30 Questions
True or false: The presence of genetic variation is not important for genetic improvement in plant breeding.
False
True or false: Plant breeders and students in plant breeding cannot benefit from understanding the sources of genetic variation.
False
True or false: The source of genetic material in a breeding program can only come from one's own breeding program.
False
True or false: Random genetic drift is a controllable process in natural selection.
False
Germplasm developers prioritize working on specific traits, while cultivar development breeders consider overall commercial suitability.
True
Engaging growers, industry, and consumers helps in setting breeding objectives.
True
Breeding populations are created by crossing parents, and selection for traits occurs alongside generation advancement.
True
The National Plant Germplasm System in the USA aids scientists in obtaining genetic diversity.
True
True or false: Artificial selection involves the deliberate choice of individuals for breeding in each generation to advance select individuals.
True
True or false: Maize evolved from its progenitor, teosinte, through natural selection.
False
True or false: Ears of teosinte disarticulate at maturity, while ears of maize remain intact for easy harvest.
True
True or false: Long-term artificial selection experiments on maize have been conducted, showing the effects of selection on oil and protein content.
True
True or false: Lethal mutations increase genetic variation.
False
True or false: Germline mutations are passed on to offspring.
True
True or false: Quality Protein Maize (QPM) has half the lysine and tryptophan content compared to regular maize.
False
True or false: The M2 generation is produced through self-fertilization of the M1 plants.
True
True or false: The primary gene pool consists of cultivated varieties, landraces, ecotypes, and wild or weedy races, and is the major source of genetic variation for breeding programs.
True
True or false: Hybrids in the secondary gene pool tend to be fertile and have good chromosome pairing during meiosis.
False
True or false: Gene transfer between the crop and species in the tertiary gene pool is very difficult and may require special techniques such as embryo rescue or chromosome doubling.
True
True or false: Wide hybridization involves crossing individuals within cultivated species, typically from the primary or secondary gene pools.
False
What are the main goals of understanding variability and heredity?
The main goals of understanding variability and heredity are to clarify their role in organic evolution and to prove the impossibility of reducing evolution to these premises.
How is heredity determined?
Heredity is determined by the principle of transmission of the hereditary code through a process similar to obtaining prints, copies from the same print (matrix).
What determines variability?
Variability is determined by the absolute stability of the molecules forming a chain of genes and the influence of external conditions that determine the specific manifestation of a particular genetic germ in these specific conditions.
What is the significance of mineral nutrition for plants?
The main importance is mineral nutrition, a change in the composition of which causes plants to transform their form.
What are correlations in ontogenetic development?
Correlations are secondary changes that occur during ontogenetic development under the influence of some primary change.
Who introduced the concept of correlations?
Charles Darwin introduced the concept of correlations.
What is the importance of correlative variability?
Correlative variability explains the emergence and preservation of implicitly adaptive features in offspring.
What is the difference between genotype and phenotype?
The genotype refers to the system of heredity units (genes) that determine the development of different phenotypes. The phenotype, on the other hand, is the set of signs and properties of an individual, influenced by both genotype and environment.
What are mutations and how do they affect the phenotype?
Mutations are discrete changes in the general code of hereditary information. Changes in the genotype, resulting from mutations, lead to changes in the phenotype.
What are the factors that can cause non-hereditary changes in an organism's phenotype?
Non-hereditary changes, called modifications, arise under the influence of environmental factors within one reaction norm. These factors include temperature, humidity, light, chemical properties of water and soil, and the effects of other organisms.
Study Notes
Understanding Gene Pools in Crop Breeding
- Gene pools of a crop species are categorized as primary, secondary, and tertiary based on the ease of gene transfer between them.
- The primary gene pool consists of cultivated varieties, landraces, ecotypes, and wild or weedy races, and is the major source of genetic variation for breeding programs.
- The secondary gene pool includes related species within the same genus, and gene transfer between the crop and these species is possible but difficult.
- Hybrids in the secondary gene pool tend to be sterile and have poor chromosome pairing during meiosis.
- The tertiary gene pool includes distant relatives in other genera or distantly related species within the same species.
- Gene transfer between the crop and species in the tertiary gene pool is very difficult and may require special techniques such as embryo rescue or chromosome doubling.
- Bridging species can facilitate gene exchange between crop species and tertiary gene pool species by developing complex hybrids.
- Wide hybridization involves crossing individuals outside of cultivated species, typically from the secondary or tertiary gene pools.
- Wide crosses may be useful for transferring important traits such as disease resistance that are not found in cultivated genotypes.
- In wheat, the T1BL.1RS wheat-rye hybrid has been widely used in breeding programs for disease resistance and yield improvement.
- In rice, genes for resistance to diseases such as grassy stunt virus and bacterial blight have been successfully transferred from wild species to cultivated rice.
- Other examples of wide hybridization can be found in Table 1.
Variability and Heredity in Biology
- The nature of observed variability in biology is dual and contradictory.
- Charles Darwin distinguished several forms of variability.
- Johannsen proposed the terms genotype and phenotype.
- The phenotype is the set of signs and properties of an individual, influenced by both genotype and environment.
- The genotype is a system of heredity units (genes) that determine the development of different phenotypes.
- Changes in the genotype result in changes in the phenotype.
- Phenotypic variability can be hereditary (genotypic) or non-hereditary (modification).
- Hereditary changes are mutations, which are discrete changes in the general code of hereditary information.
- Mutations can affect genes, chromosomes, the number of chromosomes, or extra-nuclear cell structures.
- Non-hereditary changes, called modifications, arise under the influence of environmental factors within one reaction norm.
- Environmental factors include temperature, humidity, light, chemical properties of water and soil, and the effects of other organisms.
- Temperature, humidity, and light have significant modifying effects on organisms, causing diverse changes in color, shape, and size.
Test your knowledge on gene pools in crop breeding with this quiz. Learn about the different categories of gene pools, the challenges of gene transfer, and the importance of wide hybridization for improving crop traits. Explore real-life examples of successful gene exchange between crop species and related species.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
