AP Biology Test #2 Molecules And Cells
Multiple Choice: Choose the BEST answer form the choices given.
Questions and Answers
- 1.
Carbohydrate-containing layer at the surface of the plasma membrane
- A.
Glycocalyx
- B.
Cholesterol
- C.
Triglyceride
- D.
Phospholipid
- E.
Protein
Correct Answer
A. GlycocalyxExplanation
The correct answer is glycocalyx. The glycocalyx is a carbohydrate-containing layer that is present at the surface of the plasma membrane. It consists of glycoproteins and glycolipids, which are proteins and lipids with attached carbohydrate chains. The glycocalyx has multiple functions, including cell recognition, protection against pathogens, and cell adhesion. It also plays a role in cell signaling and communication. Therefore, the glycocalyx is the most appropriate answer in this context.Rate this question:
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- 2.
The process taking place in the diagram below is
- A.
Osmosis
- B.
Facilitated diffusion
- C.
Cyclosis
- D.
Pinocytosis
- E.
Exocytosis
Correct Answer
B. Facilitated diffusionExplanation
The process taking place in the diagram is facilitated diffusion. Facilitated diffusion is the passive movement of molecules across a cell membrane with the help of transport proteins. In this process, molecules move from an area of higher concentration to an area of lower concentration, without the need for energy input. The diagram likely shows the transport proteins embedded in the cell membrane, allowing the molecules to pass through.Rate this question:
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- 3.
Refer to the molecule below
- A.
This molecule is used to transport oxygen in the blood
- B.
Starch is a polymer of this molecule
- C.
This is a sterol found in cell membranes and is associated with atherosclerosis
- D.
This molecule could result from the hydrolysis of a protein
- E.
None of the above
Correct Answer
A. This molecule is used to transport oxygen in the bloodExplanation
The molecule referred to in the answer is hemoglobin. Hemoglobin is a protein found in red blood cells that binds to oxygen and transports it throughout the body. It is responsible for the red color of blood and plays a crucial role in oxygen delivery to tissues. Therefore, it is used to transport oxygen in the blood.Rate this question:
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- 4.
Refer to the molecule below
- A.
This molecule is used to transport oxygen in the blood
- B.
Starch is a polymer of this molecule
- C.
This is a sterol found in cell membranes and is associated with atherosclerosis
- D.
This molecule could result from the hydrolysis of a protein
- E.
None of the above
Correct Answer
B. Starch is a polymer of this moleculeExplanation
Starch is a polymer of glucose. Glucose is a simple sugar molecule that is used by cells as a source of energy. Starch is a polysaccharide, which means it is made up of many glucose molecules bonded together. It is commonly found in plants and serves as a storage form of energy. When consumed, starch is broken down into glucose molecules by enzymes in the body, which can then be used for energy production.Rate this question:
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- 5.
Refer to the molecule below
- A.
This molecule is used to transport oxygen in the blood
- B.
Starch is a polymer of this molecule
- C.
This is a sterol found in cell membranes and is associated with atherosclerosis
- D.
This molecule could result from the hydrolysis of a protein
- E.
None of the above
Correct Answer
C. This is a sterol found in cell membranes and is associated with atherosclerosisExplanation
The given molecule is a sterol found in cell membranes and is associated with atherosclerosis. Sterols are a type of lipid and are important components of cell membranes. Atherosclerosis is a condition characterized by the buildup of plaque in the arteries, and sterols, such as cholesterol, play a role in this process. Therefore, the given molecule fits the description of a sterol found in cell membranes and associated with atherosclerosis.Rate this question:
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- 6.
Refer to the molecule below
- A.
This molecule is used to transport oxygen in the blood
- B.
Starch is a polymer of this molecule
- C.
This is a sterol found in cell membranes and is associated with atherosclerosis
- D.
This molecule could result from the hydrolysis of a protein
- E.
None of the above
Correct Answer
E. None of the above -
- 7.
Refer to the molecule below
- A.
This molecule could result from the hydrolysis of a protein
- B.
