Genetics and Plant Breeding
Unit 1. Inheritance and crop improvement. Covers Cell structure and cell division; Genetic material; Mendel’s laws of inheritance; Quantitative inheritance; Plant breeding: history, objectives and methods; Plant biotechnology.
About this unit
This unit explains how characters pass from parents to offspring and how breeders use that knowledge to develop better crop varieties. It starts with the cell and cell division, moves to DNA, RNA and chromosomes, then Mendel's laws and quantitative inheritance, and finishes with the methods of plant breeding and modern plant biotechnology. These ideas explain high-yielding varieties, hybrids and Bt crops that you meet in crop production.
How to prepare
Practise Mendelian ratios (3:1, 1:2:1, 9:3:3:1, 1:1) until they are automatic. Make a comparison chart of mitosis and meiosis. Learn the base-pairing rules for DNA. For breeding, list each method with one example and whether it suits self- or cross-pollinated crops. Learn key terms: heterosis, polyploidy, totipotency, transgenic.
Topics in this chapter
Cell structure and cell division
The cell, mitosis and meiosis and their significance.
6 questionsGenetic material
Organisation of genetic material in chromosomes; DNA and RNA.
6 questionsMendel’s laws of inheritance
Mendel’s laws, the reasons for his success and the absence of linkage in his experiments.
6 questionsQuantitative inheritance
Continuous and discontinuous variation; monogenic and polygenic inheritance.
6 questionsPlant breeding: history, objectives and methods
Introduction, selection, hybridisation, mutation, polyploidy, tissue and cell culture in self- and cross-pollinated crops.
6 questionsPlant biotechnology
Definition, scope in crop production and role in plant breeding.
5 questions