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#asexual reproduction

13 public questions tagged with this topic.

Apomixis refers to:

Apomixis signifies alternative reproductive pathway where seeds form without meiosis and syngamy, producing offspring clonal to maternal parent preserving heterozygosity and hybrid genotype. Developmental routes include apospory where embryo sac initiates from somatic nucellar cell bypassing megaspore mother cell differentiation, diplospory where megaspore mother cell undergoes mitosis instead of meiosis forming unreduced embryo sac, and adventitious embryony where embryo develops directly from nucellar tissue. Unreduced egg cell then develops parthenogenetically via activation of egg cell transcription factors like BABY BOOM without sperm contribution. Endosperm formation may require pseudogamy where central cell still fertilized or autonomous where it develops spontaneously. Genetic control governed by apomixis-specific genomic region ASGR containing genes for apomeiosis and parthenogenesis, studied in Pennisetum and Hieracium. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs.

Ref: Bicknell & Koltunow Annu Rev Plant Biol apomixis mechanisms; Carman et al Apomixis genetics; NCERT Biology Apomixis introduction.

Asexual reproduction in plants produces:

Asexual reproduction in higher plants bypasses syngamy, producing progeny via mitotic divisions from somatic tissues, preserving maternal genotype intact except somatic mutations. Modes include vegetative propagation through runners, rhizomes, suckers, tubers, bulbs, corms and apomictic seed formation via nucellar embryony where diploid nucellar cells develop into embryos without meiosis. Because meiosis absent, segregation does not occur and heterozygosity fixed, resulting in clones that are phenotypically uniform. Meristematic activity regulated by cytokinin-auxin balance induces adventitious shoot formation. Commercial advantage includes rapid multiplication of elite hybrids retaining complex traits like sugar content in sugarcane, fruit quality in mango and disease resistance, though lack of recombination restricts adaptation to evolving pathogens and environmental change. This understanding supports competitive exam preparation for NEET, GATE and CSIR NET concepts linking genotype with phenotype through molecular pathways involving transcription factors, hormones and metabolic enzymes that regulate development, adaptation and reproductive biology in applied breeding programs. Additional insights from genomic studies reveal QTL clusters, epigenetic modifications and protein interactions that influence trait expression under varied agro-climatic conditions and management.

Ref: Hartmann & Kester Plant Propagation Asexual cloning; NCERT Class XII Reproduction chapter; Acquaah Clonal crops.

Which group of fungi is commonly known as “imperfect fungi” because only its asexual or vegetative phases are known?

Deuteromycetes are called imperfect fungi because only their asexual or vegetative phases are known. When their sexual forms are discovered, they are moved to the fungal classes to which they correctly belong.

Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Phycomycetes Ascomycetes Basidiomycetes

Only the asexual and vegetative phases of a fungus are known, and it reproduces by conidia. What should happen if its se

Deuteromycetes include fungi for which only the asexual or vegetative stages are known. When the sexual stage is discovered and its relationship is established, the fungus is moved to the appropriate fungal class, often Ascomycetes or Basidiomycetes.

Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Phycomycetes Ascomycetes Basidiomycetes

Which group shows both sexual and asexual reproduction?

Both sexual and asexual strategies occur widely demonstrating evolutionary flexibility: Cnidaria reproduce asexually by budding, fission, pedal laceration and stolon extension while medusae and polyps release gametes sexually, showing generational alternation metagenesis. Ctenophora hermaphroditic individuals broadcast gametes but some benthic platyctenids undergo fragmentation and dissogony where larva matures precociously reproducing before adult form. Rotifera exhibit heterogonic cycle with amictic parthenogenesis producing diploid females rapidly colonizing, mictic sexual phase yielding haploid males and diapausing resting eggs surviving desiccation. Combined capacity for rapid clonal expansion and recombination provides colonization advantage, thus all listed phyla display both modes unlike obligately sexual taxa.

Ref: NCERT Class 11 Biology, Chapter 4: Asexual and sexual reproduction Cnidaria Ctenophora Rotifera

Most ectoprocts reproduce asexually to form

Primary mode of propagation and colony expansion in ectoprocts involves asexual budding where daughter zooids bud from parental body wall producing interconnected zoarium of polymorphic zooids specialized for feeding, defense, reproduction and support. Budding generates modular growth optimized for sessile filter feeding maximizing space capture. Sexual reproduction also present producing cyphonautes triangular shelled or coronate non-feeding larvae settling to form ancestrula founding new colony. Freshwater phylactolaemates additionally produce statoblasts as dormant chitinous propagules highly resistant to desiccation, emphasizing prevalence of asexual colony formation and resilience enabling survival in variable environments and dispersal across habitats.

Ref: Ruppert et al., Invertebrate Zoology, Chapter 23: Bryozoa budding colony formation

Most deuteromycetes reproduce asexually by

Most deuteromycetes propagate asexually through conidia, non-motile mitosporic propagules produced exogenously on differentiated hyphae termed conidiophores through blastic or thallic development. Conidial types include microconidia, macroconidia, phialospores formed from phialides, porospores through pores, arthrospores via fragmentation, often multicellular, melanized, ornamented favoring airborne dispersal and stress tolerance. No ascospores, basidiospores, zygospores or flagellated zoospores develop due to absence of meiosporangia. Genetic variation arises via parasexual cycle involving heterokaryosis, diploidization and mitotic crossing over plus mutation ensuring adaptability despite lack of meiosis.

Ref: NCERT Class 11 Chapter 2 Fungi; Alexopoulos Introductory Mycology Form-class Deuteromycetes

Saccharomyces cerevisiae reproduces asexually mainly by

Saccharomyces cerevisiae, commonly known as baker's or brewer's yeast, is a unicellular ascomycete where asexual reproduction predominantly involves budding, an asymmetric mitotic process producing genetically identical daughter cells. A small bud emerges on mother cell surface after S-phase, nucleus divides by mitosis, one nucleus migrates into growing bud along with cytoplasm and organelles, cytokinesis forms septum leaving chitinous bud scar. Mother continues producing multiple buds sequentially, daughter enlarges to parent size before separation. This rapid proliferation dominates sugar-rich environments like dough fermentation, differing from fragmentation, exogenous conidia formation or transverse binary fission.

Ref: NCERT Class 11 Biology Chapter 2: Fungi; Lodish Molecular Cell Biology 8th ed., Yeast Cell Cycle

In Deuteromycetes, asexual reproduction typically occurs via the production of spores known as:

Because Deuteromycetes are defined by their lack of known sexual reproduction, they rely entirely on asexual mechanisms to propagate. The NCERT textbook specifies that members of Deuteromycetes reproduce asexually exclusively by producing spores called 'conidia'. These are exogenously produced spores, similar to those found in Ascomycetes, hinting at their close evolutionary relationship before their sexual stages are confirmed.

Ref: NCERT Class 11 Biology > Chapter 2: Biological Classification > 2.3 Kingdom Fungi