Integrated Principles of Zoology Study Set 3

Biology

Quiz 3 :

Cells As Units of Life

Quiz 3 :

Cells As Units of Life

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Distinguish among cilia, flagella, and pseudopodia.
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Cilia are tiny hairs along the outside of the cell membrane which can push the cell along, and flagella are much larger hairs which can move back and forth to propel the cell.
Cilia and flagella also differ in their beating patterns.
img Pseudopodia are only temporary structures formed for the sake of movement. They are formed with the flow of cytoplasm into one part of the organism. Due to this flow, the plasma membrane extends and forms a protrusion which helps the animal to move.
img

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Our current concept of the plasma membrane is known as the fluid-mosaic model. Why
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img This model of the membrane consists of a fluid phospholipid bilayer with a mosaic of interspersed proteins embedded in the lipid layers. The phospholipids are not static and are in a state of constant lateral motion.
Some proteins extend through both lipid layers, while others may extend only halfway or be loosely bound to the surface of the membrane.
Hence this model is known as fluid mosaic model.

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Distinguish among phagocytosis, pinocytosis, receptor-mediated endocytosis, and exocytosis.
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Phagocytosis is the process where the cell engulfs large objects while pinocytosis is the process where small molecules or ions attach to cell receptors and are invaginated along with the receptors.
Phagocytosis forms phagosomes while pinocytosis forms caveolae. In phagocytosis the phagosome fuses with the lysosome. In pinocytosis this fusion does not occur.
In receptor mediated endocytosis there are pits coated with clathrin. These pits contain receptors for specific ligands. When the specific ligand attaches to its receptor, the cell membrane invaginates to form a vesicle.
In exocytosis, the debris or the waste material present in the cell is pushed into a vesicle. This vesicle is then transported to the plasma membrane where the vesicular membrane fuses with the plasma membrane. This results in the throwing out of debris out of the cell.
Endocytosis is the process of taking materials into the cell while exocytosis is the process of throwing materials out of the cell.

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Explain the difference (in principle) between a light microscope and a transmission electron microscope.
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Explain phases of the cell cycle, and comment on important cellular processes that characterize each phase. What is G 0
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Name two functions each for actin and for tubulin.
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You place some red blood cells in a solution and observe that they swell and burst. You place some cells in another solution, and they shrink and become wrinkled. Explain what has happened in each case.
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The plasma membrane is an effective barrier to molecular movement across it, yet many substances do enter and leave the cell. Explain the mechanisms through which this is accomplished and comment on the energy requirements of these mechanisms.
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Name the stages of mitosis in order, and describe the behavior and structure of the chromosomes at each stage.
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Define the following: chromosome, centromere, centrosome, kinetochore, mitosis, cytokinesis, syncytium.
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What are the functions of each of the main constituents of the plasma membrane
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Briefly describe ways that cells may die during the normal life of a multicellular organism.
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Briefly describe the structure and function of each of the following: plasma membrane, chromatin, nucleus, nucleolus, rough endoplasmic reticulum (rough ER), Golgi complex, lysosomes, mitochondria, microfilaments, microtubules, intermediate filaments, centrioles, basal body (kinetosome), tight junction, gap junction, desmosome, glycoprotein, microvilli.
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