Bio Revision zzz...

heys...
studying for bio now...
sianzzz.
bio so boring... anyways bio revision:

What is a reflex action?
A reflex action is an immediate response to a specific stimulus in higher animals.

State two reflex actions involving glands as effectors.
Upon seeing sour plum, salivary glands secrete saliva.
When dust gets into eyes, tear glands secrete tear.

Describe a simple spinal reflex action.
An example is when the hand touches a hot object unknowingly. The heat from the object stimulated the nerve endings in one's skin. Nerve impulses produced travel along the sensory neurone to the spinal cord. In the spinal cord, nerve impulses are first transmitted across a synapse to a relay neurone and then transmitted across another synapse to the motor neurone. The nerve impulses leave the spinal cord along the motor neurone to the effector which is the biceps muscle in the upper arm. The muscle then contracts to withdraw the hand suddenly.

State a test which must be carried out necessarily before exposing the plant to light and explain why.
Starch test. This to ensure that no starch was present before the experiment, and that the starch detected at the end was produced during the experiment.

What is the role played by A and B at birth?
A, the uterine muscles contracts and relaxes rigoriously to help pushing the baby out of the womb at birth. B, the amniotic fluid, acts as a lubricant to reduce friction in vagina at birth.

Name fluid X and explain the importance of this fluid.
This is the pleural fluid. It reduces the friction between the lungs and the inner surface of the thoracic cavity during the ventilation movement.

Explain the function of muscle type M in inspiration.
During inspiration, intercoastal muscles contract to move the ribs and the sternum forwards and upwards. The cross-sectional area of the chest decreases, thus the pressure in the lungs inreases, as a result air flows into the lungs.

A man was struck on the sternum by a fist. State and explain the immediate effect on his breathing.
The sternum was being pressed backwards, reducing the cross-sectional area of the chest, thus increasing the lung pressure that gushes air out of the mouth and nose.

Label A and B.
A is the erector muscle. B is the blood capillaries.

Describe and explain the immediate responses of A and B when cold water was splashed onto the skin suddenly.
A will contract to pull hairs to stand on one end to build a barrier to trap air and prevent heat loss. The arteriole constricts to reduce blood flow into the capillary B to conserve heat in the blood.

See what i mean?
Boring eh?
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Jiayou for Bio!
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