what are the exceptions in biology?

1. All living cells have a nucleus except mature red blood cells of mammals.

2. Red blood cells of all mammals are without nucleus except those of camel.

3. Roots are positively geotropic but roots of mangrove plants - Rhizophora and Sonneratia are negatively geotropic.

4. Stem is the part of plant above the ground but potato, corm and ginger are underground stems.

5. Cuscuta, a parasitic plant is classified with dicotyledonous plants but lacks cotyledons.

6. Blood of all vertebrates is red due to the presence of hemoglobin but a shark, Carcharhinus, has colourless blood.

7. DNA is hereditary material in all living beings except some viruses such as tobacco mosaic virus or influenza virus.

8. Axolotl, the aquatic larvae of American salamander develops gonads and reproduces in spite of retaining its larval characters.

9. Periapt's, a small worm-like animal is placed with phylum Arthropod.

10. Plants are mostly green with chlorophyll and animals without chlorophyll. Euglena is classified with animal kingdom.

11. Mushrooms are plants devoid of chlorophyll.

12. Mammals are viviparous but duck-billed platypus and spiny anteater are egg-laying mammals.