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Q1. Name the two parts of the human body which are connected to each other through the Eustachian tube.  

Solution

The cavities of the middle ear and the pharynx are connected to each other through the Eustachian tube.  

Q2. What is corpora quadrigemina?

Solution

Corpora quadrigemina is the collection of four round lobes which represent the dorsal portion of the midbrain.

Q3. Name the gap which exists between pre-synaptic and post-synaptic neurons.

Solution

Synaptic cleft

Q4. Name the pigment present in the photopigments.

Solution

Opsin

Q5. Draw a well-labelled diagram to explain the transmission of the nerve impulse at a synapse.

Solution

Transmission of nerve impulse at synapse:  

Q6. Eyes are the most important sense organs in animals without which it would have been difficult to experience the beauty of life.

Name the photoreceptor cells and their pigments present in the retina.

Name the compounds present in the photopigments.

State the functions of rods and cones.

What values do you learn from questions (a) and (c)?

Solution

Cones and rods. Iodopsin is present in cone cells, and rhodopsin is present in rid cells.

Opsin and retinal are present in photopigments.

Rod cells are responsible for coloured and daylight vision, while cones are responsible for twilight vision.

In team work, to achieve success in any task, synchronisation in the work of team members is of utmost importance.

Q7. Name the two photoreceptor cells present in the eye.

Solution

Rods and cones

Q8. Differentiate between aqueous chamber and vitreous chamber.

Solution

Aqueous Chamber Vitreous Chamber

It is the space between the cornea and the lens.

It is the space between the lens and the retina.

It is filled with a fluid called the aqueous humour.

It is filled with the vitreous humour.

 

Q9. Name the visible coloured portion of the eye.

Solution

Iris

Q10. Name the three cells present in the retina of the eye.  

Solution

Three cells present in the retina of the eye are ganglion cells, bipolar cells and photoreceptor cells.  

Q11. Describe the structure of a neuron.

Solution

Structure of neuron: Neuron is composed of cell body, dendrites and axon. The cell body contains cytoplasm. The cytoplasm consists of Nissl’s granules which are also present in dendrites. Dendrites are the short cytoplasmic branches given out by the cell body. Dendrites carry nerve impulse towards the cell body. Axon is the longest process given out by the cell body. In case of myelinated neuron, axon is covered with a myelinated sheath formed by Schwann cells. The gap between the two adjacent myelinated regions is called Node of Ranvier. The distal end of the axon called axon-terminal has bulb like structures call synaptic knobs which contain neurotransmitters.

Q12. What are nodes of Ranvier?

Solution

Nodes of Ranvier are the gaps present between the two adjacent myelinated sheaths of the myelinated nerve fibres.

Q13. Apart from the skull, name the covering which protects the brain. Write the names of the three layers which form this protective covering.  

Solution

Cranial meninges.     It is made of the following three layers:    

Outer dura mater  

Middle arachnoid  

Inner pia mater  

Q14. State the function of the crista ampullaris and the macula.  

Solution

The crista ampullaris and the macula are responsible for maintaining body balance and posture.  

Q15. State the three types of neurons on the basis of number of axons and dendrites present. Also, state the number of axons and dendrites present and their location in the neural system.

Solution

The three types of neurons on the basis of number of axons and dendrites are

Multi-polar neuron

Bipolar neuron

Unipolar neuron

Multi-polar neuron: It has one axon and two or more dendrites. It is found in the cerebral cortex.

Bipolar neuron:It has one axon and one dendrite. It is found in the retina of the eye.

Unipolar neuron: It has a cell body with only one axon. It is found during embryonic development.

Q16. Draw a labelled diagram of a neuron.

Solution

Neuron:  

Q17. Define coordination in living organisms. Why is it necessary? Give any one example.

Solution

Coordination is the process in which one or more tissues or organs interact and complement the function of each other to maintain the homeostasis of the body. During physical exercise, there is always increased energy demand. To fulfil this demand, the supply of oxygen to the cells in concern increases. To provide more oxygen, our respiration rate, heartbeat and blood flow increase.

Q18. Name the ions to which the axonal membrane is more permeable during the resting potential.

Solution

Potassium ions

Q19. Name the layer of cranial meninges which is in direct contact with the brain tissue.

Solution

Pia mater

Q20. How many sodium ions move outwards per two potassium ions during the conduction of nerve impulse?

Solution

Three sodium ions

Q21. State the significance of the cone cells.

Solution

Cone cells are responsible for colour vision and photopic vision.

Q22. Write any two points of difference between the middle layer and the inner layer of the eye.

Solution

Middle layer of eye (Choroid) Inner layer of eye (Retina)

Blood vessels are present.

Blood vessels are absent.

Iris, lens and pupil belong to the choroid layer.

Contain rod and cone cells.

Iris, lens and pupil help light rays to focus on the eye and enter the eye.

Retina is responsible for the formation of images.

 

Q23. State the locations of the following:

Vitreous humour

Bipolar cells

Solution

Vitreous humour: It is present in the vitreous chamber which is situated between the lens and the retina.

Bipolar cells: They are present in the retina.

Q24. Where are the non-myelinated neurons present in the neural system?  

Solution

Autonomic and somatic neural systems  

Q25. Name the granular bodies present in the cytoplasm of neurons.

Solution

Nissl’s granules

Q26. What is the significance of the corpus callosum?

Solution

The corpus callosum connects the two cerebral hemispheres.

Q27. What is the other name for the ear drum?

Solution

The other name for the ear drum is tympanic membrane.

Q28. Name the two parts which form the outer ear.  

Solution

Pinna and external auditory meatus form the outer or external ear.  

Q29. Name the three ossicles present in the ear.

Solution

Three ossicles present in the ear are malleus, incus and stapes.

Q30. At the action potential, what charge is present on the inner surface of the axonal membrane?

Solution

Positive charge

Q31. To what colours of light do the photopigments respond?  

Solution

Photopigments respond to green, red and blue light.  

Q32. Name the space between the cornea and the lens.

Solution

Aqueous chamber

Q33. Which types of neurons are found in the retina of the eye?

Solution

Bipolar neurons

Q34. Name the pigment spot present at the posterior pole of the eye.  

Solution

Macula lutea  

Q35. Name the photosensitive compounds present in the photopigments.

Solution

The photosensitive compounds present in the photopigments are Opsin - a protein and retinal (an aldehyde of vitamin A).

Q36. What are the two nerve fibres of PNS?

Solution

The two nerve fibres of PNS are

Afferent fibres

Efferent fibres

Q37. What causes the change in the structure of opsin?

Solution

Light induced dissociation of retinal causes change in the structure of opsin.

Q38. Name the external layer of the eyeball.  

Solution

Sclera  

Q39. Name the structure which connects the middle ear and the pharynx. Also state its function.

Solution

The Eustachian tube connects the middle ear and the pharynx. It equalises the pressure on either side of the tympanic membrane or the ear drum.

Q40. Where are the eyes located?

Solution

Eyes are located in socket-like structures called orbits of the skull.