(a) Define crop improvement. [2 marks]
(b) Copy and complet the table below based on Mendel’s Law of Indepen-dent Assortment of Genes (Dihybrid inheritance).
| TC | Tc | tC | tc | |
| TC | TTCC | |||
| Tc | Ttcc | |||
| tC | ttCc | |||
| tc | ttcC |
Use the following information: T = Tall; C = Coloured; t = Dwarf; c = White. (Where T and C are dominant character; while t and c are recessive TC TTCC characters) [6 marks]
(c) Calculate the percentage of plants in (b) above that are: (i) Tall coloured; (ii) Tall white; (iii) Dwarf coloured; (iv) Dwarf Tc Ttcc white [8 marks]
Explanation
(a) Definition of crop improvement: This is the science (ii) that deals with the development of new crop varieties with superior quality and quantity.
(b)
| TC | Tc | tC | tc | |
| TC | (TTCC) | TTCc | TtCC | TtCc |
| Tc | TTcC | (TTcc) | TtcC | Ttcc |
| tC | tTCC | tTCc | ttCC | ttCc |
| tc | tTcC | tTcc | (ttcC) | (ttcc) |
(c) Tall Coloured: TTCC, TTCc, TtCC, TtCc, TTcC, TtcC, tTCC, tTCc, tTcC = 9
Tall white: TTcc, Ttcc, tTcc, = 3
Dwarf Coloured: ttCC, ttCc, ttcC = 3
Dwarf white: ttcc = 1 ,.
Calculation of percentage of plants that are:
Tall Coloured = 9/16 x 100 = 56.25%
(ii) Tall White = 3/16 x 100 = 18.75%
(iii) Dwarf Coloured = 3/16 x 100 = 18.75%
(iv) Dwarf White = 1/16 x 100 = 6.25% %
Total = 100.00%