Sex Genes And Agriculture Flashcards
What are the two main modes of plant reproduction?
- Sexual Reproduction: Produces genetically diverse offspring via fertilization.
- Asexual Reproduction: Produces genetically identical clones through vegetative propagation.
What is the difference between self-pollination and cross-pollination?
- Self-pollination: Pollen from a flower fertilizes its own ovule.
- Cross-pollination: Pollen fertilizes the ovule of another flower, increasing genetic diversity.
Define monoecious and dioecious plants with examples.
- Monoecious: Male and female flowers occur on the same plant (e.g., maize).
- Dioecious: Male and female flowers are on separate plants (e.g., holly, date palm).
What is self-incompatibility, and why is it important?
Self-incompatibility prevents self-fertilization, promoting outcrossing. It is controlled by the S-locus.
What are the two types of self-incompatibility?
- Gametophytic SI: Controlled by the haploid pollen genotype.
- Sporophytic SI: Controlled by the diploid parent plant’s genotype.
What is hybrid vigor, and why is it important in agriculture?
Hybrid vigor (heterosis) is the improved performance of F1 hybrids compared to parents, including higher yield, growth rate, and resistance to stress.
What is inbreeding depression, and how does it impact plants?
Inbreeding depression occurs due to the expression of deleterious alleles in self-fertilized or closely related plants, reducing fitness and yield.
What causes genetic bottlenecks in crops, and what are their consequences?
Bottlenecks occur due to domestication and breeding, leading to a loss of genetic diversity, making crops vulnerable to disease and climate change.
How is polyploidy beneficial in agriculture?
Polyploid plants have larger cells, increased size, and enhanced stress tolerance. Examples: wheat (hexaploid), strawberries (octoploid).
What is allopolyploidy, and how does it occur?
Allopolyploidy combines genomes of different species through hybridization and chromosome doubling. Example: Triticale (wheat x rye).
What is mutation breeding, and how is it used?
Mutation breeding uses chemicals (e.g., EMS) or radiation to induce mutations, creating plants with beneficial traits (e.g., disease resistance).
What were the key advancements of the Green Revolution?
Development of high-yielding, disease-resistant crop varieties (e.g., dwarf wheat and rice) using traditional breeding and modern inputs.
What are GM crops, and give two examples.
GM crops contain foreign genes introduced via genetic engineering. Examples:
1. Bt Corn: Produces a bacterial toxin toxic to pests.
2. Golden Rice: Contains genes for beta-carotene (Vitamin A precursor).
What is CRISPR-Cas9, and how is it used in agriculture?
CRISPR-Cas9 is a gene-editing tool that enables precise modification of plant genomes to enhance traits like disease resistance and drought tolerance.
What experiment proved the effectiveness of Bt crops?
Bt crops were tested against pests like European corn borer. Results showed reduced pest damage and improved yields.
What is marker-assisted selection (MAS), and why is it useful?
MAS uses molecular markers to select plants with desirable traits, speeding up breeding programs and increasing precision.
Why are wild relatives of crops important in agriculture?
Wild relatives provide genetic diversity for breeding resistance to diseases, pests, and environmental stress.
What are seed banks, and why are they critical?
Seed banks preserve genetic material of plants to safeguard against biodiversity loss. Example: Svalbard Global Seed Vault.
What is CMS, and how is it used in hybrid seed production?
CMS prevents pollen formation, ensuring hybrid seed production without manual emasculation.
How was hybrid vigor demonstrated in maize?
Crossing two inbred maize lines resulted in F1 hybrids with higher yield, growth, and stress resistance compared to the parent lines.
What are the arguments for and against GM crops?
- For: Increased yields, reduced pesticide use, nutritional benefits.
- Against: Environmental concerns, loss of biodiversity, consumer skepticism.
What is domestication syndrome?
Traits favored during domestication, such as reduced seed shattering and increased seed size, that distinguish crops from wild relatives.
