Most likely Insulin because they decrease it rather than increase it
Sand is granular and coarse meaning that water and nutrients can flow through it quite easily. Clay on the other hand has very fine particles that cling together to form a waterproof substance which traps/ stops any nutrients or water from moving down. Clay's also quite difficult for plants to get their roots into. Silt has a texture between clay and sand, meaning that it is the ideal substance as it allows the best water and nutrition movement in the soil. Most plants will grow best in silt, but there are some plants who are more adapted to living in sand (e.g. Marram grass) or clay.
You would add H+ ions if you added an acid. Thus lowering the pH.
Chromosome is a structure that contains DNA molecules packaged around histone proteins, therefore carries the heredity material. Chromosomes number determines whether a cell is haploid (n) or diploid (n). A diploid cell has both set of homologous chromosomes while the haploid cell has only one set. Nucleus is the cellular structure that is responsible for the localized storage of chromosomal DNA.