CBSE Questions for Class 11 Medical Biology Neural Control And Coordination Quiz 15 - MCQExams.com

• Retina is the sensory layer of the eye that has rod and cone cells for vision. Rod cells help with the vision in the dim light while the cone cells help in the vision in strong light.
• Blindspot is the point of the eye which is devoid of rod and cone cells. The optic nerve emerges from this point which carries the optic impulse to the occipital lobe of the brain for interpretation.
• The aqueous chamber is filled with transparent fluid known as aqueous humor. It maintains the intraocular pressure and refractive index of the eye. 
• The choroid is the vascular layer that absorbs the light and prevents the internal reflection of light in the eye. The anterior part of the choroid layer forms the ciliary body.
  Hence, the correct option is A.
  

• The sympathetic nervous system is part of the autonomous nervous system and is involved in the stimulation of activities that prepare the body for action, such as increasing the heart rate, increasing the release of sugar from the liver into the blood and other flight or fight responses of the body. 
• The parasympathetic nervous system decreases respiration and heart rate and increases digestion by the increase in saliva production and other digestive juices.
  

So the correct answer is option A.

• Nissl's bodies are the large granules in the neurons. 
• Ossein is the collagen of the bone matrix. 
• RBCs of man are non-nucleated. They are oval-shaped cells. 
• Lymphocytes are the factories for antibody production.
  
  Hence, the given option B is correct.

• The cornea, the main focusing part, is the clear front surface of the eye. Like a window, it allows light to enter the eye. Vision could be markedly reduced or lost if the cornea becomes cloudy or scarred. This condition is known as corneal blindness.
• Eye donation is an act of donating one’s eyes after his/her death. Only corneal blinds can be benefited through this process, not other blinds.
• A cornea transplant is a surgical procedure that replaces a disc-shaped segment of an impaired cornea with a similarly shaped piece of a healthy donor cornea.
• So, the correct answer is option A.

• Neurons are the structural and functional units of the nervous system. These neurons contain an aggregation of parallel cisternae of rough endoplasmic reticulum with rosettes of free ribosomes around the nucleus is called nissl bodies.
• Nissl bodies are the sites where protein synthesis occurs and provide it to cyton. Nissl substance is basophilic in nature and can be sharply stained with basic aniline dyes. 

• Neuroglial cells are specialised cells found in the brain and spinal cord supporting the neurons and their fibres. 
• Half of all the brain cells are neuroglial cells. There are two types of neuroglial cells macroglia and microglia. 
• The macroglia are large glial cells, and form from the ectoderm of the embryo. Microglia cells are small glial cells which are formed from the mesoderm of the embryo.

• The myelin sheath on the neurons produced by the oligodendrocytes in the CNS and the Schwann cells in the PNS provides an insulated covering to the neuron. 
• This insulated neuron has regions that are not covered with myelin called the nodes of Ranvier. This arrangement helps the nerve impulses to jump from node to node instead of traveling the entire length of the neuron.
•  This increases the velocity of the transmission of nerve impulses. If the entire length of the nerve fiber is covered with myelin, the conduction becomes very slow.

Correct Option: D

Explanation:

• Fovea centralis is a highly sensitive area of the retina.

• It has a high concentration of cones.

•  These cones are less sensitive to light and help in perceiving finer changes in the image.

• Cones are required for light vision.

Hence, the region which is sensitive in the retina is the fovea centralis.