Biology 9 Lesson 36: Selection methods
1. Theoretical Summary
1.1. Breed selection
– Breed selection is the process of selection conducted by humans on plants and animals, consisting of two parallel sides, both accumulating beneficial mutations – and eliminating those that are not beneficial to humans, creating varieties. plan, pets.
b. The role of selection in breeding
– Select high yielding, high quality, resistant varieties.
– Satisfy human needs.
– Create new varieties to meet the ever-changing needs of people.
– Restore old varieties showing signs of degeneration.
1.2. Selection methods
a. Mass selection method
– Mass selection is selection based on phenotype, selecting individuals with good phenotype, suitable for selection purposes for breeding.
– Batch selection method has 2 forms: Single batch selection and many times batch selection.
– These two forms are similar in procedure but differ in the year of starting selection.
– This method applies not only to plants but also to livestock.
- Advantages: Easy to implement, inexpensive and can be applied on a large scale.
- Disadvantages: Can’t check genotype, so it can’t consolidate good variation, easily lead to degeneration after a period of selection.
b. Individual selection
– Individual selection is to select a small number of good individuals, from which to multiply individually line by line.
– The method of mass selection also has two types of selection: single selection of individuals and repeated selection of individuals.
- Advantages: Genotyping, accumulation and consolidation of good mutations should be highly effective.
- Disadvantages: Time consuming, labor intensive, difficult to implement, difficult to apply widely.
2. Illustrated exercise
Compare the advantages and disadvantages of the method of mass selection and individual selection?
3.1. Essay exercises
Question 1: How is the method of mass selection once and many times conducted, what are the advantages and disadvantages, and what type of objects is it suitable for?
Verse 2: How is individual selection done? What are the advantages and disadvantages compared to the mass selection method and for which objects is it appropriate?
3.2. Multiple choice exercises
Question 1: The role of selection in breeding is:
A. Improve productivity and quality of livestock and plants
B. Creating new varieties to contribute to the development of animal husbandry and cultivation
C. Restore degraded varieties, create new varieties or improve old varieties
D. Remove old and degraded varieties
Verse 2: The advantages of the batch selection method are:
A. The application is effective on all animals and plants
B. Fast produces results and results are always stable
C. Simple, easy to do, less expensive, can be widely applied
D. Only applied once on all creatures
Question 3: There are many good varieties that have shown obvious signs of degradation in a number of crops
A. the emergence of mutations and artificial hybridization, due to both mechanization in planting, harvesting and storage.
B. the occurrence of artificial mutations and natural hybridization, due to both mechanization in planting, harvesting and storage.
C. the occurrence of mutations and natural hybridization, due to both mechanization in planting, harvesting and storage.
D. the occurrence of artificial mutations and artificial hybridization, due to both mechanization in planting, harvesting and storage.
Question 4: In order to create a good variety, people often carry out
A. Direct breeding of beneficial mutations.
B. direct breeding of beneficial combinations.
C. based on combinatorial variation, mutations are evaluated and selected through a generation.
D. based on combinatorial variation, mutations are evaluated and selected through many generations.
After completing this lesson, you should:
- Describe how selection is and the role of selection in breeding.
- Analyze and compare the advantages and disadvantages of each selection method.