Answer: definetly A, food webs
Explanation:
the other options are not even related to organisms
The source of all energy in the pyramid in model one is the hawk
All mentioned complexes (receptor-hormone, antibody-antigen, enzyme-substate) are involved in a molecular recognition.The molecular recognition involves <span>non-covalent </span> interaction between molecules. To form complex, molecules must be complementary in shape and charges, and usually, they are compared to key and lock. This way, the selectivity and specificity of recognition between molecules are assured.
C. The cell must be a plant cell.
Only plant cells have cell walls. Bacteria cells and animal cells do not. Both animal cells and plant cells have membrane-bound organelles, but since the student saw a cell wall, it must be a plant cell.
Hope this helps! :)
