Biology · SEXUAL REPRODUCTION IN FLOWERING PLANTS

Sporopollenin, a constituent of the exine of pollen grains, is considered one of the most resistant organic substances because it:

1. A
   Is degraded rapidly by pectinase and cellulase
2. B
   Can withstand high temperatures, strong acids, and alkali, and no enzyme that degrades it is known
3. C
   Forms a continuous hydrophilic coat over the intine
4. D
   Is composed exclusively of cellulose and pectin