Answers to Hands-on Pg 50-53

Aim : To study the growth pattern of maize plant (Zea mays)

Variables : Manipulated variable : Time of growth

                   Responding variable : Mass of seedlings

                   Fixed variable : Amount of water, fertilizer

Time (weeks)	Mass of 3 seedlings (g)		Mean mass of 1 seedling (g)
	Fresh	Dry	Fresh	Dry
0	0.90	0.60	0.30	0.20
1	0.60	0.45	0.20	0.15
2	0.90	0.60	0.30	0.20
3	1.20	0.90	0.40	0.30
4	2.40	1.80	0.80	0.60
5	4.20	3.15	1.40	1.05
6	6.00	5.25	2.00	1.75
7	8.85	7.50	2.95	2.50
8	11.40	10.20	3.80	3.40
9	14.10	13.20	4.70	4.40
10	15.30	14.70	5.10	4.90
11	15.90	15.00	5.30	5.00
12	16.20	15.30	5.40	5.10

Draw a graph based on the above table

Discussion :

1. Sigmoid growth curve
2. Week 5 to week 8
3. Growth rate is negative from the beginning of the activity ti week 1.  This is because the germinating seeds use food stored in the endosperm.  Week 1 to wek 4 shows slow growth rate because young leaves are starting to grow and photosynthesis has just begun.  Week 5 – 8 shows highest growth rate.  The growth rate slows down from week 8 onwards because the plant has reached maturity.

Conclusion :

The growth pattern of the maize seedling represented by a graph of the mass of maize seedlings against time is a sigmoid curve. The hypothesis is accepted.