1.What is happen in the human body, When the temperature of atmosphere decreases :
1 mark
AIncrease of ADH secretion
Why this is wrongADH controls water reabsorption in the kidneys and is not concerned with raising body heat, so cold does not raise it for warming.
BDecrease of adrenalin secretion
Why this is wrongAdrenaline raises metabolic activity, so the body would not reduce its secretion when it needs more heat, not less.
CIncrease of thyroid gland activity Correct answer
DIncrease of insulin secretion
Why this is wrongInsulin lowers blood glucose after eating and is unrelated to temperature regulation, so it would not rise in the cold.
Why this is correctCold exposure increases thyroid activity to raise metabolic heat production.
When the atmospheric temperature drops, the body tries to produce more heat to keep its temperature constant, and the thyroid gland is the main heat-raising organ: it increases its activity and secretes more thyroxin, which raises the metabolic rate and so increases heat production. The other listed hormones regulate water, blood glucose, or stress rather than long-term heat production. A reusable method: cold exposure → look for the response that increases metabolism and heat, namely increased thyroid activity.
2.On measuring the speed of motor response for two brothers some differences appear in their response. Which of the following explain that?
1 mark
AStrength of joints and ligaments
Why this is wrongJoints and ligaments affect the range and stability of movement, not how fast the nerve signal reaches the muscle.
BStrength of muscles and elasticity of tendons
Why this is wrongMuscle strength and tendon elasticity affect the force of contraction, not the speed at which the impulse arrives.
CEfficiency of nerve impulse transmission the muscles Correct answer
DEfficiency of endocrine glands linked to muscles performance
Why this is wrongEndocrine glands act slowly through hormones in the blood, far too slowly to explain a fast motor response.
Why this is correctMotor response speed mainly depends on how efficiently nerve impulses reach and activate muscles.
The speed of a motor response is governed mainly by how quickly nerve impulses travel along the nerves and cross the synapses to stimulate the muscles. So a difference in response speed between two brothers reflects the efficiency of their nerve impulse transmission to the muscles, not the strength of the moving parts. A reusable method: when a question asks about the speed of a response, focus on the nervous pathway, because speed is a property of signal conduction.
3.The receptors of ADH hormone are found in:
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AKidneys only
Why this is wrongThe kidneys are one true target, but ADH also acts on blood vessel walls, so kidneys only is incomplete.
BArtery walls only
Why this is wrongArtery walls are one true target, but ADH also acts on the kidneys, so artery walls only is incomplete.
CKidneys and artery walls Correct answer
DSmooth muscles and kidneys
Why this is wrongADH acts on the smooth muscle specifically in the walls of blood vessels, not on smooth muscle in general, so smooth muscles and kidneys misstates the vascular target.
Why this is correctADH acts on kidney tubules for water reabsorption and vascular walls for vasoconstriction.
ADH (vasopressin) has two target sites: it increases water reabsorption in the collecting ducts of the kidneys, and it causes vasoconstriction by acting on the smooth muscle in the walls of blood vessels (arteries and arterioles). Therefore its receptors are found in both the kidneys and the artery walls. A reusable method: list ADH's two effects (water retention and vasoconstriction) and match each to the tissue that carries its receptors.