Sexual Reproduction in Flowering Plants – Quick Revision

Chapter Weightage (Relevant Sections Only)

• Sexual Reproduction in Flowering Plants: $6.02\%$ (1 Q)

• Principle of Inheritance & Variation: $9.40\%$ (2 Q blocks)

• Molecular Basis of Inheritance: $11.65\%$

• Microbes in Human Welfare: $2.26\%$

• Organisms & Population: $4.51\%$

• Ecosystem: $4.89\%$

• Biodiversity & Conservation: $3.76\%$

Life-Cycle Phases in Plants

• Juvenile/Vegetative: growth of roots, stem, leaves (no flowers)

• Reproductive: flowering → seed formation

• Senescent: metabolic decline → death

Reproduction Types

• Asexual: fission, budding, fragmentation, regeneration, gemmae; vegetative (runner, stolon, offset, sucker, tuber)

• Sexual: $2n \xrightarrow{meiosis} n$ gametes → fusion → $2n$ zygote → embryo → seed (end product)

Sexual Reproduction in Flowering Plants

• Angiosperms: seeds enclosed in fruit
  • Monocots: one cotyledon (e.g., wheat)
  • Dicots: two cotyledons (e.g., pea)

• Stamen: microsporangium → pollen grains

• Pistil: megasporangium → embryo sac

• Key events: pollination → double fertilization → post-fertilization (seed & fruit formation)

• Ovule → seed; integument → seed coat; ovary → fruit; ovary wall → pericarp (fruit wall)

• Special phenomena: apomixis, polyembryony

Floral Whorls (Structure/Questions Focus)

• Outermost whorl: calyx (sepals)

• Calyx absent in unisexual flowers lacking corresponding sex organ (missing androecium or gynoecium)

• Sepal whorl = calyx; petal whorl = corolla; stamen whorl = androecium; carpel whorl = gynoecium

Plant Categories (Terminology)

• Annual: complete life cycle within one year (seed once) – e.g., wheat

• Biennial: two years (year $1$: vegetative, year $2$: reproductive) – e.g., carrot

• Perennial: live many years, flower repeatedly – e.g., mango
  • Exception: bamboo & Neelakurinji (perennial but flower only once)

Vascular vs Non-Vascular Overview

• Vascular, diploid sporophyte dominant: pteridophytes, gymnosperms, angiosperms

• Non-vascular: algae, fungi (haploid dominant), bryophytes (haploid gametophyte plant body)

Quick Concept Check (Typical MCQs)

• Floral whorl absent in unisexual flower: either androecium or gynoecium

• Outermost whorl: calyx

• Whorl of sepals: calyx

• Part developing into fruit: ovary

End Goal for Next Lecture

• Deep-dive into flower structure & terminology.