to 10.

(b) Write one important role of parts shown as 3 and 7.

(c) Write one structural difference between the parts shown as 9 and 10.

(d) Mention one functional difference between the parts shown as 6 and 8.

Solution E.3

(a) 1 - Aqueous chamber, 2 - Lens, 3 - Iris, 4 - Cornea, 5 - Conjunctiva, 6 - Sclera, 7 - Choroid, 8 - Retina, 9 - Yellow spot, 10 - Optic nerve (Blind spot)

 

(b) Part 3 (Iris) - It contains radial muscles to dilate the pupil and circular muscles to constrict the pupil.

Part 7 (Choroid) - It is the middle layer of the eyeball, richly supplied with blood vessels and provides nourishment to the eye.

 

(c) Part 9 (yellow spot) contains sensory cells especially the cone cells while part 10 (blind sport) contains no sensory cells.

 

(d) Part 6 (sclera) gives shape to the eyeball and part 8 (retina) acts as screen to form image of an object. 

Question E.4

Given below is a diagram depicting a defect of the human eye? Study the same and answer the questions that follow:

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

(a) Name the defect shown in the diagram.

(b) Give two possible reasons for this defect.

(c) Name the parts labeled 1 to 4.

(d) Name the type of lens used to correct this eye defect.

(e) Draw a labeled diagram to show how the above mentioned defect is rectified using the lens named above.

Solution E.4

(a) Myopia

(b) The two possible reasons for myopia are either the eye ball is lengthened from front to back or the lens is too curved.

(c) 1 - vitreous humour, 2 - blind spot, 3-lens, 4-pupil

(d) Concave lens

(e)

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

Question E.5

The figure below is the sectional view of a part of the skull showing a sense organ:

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs(i) Name the sense organ.

(ii) What are the parts labeled 'm', 'i' and 's'? What do these parts constitute collectively?

(iii) What do you call the part shown in the form of a spiral? What is its function?

(iv) Name the part labeled 'tm'. What is its function?

Solution E.5

(i) Ear

(ii) m - malleus, i - incus and s - stapes respectively. These are collectively called as ear ossicles.

(iii) Cochlea. The vibrating movements in the hair of the sense cells of cochlea transmit the impulse for hearing to the brain via auditory nerve.

(iv) Tympanic membrane. It vibrates and then sets the ear ossicles into vibration in the process of hearing.

Question E.6

Given below is a diagram of a part of the human ear. Study the same and answer the questions that follow:

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

(i) Give the collective biological term for Malleus, Incus and Stapes.

(ii) Name the parts labeled A, B and C in the diagram.

(iii) State the functions of the parts labeled 'A' and 'B'.

(iv) Name the audio receptor region present in the part labeled 'A'.

Solution E.6

(i) Ear ossicles

(ii) A - Cochlea, B - Semicircular canals, C - Ear ossicles

(iii) Cochlea helps in transmitting impulses to the brain via the auditory nerve. Semicircular canals help in maintaining dynamic equilibrium of the body.

(iv) Organ of Corti

Question E.7

Draw a labeled diagram of the inner ear. Name the part of the inner ear that is responsible for static balance in human beings.

Solution E.7

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs 

 

Utriculus and Sacculus are responsible for maintaining static balance in human beings.

Question E.8

Have a look at the posture of this woman who is reading a book and answer the questions which follow:

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs

(a) What problem is she facing? Name the problem.

(b) What are the two conditions shown in sections A and B of the eye as applicable to her?

(c) What kind of looking glasses she needs?

Solution E.8

(a) Myopia

(b) A-Normal eye, B-Myopia

(c) Looking glasses with the concave lens are required here.

Question E.9

The figure given below shows the principal parts of a human ear. Study the diagram and answer the following questions.

Selina Solutions Icse Class 10 Biology Chapter - Sense Organs 

(a) Label the parts 1 to 8.

(b) State the role of parts 6, 7 and 8.

(c) Why is it harmful to use a sharp object to remove ear wax? Mention the number and name of the part involved.

Solution E.9

(a) 1 - External ear (pinna), 2 - Ear drum (tympanum), 3 - Auditory canal, 4 - Malleus, 5 - Semicircular canals, 6 - Cochlea, 7 - Auditory nerve, 8 - Eustachian tube.

 

(b) Part 6 (Cochlea) - It contains sensory cells for hearing.

Part 7 (Auditory nerve) - It transmits impulse of hearing to the brain.

Part 8 (Eustachian tube) - It equalizes air pressure on both the sides of the tympanum.

 

(c) It is harmful to use a sharp object to remove ear wax as it can rupture the ear drum.

The part involved is part 2 - Ear drum (tympanum).