This molecule is used to transport oxygen in the blood
- C.
This is a sterol found in cell membranes and is associated with atherosclerosis
- D.
This molecule could result from the hydrolysis of a protein
- E.
None of the above
Correct Answer
A. This molecule could result from the hydrolysis of a proteinExplanation
The given molecule could result from the hydrolysis of a protein because proteins are made up of amino acids, and when proteins undergo hydrolysis, the peptide bonds between the amino acids are broken, resulting in the release of individual amino acids. The molecule shown in the question appears to be an amino acid, which is a building block of proteins. Therefore, it is possible that this molecule could be formed by the hydrolysis of a protein.Rate this question:
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- 8.
The process taking place below is called
- A.
Endocytosis
- B.
Pinocytosis
- C.
Phagocytosis
- D.
Exocytosis
- E.
Cyclosis
Correct Answer
D. ExocytosisExplanation
Exocytosis is the process where cells release substances from their cytoplasm to the external environment. This process involves the fusion of vesicles containing the substances with the cell membrane, resulting in the release of the contents outside the cell. This is the opposite of endocytosis, where substances are taken into the cell. Neither pinocytosis nor phagocytosis involve the release of substances from the cell. Cyclosis refers to the movement of cytoplasm within a cell, which is not the process described here. Therefore, the correct answer is exocytosis.Rate this question:
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- 9.
The process taking place below is called
- A.
Endocytosis
- B.
Exocytosis
- C.
Active transport
- D.
Passive transport
- E.
Facilitated diffusion
Correct Answer
A. EndocytosisExplanation
Endocytosis is the process by which cells take in materials from the external environment by engulfing them with their cell membrane. This process involves the formation of a vesicle around the material and then the vesicle is brought into the cell. This is different from exocytosis, which is the process of releasing materials from the cell. Active transport and facilitated diffusion are also different processes that involve the movement of materials across the cell membrane, but they do not involve the engulfment of materials like endocytosis does. Passive transport, on the other hand, refers to the movement of materials across the cell membrane without the need for energy, which is not the case in endocytosis.Rate this question:
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- 10.
From the appearance of the TURGID CELL, it can be concluded that
- A.
The environment is hypertonic to the cell
- B.
The environment is hypotonic to the cell
- C.
The cell is hypotonic to the environment
- D.
Solute concentration of the environment is greater than the solute concentration of the cell
- E.
The cell and the environment are isotonic to each other
Correct Answer
B. The environment is hypotonic to the cellExplanation
Based on the appearance of the turgid cell, it can be concluded that the environment is hypotonic to the cell. This is because a turgid cell is swollen and firm, indicating that water has entered the cell due to osmosis. In a hypotonic environment, there is a higher concentration of water outside the cell compared to inside, causing water to move into the cell to equalize the solute concentration.Rate this question:
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- 11.
If the concentration of the FLACCID CELL is 2% then the solute concentration in the environment of the cell may be
- A.
1.0%
- B.
5.0%
- C.
0.5%
- D.
2.0%
- E.
0.2%
Correct Answer
B. 5.0%Explanation
If the concentration of the FLACCID CELL is 2%, then the solute concentration in the environment of the cell may be 5.0%. This is because when a cell is in a hypotonic environment, water will move into the cell through osmosis to equalize the concentration of solutes on both sides of the cell membrane. Therefore, the solute concentration in the environment must be higher than the concentration inside the cell, which is 2%. Among the given options, 5.0% is the only concentration that is higher than 2%.Rate this question:
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- 12.
When the cell membrane disconnects from the cell wall due to loss of fluid this process is know as
- A.
Crenation
- B.
Cyclosis
- C.
Plasmolysis
- D.
Hemolysis
- E.
Autolysis
Correct Answer
C. PlasmolysisExplanation
Plasmolysis occurs when the cell membrane separates from the cell wall due to the loss of fluid. This process typically happens in plant cells when they are placed in a hypertonic solution, causing water to leave the cell. The loss of water causes the cell membrane to shrink away from the cell wall, resulting in plasmolysis. This can have detrimental effects on the cell's structure and function.Rate this question:
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- 13.
