) An oeganm sdioweret t that thrives both in the peesence and absence of oxygen
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) An oeganm sdioweret t that thrives both in the peesence and absence of oxygen in the wwwironnvenk even though the organism does not gain much weight. This organiom the electront molecule other than osygen to accept electrons from 14) lons diffuse acros membeanes through specific ion channels 14) A) down their concentration gradients B) C) down their electrochemical gradients D) down their chemical gradients E) down the electrical gradients 15) Why are lipids and proteins free to move laterally in membranes? 15) A) Lipids and proteins repulse each other in the membrane. B) The interior of the membrane is filled with liquid water C) Molecules such as cellulose can pull them in various directions D) There are only weak hydrophobic interactions in the interior of the membrane. E) Hydrophilic portions of the lipids are in the interior of the membrane. 16) What type of covalent bond between amino acid side chains (R groups) functions in maintaining a 16 polypeptide's specific three-dimensional shape? A) disalfide bond B) hydrogen bond C) van der Waals interaction D) ionic bond E) hydrophobic interaction 17) Which structure is the site ofthe synthesis of proteins that may be exported from the celP A) Golgi vesicles B) rough ER C) plasmodesmata D) lysosomes E) free cytoplasmic ribosomes 18) Which of the following processes includes all others? A) facilitated diffusion B) diffusion of a solute across a membrane C) transport of an ion down its electrochemical gradient D) passive transport E) osmosis 19) Why is glycolysis described as having an investment phase and a payoff phase? A) It shifts molecules from cytosol to mitochondrion. B) It uses glucose and generates pyruvate. C) It attaches and detaches phosphate groups D) It uses stored ATP and then forms a net increase in ATPExplanation / Answer
13) The correct answer is Option B ie, The organism is a facultative anaerobe.
It is because, in question it has explained that the organism can live even in the presence or absence of oxygen in air. So, the organism cannot be considered as an aerobic orgaanism ( an aerobic organism lives only in the presence of oxygen). Hence the last option is wrong. In addition if they were photosynthetic, they should be able to use sunlight as a souce or energy and there is no need to depend on other organic molecules like sugar.
And anaerobes are usually prokaryotic organisms.
The reason for the correct option B is that, the organism mentioned in question is able to use oxygen if it is present. While using oxygen for respiration, the final electron acceptor will be oxygen . That is it undergoes aerobic respiration. This is an efficient process wherein 36 ATP molecules are generated.
On the other hand, when organism lack O2 in its environment, it uses some other molecules ( weak oxidants) as the final electron acceptor ( always remember that the oxygen is the best electron acceptor). This is not efficient as in aerobic respiration. Therefore the organism uses more sugar to produce the same energy that has generated during aerobic respiration.
And also, the statement that, they doesnot gain weight due to increased uptake of sugar also depicts that the organism is a facultative anaerobe and therefore option B is correct.
14) Always the diffusion of ions accross a membrane through specific ions channels is down their electrochemical gradient. ie option C.
There are two factors that determine the movement of ions through an ion specific channel. They are,
17 ) B.
It is in Rough endoplasmic reticulum that that the proteins that are destined for export are synthesized.
The major function of rough endioplasmic reticulum (ie, endoplasmic reticulum in which the outer surface is covered by ribosmes) is protein secretion. They extend from nuclear membrane to the entire surface of the cell and they are continous membrane and serve as the largest organelle in a eukaroytic cell. Hence, it is in this rough endoplasmic reticulum that the proteins are synthesised which are meant for export and finally they travel to the golgi bodies where they are processed (golgi bodies are part of endomemrane system).
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