K.C.S.E Biology Q & A - MODEL 2004PP1QN17

K.C.S.E Biology Q & A - MODEL 2004PP1QN17

During germination and growth of a cereal, the dry weight of endosperm, the embryo and total dry weight were determined at two – day intervals. The results are shown in the table below.

a) Using the same axes, draw graphs of dry weigh of endosperm, embryo and the total dry weight against time 
b) What is the total dry weight on day 5?
c) Account for:
i) Decrease in dry weight of endosperm from day 0 to 10 
ii) Increase in dry weight of embryo from day 0 day 10 
iii) Decrease in total dry weight from day 0 to day 8 
iv) Increase in total dry weight after day 8 
d)Dormancy.
i) Within a seed
ii) Outside the seed
e) Give two characteristics of meristematic cells 

answers

​(b) 38.5 (mg); Acc. + 0.5 ( i.e. 38 – 39)
(c) (i) Hydrolysis of starch into  simple  sugars; which are translocated to the embryo;
Respiration/ to give energy/ heat/ gases
Acc. Simple sugar oxidized
(ii) New materials are  synthesized from protein); bringing about growth  of embryo; acc new cells/ protoplasm synthesized
(iii) The rate of respiration is faster than that of synthesis  of  materials for growth
(iv) First leaf (carried out photosynthesis) leading to growth
(d) (i) Presence  of absiscic acid/ germination inhibitors;
Embryo not fully developed
Absence of hormones/ enzymes that stimulate germination
Impermeable seed coat; rej hard seed coat
Acc. Inactive enzymes/ hormones/ absence of gibberellins/ cytokinins.
 (ii) – Unsuitable / unfavourable temperature
- absence  of light
- lack of water
- lack of  oxygen
(c) Dense cytoplasm
- Thin cell wall
- Absence of vacuoles ( cell sap)