Refer to the EVENTS listed below and the DIAGRAM that follows: 1 - Guard cells become turgid 2 - Stomata close 3 - Guard cells become flaccid 4 - Stomata open 5 - Ions move into guard cells increasing the solute concentration 6 - Ions leave guard cells decreasing the solute concentration 7 - Water enters guard cells from the epidermal cells 8 - Water leaves guard cells and enters epidermal cells DIAGRAM When the sun rises and a leaf begins the process of photosynthesis, which sequence of events results in the appearance of the stomata as open
- A.
2,1,6,7
- B.
6,8,3,2
- C.
1,6,4,5
- D.
5,7,1,4
- E.
3,7,5,2
Correct Answer
D. 5,7,1,4 -
- 14.
The ions, whose movement into and out of the guard cells cause the stomata and guard cells to open or close are
- A.
Na+ ions
- B.
OH- ions
- C.
Ca++ ions
- D.
I- ions
- E.
K+ ions
Correct Answer
E. K+ ionsExplanation
The movement of K+ ions into and out of the guard cells is responsible for the opening and closing of stomata. When K+ ions enter the guard cells, water follows by osmosis, causing the guard cells to swell and the stomata to open. Conversely, when K+ ions exit the guard cells, water also exits, causing the guard cells to shrink and the stomata to close. Therefore, K+ ions play a crucial role in regulating the opening and closing of stomata.Rate this question:
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- 15.
Human hair is an example of this type of secondary level protein
- A.
Beta pleated sheet
- B.
Globular protein
- C.
Alpha helix
- D.
Tertiary protein
- E.
None of the above
Correct Answer
C. Alpha helixExplanation
The alpha helix is a secondary level protein structure that is commonly found in human hair. It is formed by a coiled structure in which the polypeptide chain twists around itself. This structure provides strength and stability to the hair strands, allowing them to withstand various external forces. Therefore, human hair serves as an example of the alpha helix secondary level protein.Rate this question:
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- 16.
All of the following are considered proteins EXCEPT:
- A.
Antibodies
- B.
Enzymes
- C.
Collagen
- D.
Dehydrogenase
- E.
Steroids
Correct Answer
E. SteroidsExplanation
Proteins are large, complex molecules that play crucial roles in the body, such as acting as enzymes, antibodies, and structural components like collagen. Dehydrogenase is an enzyme, so it is considered a protein. Steroids, on the other hand, are a type of lipid and not classified as proteins. Therefore, steroids are not considered proteins.Rate this question:
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- 17.
All of the following are true amino acids EXCEPT
- A.
They compose all enzymes and some hormones
- B.
They contain an amino group and a carboxyl group
- C.
They can act as buffers
- D.
They are building blocks of steroids
- E.
They are found in hemoglobin
Correct Answer
D. They are building blocks of steroidsExplanation
The correct answer is "they are building blocks of steroids." Amino acids are the building blocks of proteins, not steroids. Steroids are a class of organic compounds that have a different structure and function than amino acids.Rate this question:
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- 18.
Carbon 13 and Carbon 14 are isotopes and therefore have different numbers of
- A.
Electrons
- B.
Neutrons
- C.
Protons
- D.
Electrons and neutrons
- E.
Protons and electrons
Correct Answer
B. NeutronsExplanation
Isotopes are atoms of the same element that have different numbers of neutrons. Carbon 13 and Carbon 14 are both isotopes of carbon, but they have different numbers of neutrons. Therefore, the correct answer is neutrons.Rate this question:
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- 19.
The biochemical process by which most organisms extract energy from food is known as
- A.
Anabolism
- B.
Saprophytism
- C.
Parasitism
- D.
Commensalism
- E.
