Answer : (a)

The diencephalon is part of the prosencephalon (forebrain), which develops from the foremost primary cerebral vesicle, that gives rise to posterior forebrain structures including the thalamus, hypothalamus, posterior portion of the pituitary gland, and pineal gland. Answer : (d)

Answer : (a)

Hypothalamus in the thermoregulatory centre of our brain. It is responsible for maintaining constant body temperature. Answer : (b)

Note The cornea, The cornea is the transparent part of the eye that covers the front portion of the eye, is the most sensitive to touch. Further, If we talk about sensitivity to light,then of course it will be the retina. In option (d) states only sensitive but dont mention about type. But other options are not correct, option (d) is correct The outer covering of the eyeball consists of a relatively tough, white layer called the sclera (or white of the eye) The cornea is composed of proteins (Collagen) and cells. Near the front of the eye, in the area protected by the eyelids, the sclera is covered by a thin, transparent membrane (conjunctiva), which runs to the edge of the cornea.Option (a) mention about eye ball, Option (a) is not correct. Answer : (d)

Answer : (d)

The medulla oblongata: contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic functions of breathing, heart rate and blood pressure. Temperature regulation: Temperature regulated by a homeostat with temperature sensors and hypothalamus of the brain. Answer : (b)

The rods are incredibly efficient photoreceptors. More than one thousand times as sensitive as the cones, they can reportedly be triggered by individual photons under optimal conditions. Answer : (a)

Homeostasis in terms of body temperature. When your hypothalamus senses that you’re too hot, it sends signals to your sweat glands to make you sweat and cool you off. When the hypothalamus senses that you’re too cold, it sends signals to your muscles that make your shiver and create warmth. Answer : (d)

The mechanical role of the tectorial membrane in hearing. Basilar membrane: Closely associated with the function of separating the two fluids is the function of providing a base for the sensory cells of hearing, the hair cells. Reissner’s membrane: its primary function is to allow transport of nutrients in inner year Answer : (b)

Vater’s corpuscles are rapidly adapting (phasic) receptors that detect gross pressure changes and vibrations in the skin Answer : (a)

Choroid plexus: a multilobed vascular membrane, projecting into the cerebral ventricles, that secretes cerebrospinal fluid. Diencephalon:Vital structures of the brain such as the thalamus, hypothalamus, epithalamus, and the pituitary gland are all housed within the autonomic region within the diencephalon. Answer : (d)

Hearing aid it’s a device that amplifies the sound of the surrounding for someone who suffers from hearing loss. Answer : (c)

Aqueduct of Sylvius: A canal between the third and fourth ventricles in the brain within the system of four communicating cavities that are continuous with the central canal of the spinal cord. Answer : (d)

Motor nerve is a kind of nerve that carries impulses from the central nervous system that trigger muscles to contract. The abducens nerve is a somatic efferent nerve that, in humans, controls the movement of a single muscle, the lateral rectus muscle of the eye. Answer : (b)

Option b,c and d have "Two Eyes to the Side - Nature has given animals the physical attributes necessary for survival. Lateral placement of the eyes is essential to the survival of hunted animals or herbivorous animals as it allows them to increase side or peripheral vision. While cat have forward looking eyes, as a result cat can have better perception of depth orforward stereoscopic visual field Answer : (a)

Saltatory conduction: conduction in which the nerve impulse jumps from one node of Ranvier to the next.Saltatory conduction a form of fast nerve impulse conduction where the impulse may jump between nodes normally insulated from each other. Answer : (b)

The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. Answer : (d)

There are twelve pairs of cranial nerves in man. They are numbered by Roman numeral I to XII. Thus number of cranial nerves in mammal is 24 Answer : (c)

The pupil is the opening in the center of the iris where light enters the eye. The iris opens and closes to control the amount of light entering the eye through the pupil. Answer : (c)

Intercellular communication refers to the communication between cells. Membrane vesicle trafficking has an important role in intercellular communications in humans and animals, e.g., in synaptic transmission, hormone secretion via vesicular exocytosis. Answer : (c)

The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline. Spinal cord and cranial nerves are made ofmyelinatedand non-myelinated nerve fibres Answer : (d)

The junction between the retina and ciliary body. The oraserrata marks the transition from the non-photosensitive area of the retina to the multi-layered photosensitive region of the retina. Answer : (a)

At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron. Answer : (c)

The ventromedial hypothalamus (VMH) is a distinct morphological nucleus involved in feeding, fear, thermoregulation, and sexual activity. A lesion to the VMH makes over eat and increases hunger, leading to obesity Answer : (b)

