Actin can reversibly assemble into filaments that consist of two helices of actin subunits

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#XL - R Botany

“Ernst Mayr” pioneered the currently accepted definition of a “Biological Species concept”

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#XL - R Botany

Modification of stem

I.Aerial stem modification

Aerial modification can be classified into tendrils, thorns, and phylloclade. 

Stem tendrils which develop from axillary buds, are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins, watermelon) and grapevines

I.Aerial stem modification

Some plants of arid regions modify their stems into flattened (Opuntia), or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carryout photosynthesis.

Example- Cactus (Opuntia), Sparrow grass (Asparagus), etc. 

I.Aerial stem modification

Axillary buds of stems may also get modified into woody, straight and pointed thorns, hard, spiny structure protect plants from grazing animals.

Found in many plants such as- Pomegranate (Punica granatum), Paper flower (Bougainvillea glabra), Lemon (Citrus limon), etc.

II.Subaerial Stem modification

Subaerial modification can be classified into four types, namely stolon, runner, sucker, and offset. 

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#XL - T Zoology

#Id: 9676

#XL - T Zoology

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#XL - Q Biochemistry

Hac1 activates transcription of genes encoding several protein-folding catalysts.