Catabolism
Correct Answer
E. CatabolismExplanation
Catabolism is the correct answer because it refers to the biochemical process through which organisms break down complex molecules to release energy. This process involves the breakdown of food molecules such as carbohydrates, proteins, and fats, and the release of energy in the form of ATP. Anabolism, on the other hand, refers to the process of building complex molecules from simpler ones, which is the opposite of catabolism. Saprophytism, parasitism, and commensalism are not related to the extraction of energy from food.Rate this question:
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- 20.
Cyanide poisoning is fatal within minutes since it binds irreversibly with the active sites of respiratory enzymes. Cyanide acts as a(an)
- A.
Competitive inhibitor
- B.
Coenzyme
- C.
Allosteric inhibitor
- D.
Allosteric stimulator
- E.
Enzyme cofactor
Correct Answer
A. Competitive inhibitorExplanation
Cyanide poisoning is fatal within minutes because it binds irreversibly with the active sites of respiratory enzymes. This means that cyanide acts as a competitive inhibitor, which competes with the substrate for the active site of the enzyme. By binding to the active site, cyanide prevents the substrate from binding and carrying out its normal function. This inhibition of respiratory enzymes ultimately leads to the cessation of cellular respiration and, consequently, cell death.Rate this question:
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- 21.
Which of the following is a structural polysaccaride
- A.
Amylose
- B.
Cellulose
- C.
Glycogen
- D.
Amylopectin
- E.
Starch
Correct Answer
B. CelluloseExplanation
Cellulose is a structural polysaccharide because it is a major component of plant cell walls, providing structural support to the plant. It is made up of long chains of glucose molecules linked together, forming a strong and rigid structure. Amylose, amylopectin, and glycogen are all storage polysaccharides, used for energy storage in plants and animals. Starch is a mixture of amylose and amylopectin, also used for energy storage.Rate this question:
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- 22.
During the synthesis of a polypeptide chain from 40 amino acids, the number of water molecules released is
- A.
40
- B.
42
- C.
25
- D.
39
- E.
80
Correct Answer
D. 39Explanation
During the synthesis of a polypeptide chain, each amino acid is joined together by a dehydration synthesis reaction, which results in the release of one water molecule for each bond formed. Since there are 40 amino acids in this chain, there will be a total of 39 water molecules released during the synthesis process.Rate this question:
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- 23.
Humans lack the enzyme necessary to digest which of the following carbohydrates?
- A.
Cellulose
- B.
Amylose
- C.
Sucrose
- D.
Lactose
- E.
Maltose
Correct Answer
A. CelluloseExplanation
Cellulose is the correct answer because humans lack the enzyme called cellulase, which is required to break down cellulose into its constituent glucose molecules. While humans can digest other carbohydrates such as amylose, sucrose, lactose, and maltose with the help of specific enzymes, cellulose cannot be broken down and remains undigested in the human digestive system.Rate this question:
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- 24.
The major component of the fluid bilayer of a plasma membrane.
- A.
Glycocalyx
- B.
Cholesterol
- C.
Triglyceride
- D.
Phospholipid
- E.
Protein
Correct Answer
D. PhospholipidExplanation
Phospholipids are the major component of the fluid bilayer of a plasma membrane. They have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails, which allow them to form a double layer in the membrane. This arrangement provides a barrier that separates the inside and outside of the cell, while still allowing for the passage of certain molecules. Phospholipids play a crucial role in maintaining the integrity and fluidity of the cell membrane.Rate this question:
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- 25.
Carrier molecule in the plasma membrane.
- A.
Glycocalyx
- B.
Cholesterol
- C.
Triglyceride
- D.
Phospholipid
- E.
Protein
Correct Answer
E. ProteinExplanation
Proteins are the carrier molecules in the plasma membrane. They play a crucial role in transporting various substances across the membrane, including ions, nutrients, and waste products. Proteins also help in cell signaling and communication by acting as receptors or channels. Additionally, proteins provide structural support and help maintain the integrity of the plasma membrane. Therefore, proteins are essential components of the plasma membrane and function as carrier molecules.Rate this question:
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- 26.
Steroid affecting the fluidity of the plasma membrane.
- A.
Glycocalyx
- B.
