The document contains a biology worksheet for senior students with questions about human anatomy and physiology. It includes multiple choice and short answer questions about muscle movement, reflex arcs, homeostasis, and temperature regulation. Specifically, it asks about which muscles contract to lower the arm, the location of relay neurons, stimuli detected by skin, identification of muscles in a reflex diagram, and the process of a reflex arc. It also questions the importance of homeostasis, the role of sweating in temperature regulation, and changes in skin blood flow in response to cold temperatures.

1. FEBRUARY ACTIVITIES - 2019 Senior 3
3rd
term
1) The diagram shows an arm being lowered. What causes this movement?
A Biceps muscles contracts, triceps muscles contracts.
B Biceps muscle relaxes, triceps muscle contracts.
C Triceps muscles relaxes, biceps muscle contracts.
D Triceps muscles relaxes, biceps muscle relaxes.
2) Where are the relay neurones situated?
A effector
B spinal cord
C spinal nerve
D receptor
3) The diagram shows a reflex arc. The arm moves in response to touching a pin.
a- State two other stimuli detected by the skin.
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b- Name the muscles P and Q.
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2. c- Describe, naming each structure involved, what happens in this reflex arc after the person puts their finger on the
pin until the arm moves in response.
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4) Homeostasis is the maintenance of a constant internal environment, including a constant body temperature.
(a) Suggest why it is important that the body temperature of humans is kept constant.
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(b) Describe and explain the effect of sweating in maintaining human body temperature.
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(c) Blood flow through the skin changes in response to changes in the air temperature.
State and explain what happens to blood flow through the skin when the temperature of the surrounding air becomes
very cold and describe how this helps to reduce heat loss.
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