(A) Mitochondria, I believe.
Answer:
Thymosin
Explanation:
Thymosin is the term used to refer to a set of thymus polypeptide hormones that influence the maturation of T lymphocytes intended to play an active role in cell mediated immunity. Thymosin may serve as an immunotransmitter by modulating the hypothalamic-pituitary-adrenal and gonadal axes. It also helps to counteract the harmful effects of cortisol.
If in an eight-cell embryo of an organism, the cells of the upper tier are aligned over the cells of the lower tier at a slight angle, it is likely that the organism is a vertebrate.
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Answer:
(c) directional selection
Explanation:
Directional selection is a type of natural selection that occurs when members of a population of a species with a particular extreme phenotype is selected or favored against the other phenotypes when natural forces act on the population of a species. Individuals having the particular traits that are favored survive and become more common that others with traits that are less favored.
Directional selection may likely result in the species of butterflies in which darkly collared butterflies are not preyed upon, ensuring their survival, while the other butterflies with other colors will be phased out with time. Darkly colored butterfly will be selected for while the others will be selected against.
