16. By definition, procaryotic cells do not possess_ A) a nucleus- C) ribosomes

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16. By definition, procaryotic cells do not possess_ A) a nucleus- C) ribosomes D) membrane bilayers 17. Which of the following organelles has both an outer and an inner membrane? A) endoplasmic reticulum C) lysosome D) peroxisome 18. Drosophila melanogaster is a/an This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model. A) insect B) bird C) amphibian D) mammal 19. For which of the following would you use an electron microscope rather than a light microscope? A) To pick out individual human cells from a cell culture in order to grow new cultures from them. B) To watch organelles move inside a cell. C) To look at cells stained with fluorescent dyes. D) To see ribosomes. 20. The Ras protein is a GTPase that functions in many growth-factor signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells? A) A change that prevents Ras from being made B) A change that increases the affinity of Ras for GDFP C) A change that prevents the hydrolysis of GTP by Ras D) A change that increases the rate of hydrolysis of GTP by Ras 21. Which of the following statements are true? A) Peptide bonds are the only covalent bonds that can link together two amino acids in proteins. B) A protein chain ends in a free amino group at the C-terminus. C) Nonpolar amino acids tend to be found in the interior of proteins. D) The sequence of the atoms in the polypeptide backbone varies between different proteins 22. Although all protein structures are unique, there are common structural building blocks that are refer to as regular secondary structures. Some have helices, some have sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements? A) side-chain interactions B) hydrogen bonds along the protein backbone C) the hydrophobic core interactions D) specific amino acid sequences-

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as per chegg guidelines if you post more than 1 ques i have to answer only 1 ques

ques17--( B ) MITOCHONDRIA is the organelle that has both outer and inner membranes. these membranes are made up of phospholipids and proteins.the inner membrane is folded into cristae.in the inner membrane ETC is embedded and uses both compartments to make ATP.

ques18-- (A) INSECT -- DROSOPHILA MELANOGASTER is a species of fly.it is commonly known as common fruit fly or vinegar fly.

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