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Questions and Answers
What is the primary focus of plant genetics?
What is the primary focus of plant genetics?
What did Gregor Mendel discover in his research?
What did Gregor Mendel discover in his research?
What are chromosomes primarily responsible for during cell division?
What are chromosomes primarily responsible for during cell division?
What is a locus in the context of genetics?
What is a locus in the context of genetics?
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Which of the following is NOT a role of biodiversity in crop improvement?
Which of the following is NOT a role of biodiversity in crop improvement?
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What defines an organism as diploid?
What defines an organism as diploid?
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What is the role of meiosis in sexual reproduction?
What is the role of meiosis in sexual reproduction?
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How does climate change impact plant genetic diversity?
How does climate change impact plant genetic diversity?
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What term describes the complete set of chromosomes in a given species?
What term describes the complete set of chromosomes in a given species?
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What does the term 'allele' specifically refer to?
What does the term 'allele' specifically refer to?
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How is genetic variation primarily achieved?
How is genetic variation primarily achieved?
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Which of the following correctly defines a gene?
Which of the following correctly defines a gene?
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If an individual is heterozygous at a locus, what does that mean?
If an individual is heterozygous at a locus, what does that mean?
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What is the composition of a genotype?
What is the composition of a genotype?
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What distinguishes a haploid cell from a diploid cell?
What distinguishes a haploid cell from a diploid cell?
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What is meant by the 'phenotype' of an individual?
What is meant by the 'phenotype' of an individual?
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What defines a locus as homozygous?
What defines a locus as homozygous?
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Which method is described as the simplest for genotype assessment?
Which method is described as the simplest for genotype assessment?
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What are molecular markers used for?
What are molecular markers used for?
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What process is used to visualize DNA fragments after gel electrophoresis?
What process is used to visualize DNA fragments after gel electrophoresis?
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Which statement correctly reflects the limitations of morphological markers?
Which statement correctly reflects the limitations of morphological markers?
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How do restriction endonucleases function in molecular marking?
How do restriction endonucleases function in molecular marking?
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What impact does a plant species' mating system have on its genetic variation?
What impact does a plant species' mating system have on its genetic variation?
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Which of the following traits is NOT commonly associated with morphological markers in plants?
Which of the following traits is NOT commonly associated with morphological markers in plants?
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What defines self-pollination in plants?
What defines self-pollination in plants?
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Which process leads to genetically equal offspring to the parental plant?
Which process leads to genetically equal offspring to the parental plant?
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What is the consequence of inbreeding in cross-pollinated species?
What is the consequence of inbreeding in cross-pollinated species?
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What is heterosis more commonly referred to as?
What is heterosis more commonly referred to as?
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How does self-pollination affect heterozygosity in plants?
How does self-pollination affect heterozygosity in plants?
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Which statement best characterizes apomictic species?
Which statement best characterizes apomictic species?
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What role does heterozygosity play in plant reproduction?
What role does heterozygosity play in plant reproduction?
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What is the primary impact of inbreeding on plant performance in self-pollinated species?
What is the primary impact of inbreeding on plant performance in self-pollinated species?
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What primarily drives evolution leading to local adaptation in plant populations?
What primarily drives evolution leading to local adaptation in plant populations?
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Which trait associated with fitness may affect plant survival?
Which trait associated with fitness may affect plant survival?
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What is genetic drift likely to occur?
What is genetic drift likely to occur?
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What effect does artificial selection have on plant populations?
What effect does artificial selection have on plant populations?
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What does it mean when a trait is described as 'heritable'?
What does it mean when a trait is described as 'heritable'?
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What is the relationship between fitness and allele frequencies in a population?
What is the relationship between fitness and allele frequencies in a population?
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Which process can lead to the complete exclusion of alleles in a small sample during genetic drift?
Which process can lead to the complete exclusion of alleles in a small sample during genetic drift?
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How does natural selection relate to alleles and fitness in a population?
How does natural selection relate to alleles and fitness in a population?
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What is genetic erosion primarily associated with?
What is genetic erosion primarily associated with?
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What is one major cause of crop diversity erosion?
What is one major cause of crop diversity erosion?
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Which of the following is an example of a factor contributing to the disappearance of crop diversity?
Which of the following is an example of a factor contributing to the disappearance of crop diversity?
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How has the seed market been affected in recent years according to the information provided?
How has the seed market been affected in recent years according to the information provided?
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What was the fate of many cabbage varieties over the years as highlighted in the study?
What was the fate of many cabbage varieties over the years as highlighted in the study?
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In the context of crop diversity, what does the term 'resilience' refer to?
In the context of crop diversity, what does the term 'resilience' refer to?
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What can be implied about the relationship between extreme weather events and crop diversity?
What can be implied about the relationship between extreme weather events and crop diversity?
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What is a likely consequence of losing crop varieties according to the provided information?
What is a likely consequence of losing crop varieties according to the provided information?
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Study Notes
Principles of Genetics
- The study of genes, genetic variation, and heredity in plants is known as plant genetics.
