Question

РЕШИТЕ ПОЖАЛУЙСТА СРОЧНООрганы гаметофита плауновидных, продуцирующие спермии, созревают раньше, чем органы, образующие яйцеклетки. Для предотвращения какого явления возникла эта особенность? Раковина моллюсков состоит из трех слоев: рогового, фарфорового и перламутрового. Многие раковины имеют причудливую форму, различаются по окраске и строению. Клетки какого органа этому способствуют? Недостаток чего или кого осенью заставляет птиц первыми мигрировать в места зимовок?

Answer 1

3) сокращение длиеы светого дня

Answer 2

Gametophyte Organs in Ferns

In ferns, the organs of the gametophyte that produce sperm mature earlier than the organs that produce eggs. This characteristic evolved to prevent self-fertilization, which is known as selfing. Selfing can lead to reduced genetic diversity and can be disadvantageous for the long-term survival of a species. By having the sperm-producing organs mature earlier, ferns ensure that the sperm is released before the eggs are receptive, reducing the chances of self-fertilization [[1]].

Cell Types in Mollusk Shells

The shells of mollusks consist of three layers: the periostracum (outer organic layer), the prismatic layer (middle layer made of calcium carbonate crystals), and the nacreous layer (innermost layer made of calcium carbonate crystals arranged in a laminated structure). The cells responsible for the formation of the nacreous layer, called mantle cells, play a crucial role in creating the intricate shapes, colors, and structures seen in many mollusk shells [[2]].

Migration of Birds in Autumn

In autumn, the scarcity of food resources, particularly insects and seeds, can lead to a shortage of resources for birds. This scarcity, combined with the decreasing temperatures and shorter daylight hours, triggers the migration of birds to more favorable habitats with abundant food sources. The first birds to migrate are often those that rely heavily on specific food sources that become limited during the autumn season. By migrating to areas with more abundant resources, these birds can ensure their survival during the winter months [[3]].

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