Natural and Artificial Selection

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Natural Selection Noun

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[nach-er-uhl suh-lek-shun]

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Natural Selection

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A process where organisms better suited to their environment survive and reproduce more successfully, passing on favorable traits.

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Example: Giraffes with longer necks can reach high leaves (an advantage), so they are more likely to survive, while giraffes with shorter necks cannot.

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Artificial Selection Noun

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[ahr-tuh-fish-uhl suh-lek-shun]

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Artificial Selection

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The process by which humans intentionally breed plants or animals to select for specific, desirable traits in their offspring.

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Example: Humans select organisms with desired traits to breed, like choosing Dalmatians with more spots, causing that trait to become more common in future generations.

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Trait Noun

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[treyt]

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Trait

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A specific, genetically determined characteristic or quality belonging to an organism that can be passed to its offspring.

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Example: This diagram shows how alleles (versions of a gene, like 'A' and 'a') on chromosomes determine if an organism is homozygous or heterozygous for a trait.

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Population Noun

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[pop-yoo-ley-shun]

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Population

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A group of interbreeding individuals of the same species that live in the same geographic area at the same time.

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Example: This graph shows a population's size increasing over time until it reaches the environment's carrying capacity, where growth levels off due to limited resources.

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Generation Noun

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[jen-uh-rey-shun]

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Generation

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A single step in the line of descent from an ancestor, representing a group of organisms born and living together.

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Example: This diagram shows a parent hydra producing a genetically identical offspring, which becomes a new generation through the process of budding.

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Evolution Noun

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[ev-uh-loo-shun]

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Evolution

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The gradual change in the heritable characteristics of biological populations over successive generations through processes like natural selection.

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Example: This diagram shows that different groups of animals evolved from common ancestors over time, with branching points representing the divergence of new species.

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Inheritance Noun

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[in-her-i-tuhns]

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Inheritance

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The biological process by which genetic information and traits are passed down from parents to their offspring through genes.

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Example: This family tree, or pedigree chart, shows how a specific trait (represented by the red color) is passed down from parents to their children, demonstrating inheritance.

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Gene Noun

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[jeen]

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Gene

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A specific sequence of nucleotides in DNA or RNA that is the basic physical and functional unit of heredity.

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Example: This diagram shows that a gene is a specific segment of a DNA molecule, which is tightly coiled into a chromosome inside a cell's nucleus.

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Mutation Noun

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[myoo-tey-shun]

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Mutation

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A permanent alteration in the nucleotide sequence of an organism's genome, which can be inherited or occur spontaneously.

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Example: This diagram shows that a mutation is a change in a gene, which can cause the cell to produce an abnormal protein, leading to a new trait.

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Offspring Noun

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[awf-spring]

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Offspring

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The young born of living organisms, produced either by a single organism or by the sexual reproduction of two.

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Example: A single parent organism, like this planarian worm, can be cut into pieces, and each piece can regenerate into a new, complete offspring.