hkcee biology p1_sense organ

HKCEE Sense Organ (1982 – 2008)_ P. 1 1982

5 c) The diagrams below show the light rays are focused when two boys are looking at their own wrist watches.

A belongs to a boy with normal eyesight and B to the other boy with defective eyesight.

(i) Name the defect found in B. (1 mark)

(ii) Draw a diagram to illustrate how the vision of B may be corrected. (2 marks)

(iii) What changes occur in the eyes when the boys focus on a distant clock? (3 marks)

(iv) State and explain what happens to the pupil of the eye when a person steps out of a dark room into

bright daylight. (3 marks)

(v) State one advantage of the relax action in (iv). (1 mark)

Marking scheme:

5c)

(i) long sightendness/ ling-sight/hypermetropia ---------------------------------------------------------------------------- 1

(ii) correct shape of lens used (convex) ---------------------------------------------------------------------------------------1

correct light path (focused on retina) --------------------------------------------------------------------------------------1

(iii) ciliary muscles relax ----------------------------------------------------------------------------------------------------------1

suspensory ligament stretched/ increases in tension-----------------------------------------------------------------1

lens becomes flatten/ less convex/ less converging-------------------------------------------------------------------1

(iv) iris/ circular muscle (NOT radial muscles) -------------------------------------------------------------------------------1

contract----------------------------------------------------------------------------------------------------------------------------1

pupil constricts-------------------------------------------------------------------------------------------------------------------1

(v) protect retina/ eye from over stimulation/ bright light ------------------------------------------------------------------1

Marker’s report:

5c) (ii) In most cases the diagrammatic illustrations were poor. The light rays, in particular, were not properly

drawn. Some candidates even put the converging lens inside the eyeball.

(iii) Candidates were often confused with the functions of ciliary muscles and suspensory ligaments

(iv) It is the circular muscle and not the radial muscle of the iris which contracts to bring about the

contraiction of the pupil. Some candidates confused the two muscles while others confused the word

contract and constrct.

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5 (a) A young lady, with one of her eye covered, is using her uncovered normal eye to observe, at random nd

one at a time, the following objects within a period of eight seconds:

(W) a stationary objects nearby

(X) a stationary objects far away

(Y) an objects approaching her

(Z) an object moving away from her

The change in the curvature of the lens of the uncovered eye during these wigh seconds is shown in the sketch

below:

(i) Using the letters (W), (X), (Y) and (Z), indicate which object is being observed during the following periods:

(4 marks)

Periods Object is being observed

0 – 2 seconds

2 – 4 seconds

4 – 6 seconds

6 – 8 seconds

(ii) What is the state of the suspensory ligaments of the uncovered eye

(1) for observing object (W)? (1 mark)

(2) for observing object (X)? (1 mark)

(iii) Which structure, other than the suspensory ligament in the eye, is responsible for changing the

curvature of the lens? (1 mark)

(iv) Draw a simple diagram to show the path of the light rays when the eye was watching object (X).

(2 marks)


HKCEE Sense Organ (1982 – 2008)_ P. 3 (cont’d [85/5a])

Marking scheme:

5 (a)

(i)

Periods Object is being observed

0 – 2 seconds X ----------------------------------------------------------------------------- 1

2 – 4 seconds Y ----------------------------------------------------------------------------- 1

4 – 6 seconds Z ----------------------------------------------------------------------------- 1

6 – 8 seconds W ----------------------------------------------------------------------------- 1

(ii) (1) W – slackened/ relaxed state ----------------------------------------------------------------------------------------------- 1

(2) X – stretched/ tensed state (not contract) ------------------------------------------------------------------------------- 1

(iii) ciliary body/ ciliary muscles -------------------------------------------------------------------------------------------------------- 1

(iv)

Marker’s report:

5(a)

(ii) (2) The suspensory ligament cn only undergo change in tension, but many candidates wrongly regarded it as

undergoing contraction.

(iv) Some candidate did not draw parallel lines for the rays coming from a distant object; others did not put the

focal point on the retina.



4 (a) The diagram below shows a section of a human eye:

(i) If a person is watching a nearby object which is moving away from him, what change will occur in

the shape of structure A? (3 marks)

(ii) State the change in the size of B when the person walks out from a dark room into bright daylight.

What us the significance of this change? (2 marks)

(iii) Describe how the eye and the nervous system work together to bring about the reflex in (ii).

