Phloem

• Made of: phloem sieve tubes, companion cells, and phloem parenchyma; function: transport products of photosynthesis (sucrose, amino acids) from source cells (palisade + spongy mesophyll cells) to sink cells (any respiring cell)
• Sieve tube cells are living cells that lose their nuclei and some organelles but retain a cytoplasmic lining, together they form a long tube (line up end to end); the cross walls do not break down completely, but form sieve plates
• Companion cells: Each sieve tube cell has an adjacent companion cell that metabolically supports the sieve tube cell 
• Fibres are lignified, dead cells that have a structural support function in the plant and parenchyma cells are living cells that store starch
• Phloem adaptations

  A) nuclei

  B) organelles

  C) cytoplasm

  D) more

  E) phloem sap

  F) less

  G) sieve tube

  H) sieve plates

  I) phloem sap

  J) sieve tube

  K) cytoplasm

  L) nucleus

  M) mitochondria

  N) metabolic

  O) phloem sieve

  P) ATP

  Q) plasmodesmata

  R) companion

  S) sieve tube

  T) transfer