32) Paleontologists have discovered ancient prokaryotic fossils dated at over 3.

Question

32) Paleontologists have discovered ancient prokaryotic fossils dated at over 3.5 billion years old. These fossils resemble prokaryotes that are capable of living in extreme conditions such as high temperature and salinity. What domain do these prokaryotes belong to? A) Protists C) Archaca D) Archetista E) Eukarya 33) In the fluid-mosaic model of the plasma membrane, the phospholipid molecules are oriented so that tails are facing the the heads are facing the outside environment and the interior of the membrane. A) hydrophobic, hydrophilic B) hydrophilic, hydrophobic D) heterotrophic, autotrophic E) ectothermic, endothermic 34) A short chain of sugar attached to a protein molecule on the plasma membrane is called B) a protosugar C) a glycocalyx. D) a glycolipid. E) a glycoprotein. 35) Which of the following can cross the plasma membrane because of its selective permeability? A) gases such as oxygen and carbon dioxide B) ions C) large, polar molecules D) large, nonpolar molecules E) glycoproteins 36) During a hurricane, salt water invades fresh water marshes causing many of the plants to die. The plants are killed because the salt water solution is cells. to the plants, drawing water from their A) isotonic B) hypotonic C) mesotonic D) oligotonic E) hypertonic What is the function of cholesterol in the plasma membrane? A) cell marker B) receptor C) support D) channel E) enzyme 38) A solution is at equilibrium across a plasma membrane. If 50 molecules were to enter the cell, how many molecules would need to exit the cell in order to maintain the equilibrium? A) 50 B) 75 C) 25 D) 0 E) 100

Explanation / Answer

32.Archea is the answer , domain archea are also called extremophiles because they grow in extreme saline , hot conditions. They are extreme thermophiles , extreme halophiles.

33.Hydrophilic heads and hydrophobic tails , the head of the plasmamembrane lipids face the external environment which is hydrophilic , so the head region is hydrophilic and the tails are towards the innerside of the membrane and are hydrophobic,they do not come in contact with water even the hydrophic chains of the proteins are embedded in the hydrophobic tails.

34.they are called glycoproteins, glyco is sugar , sugar associated with protein is glycoprotein

35.Ions , certain ions cannot just traverse the membrane , they need some transporters which need energy in the form of ATP to pump .

36. Hypertonic solution, When the cell is placed in hypertonic solution water moves from the high water concentration area to the low water concentration area , it means in the hypertonic solution water concentration is low and in plants the water concentration is high as a result exosmosis occured and the plants have lost water .so the answer is hypertonic.

37. cholesterol gives additional support to the membrane. Support is the answer.

38.50 molecules , if 5 molecules leave then , to maintain equillibrium 50 molecules must come in .

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