K.C.S.E Biology Q & A - MODEL 2003PP1QN17

K.C.S.E Biology Q & A - MODEL 2003PP1QN17

Some students used a model to demonstrate the effect of sweating on human body temperature. Two boiling tubes A and B were filled with hot water. The temperature of water in the tubes was taken at the start of the experiment and then at 5 minutes interval. The surface of tube A was continuously wiped with a piece of cotton wool soaked in methylated spirit. The results obtained are shown in the table below.

a) On the same axes, plot graphs of temperature of water in the tubes against time.
b) At what rate was the water – cooling in tube A?
c) Why was tube B included in the set up?
d) Account for the rate of cooling in tube A.
e) State two processes of heat loss in tube b.
f) What would be the expected results if tube A was insulated?
g) What would the insulation be comparable to in:
i) Bird
ii) Mammals?
h) Name the structures in the human body that detect:
i) External temperature changes
ii) Internal temperature changes

answers

​    b)     80 – 18 = 62; 2.48C /Min
            2.5            25                                      
 
    c)     Control
    d)     Rate was faster in tube A; because the film of methylated sprit evaporated; removing heat from the tube;
    e)     Convection ; radiation
    f)     Lower rate of heat loss;
    g)     i) birds
               Feather
            ii) Mammals?
                Fur
    h)     i) external temperature changes
                Temperature
            ii) Internal temperature changes
                 Hypothalamus