BIOLOGY 1 Marks Question

The cerebrum is the most developed.

The hypothalamus of the central neural system acts as a master clock.

The cochlea determines the pitch of a sound.

The Inner ear has three semi-circular canals forming cochlea. Cochlea is responsible for maintaining the body balance.

Aqueous humor and vitreous humor:

Aqueous humor	Vitreous humor
It is a thin, watery fluid present between the cornea and the lens.	It is a transparent gel present between the lens and the retina.

3. Blind spot

Solution:
Blind spot is the part where the optic nerve passes out of the retina. Photoreceptors are absent from this region.

Cerebral aqueduct.

Brain.

Right and left hemispheres of the cerebrum are connected by corpus callosum. Each hemisphere is divided into frontal lobe, temporal lobe, parietal lobe and occipital lobe.

Vestibular apparatus.

Impulse conduction depends upon:

1. permeability of axolemma (axon membrane).
2. Osmotic equilibrium between the axoplasm and extracellular fluid present outside the axon.

1. Hypothalamus.
2. Medulla.

1. Synaptic knobs.
2. Schwann cell.

Choroid layer.

Pinna collects the vibrations in the air and directs them to the ear.

1. Cerebral aqueduct.
2. Corpora quadrigemina.

It is to provide accommodation for a large number of neurons.

Eustachian tube helps in equalizing pressure on both sides of the eardrum.

Scala media.

Ciliary muscles.

Sympathetic nervous system and parasympathetic nervous system.

1. Sensory.
2. Neurons.

The cerebrum is the most developed.

A synapse is formed by the membranes of a pre-synaptic neuron and a post-synaptic neuron, with or without a gap between them.

The hypothalamus of the central neural system acts as a master clock.

Nervous system and endocrine system.

1. In the sockets, called orbits.
2. Inside the spinal cord.

They are present in the taste buds located in the tongue.

They communicate through oval window and round window respectively.

Transmission of neural impulses.

The cochlea determines the pitch of a sound.

External auditory canal, → Ear drum, → Stapes, → Incus, → Malleus, → Cochlea.

Non-myelinated nerve fibre.

The efferent nerve fibres transmit motor impulses from CNS to the concerned tissues/ organs and form the motor or efferent pathway.

Cone cells.

Forebrain, which mainly includes cerebrum.

Sclera (outermost layer).

1. Synaptic vesicles are present in the synaptic knob, the bulb-like structures at the ends of the branches of axon.
2. They contain neurotransmitters.

Grey matter and white matter.

Eustachian tube.

Myelinated and non-myelinated.

1. The projecting ridge having hair cells, found in the base of the semicircular canals (called ampulla), is called crista ampullaris.
2.  

1. The projecting ridge found in the utricle and saccule of the vestibular apparatus, is called macula.
2. Both are receptors to maintain the balance of the body.

Threshold stimulus: It fires the signals in the neuron.

Synapse acts as a one-way valve because neurotransmitter is secreted at the terminal knobs of axon only. The dendrite membrane (postsynaptic membrane) has the specific protein receptor molecules to break this neurotransmitter.

The nose contains mucus-coated receptors which are specialised for receiving the sense of smell and are called olfactory receptors. These are made up of olfactory epithelium which consists of three kinds of cells. The neurons of the olfactory epithelium extend from theoutside environment directly into a pair of broad bean-sized organs called olfactory bulb. Olfactory bulbs are extensions of the brains limbic system.

Because there is no photoreceptor cell.

The Inner ear has three semi-circular canals forming cochlea. Cochlea is responsible for maintaining the body balance.

Forebrain.

Central neural (nervous) system, lies along the main central axis of the body.