K.C.S.E Biology Q & A - MODEL 1997PP1QN18

K.C.S.E Biology Q & A - MODEL 1997PP1QN18

An experiment was carried out to determine the growth rates of bamboo and a variety of maize plants in two adjacent plots. The average height and average dry weight of plants from the two populations were determined over a period of twenty weeks. The data is as shown in the table below.

(a) Between which two weeks did the greatest increase in weight occur in
(b) Bamboo plants
(ii) Maize plants
(b) (i) Which of the two types of plants had a higher productivity by the end of the experiment
(ii) Give a reason for your answer in (b) (i) above
(c) Between weeks 14 and 18, the average height of the maize plants remained constant while average dry weight increased.
Explain this observation
(d) Suggest how the change in the average dry weight bamboo and maize
Plants would have been at week 22 if the experiment was continued.
(e) Why was it appropriate for this experiment to use
(i) Dry weight instead of fresh weight
(ii) Weight and height
(f) Describe how the average height and weight of the plants were determined in this experiment.
Average height
Average dry Weight
(g) Give a reason why secondary thickening does not occur in bamboo and  maize plants

answers

(a) (i) Bamboo plants
 4 and 6
(ii)Maize plants
12 and 14
(b) (i) Bamboo
(ii) It had accumulated  more  weight and therefore greater  dry  weight
(c) Maize plants  have reached maturity/maximum height food being  manufactured (in green parts); is utilized for  growth storage primary in the cob.
(d)Increase in weight – bamboo reject both increase/ decrease accept bamboo and maize increase/ decrease.
(e)
(i)  Dry weight  instead of fresh  weight
Fresh weight is dependant on the amount of water  present in the plants and this fluctuates depending on environmental factors.
(ii) Weight and height
Both given a better measure of growth
(f) Average height
At every  2 weeks measure the height of samples of plants in each plot:
Divide the total  height by the number of plants in each of  plot.
Average dry weight
Harvest the sample measure of the plants in each plot; dry to constant weight:
And divide by the number of plants
(g) Being  monocots/ lack  (Inter) fascicular cambium: