T-independent response

Type 1 T-independent (TI-1) antigens bind to B cells through both Ig and innate immune receptors. LPS from Gram negative organisms binds to B cells via both mIg and TLR, resulting in signaling from both receptors. 

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III.Vascular plants  (pteridophyta)

Homosporous or Heterosporous

Sexual reproduction- Oogamous

Antheridium-  Sessile and reduced in size

Haplodiplontic-  alteration of generation

Spores produced inside the sporangia on leaves

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Habitat

Plants annual or perennials.

Xeric- Selaginella lepidophylla

Aquatic- Azolla, Marsilea, Salvinia

Epiphytic- i.e., growing on large trunks of trees. Ex- Lycopodium

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III. Vascular plants (pteridophyta)

EVOLUTION OF ROOTS

Instead of the rhizoids seen in bryophytes, roots evolved in the sporophytes of almost all vascular plants

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III. Vascular plants  (pteridophyta)

EVOLUTION OF LEAVES

spore-bearing leaves called sporophylls

In terms of size and complexity, leaves can be classified as either microphylls or megaphylls

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Sporophylls and Spore Variations

Sporophylls produce clusters of sporangia known as “sori”

Groups of sporophylls form cone-like structures called “strobili”