(4 marks)

(iv) How may a small object be seen by the person when its image falls on spot

(1) X?

(2) Y?

Briefly explain your answer. (4 marks)



Marking scheme:

4. (a) (i) the lens will become thinner / flatter / less convex -------------------------------------------------------1

ciliary muscle relaxes -------------------------------------------------------------------------------------------1

the tension in the suspensory ligament is increased thus pulling the lens thinner --------------1

(ii) the size of 5 deceases ------------------------------------------------------------------------------------------1

to reduce the amount of light entering the eye /

to prevent the eye from over-stimulation by light---------------------------------------------------------1

(iii) light stimulates the light-sensitive cells in the retina to produce nervous impulses -------------1

which are conducted by sensory nerve fibres / optic nerve -------------------------------------------1

to the brain / CNS ------------------------------------------------------------------------------------------------1

the nervous impulses transmitted to the iris through motor nerve fibres

causing the contraction of the (circular) muscles of the iris -------------------------------------------1

(iv) (1) when the image falls on X, the object can be seen ----------------------------------------------1

` clearly because X contains a large number of cones light sensitive cells ------------------1

(2) when the image falls on Y, the object cannot be seen -------------------------------------------1

because no light-sensitive cells are present at Y -------------------------------------------------1

Do not accept no image formed on Y

Total: 13 marks

Marker’s report:

Q.4 (a) The good performance on this part revealed that most candidates had a good understanding of the

functioning of the eye. The relatively poor performance on part (iii) suggests, however, that the

candidates were rather weak in the basic concepts of reflex action. Many of them could not point out

precisely that the receptors involved in the pupil reflex are the light-sensitive cells in effectors are the

muscles of the iris. For part (iv), some candidates wrongly called the light-sensitive cells in the retina

as optic cells.



5. (b)

In an experiment to study the sensitivity of different parts of the skin to touch, student X used a felt

pen to mark out an area on a certain part of the skin of student Y as shown in the diagram above.

While student Y was blindfolded, student X used a pin to touch gently every mark on the test region.

Student Y would say "yes" if he felt the touch. The percentage of positive responses (that is, when

student Y could feel the touch) was recorded. The experiment was then repeated on different regions

of the skin and the results are summarised as below :

Region of skin Percentage of positive responses

back of hand

palm of hand

fingertip

forearm

50

85

100

75

(i) Which of the tested regions was most sensitive to touch ? (1 mark)

(ii) Why was student Y unable to feel the touch of the pin on some occasions during the experiment

? (1 mark)

(iii) Describe the nervous pathway that enables student Y to feel the touch and to speak out.

(4 marks)

(iv) At one point during the experiment, student X carelessly applied a strong force on the pin and

student Y. withdrew his hand immediately.

(1) Name this type of response. (1 mark)

(2) This type of response usually occurs very rapidly. What is the significance of this

characteristic ? (1 mark)

(3) State ANOTHER characteristic of this type of response. (1 mark)


HKCEE Sense Organ (1982 – 2008)_ P. 7 (cont’d [90/5b])

Marking scheme:

5. (b) (i) fingertip ------------------------------------------------------------------------------------------------------------1

(ii) because the pin (stimulus) is not applied directly onto a touch receptor / nerve ending ------1

(or other reasonable answers)

(iii) touch receptor stimulated -------------------------------------------------------------------------------------1

nerve impulses pass along the sensory neurone -------------------------------------------------------1

and via the relay neurone / assoication neurone / intermediate nueorne

to the brain where the sensation of touch is produced ------------------------------------------------1

and then nerve impulses sent from the brain via the

motor neurone to the muscles responsible for speech ------------------------------------------------1

(N.B. accept flowchart)

(iv) (1) * reflex ------------------------------------------------------------------------------------------------------1

(2) avoid danger immediately / provide immediate protection -------------------------------------1

(3) inborn / learning not required )

involuntary / not controlled by will ) any ONE --------------------------------------------------1

stereotype / fixed response )

Total : 9 Marks

Marker’s report:

5. (b) (iii) While this part was well attempted, some candidates did not present a complete nervous

pathway to indicate the coordinating role of the brain in sensation and in voluntary action.



