Isotopes a. found in nature are usually radioactive. b. are atoms with the same number of electrons, but different numbers of protons. c. are atoms of the same element. d. both a and c Known elements and their symbols could be found on a a. thermometer b. Richter scale. c. keyboard d. Periodic table Mitochondria A) Are involved in cellular respiration B) Break down ATP to release energy for cells C) Are present in animal cells but not plant cells D) All of the above are correct Mitochondria are a. the largest organelle in eukaryotic cells. b. processing centers for synthesizing proteins. c. the major energy production center in eukaryotes. d. attached to endoplasmic reticulum. Most plants appear green because chlorophyll a. does not absorb green light. b. reflects violet light c. absorbs green light. d. none of these Na+ represents a a) gain of electrons b) gain of protons c) loss of electrons d) loss of protons Phospholipids are components of: A) cell walls. B) RNA C) plasma membrane D) DNA. E) All of the above. Prokaryotes and eukaryotes have many similarities. Which of the following are true? a. They both have DNA b. They are both contained by a membrane. c. They both have cell walls. d. a and b. Proteins are produced by a. vesicles. b. lysosomes c. smooth endoplasmic reticulum. d. ribosomes Rough endoplasmic reticulum has _attached to its a. smooth endoplasmic reticulum b. ribosomes c. mitochondria d. golgi apparatus