Answer:
D. Sterility Locus
Explanation:
Angiosperms have several mechanisms to prevent self-pollination due to the advantage of cross-pollination. One of such mechanisms is self-incompatibility genes present on the sterility locus.
These genes determine the germination of the pollen on the stigma. If both the pollen and stigma carry the same allele of the gene present at the sterility locus, the germination of pollen is prevented.
The sterility locus has multiple alleles and the presence of the same alleles at the same locus in both pollen and stigma prevents the pollen germination.
For example, pollen from S1S2 individuals can not germinate on the stigma with the S1S3 genotype. Here, the pollen does not obtain water as required for germination from the stigma and are unable to germinate.
Answer:
Continental air masses are characterized by dry air near the surface while maritime air masses are moist. Polar air masses are characterized by cold air near the surface while tropical air masses are warm or hot. Arctic air masses are extremely cold.
James Dewey Watson is an American molecular biologist, geneticist and zoologist. In 1953, he co-authored with Francis Crick the academic paper proposing the double helix structure of the DNA molecule. Watson, Crick, and Maurice Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material". Watson earned degrees at the University of Chicago and Indiana
