Theory question 106
Crop Improvement(a) List five aims of crop improvement.
(b) Define the term selection in crop improvement
(c) List three methods of selection
(d) Explain the following genetic terms: (i) homozygotes; (ii) back cross; (iii) dominance.
Show the model answer
(a) Any five: higher yield; pest and disease resistance; better quality; adaptation to climate/soil; early maturity; uniformity; resistance to lodging
(b) Selection is choosing plants with desirable characters from a population and using them as parents for the next generation
(c) Any three: mass selection; pure-line selection; pedigree selection; progeny selection; recurrent selection
(d)(i) Homozygote: an organism with two identical alleles for a character (e.g. TT or tt)
(ii) Back cross: crossing an offspring (F1) with one of its parents
(iii) Dominance: when one allele shows its effect and hides the other (recessive) allele in a heterozygote
Short definitions with examples.