58,59,60 Where is smooth endoplasmic reticulum (SER) especially abundant? brain. liver. heart. lungs. skin. What is the function of the tonoplast? A Provides channels for maintaining fluid balance Protein synthesis Photosynthesis Cell division Storage of genetic information Which is involved in crawling, \"pinching\' extensions? Microtubules. Intermediates. Actin. None of the above. All of the above. Solution 58.Where is Smooth Enddoplasmic reticulum (SER) especially abundant? ANS-B. Liver (abundant in mamalian liver and gonads cells) 59.What is the function of the tonoplast? ANS- A.Provides channels for maintaining fluid balance (tonoplast is a stretchy membrane and it function to separate the fluid filled vacuole from surrrounding cytoplasm.water flowing in and out of the vacuole is regulated by tonoplast) 60.Which is involved in crawling \"pinching\" extensions? ANS-C. Actin (microfilaments or actin is responsible for cellular movements such as contraction,crawling,\"pinching\" during division,and formation of cellular extension).