Question

Basal placentation occurs in
A) Brassicaceae
B) Asteraceae
C) Liliaceae
D) Both Poaceae and Asteraceae

Answer 1

Hint:The basal placenta is located in the syncarpous ovary, mono to multi-carpellary. A single ovule is normally connected to the base.

Complete answer:
First we should know about the placentation to answer this question. Placentation relates in biology to the placenta’s development, shape and function, or organisation. The aim of Placentation is to transfer food, respiratory gases and water to a developing embryo from mother tissue and, in some cases, to extract waste from the embryo.
Now, let us find the solution from the options-
- In Brassicaceae, the parietal placentation occurs where the placenta is created by the swelling of the margins of coherence, and the ovules grow on the latter in rows. Thus, the option A is incorrect.
- In Liliaceae, the axile placentation occurs where the placenta relates to the confluent margins of carpels, growing from the central axis. Thus, the option C is incorrect.
- In Poaceae and Asteraceae, the basal placentation occurs where the placenta forms immediately at the base of the unilocular ovary on the thalamus and carries a single ovule.

Thus, the correct answer is option (D) Both Poaceae and Asteraceae.

Note:The effect of genetic drift is higher when there are less copies of an allele, and the effect is lower when there are more copies. Ronald Fisher, who used Mendelian genetics to explain natural selection, held the opinion that genetic variation plays a small role in evolution at most, and for many decades, this became the dominant view.