Answer: Subsistence agriculture.
Explanation: Subsistence agriculture is a type of farming in which farmers cultivate and grow food crops and livestocks to meet their needs and that of their family.
In this type of agriculture, farm products is aimed to survival and it doesn't involve use of large-scale irrigation, chemical fertilizer, or machinery and technology.
Answer:
Explanation:
Le parti principali del tessuto linfatico sono il midollo osseo, la milza, la ghiandola del timo, i linfonodi, i linfonodi e le tonsille.
The two basic reaction types are synthesis and decomposition. ... Decomposition reactions are the opposite of synthesis reactions because they take apart larger molecules and/or compounds. The generic equation for a synthesis reaction is A + B à AB, where A and B are the pieces that make up the compound/molecule AB.
No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive.
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
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Answer:
A biological community in which association takes place between the organisms and their physical surroundings is termed as an ecosystem. It can also be defined as an association between the nonliving and living components found within the environment. A particular geographical region, which is specified for the species thriving within it is known as a biome.
A branch of science, which deals with the natural procedures that comprise fire within an ecosystem and the ecological influences it imparts, the association between the biotic and the abiotic constituents of an ecosystem with the fire, and the role played by fire within an ecosystem is termed as a fire ecology.
Different kinds of ecosystems like savanna, prairie, coniferous forests and chaparral have originated by the contribution of the fire, which plays an essential role in the renewal and vitality of the habitat. Different kind of plant species needs the assistance of fire to establish, to reproduce, or to germinate. In case, if the suppression of wildfire takes place, it will eventually result in the eradication of various plant species and the animals that rely upon them.