3 (b)

(i)A man came out of the cinema as shown in the diagram on the opposite page. Describe how his

eyes would adapt to the bright daylight. Explain why this would be necessary. (4 marks)

(ii) After looking at his watch, the man tried to locate the bus stop at the end of the street. Describe

and explain the changes that occurred in his eyes. (3 marks)

(iii) The man had an eye defect in which he was unable to see clearly the number painted on the

sign post of the bus stop. Draw a simple diagram to show the path of the light rays when his eye

was focusing on the number on the sign post. (2 marks)

(iv) The man tried to shield his eyes from the strong sunlight by putting his hand above his forehead

as shown in the diagram. Is this action reflex or voluntary ? (1 mark)



Marking scheme:

3. (b) (i) the iris muscle (circular muscle) contracts ----------------------------------------------------------------1

to reduce the size of the pupil -------------------------------------------------------------------------------1

to prevent too much light entering the eyeballs ---------------------------------------------------------1

to over stimulate / damage the retina ----------------------------------------------------------------------1

(ii) the ciliary muscle relaxed -------------------------------------------------------------------------------------1

increasing the tension on the suspensory ligaments ---------------------------------------------------1

the lens became less convex --------------------------------------------------------------------------------1

to enable it to focus on a far away object.

(iii)

------------------------------------------2

N.B. No lens, no mark

No arrows, deduct 1 mark

Light rays not reaching retina, deduct 1 mark

(iv) voluntary ----------------------------------------------------------------------------------------------------------1

Total : 10 marks

Marker’s report:

3. (b) (i) Some candidates confused the terms "iris" and "pupil". They failed to realize that the pupil is an

aperture or opening at the centre of the iris which is a circular muscular sheet at the front of the

eye ball. Also quite a few candidates confused the terms: "eye muscles", "ciliary muscles" and

"iris muscles" in their descriptions.

(ii) Many candidates did not realize that in the eye, the relaxation of the ciliary muscles would lead

to an increase in tension of the suspensory ligament. As a result the suspensory ligament would

become tightened or taut but it would not contract on its own.

(iii) Some candidates did not complete the ray diagram fully whilst others forgot to put in the arrows

to indicate the direction of the light rays all the way onto the retina.



1. (c) (ii) (1) A cloudy cornea can cause blindness. What treatment can be given to a man with such a

cornea to restore his vision ? (1 mark)

(2) Explain why only a small number of such patients can receive this treatment in Hong

Kong. (2 marks)

Marking scheme:

1. (c) (ii) (1) Cornea transplant ----------------------------------------------------------------------------------------1

(2) This treatment requires the donation of cornea form other people --------------------------1

Very few people are willing to do this after death ------------------------------------------------1

Total : 8 marks

Marker’s report:

1. (c) (i) This question asked for a concise account of the functioning of the semicircular canals in

detecting body movements. However, most answers did not show a mastery of the concept

involved and the description was often incomplete and incomprehensive. It should be noted that

the endolymph inside the semicircular canal does not actually move backward. As the head

moves forward, the endolymph lags behind due to inertia, i.e. it shows a backward movement

relative to the head. Many candidates did not point out that the sensory hair cells in the

semicircular canal are stimulated as a result of the relative movement of the endolymph.

(ii) Most candidates answered correctly that very few people were willing to donate their cornea

after death, so that only a small number of patients could receive this treatment in Hong Kong.

This shows that candidates have a good social awareness of the problems regarding this

treatment.



1. (c) A boy was standing by the roadside and saw a bus moving towards him. The photographs below

show what he saw when the bus was 10m and 5m away from him respectively :

Bus at 10 m away

Bus at 5 m away

(i) (1) What kind of eye defect did the boy probably have ? (1 mark)

(2) State two features of the eyeball that might have caused this eye defect.

