24. Which one of the following nucleotides is found in RNA? A) uracil B) cytosin
ID: 267970 • Letter: 2
Question
24. Which one of the following nucleotides is found in RNA? A) uracil B) cytosine C) adenine D) thymine E) All of these choices are correct 25. Which of the following is a type of cell communication where the signaling molecule is released by the same cell that responds to the signal? A) contact-dependent B) paracrine C) autocrine D) endocrine E) All of these choices are correct. 26. In the context of cell signaling, to what does the term ligand refer? A) B) C) D) a signaling molecule the extracellular domain of a receptor protein the proteins activated as part of a signal transduction pathway a type of gated channel 27. Which one of the following statements BEST represents the relationship between cellular respiration and photosynthesis? A) Photosynthesis stores energy in organic molecules, while respiration releases it, B) Photosynthesis occurs only during the day and respiration occurs only at night. C) Respiration occurs only in animals and photosynthesis occurs only in plants D) Respiration stores energy E) Photosynthesis reverses the biochemical pathways of respiration. in organic molecules, while photosynthesis releases it. Page 5Explanation / Answer
24. Answer is option a) Uracil. This is the nitrogen base found in RNA in place of thymine in DNA. Rest of the bases adenine and cytosine are common for both.
25. Answer is option c) autocrine cell communication where signalling molecule is released by the the same cell that responds to the signal.
Contact-dependent is a type of signalling in multicellular organisms which require close contact.
Paracrine communication is that where a cell release a substance which alters the behaviour of the nearby cells.
Endocrine signalling happens when cells release hormones which acts on distant target cells.
26. Answer is option a) signalling molecule. Voltage gated channels are a type of gated channel. G proteins have extracellular domain of a receptor protein.
27. Answer is option a) photosynthesis stores energy in organic molecules while respiration releases it. Plants prepare food while respiration releases ATP.
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