CBSE Questions for Class 11 Medical Biology Neural Control And Coordination Quiz 1 - MCQExams.com

• Organ of Corti - is the organ of the inner ear located within the cochlea on the basilar membrane, which contributes to the audition. 
• Cochlea - The coiled part of the inner ear containing the organ of Corti, which produces nerve impulses in response to sound vibrations.
• Eustachian tube - It is the tube that connects the middle ear with the pharynx. It helps in maintaining the positive pressure inside the middle ear.
• Stapes - It is the smallest bone of the body that attaches to the oval window present at the initial point of the inner ear.
• Thus, the correct answer is (B) - (a)−(iv), (b)−(ii), (c)−(i), (d)−(iii).

Correct option: C

Explanation:

·  Nissl bodies or nissl granules or tigroid substances are found in neurons of nerve cells and are made of free ribosomes and rough endoplasmic reticulum (RER).

·  Neurons are fundamental units of the brain and nervous system its function is to transmit information to other muscle, nerve cells, or gland cells.

·  Types of neurons are sensory neurons, motor neurons, and associated neurons.  

Hence, nissl bodies are mainly composed of ‘Free ribosomes and Rough endoplasmic reticulum (RER)’.

The vascular layer of the eye, that lies between the retina and the sclera is called as choroid. It contains the retinal pigmented epithelial cells and provides oxygen and nourishment to the retina. The dark-colored pigment in the choroid absorbs light and limits reflections within the eye, that could degrade vision.

Mixed nerve or relay nerve contain both afferent and efferent axons. It conducts both incoming sensory information and outgoing muscle commands in the same bundle. Afferent nerves or sensory neurons conduct signals from sense organs to central nervous system, for example from the mechanoreceptors in skin. Efferent nerves or motor neurons conduct signals from the central nervous system along motor neurons to their target muscles and glands. 

Sensory neurons are the ones which respond to touch, sound, light and all other stimuli convey the impulse from the receptor (sense organ) to the main nervous system (the brain or spinal cord). Therefore the correct answer is option D.

• Whenever the sympathetic system is activated, the metabolism of our body increases.
•  This increases CO2 levels and reduces the pH of the blood. This acts as a stimulus for the respiratory centre and the respiratory rate increases. The sympathetic system is usually activated at the time of exercise. Hence, The sympathetic nervous system causes Increased respiration.
 So, the correct answer is 'Increased respiration'.

• The autonomic nervous system consists of a somatic afferent pathway, a central nervous system integrating complex (brain and spinal cord), and two efferent limbs, the sympathetic and the parasympathetic nervous systems. Hence, Efferent and Afferent pathways are functions of the autonomic nervous system.

• The organ of sight is called an Eye.
• The adult human eyeball is nearly a spherical structure. 
  
• The retina of the eye has two types of photoreceptor cells, namely, rods and cones. The daylight (photopic) vision and colour vision are functions of cones and the twilight (scotopic) vision is the function of the rods.
• Hence Eyes helps to see the world.
• So, the correct answer is 'Eyes'.

•  The bird's eye resembles that of a reptile, with ciliary muscles that can change the shape of the lens rapidly and to a greater extent than in the mammals. 
• Birds have the largest eyes relative to their size in the animal kingdom.
  
• Vision helps the bird to estimate the distance during flight or on land or during predation etc.
• So, the correct answer is 'Vision'.

• Centrosomes are key to the division of cells and produce the spindle fibres that are required during metaphase of mitosis. 
• Each centrosome consists of two centrioles that are orientated at right angles to each other. 
• Nerve cells are not able to multiply because they lack centrioles as they can not participate in mitosis and meiosis activity but still they get longer without dividing during childhood.
•  It occurs due to synpatic or axon pruning . Unlike other types of cells, neurons do not divide in their life time. Hence, Nerve cells do not divide as they lack centrosomes.