- Understanding plant genetics is crucial for crop breeding and conservation of plant genetic diversity.
- Plant genetic resources include genotypes of particular species collected from different sources and geographical origins for use in plant breeding.
- Germplasm is the sum total of hereditary material (alleles of various genes) in a crop species and its wild relatives.
- Different types of plant genetic resources exist including landraces, farmers' varieties, parental lines of hybrids, released varieties, primitive cultivars and wild/weedy relatives.
- Biodiversity is crucial for crop improvement, influencing the resilience of ecosystems and the stability of societies.
- Destroying biodiversity is akin to setting fire to the planet's lifeboat.
- Each species has a characteristic number of chromosomes in its somatic (non-reproductive) cells.
- There are different methods of assessing genotypes, both morphological and molecular.
- Morphological markers are easily observed genetically-determined traits.
- Molecular markers identify differences in the genetic code and are used for DNA fingerprinting.
- Plant DNA is segmented by enzymes called restriction endonucleases.
- DNA fragments are separated by gel electrophoresis.
- Alleles are variations of genes that may differ between chromosomes in a diploid species or among chromosomes in a polyploid species.
- Multiple alleles of a gene develop through mutations, which are structural or chemical changes in DNA.
- Reproductive cells (like sperm and egg) are haploid, with half the number of chromosomes as a diploid cell.
Genetic Variation in Plants
- Genetic variation is the result of differences between individuals in a population.
- It's influenced by allelic differences due to mutations and random assortment of alleles during meiosis (a special type of cell division that creates sperm and egg cells).
- A diploid organisms has two genomes, one from each parent.
- The total chromosomal DNA of an organism is called its genome.
- Genotype refers to the set of alleles an organism possesses at a given locus or over many loci.
- Phenotype refers to the observable characteristics of an organism.
- If different alleles exist at a given locus, that locus is called heterozygous.
- If alleles at a locus are the same, that locus is homozygous.
- Different methodologies exist that can help in the assessment of genotypes (morphological and molecular).
- Although morphological markers are simple to use, their availability is limited, mostly focusing on intensively studied cultivated varieties.
- Molecular markers use the genetic code(DNA) for identification, through the process called DNA fingerprinting.
Reproduction, Mating Systems, and Genetic Variation
- Reproduction in plants can range from complete self-pollination to complete cross-pollination.
- Individuals in self-pollinated species tend to be highly homozygous.
- In cross-pollinated species, heterozygosity is more common and preserved across generations.
- Apomixis is an asexual reproductive process where seeds develop from body cells rather than the combination of sperm and egg.
- Inbreeding may lead to a decline in plant performance known as inbreeding depression.
- A single genotype can occupy large areas in apomictic species, leading to less genetic diversity.
- Heterosis, or hybrid vigor is observed when the offspring of a mating have superior performance compared to the parent plants.
Crop Diversity
- Crop diversity is essential for sustainable food production and ensuring food security in the face of climate change and other challenges.
- Conserving and utilizing crop diversity is important as it enables species to adjust to a range of circumstances and various environmental conditions.
- Plant species exhibit great variability in sexual reproduction significantly affecting genetic constitution of species.
- Current practices are limited to using a small sample of limited crop diversity.
- The loss of plant varieties and wild relatives is irreversible, making their conservation vital.
- The global loss of varieties is problematic as it is now fewer than 200 of the 20,000 edible plants which make up the majority of our food crops globally.
- Many crop varieties are now endangered or have become extint.
- The reduction in crop biodiversity makes crop species susceptible to pests and disease, and reducing resilience to environmental changes affecting agricultural production.
- Genetic uniformity makes crop species vulnerable to epidemics, whereas diversity makes them more resilient.
- A handful of multinational companies currently supply most commercial seeds, which contributes to the decline of crop diversity.
- Artificial selection is comparable to natural selection as plant breeders choose (retain) plants with desirable traits.
Genetic Erosion
- The loss of genetic diversity in crops and wild relatives is referred to as genetic erosion.
- The modernization of agriculture, including the replacement of traditional varieties with high-yield cultivars; natural disasters; and large-scale habitat loss contribute to genetic erosion.
- Genetic uniformity contributes to a species being susceptible to epidemics.
Evolution and Natural Selection
- Evolution is a collection of processes that results in allele frequency changes over time.
- Natural selection is based on fitness—the tendency of an individual and its offspring to survive—and may be connected to a plant's longevity, fertility, ability to produce viable offspring.
- Genetic variation influencing a trait is heritable (heritability > 0), higher fitness individuals have more offspring on average, and genetic composition in the population becomes more similar to that of the more fit individuals.
Other Processes that Can Lead to Genetic Changes
- Random genetic drift is a process driven by chance.
- The founder effect is a type of genetic drift that occurs when a new population is established from a very small number of individuals from an original population.
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Description
This quiz explores the fundamental concepts of plant genetics, including gene variation, heredity, and the importance of biodiversity in crop breeding. Additionally, it covers the types of plant genetic resources and the significance of preserving genetic diversity for sustainable agriculture. Test your knowledge and understanding of these critical topics.