Cholesterol
- C.
Triglyceride
- D.
Phospholipid
- E.
Protein
Correct Answer
B. CholesterolExplanation
Cholesterol is a steroid that is present in the plasma membrane. It plays a crucial role in regulating the fluidity of the membrane. Cholesterol molecules are interspersed between the phospholipids in the membrane, reducing their mobility and preventing the membrane from becoming too fluid or too rigid. This helps maintain the integrity and stability of the plasma membrane. Therefore, cholesterol affects the fluidity of the plasma membrane.Rate this question:
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- 27.
It is believed that an increase in the CO2 in the earth's atmosphere is causing
- A.
A decrease in the earth's temperature
- B.
A depletion of the ozone layer
- C.
An increase in the U-V radiation reaching the earth
- D.
The greenhouse effect
- E.
The pollution of our rivers
Correct Answer
D. The greenhouse effectExplanation
The increase in CO2 in the earth's atmosphere is causing the greenhouse effect. The greenhouse effect refers to the trapping of heat in the earth's atmosphere due to the presence of greenhouse gases like CO2. When CO2 levels increase, more heat is trapped, leading to a rise in global temperatures. This phenomenon is responsible for climate change and its associated impacts, such as melting ice caps, rising sea levels, and extreme weather events.Rate this question:
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- 28.
Lipid molecules are also known as triglycerides since they contain three
- A.
Glycerol molecules
- B.
Fatty acids
- C.
Hydroxy alcohols
- D.
Phosphates
- E.
Polar groups
Correct Answer
B. Fatty acidsExplanation
Lipid molecules are known as triglycerides because they consist of three fatty acid molecules. Fatty acids are organic molecules that have a long hydrocarbon chain with a carboxyl group at one end. They are the building blocks of lipids and play a crucial role in energy storage and insulation in the body. Therefore, the correct answer is fatty acids.Rate this question:
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- 29.
The chromosomes of eukaryotic cells contain DNA-histone complexes known as
- A.
Chromoplasts
- B.
Nucleosomes
- C.
Nucleoli
- D.
Centrosomes
- E.
Leucoplasts
Correct Answer
B. NucleosomesExplanation
Nucleosomes are the correct answer because they are DNA-histone complexes found in the chromosomes of eukaryotic cells. Nucleosomes consist of DNA wrapped around histone proteins, which help to package and organize the DNA in the nucleus. This packaging allows for efficient storage of the long DNA molecules and also plays a role in gene regulation by controlling access to the DNA.Rate this question:
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- 30.
A complex polysaccharide that forms the exoskeleton of insects, crustaceans and other invertebrates is
- A.
Cellulose
- B.
Glycogen
- C.
Bone
- D.
Chitin
- E.
Pectin
Correct Answer
D. ChitinExplanation
Chitin is a complex polysaccharide that forms the exoskeleton of insects, crustaceans, and other invertebrates. It is a structural component that provides strength and protection to their bodies. Chitin is a tough and flexible material that is resistant to degradation, making it ideal for forming the exoskeleton. Cellulose is another polysaccharide, but it is found in the cell walls of plants, not in the exoskeleton of invertebrates. Glycogen is a storage form of glucose in animals, bone is a mineralized connective tissue found in vertebrates, and pectin is a structural polysaccharide found in plant cell walls.Rate this question:
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- 31.
According to the fluid mosaic model of the plasma membrane all of the following constitute the membrane EXCEPT:
- A.
Glycolipids
- B.
Glycoproteins
- C.
Monosaccharides
- D.
Oligosaccharides
- E.
Transmembranal proteins
Correct Answer
C. MonosaccharidesExplanation
The fluid mosaic model of the plasma membrane describes the structure of the cell membrane as a fluid-like bilayer with embedded proteins. According to this model, the membrane is composed of various components, including phospholipids, cholesterol, proteins, and carbohydrates. Glycolipids and glycoproteins are examples of carbohydrates that are present in the membrane. Transmembranal proteins are also a component of the membrane. However, monosaccharides are not considered a part of the membrane structure. Monosaccharides are single sugar molecules and are not typically found as a structural component of the cell membrane.Rate this question:
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- 32.
