Crossword puzzle:

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Across
  1. 4. Slimy,Green patches in ponds or in other stagnant water
  2. 5. Organism that provides nourishment to the parasite
  3. 6. The mode of nutrition where two different organisms work together for their mutual benefit
  4. 7. The process of taking in food by an organism and its utilization by the body
Down
  1. 1. A chlorophyll containing partner,which is an algae and a fungus live together
  2. 2. It is a leguminous plant
  3. 3. Organisms that live on other living organisms and derive the food from them