Answer:
Seedless vascular plants are plants that contain vascular tissue, but do not produce flowers or seeds. In seedless vascular plants, such as ferns and horsetails, the plants reproduce using haploid, unicellular spores instead of seeds. The spores are very lightweight (unlike many seeds), which allows for their easy dispersion in the wind and for the plants to spread to new habitats. Although seedless vascular plants have evolved to spread to all types of habitats, they still depend on water during fertilization, as the sperm must swim on a layer of moisture to reach the egg. This step in reproduction explains why ferns and their relatives are more abundant in damp environments, including marshes and rainforests. The life cycle of seedless vascular plants is an alternation of generations, where the diploid sporophyte alternates with the haploid gametophyte phase. The diploid sporophyte is the dominant phase of the life cycle, while the gametophyte is an inconspicuous, but still-independent, organism. Throughout plant evolution, there is a clear reversal of roles in the dominant phase of the life cycle
Explanation:
Answer:
Sheep and goats are important livestock species in developing countries. Of the world's 1,614million sheep and 475 million goats, 65% and 95%, respectively, are located in developing countries. Fifty-three percent of the total small-ruminant population in the developing countries is found in Asia, particularly in India and Pakistan, 33% in Africa, and 14% in Latin America (FAO, 1984).
Goats are hardy and well-adapted to harsh climates. Due to their grazing habits and physiological characteristics, they are able to browse on plants that would normally not be eaten by other livestock species. Thus, the presence of goats in mixed species grazing systems can lead to a more efficient use of the natural resource base and add flexibility to the management of livestock. This last characteristic is especially desirable in fragile environments.
Sheep and goats contribute to a broad range of production systems. The most common system throughout the developing countries involve either the extensive system with large herds and/or flocks grazing on arid and semi-arid rangelands or the intensive system with smaller herds and/or flocks kept in confinement, mostly in the humid tropics.
Diffusion is the movement of particles from a high concentration area to a low concentration area.
Things that can go through a membrane are ions (charged), small polar molecules. Big molecules can't go through the membrane due to its large size and disrupting the membrane.
Passive transport is the movement of substances acrpss the cell membrane w/o the use of energy. Active transport needs energy to move substances across a cell membrane.