Unsaturated and saturated fatty acids differ in that the former have...
- A.
More oxygen atoms
- B.
Fewer carboxyl groups
- C.
Carbon to carbon double bonds
- D.
More hydrogen atoms
- E.
Amino groups
Correct Answer
C. Carbon to carbon double bondsExplanation
Unsaturated fatty acids have carbon to carbon double bonds, whereas saturated fatty acids do not have any double bonds between carbon atoms. This difference in the chemical structure of the fatty acids affects their physical properties and biological functions.Rate this question:
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- 33.
Strontium 90 is a radioactive isotope with a half-life of 28 years. Starting with 12g. of 90Sr, approximately how much of the isotope will remain in 84 years.
- A.
1.5 grams
- B.
3.0 grams
- C.
6.0 grams
- D.
12.5 grams
- E.
24.0 grams
Correct Answer
A. 1.5 gramsExplanation
Since the half-life of strontium 90 is 28 years, after 28 years, half of the initial amount will remain, which is 6 grams. After another 28 years (56 years total), half of the remaining 6 grams will remain, which is 3 grams. After another 28 years (84 years total), half of the remaining 3 grams will remain, which is 1.5 grams. Therefore, approximately 1.5 grams of strontium 90 will remain after 84 years.Rate this question:
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- 34.
All of the following are found in prokaryotic cells EXCEPT:
- A.
The plasma membrane
- B.
Circular DNA
- C.
Ribosomes
- D.
A nuclear envelope
- E.
Plasmids
Correct Answer
D. A nuclear envelopeExplanation
Prokaryotic cells are characterized by the absence of a nucleus, which means they lack a nuclear envelope. Instead, their genetic material is present in the form of circular DNA. Prokaryotic cells do have a plasma membrane, ribosomes, and may also contain plasmids, which are small, circular DNA molecules separate from the main chromosome.Rate this question:
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- 35.
MItochondria are referred to as the "power-houses" of the cell. Which of the following best supports this statement:
- A.
Mitochondria are present in almost all plant and animal cells
- B.
Mitochondria are self-replicating
- C.
ATP is found in mitochondria
- D.
The Calvin cycle occurs in mitochondria
- E.
Mitochondria have cristae
Correct Answer
C. ATP is found in mitochondriaExplanation
ATP (adenosine triphosphate) is the main source of energy for cellular activities. It is produced through the process of cellular respiration, which takes place in the mitochondria. Therefore, the presence of ATP in mitochondria supports the statement that mitochondria are the "power-houses" of the cell.Rate this question:
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- 36.
Which of the following is an structural isomer of glucose?
- A.
Lactose
- B.
Starch
- C.
Maltose
- D.
Fructose
- E.
Sucrose
Correct Answer
D. FructoseExplanation
Fructose is a structural isomer of glucose because it has the same chemical formula (C6H12O6) but a different arrangement of atoms. In glucose, the hydroxyl group (-OH) on carbon 1 is on the right side, while in fructose, the hydroxyl group on carbon 2 is on the left side. This difference in arrangement gives fructose its unique properties and distinguishes it as a structural isomer of glucose.Rate this question:
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- 37.
Buffers are important in living systems since they...
- A.
Tend to prevent drastic changes in pH
- B.
Help to produce a pH of more than 14
- C.
Help to produce a pH of less than 1
- D.
Tend to produce drastic changes in pH
- E.
Help to maintain a pH of 4 in all cells
Correct Answer
A. Tend to prevent drastic changes in pHExplanation
Buffers are important in living systems because they tend to prevent drastic changes in pH. Buffers are substances that can resist changes in pH by accepting or donating protons (H+ ions) when necessary. They help to maintain the pH within a narrow range, which is crucial for the proper functioning of biological processes. Without buffers, even slight changes in pH could have harmful effects on enzymes, proteins, and other biomolecules, disrupting their structure and function. Therefore, buffers play a vital role in maintaining the stability and homeostasis of living systems.Rate this question:
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- 38.
