SKEMA JAWAPAN SAINS (SPM) : Body Coordination

BODY COORDINATION

SECTION B

1.         (a)        (i) X: Sensory neurone

                                         Y: Interneurone/relay neurone

                                          Z: Motor neurone

(ii) To transfer nerve impulses from the sensory neurone to the motor  

      neurone

            (b)        (i)         Synapse

                        (ii)        Electrical impulse

(c)      No reflex action will occur

(d)     (i)      reflex action

(ii)     Spinal cord

2.         (a)        Cerebrum

                                    Controls all the voluntary action and mental action

                                    Cerebellum

                                    Regulates body movement, maintains posture and balance

                                    Medulla oblongata

                                    Controls involuntary action

            (b)        To increase the surface area of the cerebrum so that there can be more

                        neurons in it

            (c)        carries out reflex action

3.         (a)        (i)         X is thyroid gland

                        (ii)        The rate of metabolism in the body slows down

            (b)        (i)         Y is ovary

                        (ii)        Controls the development of female secondary sexual characteristics

            (c)        (i)         Overproduction of human growth hormone

                        (ii)        Pituitary gland

SECTION C

1.  (a) The differences between voluntary actions and involuntary actions

Voluntary action	Involuntary action
Responces are controlled by the cerebrum	Responces are controlled by the medulla oblongata
Actions are under conscious control	Actions cannot be controlled by the conscious mind
The response can be sped up or slow down	The response is usually fast
The actions are controlled by the somatic nervous system	The actions are controlled by the autonomic nervous system
Receive stimuli from the external environment through the skin	Receive stimuli from the internal organ

(b) Identify two common charcteristics

• These actions occur rapidly and automatically when triggered by a stimulus
• These actions are not under our conscious control

Develop initial concept

• Rapid, automatic responses to stimuli that can protect the body and which are not under our conscious control are reflex action

Give othe examples

• Removing the finger from the sharp pin
• Closing eyelids or blinking when a fast moving object approaches the eye
• Coughing when something blocks the air passage

Give other non examples in relation to the concept

• Writing, dancing, eating, cooking

Explain the actual concept

• A reflex action is a rapid  automatic response to a stimulus and it is not under our conscious control and can protect the body from harm in critical situation.