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Coordination and Irritability
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Superior
Hypothalamus hypophyseal
artery Neurosecretory cells
Primary capillary plexus of
Infundibulum Hypophyseal hypophyseal portal system
portal vein
Posterior pituitary
Pituitary gland Anterior Secondary capillary plexus of
pituitary hypophyseal portal system
Figure 4.37: Relationship between the hypothalamus and pituitary gland
compared to animals. Unlike animals,
Exercise 4.4 plants do not move from one place to
another; although the movement is shown
1. Support the statement “Lactation by the characteristics of plants’ sensitivity
and shivering are both mammalian and response to external stimuli, which
body activities backed by hormonal results into growth movements and also
coordination”.
movement of organs. There are three types
2. We can perform all body functions of growth movements in plants, namely
when there is a good interaction tactic movement, nastic movement, and
between our hormonal and nervous tropic movement.
systems. Justify the statement.
3. Without the pituitary gland, life can 4.4.1 Tactic movement
not be sustained. Substantiate. Tactic movement; also known as taxis
4. Ms. Siambiliki was clinically (plural taxes) is the type of movement
diagnosed with hypothalamic which involves the entire cell or organism
dysfunction. What health problems moving from one place to another in
might she be facing? response to external stimuli, such as light,
water, and chemicals. Tactic movement
4.4 Coordination in plants occurs in plant reproductive cells and in
Plants do not have a nervous system; they some organisms such as Euglena, and
rely on chemical coordination. Therefore, Chlamydomonas. Tactic moments may
most of their responses are slower be grouped as positive taxis and negative
Form Five Student’s Book
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