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Courtship in america dating in the 20th century

Amphibian larvae are aquatic, and have gills for respiration; they undergo metamorphosis to the adult form.

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The pupil of a human eye is a self-adjusting aperture. archetype: The original form or body plan from which a group of organisms develops.Then, even if circumstances change such that it no longer provides any survival or reproductive advantage, the behavior will still tend to be exhibited -- unless it becomes positively disadvantageous in the new environment.adaptive radiation: The diversification, over evolutionary time, of a species or group of species into several different species or subspecies that are typically adapted to different ecological niches (for example, Darwin's finches).In a diploid cell there are usually two alleles of any one gene (one from each parent).Within a population there may be many different alleles of a gene; each has a unique nucleotide sequence.They have moist scaleless skin which is used to supplement the lungs in gas exchange.The eggs are soft and vulnerable to drying, therefore reproduction commonly occurs in water.acquired trait: A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation (for example, the large muscles of a weightlifter).adaptation: Any heritable characteristic of an organism that improves its ability to survive and reproduce in its environment.agnostic: A person who believes that the existence of a god or creator and the nature of the universe is unknowable.algae: An umbrella term for various simple organisms that contain chlorophyll (and can therefore carry out photosynthesis) and live in aquatic habitats and in moist situations on land. Algae range from macroscopic seaweeds such as giant kelp, which frequently exceeds 30 m in length, to microscopic filamentous and single-celled forms such as Spirogyra and Chlorella. For example, if a gene determines the seed color of peas, one allele of that gene may produce green seeds and another allele produce yellow seeds.

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