Zaymiey

🔬 Biology  ·  Plant Kingdom  ·  NEET

Why are cyanobacteria (blue-green algae) placed in Kingdom Monera and not in Plantae?

Answer: They are prokaryotes (no membrane-bound nucleus) unlike plants which are eukaryotes.

  • A They are sometimes mistakenly thought to be incapable of carrying out oxygenic photosynthesis
  • B They are prokaryotes (no membrane-bound nucleus) unlike plants which are eukaryotes
  • C They are sometimes mistakenly thought to largely lack chlorophyll a, the pigment required for light absorption
  • D They are sometimes mistakenly thought to reproduce mainly through sexual fusion of differentiated gametes

Correct answer: B. They are prokaryotes (no membrane-bound nucleus) unlike plants which are eukaryotes

Explanation: Cyanobacteria are prokaryotes: no membrane-bound nucleus, no membrane-bound organelles, no true chloroplasts (photosynthetic membranes are in the cytoplasm). All true plants are eukaryotes. Hence cyanobacteria belong to Monera.

Plant Kingdom: Increasing ComplexityAlgaeno roots/leavesBryophyta"amphibians"no vascular tissuePteridophytafirst vascularno seedsGymno-spermsnaked seedsAngio-spermsseeds in fruitNeed for external water decreases left→right; seed enclosure only appears in angiosperms

Plants evolved from water-dependent algae through increasingly land-adapted groups, gaining vascular tissue (Pteridophyta), then seeds (Gymnosperms), and finally fruit-enclosed seeds (Angiosperms) - each step reducing dependence on water for reproduction.

Concept context

Classification of plants from algae to angiosperms. Understanding plant diversity is essential for NEET.

Read the full Plant Kingdom notes →