Structure and Function of Cell Membrane Reading Answers

In this article the Structure and function of cell membrane reading answers are given as IELTS practice test, along with answers and explanations. It consists of 13 questions in 3 different types namely- 3 questions as diagram labeling, 5 questions as matching information, and 5 questions as summary completion. Read the passage and questions carefully and try to answer them.

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Table of content:

• Solutions for structure and function of cell membrane
• Structure and function of cell membrane IELTS reading practice test
• Passage
• Questions
• Answers with explanation

Solutions for Structure and Function of Cell Membrane

We have given the Structure and function of cell membrane reading answers, in the table given below.

Answer Table

28. Protein	31. D	34. A	37. Proteins	40. Phospholipids
29. Phospholipid	32. B	35. C	38. Semi-permeable
30. Cholesterol	33. F	36. Aqueous	39. Transport

Structure and function of cell Membrane IELTS reading practice test -Exam Review

Here, we have given the structure and function of cell membrane IELTS reading answers as a sample article for the IELTS reading practice test. This article will help you attain a band score in your exams. Check out the given passage to answer the questions.

Passage

In this article, the Structure and function of cell membrane reading answers with location is given. Be focused on the passage while reading it and answer the given questions.

Structure and function of cell membrane reading answers

A. Human body is made up of millions of cells - little building blocks of life. Each cell contains many functional subunits (organelles) that enable its proper functioning and is protected from the external environment by a cell membrane. While structure and function of organelles are extensively covered in various biology courses, the importance of study of cell membranes is often underrated. This article is dedicated to provide a short introduction into the basic functions and anatomy of a cell membrane.

B. Cell membranes protect and organize cells. Most importantly they serve as barriers, discriminating the cell’s interior from the outer milieu. Because cells always exist in aqueous environments their membranes should be structured in such a way so they do not solve in water. This function is ideally carried by special chemical molecules - phospholipids. These molecules are constructed from two parts: tails made up of 2 molecules of fat that ‘avoid’ water and heads that have an affinity for water. For this specific behavior the phospholipid’s tails are called hydrophobic (‘hydro’ means water and ‘phobia’ means fear) and heads are called hydrophilic (‘philos’ means love). When phospholipids are added to water, they self-assemble into double-layered structures, shielding their hydrophobic portions from water and exposing their hydrophilic portions to the environment. This phospholipid bilayer may resemble a sandwich, where phospholipid heads are bread rolls and tails are the sandwich filling.

C. In addition to lipids, membranes are loaded with proteins. They usually go through the lipid bilayer and are exposed to both aqueous environment and cell's interior. In fact, proteins account for roughly half the mass of most cellular membranes. They make the membrane semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly. Small molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly. On the other hand, cell membranes restrict diffusion of highly charged molecules, such as ions, and large molecules, such as sugars and amino acids. The passage of these molecules relies on specific transport proteins embedded in the membrane.

D. Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to enhance passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy. The ability to maintain concentration gradients and sometimes move materials against them is vital to cell health and maintenance. Thanks to membrane barriers and transport proteins, the cell can accumulate nutrients in higher concentrations than exist in the environment and, conversely, dispose of waste products.

E. Other membrane-embedded proteins have communication-related jobs. Large molecules from the extracellular environment, such as hormones or immune mediators, bind to the receptor proteins on the cell membrane. Such binding causes a conformational change in the protein that transmits a signal to intracellular messenger molecules. Like transport proteins, receptor proteins are specific and selective for the molecules they bind.

F. Another important type of membrane’s components are cholesterol molecules, which account for about 20 percent of the lipids in animal cell plasma membranes. However, cholesterol is not present in bacterial membranes or mitochondrial membranes. The cholesterol molecules are embedded in place of phospholipid molecules and help to regulate the stiffness of membranes. To function properly, the cell membrane should be in fluid state. Cholesterol reduces membrane fluidity at moderate temperatures by reducing the moving of phospholipids. But at low temperatures, it hinders solidification by disrupting the regular packing of phospholipids.

Questions

Questions 28-30

• Label the diagram below.
• Write NO MORE THAN ONE WORD from the passage for each answer. Do not write the articles.

Which elements of cell membrane correspond to the numbers in the diagram?

28. ____________
29. ____________
30. ____________

Questions 31-35

• Reading Passage 3 has six paragraphs, A-F.
• Which paragraph contains the following information?
• Write the correct letter, A–F, in boxes 31–35 on your answer sheet.

31. Specific proteins transport nutrients from the external environment against the concentration gradient.
32. The barrier function of cell membranes is supported by a bilayer of phospholipids.
33. The level of membrane fluidity is regulated by cholesterol molecules.
34. The importance of cell membranes are often underestimated.
35. Proteins make the membrane semi-permeable.

Questions 36–40

• Complete the summary below.
• Choose ONLY ONE WORD from the passage for each answer.
• Write your answers in boxes 36–40 on your answer sheet.

Cell membranes protect cells and organize their activities. The first main function of cell membrane - barrier function - is carried by phospholipids. These molecules don’t solve in water and, thus, are ideal for cells that always exist in 36.______  environment.
In addition to lipids, membranes are loaded with 37._________  that makes the membrane 38.________  , which means that some molecules can diffuse across the lipid bilayer but others cannot. One of the most important types of membrane proteins is 39.________  proteins and receptor proteins.
The last type of membrane elements are cholesterol molecules, which are embedded in place of 40._________  molecules and help to regulate the stiffness of membranes.

Answers for Structure and function of cell membrane with explanation

We have given the Structure and function of cell membrane reading answers with an explanation, this section will help you to identify your errors in the answering process. 

