BIOLOGY 3 Marks Question

1. Malleus
2. Incus
3. Stapes

1. The cause of Vijay's sickness is the change of altitude in which there is change in the physiology of the body.
2. Internal ear gets affected which control balancing of body.
3. Eustachian tube maintains the air pressure in the ear.
4. The guide is a very sensible person and is caring too.

1. Multipolar neurons:

1. A multipolar neuron has one axon and many dendrons.
2. They are found in the cerebral cortex.

2. Bipolar neurons:

1. A bipolar neuron has one axon and one Dendron.
2. They are found in retina.

3. Unipolar neurons:

1. Cell body has only one axon.
2. They are found in the embryonic stage.

1. No, actually he was not able to differentiate colours.
2. In human, colours vision results from the activity of cone cells of retina of eyes as these contain three different pigments each absorbing light of different wavelength. The sensation of different colours are produced by various combination of these cones and their pigments.
3. The daylight vision and colour vision are functions of cones cells of retina.
4. The teacher showed his concerns about his student.

1. Coordination and integration of body organs by neural system. Which regulate normal physiology of human body.
2. Coordination is the process through which two or more organs interact and complement the functions of one another. On the other hand, integration is a process, which makes two or more organs to work as a functional unit in harmony.
3. When we do exercise, we observe significant increase in the rate of respiration, heartbeat, bloodflow, sweating, etc., to meet enhanced needs of nutrients and energy for increased activities of lungs, hearts, muscles and many other body organs. When we stop exercising, we witness that the increased activities of lungs, heart, nerves, kidneys, muscles, etc., gradually return to normal. Thus, during exercise, functions of various organs of the body are coordinated and integrated.
4. He has a good knowledge of biology. He has the ability to apply his learning to the practical life.

1. The electrical potential difference across the plasma membrane of a resting neuron, is called resting potential.
2. At rest, the membrane of the axon is more permeable to potassium and almost impermeable to sodium; hence the axoplasm has more potassium ions and the extra cellular fluid has more sodium ions.
3. The sodium-potassium pump transports actively three sodium ions to the outside and only two potassium ions enter the axoplasm, making the axoplasm negatively charged and the exterior positively charged.
4. When the membrane is stimulated by a threshold stimulus, the membrane becomes freely permeable to Na⁺; the rapid influx of Na⁺ causes depolarisation, i.e. the interior/axoplasm becomes positively charged and the exterior negatively charged.
5. The electrical potential difference across the membrane at the depolarised state, is called action potential.

1. When the polarised membrane of a resting axon is stimulated at a site (A), the permeability of the membrane is changed at that site; it becomes more permeable to sodium ions.
2. So, there is a rapid influx of Na⁺ ions that leads to the reversal of the polarity, i.e. the exterior of the membrane becomes negatively charged and the interior/axoplasm becomes positively charged.
3. The electrical potential difference across the membrane at the stimulated site (A), is called action potential.
4. The site (B) ahead of A, is in the polarised state, i.e. it is positively charged on the outside and negatively charged on the inside.
5. Consequently, there is a flow of current from site A to B in the axoplasm and from B to A on the extracellular fluid and an action potential is generated at B.
6. These events are repeated all along the length of the axon and the impulse/ action potential is conducted.

1. Pavlov's experiment.
2. Pavlov's Experiment: The concept for which Pavlov experiment is done is to check the conditioned reflexes. Students conduct this experiment to know this concept of conditioned reflex, to examine the rate of salivations among dogs. Everytime when bell is rung they fed the dog. He learned that when the bell was rung without food being presented to the dog. The dog will subsequently initiate salivation. The dog had associated the sound of the bell with the feeding time. This shows to the association of an expected response (drool) to an unlikely stimulus (the bell).
3. Conditioned reflex is acquired after birth, i.e., they are adopted during the course of lifetime.
4. Scientific attitude, awareness and sense of responsibility.

1. Tumour in hypothalamus.
2. Hypothalamus.
3. The hypothalamus lies at the base of thalamus in the forebrain.
4. Humanity and responsibility towards the patient. He is devoted to his duties and has professional ethics.

1. The cranial meninges has three layers:

1. The outermost, dura mater.
2. The middle, arachnoid.
3. The innermost, pia mater.

1. Cerebrum is concoined with memory, intelligence and motor signalling to skeletal muscles.
2. Hypothalamus has centres to control body temperature, thirst and hunger and secretes neurohormones.
3. Medulla has centres which control cardiovascular reflexes, gastric secretions and respiration.
4. Cerebellum controls the coordination of muscular activities and the posture of the body.

1. The cranial meninges consists of three layers:

1. The outer pia mater.
2. The middle arachnoid.
3. The inner dura mater.

1. The cerebellum integrates the information from semicircular canals of the ear and the auditory system.
2. The cerebrum is responsible for memory, communication and intersensory associations.

1. Dendrites.
2. Cell body.
3. Axon.
4. Axon terminal.
5. Synaptic knob.

• Dendrites: Short fibres which branch repeatedly and project out of the cell body also contain Nissi's granules and are called dendrites. These fibres transmit impulses towards the cell body.
• Axon: The axon is a long fibre, the distal end of which is branched. Each branch terminates as a bulb-like structure called synaptic knob which possess synaptic vesicles containing chemicals called neurotransmitters. The axons transmit nerve impulses away from the cell body to a synapse or to a neuro-muscular junction.

1. Malleus
2. Incus
3. Stapes

Limbic system:

1. The regulation of sexual behaviour.
2. Expression of emotional reactions.
3. Motivation.
4. Olfaction.
5. Autonomic responses.