All the following regarding regulation of a physiological function by either a neurotransmitter or a hormone are true except:

1. Target cells must have specific receptor proteins with which these molecules combine.
2. When these molecules bind to target cells, specific sequences of changes must occur.
3. There must be an "off-switch" that will stop the induced changes.
4. Second messengers will always be involved in the response of the target cell.

Synergism between hormones can be best described as:
1. Two or more hormones working together to produce a particular result.
2. One hormone is needed to enhance the responsiveness of an organ to a second hormone.
3. Either of the hormones does not act alone.
4. The effects of the two hormones are opposite to each other.

Modified fatty acids, prostaglandins, act as localized hormones that regulate neighboring cells. Such a regulation is called as:
1. endocrine
2. paracrine
3. eccrine
4. glycoprotein

It is not advised to consume alcoholic beverages on hot days because alcohol inhibits the release of:
1. antidiuretic hormone
2. oxytocin
3. thyroxine
4. triiodothyronine

The most likely cause of the Type I [juvenile-onset IDDM] is:
1. The receptors on the target cells become no longer responsive to insulin.
2. Immune cells attack the pancreas that can then no longer produce insulin.
3. The individual consumes too much sugar, which causes an overload in the bloodstream.
4. Obesity seems to be the most common cause of IDDM.

A paracrine regulator is the one that:
1. is alternatively named a hormone
2. travels through the blood
3. is secreted by the parathyroid gland
4. acts within an organ as a local regulator

Toxic agents present in food which interfere with thyroxine synthesis lead to the development of
1. toxic goitre
2. cretinism
3. simple goitre
4. thyrotoxicosis

Compared to a bull, a bullock is docile because of:
1. higher levels of thyroxine
2. higher levels of cortisone
3. lower levels of blood testosterone
4. lower levels of adrenalin/noradrenalin in its blood

Genetically engineered bovine (bST), sometimes called rbST (recombinant bovine somatotropin) or rbGH (recombinant bovine growth hormone) are used in
1. therapeutic drugs
2. agriculture
3. dairy industry
4. DNA fingerprinting

Assertion: Prostaglandins send only paracrine (locally active) or autocrine (acting on the same cell from which it is synthesized) signals.
Reason: Prostaglandins, found in almost every tissue in humans, are derived enzymatically from the fatty acid arachidonic acid.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.