An organism could be classified as a bacterium based upon the presence of...
- A.
A nuclear membrane
- B.
Chloroplasts
- C.
A circular chromosome
- D.
Mitochrondia
- E.
Golgi complexes
Correct Answer
C. A circular chromosomeExplanation
An organism could be classified as a bacterium based upon the presence of a circular chromosome. Bacteria are prokaryotic organisms, which means they lack a true nucleus and their genetic material is organized in a circular chromosome. This characteristic distinguishes them from eukaryotic organisms, which have a nuclear membrane and linear chromosomes. The presence of a circular chromosome is a defining feature of bacteria and is used to classify them as such.Rate this question:
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- 39.
Which of the following is an organic compound?
- A.
Calcium phosphate
- B.
Sucrose
- C.
Water
- D.
Sodium chloride
- E.
Ammonia
Correct Answer
B. SucroseExplanation
Sucrose is an organic compound because it is composed of carbon, hydrogen, and oxygen atoms bonded together in a specific arrangement. Organic compounds are compounds that contain carbon atoms, and sucrose fits this criteria as it is a type of sugar found in plants. Calcium phosphate, water, sodium chloride, and ammonia do not contain carbon atoms and are therefore not organic compounds.Rate this question:
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- 40.
Human red blood cells were placed into a solution isotonic to the cells. Which of the following resulted?
- A.
The cells hemolyzed
- B.
The cells crenated
- C.
The cells remained unchanged
- D.
The cells increased in volume
- E.
The cells decreased in volume
Correct Answer
C. The cells remained unchangedExplanation
When red blood cells are placed in a solution that is isotonic to them, it means that the concentration of solutes in the solution is the same as the concentration inside the cells. This creates an equilibrium, where there is no net movement of water into or out of the cells. As a result, the cells do not gain or lose water, and their volume remains the same. Therefore, the correct answer is that the cells remained unchanged.Rate this question:
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- 41.
An organism that has a nutritional mutation preventing the synthesis of necessary metabolities is known as a(n)...
- A.
Autotroph
- B.
Heterotroph
- C.
Chemotroph
- D.
Auxotroph
- E.
Phototroph
Correct Answer
B. HeterotrophExplanation
An organism that has a nutritional mutation preventing the synthesis of necessary metabolites is known as a heterotroph. Heterotrophs are unable to produce their own food and rely on consuming organic matter from other organisms to obtain the necessary nutrients for their survival and growth. This mutation hinders their ability to synthesize essential metabolites, making them dependent on external sources for their nutritional requirements.Rate this question:
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- 42.
The inorganic cofactor found in the chlorophyll molecule
- A.
Iron
- B.
Zinc
- C.
Magnesium
- D.
Calcium
- E.
Sulfur
Correct Answer
C. MagnesiumExplanation
Magnesium is the inorganic cofactor found in the chlorophyll molecule. Chlorophyll is a pigment that is essential for photosynthesis in plants, and it is responsible for capturing light energy. Magnesium is a central atom in the chlorophyll molecule, and it plays a crucial role in the absorption of light energy and the conversion of that energy into chemical energy. Without magnesium, plants would not be able to carry out photosynthesis effectively, leading to a lack of energy production and ultimately affecting their growth and survival.Rate this question:
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- 43.
Required in ionic form for the activity of many enzymes, the maintenance of bone, and the contraction of muscle fibers.
- A.
Iron
- B.
Zinc
- C.
Magnesium
- D.
Calcium
- E.
Sulfur
Correct Answer
D. CalciumExplanation
Calcium is required in ionic form for the activity of many enzymes, the maintenance of bone, and the contraction of muscle fibers. Calcium ions play a crucial role in various enzymatic reactions, including those involved in muscle contraction and bone formation. They also help in the transmission of nerve impulses and the release of neurotransmitters. Additionally, calcium is necessary for the proper functioning of muscles, as it is involved in the interaction between actin and myosin, which allows muscle fibers to contract.Rate this question:
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- 44.