Statement "c" not correct as :trigeminal (V, fifth) is the largest cranial nerve. It is a mixed nerve, with both sensory and motor components. It has ophthalmic, maxillary, and mandibular branches Statement "d" not correct as: The abducens nerve arises from the abducens nucleus in the pons of the brainstem. These nerves are motor nerves is true part of statement. abducens nerve is a motor nerve responsible for supplying one of the extraocular muscles of the eye Answer : (c)

The choroid lies between the retina and the sclera. In addition, there are pigment cells within the choroid that absorb stray light and so it helps to lessen glare within the eye Answer : (a)

Nodes of Ranvier, also known as myelin sheath gaps, are periodic gaps in the insulating myelin sheaths of myelinated axons where the axonal membrane is exposed to the extracellular space. Answer : (b)

The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF) and located within the brain parenchyma. The ventricular system is composed of 2 lateral ventricles, the third ventricle, the cerebral aqueduct, and the fourth ventricle Answer : (d)

Third and fourth ventricles of brain are connected by Diencephalon includes third ventricles The fourth ventricle has a diamond shape and is located in the upper portion of the medulla. Answer : (c)

The rods are incredibly efficient photoreceptors. Animals having more rods can see clearly in night. Answer : (a)

The organ of Corti, surrounded in potassium rich fluid endolymph, lies on the basilar membrane at the base of the scala media. Answer : (c)

diencephalon appears at the upper end of the brain stem, situated between the cerebrum and the brain stem. It is made up of four distinct components: the thalamus, the subthalamus, the hypothalamus, and the epithalamus. The hypothalamus controls body temperature, hunger, thirst, fatigue, sleep, and circadian cycles. Sneeze reflex centers are located in brain stem along ventro-medial part of the spinal trigeminal nucleus, lateral reticular formation. Answer : (b)

Organ of ruffini act as thermoreceptors that respond for a long time Answer : (d)

The tympanic membrane, also called an eardrum, is a thin membrane that separates the external ear from the middle ear in humans and other animals Answer : (c)

Owls can move freely during night, because they have large number of cones on their retina which help them to see in night. Answer : (a)

Vagus is the tenth cranial nerve and interfaces with parasympathetic control of the heart, lungs, and digestive tract thus shows maximum branching Answer : (b)

A structure in a living organism which responds to sound or similar vibrations; an organ of sound perception. The internal ear, which contains the essential phonoreceptors, is a closed ectodermal sac, the membranous labyrinth, peculiarly molded and called a “labyrinth” on account of its complicated structure. Answer : (d)

Eustachian tubes when pressure changes are experienced, as in ascending/descending in aircraft, mountain driving, elevator lift/drops, etc. Eustachian tubes open for a brief period, and even increase or decrease air pressure in the middle ear. Answer : (c)

The quadrate bone is part of a skull in most tetrapods, including amphibians, sauropsids (reptiles, birds), and early synapsids. In mammals the articular and quadrate bones have migrated to the middle ear and are known as the malleus and incus Answer : (c)

At a synapse, one neuron sends a message to a target neuron—another cell. Answer : (d)

Craniosacral: Denoting the cranial and sacral origins of the parasympathetic division of the autonomic nervous system Answer : (c)

Malleus: a small bone in the middle ear which transmits vibrations of the eardrum to the incus. Choroid: also known as the choroidea or choroid coat, is the vascular layer of the eye. Odontoid process :A small, toothlike, upward projection from the second vertebra of the neck around which the first vertebra rotates. Malpighian cells: A macrosclereid in the epidermis of the testa of a leguminous seed. Answer : (a)

Ossicles:it typically refers to the malleus, incus, and stapes (hammer, anvil, and stirrup) of the middle ear. Answer : (b)

Organ of cortilies on the basilar membrane at the base of the scala media. Answer : (d)

Neurotransmitter released only at axon ending and dendrites are only the receptors for the neuro transmitter Answer : (b)

Any injury or disease affecting medulla oblongata can result in paralysis of the opposite side of the body, loss of pain and temperature sensations, loss of the gag reflex and difficulty swallowing. Answer : (d)

Hydra generally react in the same way regardless of the direction of the stimulus, and this may be due to the simplicity of the nerve nets. Answer : (b)

The parasympathetic fibres begin in the central nervous system. The nerves supplying the head and neck are situated within four nuclei, located within the brainstem. Each nucleus is associated with a cranial nerve (the oculomotor, facial, glossopharyngeal and vagus nerves) – these nerves carry the parasympathetic fibres out of the brain. After leaving the brain, the parasympathetic fibres from each nuclei synapse in a peripheral ganglion (a collection of neurone cell bodies outside the CNS). These ganglia are typically located near to the target viscera. From the ganglia, post-ganglionic parasympathetic fibres continue to the organs in the head and neck, providing parasympathetic innervation. Answer : (a)

At short focal distance the ciliary muscle contracts, zonule fibers loosen, and the lens thickens, resulting in a rounder shape and thus high refractive power Answer : (b)