Robert Paine Was the First Biologist to Use the Term

question 27

Multiple Choice

Robert Paine was the first biologist to use the term keystone species in the 1960s. He was studying food webs in the rocky, intertidal pools in the Pacific Northwest. At one of his study sites, the dominant organisms in the tidal pools were mussels, barnacles, whelks, and a species of starfish known as Pisaster ochraceus . To examine the relationship between these species, Paine set up an experiment. In one area, he removed all the starfish from the tidal pools, and in an adjacent area, he left the tidal pools as he found them. Prior to removing the starfish, he sampled all the organisms in each pool. After two months, he repeated this sampling. A summary of his results is illustrated in the graph below.

After two months, Paine repeated the sampling. In this experiment, he is sampling the __________.

• A) biodiversity
• B) first trophic level
• C) energy pyramids
• D) ecological niche

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Definitions:

Replicated Chromosomes

Chromosomes that have been copied during the cell cycle, resulting in two identical sister chromatids joined at the centromere, important for cell division.

Centrioles

Two cylinder-shaped organs near the cell nucleus that are essential for cell division, by equally dividing chromosomes to the daughter cells.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Inherited Traits

Characteristics or properties genetically passed down from parents to their offspring.