(2 marks)

(ii) Draw a ray diagram to show the pathway of light entering the eye of the boy when he was

looking at the bus 10m away from him. (3 marks)

(iii) How could this eye defect be corrected ? (1 mark)

(iv) The boy had normal colour vision, but when it was getting dark, he found it difficult to distinguish

the colour of the cars on the road. Explain this briefly. (2 marks)


HKCEE Sense Organ (1982 – 2008)_ P. 12 (cont’d [96/1c])

Marking scheme:

1. (c) (i) (1) short sight--------------------------------------------------------------------------------------------------1

(2) The eyeball might be too long-------------------------------------------------------------------------1

The lens might be too thick-----------------------------------------------------------------------------1

(ii) Large, accurate diagram with smooth lines and parallel incident rays (D)------------------------1

Title --------------------------------------------------------------------------------------------------------------1/2

Presence of an arrow sign----------------------------------------------------------------------------------1/2

Focus in front of retina---------------------------------------------------------------------------------------1/2

Light rays continue to retina--------------------------------------------------------------------------------1/2

Path of light rays from the bus 10m away entering the boy's eye

(iii) Wear a concave lens / have an operation to decrease the curvature of the cornea------------1

(iv) Cones, which are responsible for colour vision,----------------------------------------------------------1

cannot function properly in dim light------------------------------------------------------------------------1

Total : 9 marks

Marker’s report:

1. (c) (i) Most candidates answered this part correctly.

(ii) The ray diagrams showed a number of mistakes which are also found in some local textbooks.

It is likely that some candidates might have memorised such errors from the textbooks without

genuine understanding. Some of the common mistakes made by the candidates are illustrated

in the following figures :

(1) (2) (3)

(1) The two parallel light rays come from different points on the object.

(2) The light rays stop after converging in front of the retina.

(3) The incident rays from the distant object are diverging instead of being nearly parallel.

The quality of drawing was rather poor; many drawings were too small, untidy and not in

proportion. Most candidates failed to give a title to their drawings.

(iv) Some answers were quite concise and accurate. Many candidates, however, confused the

functions of the rods and of the cones. For example, some stated that rods cannot detect colour but

failed to mention the role of the cones. A small number of candidates wrongly related the

phenomenon to night-blindness.



4. (a) The diagram below shows a boy, Bill, sitting for an examination in the school hall. Before the

examination started, Bill took off his glasses and relaxed.

(i) Bill looked at the clock on the wall. It was 9:00 a.m. Draw the image of the two hands of the

clock formed on the retina of his eye. (1 mark)

(ii) Describe how the image on the retina generates vision in the brain. (4 marks)

(iii) After looking at the clock, Bill turned to his watch to check the time. Describe the changes that

occurred in his eyes when he tried to focus on his watch. (3 marks)

(iv) Though Bill could clearly see the clock, he could not see his watch clearly without putting on his

glasses. Draw a ray diagram to show how his eye defect is corrected by his glasses.

(3 marks)



Marking scheme:

4. (a) (i)

.................................................................................................................................... 1

(ii) Light-sensitive cells on the retina were stimulated.................................................................1

Nerve impulses were set up...................................................................................................1

and transmitted along the optic nerve....................................................................................1

to the cerebral cortex for interpretation into vision.................................................................1

Effective Communication (C)..............................................................................................1

(iii) Ciliary muscles would contract...............................................................................................1

Suspensory ligaments would slacken....................................................................................1

Lens would become more convex..........................................................................................1

(iv) Convex lens )

Lens of the eye )

Nearby object (diverging rays) )

Converging rays )any 6.....................................................................3

Arrow sign )

Image on retina )

Title )

Path of light rays from a nearby object after correction

Total : 11 + 1 marks

Marker’s report:

Q4(a) (ii) Some candidates misinterpreted the question and described how the image was formed. Some had

the misconception that it was the image that was carried to the brain by the nerve. A great number of

the candidates did not mention the stimulation of the light-sensitive cells and the role of the cerebral

cortex for interpretation of the nerve impulses. Many inaccurate terms were used by the candidates,

such as ‘ receptors in the retina’, ‘ eye nerve’ or’ optical nerve’.

(iii) This part was well answered.

(iv) Most candidates drew the ray diagram correctly but the quality of the drawing was rater poor. Many

drawings were too small and not in proportion. Many drew a distorted eyeball, or omitted arrow signs

in the light rays. In addition, many did not give an appropriate title to their drawing. Some erroneously

drew two parallel lines for the light rays from the nearby object. Some mistook the person to be short-

sighted so they wrongly drew a concave lens in their diagram.



2 (b) An investigation was carried out to study the effect of light on the pupil of the eye. A person sat in a

room in which the light intensity could be varied. The size of the pupil of the person was measured at

different light intensities. The graph below shows the results of the investigation:

(i) Referring to the graph, describe the effect of light intensity on the size of the pupil. (2 marks)

(ii) Explain the significance of the change in pupil size in response to an increase in light intensity.

