A rat receives food pellets for pressing a lever, but only on unpredictable occasions. This BEST illustrates

4) this is any functional structure within the confines of a cell; literally a. "small organ; " it usually has a membrane-based structure 5) this is a tiny fluid-filled cavity in the cytoplasm. it can be used for storage of biochemicals. 6) this is a two-part process that ends in the assembly of proteins at the ribosomes within cells. the first part, transcription, begins in the nucleus, when the dna code is transferred to mrna. the second part, translation, takes place at the ribosomes, where both mrna and trna work to assemble proteins. 7) these are singular, relatively long, whip-like organelles that many unicellular organisms use for motion. 9) this holds an organisms hereditary information. 10) energy stored in chemical bonds of molecules. - down 1) this kind of cell from a multicellular organism does not have a large central vacuole. 2) this organelle serves to process and package lipids and proteins in the cell. 3) this kind of cell has a large central vacuole and a cell wall. 8) chloroplast thylakoids are frequently stacked to form these disks. submit