(a) Name three main parts of the human brain
(b) State the functions of the following:
(i) Cerebrum
(ii) Hypothalamus
(iii) Medulla Oblongata.
(c)(i) List three organs of a higher plant that can respond to stimulus
(ii) What is tactic movement?
(d) Explain the following terms, giving one example in each case:
(I) Phototaxis
(ii) Hydrotaxis
(iii) Chemotaxis.
Explanation
(a) Main parts of human brain are:
(a) The forebrain/ Comtractile cerebrum
(b) The midbrain/cerebellum
(c) The vacuole hindbrain/medulla oblongata
(b)(i) The cerebrum is the seat of consciousness and senses. It also Paraniyium functions in the following ways: intelligence, memory, gcanuies judgement, learning, imagination and voluntary Chicroplost actions. It collects and stores information.
(ii) Hypothalamus
(a) connects the pituitary gland or master gland to the thallamus
(b) It contains the reflex centres.
(c) It regulates body temperature.
(d) It regulates water balance and osmoregulation.
(e) It controls sleep and wakefulness.
(f) It controls blood Of drinking
(h) It is the seat of aggression and anger; pressure.
(g) It is the centre for appetite, feeding and It controls the pituitary gland. It controls speech.
(iii)(a) Medulla oblongata controls breathing and respiration;
(a) It controls heart-beat
(b) It controls digestion.
(c) It controls size of blood vessels.
(e) It controls the secretion of saliva.
(f) It controls laughing.
(g) It controls involuntary actions such as sneezing, blinking, coughing, yawning etc.
(c)(i) Organs of higher plants that respond to stimuli are:
(a) Flowers
(b) Leaf
(c) Root
(d) Stem
(e) Tendril
(ii) Tactic movement is the locomotion, and response of the entire body of an organism in response to a stimulus. It is directional; locomotion could be positive or negative.
(d)(i) Phototaxis is the movement in response to light stimulus. it is the source of light by organisms. E.g. Euglena moving away from light
(ii) Hydrotaxis is the response of a whole organism to the stimulus of water or humidity. E.g. Woodlouse moves towards areas of high humidity.
(iii) Chemotaxis is the movement of an organism in response to a chemical stimulus; E.g. Amoeba and Paramecium moving away from chemicals.