Get premium membership and access questions with answers, video lessons as well as revision papers.
-Conjunctiva is thin/transparent/tough to allow light to pass through/to protect the eye.
-Sclerotic layer is made up of (collagen) fibers/fibrous. It maintains shape of the eyeball/protects the eye.
-Cornea is transparent/curved thus refracts light rays/allows light to pass through.
-Choroid is a layer of tissue with black pigment/dark pigment. Prevents internal reflection of light in the eye/contains blood vessels that supply oxygen/nutrients/remove (metabolic) wastes from the eye.
-Retina has cones/rods for bright colour vision/low light vision.
-Yellow spot has a high concentration of cones for accurate vision/visual acuity.
-Blind spot has no cones and rods. Place where optic nerve leaves/enters the eye optic nerve has (sensory) nerve fibers for transmission of impulses to the brain (for interpretation).
-Lens is biconvex/made up of elastic material/transparent. Adjust focus on far or near objects allow light to pass through/for refraction of light rays.
-Ciliary body is made up of muscle fibers glandular which contract/relax to change shape.
-Suspensory ligaments are inelastic to hold lens in position/attach it to ciliary body.
-Iris(is the coloured part of the eye it) has radial and circular muscles which control size of pupil.
-Pupil is the small hole at the centre of iris through which light passes into the eye.
-Aqueous humor is a fluid through which oxygen/nutrients pass to the cornea/lens/maintains shape of the eyeball/refracts light rays.
-Vitreous humor is a fluid which maintains shape of eye/refracts light rays.
OR
How is the human eyeball adapted to its function?
Sclera/sclerotic layer; white fibrous layer; made up of thick connective tissue; protects the eye; maintains shape of eyeball; Cornea; transparent; disc-shaped layer; that allows light to enter the eye; refracts light towards the retina; Conjunctiva; delicate membrane; lining the inside of the eyelid; protects the cornea/eye; Eyelids and eye lashes; thin muscle with hairs; protects the cornea/eye from mechanical/chemical damage/protects the eye from entry of foreign particles; protects retina from bright light; Choroid; dark pigmented and membranous layer; that prevents light reflection within the eye/absorbs light; to prevent distortion of the image; has blood vessels; that nourish eye/retina/supply oxygen/remove carbon (IV) oxide and wastes; extends to form the ciliary body and iris; Ciliary muscles; have elastic muscles that contract and relax; to alter shape/curvature of lens during accommodation; Ciliary body; thickened front edge of the choroids layer; that produces aqueous humour; Suspensory ligaments; made up of elastic connective tissue whose contraction and relaxation helps to adjust the shape of lens during accommodation/holds lens in position; Lens; transparent; biconvex; balloon-like; it refracts light rays/focus light onto the retina; Vitreous humour; nourishes cornea/lens; refraction of light; maintains eyeball shape; Iris; thin circular ring; with circular and radial muscles; it gives eye colour/absorbs light; controls the amount of light entering the eye/adjusts size of pupil; Pupil; an aperture through which light enters the eye; Retina; has photoreceptor cells/rods/cones for image formation; generates impulses to the brain for interpretation; Fovea/Yellow spot; with only cones; for high visual acuity/most sensitive part of the retina Blind spot; point where nerve fibres emerge from the optic nerve/where optic nerve leaves eye/point where nerve fibres and blood vessels enter the eye; Optic nerve; transmits impulses to the brain; Muscles; inferior and superior oblique muscles; move eye from left to right; superior and inferior rectus muscles; move the eye up and down; external and internal rectus muscles steady the eye in its up and down movement; Tear/Lachrymal glands; secrete a watery and saline fluid containing lysozymes/lytic enzymes/is antiseptic (tears); that moisten the conjunctiva and cornea; washes away dust and other foreign objects; kills microorganisms entering the eye.
Anganifelix answered the question on April 18, 2018 at 11:08
- List the special sense organs in mammals and the major function of each. (Solved)
Major sense organs in mammals and functions, biology form four questions.
Date posted: April 18, 2018. Answers (1)
- State the general effects of drug abuse on human health (Solved)
State the general effects of drug abuse on human health.
Date posted: April 18, 2018. Answers (1)
- Define the following terms. (i) Drug (ii) Drug abuse (b) State the types of drugs, examples and side effects(Solved)
Define the following terms. (i) Drug (ii) Drug abuse (b) State the types of drugs, examples and side effects.
Date posted: April 18, 2018. Answers (1)
- Give the differences between nervous and endocrine (hormonal) communication(Solved)
Give the differences between nervous and endocrine (hormonal) communication.
Date posted: April 18, 2018. Answers (1)
- Name the main endocrine glands, their secretions and functions in human body(Solved)
Name the main endocrine glands, their secretions and functions in human body.
Date posted: April 18, 2018. Answers (1)
- What are endocrine glands?(Solved)
What are endocrine glands?
Date posted: April 18, 2018. Answers (1)
- What are the functions of a synapse?(Solved)
What are the functions of a synapse?
Date posted: April 18, 2018. Answers (1)
- Briefly describe the transmission of a nervous impulse across a neuro-muscular junction(Solved)
Briefly describe the transmission of a nervous impulse across a neuro-muscular junction.
Date posted: April 18, 2018. Answers (1)
- Describe a reflex action that will lead to the withdrawal of a hand from a hot object(Solved)
Describe a reflex action that will lead to the withdrawal of a hand from a hot object.
Date posted: April 18, 2018. Answers (1)
- Biology Revision Question(Solved)
0(a)Describe how the floral parts of named flower are adapted to wind pollination.
(b)Explain how each of the following in animals affect reproduction process.
(i) territoriality
(ii) display
(ii) Seasonal migration
Date posted: April 18, 2018. Answers (1)
- Explain how an impulse is transmitted across the synapse (gap)(Solved)
Explain how an impulse is transmitted across the synapse (gap).
Date posted: April 18, 2018. Answers (1)
- What is reflex action? (Solved)
What is reflex action?
Date posted: April 18, 2018. Answers (1)
- State the functions of the major parts of the human brain. (Solved)
Functions of major parts of the human brain, biology form four
Date posted: April 18, 2018. Answers (1)
- Describe the structure and function of a relay neurone(Solved)
Describe the structure and function of a relay neuron.
Date posted: April 18, 2018. Answers (1)
- State the structural differences between motor and sensory neurons (Solved)
State the structural differences between motor and sensory neurons
Date posted: April 18, 2018. Answers (1)
- Name the parts of a typical neuron and state the functions of each part.(Solved)
Typical parts of a neuron and their functions.
Date posted: April 18, 2018. Answers (1)
- What is a neuron? (Solved)
Neurone definition, biology form four
Date posted: April 18, 2018. Answers (1)
- State the differences between somatic and autonomic systems of peripheral nervous system(Solved)
State the differences between somatic and autonomic systems of peripheral nervous system
Date posted: April 17, 2018. Answers (1)
- What is etiolation?(Solved)
What is etiolation?
Date posted: April 17, 2018. Answers (1)
- How has industrial melanism i.e. peppered moth contributed towards the mechanism of evolution? (Solved)
How has industrial melanism i.e. peppered moth contributed towards the mechanism of evolution?
Date posted: April 17, 2018. Answers (1)