#migration

C-Elegans Development-l

Which protein is responsible for the migration of P-granules during early development?

P-granule segregation depends on microtubule cytoskeleton immediately after fertilization. Sperm centrosome generates radial microtubule array, and cytoplasmic dynein heavy chain DHC-1 with accessory LIS-1, DNC-1 dynactin and DLC-1 light chain transports RNP granules containing PIE-1, GLH-1, PGL-1 toward posterior cortex using minus-end directed movement. Actomyosin cortical flows assist initiation, but dynein inhibition via RNAi randomizes granules throughout AB and P1, disrupting germline. Proper posterior localization ensures partitioning solely into P1-P4 lineage, protecting germline RNAs, preventing somatic differentiation, preserving totipotency until Z2/Z3 formation.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 8: P-granule segregation and dynein-dependent transport mechanisms.

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Dictyostelium

Dictyostelium slug migrates towards:

The Dictyostelium slug displays pronounced positive phototaxis and thermotaxis, moving toward light and warmer areas of soil surface. Anterior prestalk tip functions as organizer sensing light via putative rhodopsin-like mechanism and lens effect, translating photic cues into altered cAMP and ammonia signaling. Light reduces ammonia retention at tip, loosening slug and steering migration. Orientation toward bright areas positions future fruiting body for efficient wind dispersal of spores away from depleted bacterial zones. Movement toward dark, moist, or dry microenvironments would retain spores underground, reducing fitness, making phototaxis essential for successful dispersal and life cycle completion.

Ref: Nature Reviews Microbiology, Dictyostelium phototaxis - anterior tip photosensing and spore dispersal strategy.

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Population Attributes - Birth Death Sex Ratio Age Distribution

Which of the following correctly defines immigration in population ecology?

Immigration refers to the movement of individuals into a population, increasing its size.

Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Attributes - Birth Death Sex Ratio Age Distribution

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Darwinism Lamarckism and Modern Synthetic Theory

Which principle is violated when allele frequencies in a population change due to migration?

Migration causes gene flow, which violates the Hardy-Weinberg Principle by altering allele frequencies.

Ref: NCERT Class 12 Biology Chapter 6: Evolution Darwinism Lamarckism and Modern Synthetic Theory

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Hardy–Weinberg principle

Migration alters allele frequencies by:

Introducing or removing alleles reflects key principle in quiz on hardy–weinberg principle, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Introducing or removing alleles aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Introducing or removing alleles fits helps integrate natural selection, drift and species concepts essential for NEET, CSIR-NET and GATE examinations. This concept integrates genetics, ecology and molecular evidence, frequently tested in NEET, GATE and CSIR-NET, highlighting links between genotype, phenotype

Ref: Hartl, Primer of Population Genetics, Hardy-Weinberg Equilibrium.

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