28. Answer: Protein

Explanation: “In addition to lipids, membranes are loaded with proteins. They usually go through the lipid bilayer and are exposed to both aqueous environment and cell's interior. In fact, proteins account for roughly half the mass of most cellular membranes”. With this line it is clear that cell membranes are loaded with proteins and they seem like roughly half the mass of most cellular membranes. Hence the given answer is located in the 1-3 lines of paragraph C. 

29. Answer: Phospholipid

Explanation: “These molecules are constructed from two parts: tails made up of 2 molecules of fat that ‘avoid’ water and heads that have an affinity for water. For this specific behavior the phospholipid’s tails are called hydrophobic (‘hydro’ means water and ‘phobia’ means fear) and heads are called hydrophilic (‘philos’ means love). When phospholipids are added to water, they self-assemble into double-layered structures, shielding their hydrophobic portions from water and exposing their hydrophilic portions to the environment. This phospholipid bilayer may resemble a sandwich, where phospholipid heads are bread rolls and tails are the sandwich filling”. With these lines it is clear that the phospholipid resembles a sandwich. Hence the given answer is located in the 5-12 lines of paragraph B. 

30. Answer: Cholesterol

Explanation: “The cholesterol molecules are embedded in place of phospholipid molecules and help to regulate the stiffness of membranes”. With this line it is clear that cholesterol molecules are embedded in place of phospholipid molecules.  Hence the given answer is located in the 3-5 lines of paragraph F. 

31. Answer: D

Explanation: “Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to enhance passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy”. With this line it is clear that some specific proteins transport nutrients from the external environment against the concentration gradient. Hence the given answer is located in the first 3 lines of paragraph D. 

32. Answer: B

Explanation: “This function is ideally carried by special chemical molecules - phospholipids. These molecules are constructed from two parts: tails made up of 2 molecules of fat that ‘avoid’ water and heads that have an affinity for water. For this specific behavior the phospholipid’s tails are called hydrophobic (‘hydro’ means water and ‘phobia’ means fear) and heads are called hydrophilic (‘philos’ means love). When phospholipids are added to water, they self-assemble into double-layered structures, shielding their hydrophobic portions from water and exposing their hydrophilic portions to the environment. This phospholipid bilayer may resemble a sandwich, where phospholipid heads are bread rolls and tails are the sandwich filling”. With these lines it is clear that the barrier function of cell membranes is supported by a bilayer of phospholipids. Hence the given answer is located in paragraph B. 

33. Answer: F

Explanation: “Cholesterol reduces membrane fluidity at moderate temperatures by reducing the moving of phospholipids”. With this line it is clear that the level of membrane fluidity is regulated by cholesterol molecules. Hence the given answer is located in the 6-7 lines of paragraph F. 

34. Answer: A

Explanation: “While structure and function of organelles are extensively covered in various biology courses, the importance of study of cell membranes is often underrated”. With this line it is clear that the importance of cell membranes are often underestimated. Hence the given answer is located in the 3-5 lines of paragraph A. 

35. Answer: C

Explanation: “In addition to lipids, membranes are loaded with proteins. They usually go through the lipid bilayer and are exposed to both aqueous environment and cell's interior. In fact, proteins account for roughly half the mass of most cellular membranes. They make the membrane semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot”. With this line it is clear that protein makes the membrane semi-permeable. Hence the given answer is located in the 1-5 lines of paragraph C. 

36. Answer: Aqueous

Explanation: “Cell membranes protect and organize cells. Most importantly they serve as barriers, discriminating the cell’s interior from the outer milieu. Because cells always exist in aqueous environments their membranes should be structured in such a way so they do not solve in water”. With this line it is clear that cell membranes protect cells and organize their activities. The barrier function is carried by phospholipids. These molecules don’t solve in water and, thus, are ideal for cells that always exist in an aqueous environment. Hence the given answer is located in the 1-4 lines of paragraph B. 

37. Answer: Proteins

Explanation:  “In addition to lipids, membranes are loaded with proteins. They usually go through the lipid bilayer and are exposed to both aqueous environment and cell's interior. In fact, proteins account for roughly half the mass of most cellular membranes. They make the membrane semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot”. With this line it is clear that lipids, membranes are loaded with proteins. Hence the given answer is located in the 1-5 lines of paragraph C. 

38. Answer: Semi-permeable

Explanation: “In addition to lipids, membranes are loaded with proteins. They usually go through the lipid bilayer and are exposed to both aqueous environment and cell's interior. In fact, proteins account for roughly half the mass of most cellular membranes. They make the membrane semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot”. With this line it is clear that the protein makes the membrane semi-permeable. Hence the given answer is located in the 1-5 lines of paragraph C. 

39. Answer: Transport

Explanation: “On the other hand, cell membranes restrict diffusion of highly charged molecules, such as ions, and large molecules, such as sugars and amino acids. The passage of these molecules relies on specific transport proteins embedded in the membrane”. With this line it is clear one of the most important types of membrane proteins is transport proteins and receptor proteins. Hence the given answer is located in the last 3 lines of paragraph C. 

40. Answer: Phospholipids

Explanation: “Another important type of membrane’s components are cholesterol molecules, which account for about 20 percent of the lipids in animal cell plasma membranes. However, cholesterol is not present in bacterial membranes or mitochondrial membranes. The cholesterol molecules are embedded in place of phospholipid molecules and help to regulate the stiffness of membranes”. With this line it is clear that the last type of membrane elements are cholesterol molecules, which are embedded in place of Phospholipids molecules and help to regulate the stiffness of membranes. Hence the given answer is located in the first 5 lines of paragraph F. 

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