1. Cell structure
A section of Biology, 9700
Listing 10 of 513 questions
A scientist carried out an experiment to separate the organelles in an animal cell by mass. The scientist mixed the cells with a buffer solution which had the same water potential as the cells. He then broke the cells open with a blender to release the organelles. The extracted mixture was filtered and then spun in a centrifuge at a high speed to separate the heaviest organelle. This sank to the bottom, forming a solid pellet, 1. solid pellet liquid above pellet The liquid above pellet 1 was poured into a clean centrifuge tube and spun in the centrifuge at a higher speed to separate the next heaviest organelle. This organelle sank to the bottom, forming a solid pellet, 2. He repeated this procedure twice more to obtain pellet 3 and pellet 4, each containing a single organelle. What is the function of the organelle extracted in pellet 2?
9700_w16_qp_12
MCQ
2016
Paper 1, Variant 2
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represents one complete cell cycle for a eukaryotic cell. Complete by naming the stages represented by J, K and L. J K L Name the stage in the cell cycle in which semi-conservative replication of DNA occurs. The development of stem cells to become neutrophils occurs in several stages. Some of these stages are capable of cell division. is a summary of neutrophil development. Some details of cellular structure are included. myeloblast no granules visible large spherical or ovoid nucleus promyelocyte capable of cell division primary granules appear smaller spherical or ovoid nucleus myelocyte secondary granules appear nucleus may appear slightly indented or flattened on one side tertiary granules appear U–shaped nucleus all three types of granule present mature neutrophil released into circulation metamyelocyte All three types of granule indicated in are membrane-bound cell structures containing hydrolytic enzymes. Each type of granule contains a different group of enzymes and other chemicals that enable the neutrophil to carry out its role. State the location in the body where development and maturation of the neutrophil occurs. Describe the shape of the nucleus in the mature neutrophil. State the alternative name of the cell structures described in as “granules”. Primary granules contain proteins known as defensins. These bind to cell surface membranes of bacteria and form very small pores in the membrane. Suggest how defensins contribute to the role of the neutrophil in killing bacteria. Secondary granules contain lysozyme. This is an enzyme that breaks bonds in peptidoglycan molecules. Explain how the action of lysozyme will lead to the destruction of the bacterial cell.
9700_w16_qp_22
THEORY
2016
Paper 2, Variant 2
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Questions Discovered
513