Biology 5.1.5

Question 1

The Eye is a ___ Organ.

Answer 1

Sense.

Question 2

What are ‘Receptors’?

Answer 2

Receptors are Groups of Specialised Cells that can Generate an Electrical Impulse in a Sensory Neurone.

Question 3

The Eye contains 2 types of Receptor Cells. What are these, and what do they do? (2)

Answer 3

-Rod Cells: Sensitive to Light Intensity.

-Cone Cells: Sensitive to different Wavelengths of Visible Light (Colour).

Question 4

Where are the Rod & Cone Cells in the Eye Located?

Answer 4

Retina.

Question 5

What is the Function of the Cornea?

Answer 5

Transparent Lens that Refracts Light as it Enters the Eye.

Question 6

What is the Function of the Iris?

Answer 6

Controls how much Light Enters the Pupil.

Question 7

What is the Function of the Lens?

Answer 7

Transparent Disc that can Change Shape to Focus Light onto the Retina.

Question 8

What is the Function of the Retina?

Answer 8

Contains Light Receptor Cells- Rods, & Colour Detecting Cells- Cones.

Question 9

What is the Function of the Optic Nerve?

Answer 9

Sensory Neurone that Carries Impulses between the Eye & the Brain.

Question 10

What is the Function of the Pupil?

Answer 10

Hole that allows Light to Enter the Eye.

Question 11

Why does the ‘Pupil Reflex Action’ Occur?

Answer 11

To Protect the Retina from Damage in Bright Light, & Protect us from not Seeing Objects in Dim Light.

Question 12

The Pupil Reflex Action is Controlled by 2 Groups of Muscle. These are: (2)

Answer 12

-The Radial Muscle.

-The Circular Muscle.

Question 13

In Dim Light, the Pupils ___, in order to allow as much Light into the Eyes as possible.

Answer 13

Dilate.

Question 14

In Bright Light, the Pupils ___, in order to Prevent too much Light Entering the Eye & Damaging the Retina.

Answer 14

Constricts.

Question 15

What is ‘Accommodation’?

Answer 15

Accommodation is the Process of Changing the Shape of the Lens to Focus on Near or Distant Objects.

Question 16

To Focus on a Near Object: (3)

Answer 16

-The Ciliary Muscles Contract.

-The Suspensory Ligaments Loosen.

-The Lens is then Thicker, & Refracts Light Rays more Strongly.

Question 17

To Focus on a Distant Object: (3)

Answer 17

-The Ciliary Muscles Relax.

-The Suspensory Ligaments are Pulled Tight.

-The Lens is then Pulled Thin, & only Slightly Refracts Light Rays.

Question 18

What are 2 Common Defects of the Eyes? (2)

Answer 18

-Myopia: Short-Sightedness.

-Hyperopia: Long-Sightedness.

Question 19

How can we easily Treat Common Eye Defects?

Answer 19

With Glasses / Contact Lenses.

Question 20

What Happens if you have ‘Myopia’? (3)

Answer 20

-Lens is too Thick & Curved.

-Eyeball is too Elongated.

-Image is in Focus in Front of the Retina.

Question 21

What type of Lens can Correct Myopia?

Answer 21

Concave Lens.

Question 22

What Happens if you have ‘Hyperopia’? (3)

Answer 22

-Lens is too Thin & Not Curved enough.

-Eyeball is too Short.

-Image is in Focus Behind of the Retina.

Question 23

What Type of Lens can Correct Hyperopia?

Answer 23

Convex Lens.

Question 24

Explain how the Eye Detects Light: (5)

Answer 24

-Light Rays Pass Through the Transparent Front of the Eye. This is Called the ‘Cornea’. The job of the Cornea is to Start the Focussing of the Light Rays.

-The Light Rays then Pass Through the ‘Pupil’, in the Centre of the ‘Iris’. The Iris is the Coloured Part of the Eye.

-The Light Rays now Pass Through the ‘Lens’. The job of the Lens is to Focus the Light Rays Onto the Back of the Eye (the ‘Retina’). One Key Feature of the Lens is that it can Change its Shape, Allowing us to Focus on Distant or Near Objects (Accommodation).

-The Light Rays are now Focussed Onto the Back of the Eye, Called the ‘Retina’. The Retina Contains Receptor Cells for Light (‘Rod Cells’), & Receptor Cells for Colour (‘Cone Cells’).

-The Receptor Cells in the Retina now Send Electrical Impulses Down the Optic Nerve, to the Brain.

Question 25

What is the ‘Sclera’?

Answer 25

The White Part of the Eye. The Sclera is the Tough Outer Structure that Protects the Eye.