(2 marks)

(iii) The pupil response to light intensity is a reflex action coordinated by the brain. By means of a

flowchart, show the nervous pathway involved.

(Hint: This nervous pathway is similar to that of a spinal reflex arc.) (3 marks)

(iv) People have different eye colours, such as brown , blue or green, but their pupils always appear to be

black. Explain why the pupil always appears to be black. (2 marks)



Marking scheme:

2. (b) (i) From 1 to 5 units of light intensity, the size of pupil decreases

with increasing light intensity ----------------------------------------------------------------------------------1

However, when the light intensity is above 5 units,

The size of the pupil will remain unchanged with increasing light intensity -----------------------1

(ii) This response helps to prevent excessive light entering the eye ------------------------------------1

so that the light-sensitive cells of the retina may not be damaged ----------------------------------1

(iii) light-sensitive cells / photoreceptors sensory neurone / optic nerve

association neurone in brain motor neurone / nerve

iris muscle (1/2 marks for each term) -----------------------------------------------------------3

Deduct 1/2 mark if there is no arrow sign.

(iv) Because all the light entering the eye is absorbed by the retina and the choroid ---------------1

As a result no light is reflected out of the eye through the pupil -------------------------------------1

Total: 9 marks

Marker’s report:

2. (b) (i)Most candidates could describe the general relationship between the size of the pupi land light

intensity. However, many failed to point out that at relatively high light intensity, the size of the pupil

would remain unchanged with increasing light intensity.

(ii) This part was well answered.

(iii) Most candidates could draw a proper flowchart with arrows indicating the direction of transmission of

nerve impulses. Some candidates, however, wrongly showed that the pupil reflex was coordinated

by the spinal cord despite the question stating clearly that that this reflex is coordinated by the

brain. They might have thought that all reflexes involved the spinal cord.

(iv) This part was poorly answered. Although the question referred to an observation in everyday life,

most candidates could not state precisely that the choroids and the retina absorb all the light

entering the eye and consequently no light is reflected out of the eye thorough the pupil.



2. (a) The diagram below shows a section of the human eye:

(i) State one function of A. What feature of A contributes to this function? (1 mark)

(ii) A small object may form an image on spot B or C, and it will be perceived differently. What is the

difference in vision? Why is there such a difference? (2 marks)

(iii) After reading her book, a student tries to look at some words written on the blackboard. What would

be the change in structure D of her eye? Explain how this change is brought about. (3 marks)

(iv) The student finds that she cannot see the words on the blackboard clearly. Draw a ray diagram to

show the path of light rays entering her eye under such a condition. (3 marks)



Marking scheme:

2. (a) (i) To supply nutrients / oxygen to the eyeball --------------------------------------------------------

as it is richly supplied with blood / capillaries -----------------------------------------------------

OR any one set

To prevent reflection of light within the eye

--------------------------------------------------------

as it contains dark pigments

--------------------------------------------------------------------------

(ii) The image formed on C can be seen, while that formed on B cannot be seen ------------------1

because there are light-sensitive cells at C, but none at B --------------------------------------------1

(iii) Structure D would become thinner / less convex --------------------------------------------------------1

this is caused by the relaxation of the ciliary muscle ---------------------------------------------------1

which leads to an increase in tension in the suspensory ligaments ---------------------------------1

and, in turn, stretches the lensEffective communication (C) ---------------------------------------------------------------------------- 1

(iv) Drawing(D): large, clear and accurate diagram ----------------------------------------------------------1

(accuracy includes outline of eyeball, lens of eye, straight lines for light rays)

(L): Parallel rays from object (with arrow sigh), focus in front of retina,

rays extended to retina -----------------------------------------------------------------------------3* 1/2

Title(T) ------------------------------------------------------------------------------------------------------------1/2

Total:10+1 marks

Marker’s report:

2. (a) (i) This part was well answered.

(ii) Some candidates wrongly identified C as the yellow spot and stated that it contained many

cones. Some also confused image formation with image perception and they stated that no

image was formed at spot B. Some candidates used inaccurate terms to explain the difference

in vision, such as spot C contained sensory cells or sensitive cells instead of rods or light-

sensitive cells.

(iii) The performance on this part was generally good, and many answers were well written. Some

errors, however, occurred consistently among the weaker candidates, such as ‘suspensory

ligaments contract’ and ‘cilia muscle relaxes’.

