Question

Discontinuous layers in the walls of pollen grains are
A)Absent
B) Foot layer
C) Baculate layer
D)Baculate layer and tectum

Answer 1

Hint: The bacula layer and tectum are parts of the exine of pollen grains and form the different patterns of pollen ornamentation.

Complete answer:
Discontinuous layers are present in the pollen wall. The pollen wall is made up of two layers, a tough and resistant exine and the inner intine. The exine is ornamented and it does not grow in certain positions around the pollen grain which marks the position from where the germ tube would arise.
Chemical called sporopollenin is found in these layers. It is chemically differentiated into two layers, the ektexine and the inner layer, Endexine. The ektexine is differentiated into tectum, bacula and a foot layer. A rod -like element called callumela or bacula is present above the foot layer which is covered by a roof-like layer called tectum. The foot and the tectum prohibits shrinking and crushing the genetic material during desiccation.
The baculate layer has pillar-like structures.
The bacula and tectum form different patterns which give specific identification to the pollen grains are all and are also used in taxonomic studies. They are discontinuous in certain portions.

Hence the correct answer is option ‘D’.

Notes: The pollen grains are contained in the anther of the stamen which is the male reproductive system of flowering plants. The ornamental patterns of the exine in the pollen grain are identifying characters for the plant and are very useful in taxonomic studies. They also attract insects.