(iv) Some candidates made large and clear drawings which showed accurately the outline of the

eyeball, the lens of the eye and the path of the rays. Again, many drawings did not have a

proper title.



3 (a) The diagram below shows a section of the human eye:

(i) Structure A has no blood capillaries.

(1) Why is the feature important to the formation of a clear image? (1 mark)

(2) From where does structure A obtain nutrients? (1 mark)

(ii) When a person steps out from a dark room into broad daylight, B becomes constricted.

(1) Explain the importance of this response. (2 marks)

(2) State the type of response illustrated by the constriction of B. (1 mark)

(3) The person also puts on his sunglasses. With regard to the nature of the response, state two ways in

which this action is different from the constriction of B. (2 marks)

(iii) In recent years, dark-coloured sunglasses are in fashion, but some of these sunglasses cannot cut

off ultra-violet light. Suggest why wearing such sunglasses under bright sunlight would be more

damaging to the eye than not wearing any sunglasses. (3 marks)


HKCEE Sense Organ (1982 – 2008)_ P. 20

(cont’d [03/3a])

Marking scheme:

3. (a) (i) (1) To allow the transmission of light to the retina without obstruction…………………….…...1

(2) aqueous humour / choroids ……………………………………………………………………..1

(ii) (1) It helps to reduce the amount of light entering the eyes……………………………………..1

so as to prevent over-stimulation / damage of the light-sensitive cells……………………..1

(2) reflex action ………………………………………………………………………………………1

(3)

Constriction of B Putting on sunglasses

cerebrum is not involved cerebrum is involved

stereotyped response i.e. same stimulus

always evokes the same response

Variable responses to the same stimulus

inborn Learned action

usually faster usually slower

ANY TWO 1,1

(ii) Dark-coloured sunglasses reduce the light intensity entering the eye………….1

So the pupil will not constrict / constrict to a smaller extent in bright sunlight………..1

As a result, more UV light can enter the eye and cause damage……………………….1

Effective communication (C)----------------------------------------------------------------------------------1

Total:10+1 marks



7. (a) The diagram below shows a section of a human eye :

(i) (1) Name structure A. (1 mark)..........................................................................................................................................................

(2) Structure A becomes weak in an old man. Explain how this will affect his eyesight when he looks at a nearby object. (4 marks)

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................(ii) Suggest one possible change of the lens which will also weaken the eyesight. (1 mark)

..........................................................................................................................................................

(iii) With reference to the function of layer C, explain why the falling off of layer B from layer C may cause blindness. (4 marks)

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................Total : 10 marks


HKCEE Sense Organ (1982 – 2008)_ P. 22

(cont’d [07/7a])

Marking scheme:

7. (a) (i) (1) * ciliary muscles 1

(2) When the man is looking at a near object, the weakened ciliary muscle

contract with less force

1

and the tension of the suspensory ligament remains high 1

Hence, the lens is not thick enough 1

and fails to converge light to form a clear image on the retina 1

Effective Communication (C) (1)

(ii) The lens becomes less elastic / cloudy 1

(iii) Layer B contains light sensitive cells 1

cannot obtain nutrients/ oxygen from layer C 1+

As a result, light sensitive cells die 1

Light falling on layer B cannot be detected / no nerve impulse can be

produced

1

Therefore the vision is impaired

Total: 10+1

Marker’s report::

Q.7 (a) The performance was good in general.

(i) (1) Most candidates could identify structure A correctly but misspelt the word

‘ciliary’. A few candidates took it as the suspensory ligament.

(2) Some candidates just recited the focusing mechanism of looking at a nearby

object by a normal person as the answer. They failed to address the question by

deducing the consequences of the weakening of structure A. Some failed to give

the precise description of the formation of image; they simply stated that the

image could not focused.

(ii) Well answered.

(iii) Many candidates only mentioned that layer C can absorb light to reduce reflection of

light inside the eyeball and missed out the function of providing nutrients and oxygen

to layer B. Some wrongly stated that image cannot be formed instead of not being

detected by the retina while some though that the image will be formed on layer C

after the detachment of layer B.


hkcee biology p1_sense organ

Documents

uncovered eye

retina eye

uncovered normal eye

marks iv state

eye covered

wigh seconds

object x

object w