Which of the following is a stereoisomer of glucose
- A.
Sucrose
- B.
Fructose
- C.
Galactose
- D.
Maltose
- E.
Amylase
Correct Answer
C. GalactoseExplanation
Galactose is a stereoisomer of glucose because they have the same molecular formula (C6H12O6) but differ in the arrangement of their atoms in space. Both glucose and galactose are aldohexoses, meaning they have six carbon atoms and an aldehyde functional group. The only difference between them is the position of the hydroxyl group on the fourth carbon atom. This difference in spatial arrangement gives galactose its own distinct properties and allows it to be classified as a stereoisomer of glucose.Rate this question:
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- 45.
The diagram below shows a plasmodesmata connection between two adjacent plant cells, what is the type of pathway of fluid from living plant cell to another living plant cell called:
- A.
Apoplastic pathway
- B.
Symplastic pathway
- C.
Kinetic pathway
- D.
Ergonomic pathway
- E.
None of the above
Correct Answer
B. Symplastic pathwayExplanation
The correct answer is Symplastic pathway. Plasmodesmata are channels that connect the cytoplasm of adjacent plant cells, allowing for the movement of fluids, nutrients, and signaling molecules. This pathway is known as the symplastic pathway because it involves the movement of substances through the symplast, which is the interconnected network of cytoplasm in plant cells. The apoplastic pathway refers to the movement of substances through the cell walls and intercellular spaces, while the kinetic pathway and ergonomic pathway are not terms commonly used in plant biology.Rate this question:
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- 46.
The diagram below shows three types of cell junctions. The ones near the top of the diagram are called:
- A.
Tight junctions
- B.
Desmosomes
- C.
Gap junctions
- D.
Plasmodesmata
- E.
None of the above
Correct Answer
A. Tight junctionsExplanation
The diagram shows three types of cell junctions, and the ones near the top are called tight junctions. Tight junctions are specialized connections between cells that form a barrier to prevent the passage of molecules and ions between cells. They are found in epithelial tissues, such as the lining of the intestines, where they help maintain the integrity and selective permeability of the tissue. Tight junctions play a crucial role in regulating the movement of substances across cell layers and maintaining tissue function.Rate this question:
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- 47.
Why is the phospholipid molecule so appropriate as the primary structural component of plasma membranes?
- A.
Phospholipids are completely insoluble in water.
- B.
Phospholipids form strong chemical bonds between the molecules, forming a stable structure.
- C.
Phospholipids form a selectively permeable structure.
- D.
Phospholipids form chemical bonds with membrane proteins that keep the proteins within the membrane.
Correct Answer
C. Phospholipids form a selectively permeable structure.Explanation
Phospholipids form a selectively permeable structure because of their unique composition. They have a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails. When phospholipids arrange themselves in a bilayer, the hydrophilic heads face outward towards the watery environment while the hydrophobic tails face inward, creating a barrier that only allows certain molecules to pass through. This selective permeability allows the plasma membrane to control the movement of substances in and out of the cell, maintaining homeostasis and allowing for essential cellular processes to occur.Rate this question:
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- 48.
Which increases the fluidity of the plasma membrane?
- A.
Having a large number of membrane proteins
- B.
The tight alignment of phospholipids.
- C.
Cholesterol present in the membrane.
- D.
Double bonds between carbon atoms in the fatty acid tails.
Correct Answer
D. Double bonds between carbon atoms in the fatty acid tails.Explanation
Double bonds between carbon atoms in the fatty acid tails increase the fluidity of the plasma membrane. This is because the double bonds create kinks in the fatty acid tails, preventing them from packing tightly together. As a result, the membrane becomes more fluid and flexible, allowing for easier movement of molecules and proteins within the membrane. In contrast, having a large number of membrane proteins, tight alignment of phospholipids, and cholesterol present in the membrane do not directly affect the fluidity of the plasma membrane.Rate this question:
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- 49.
Which best describes the structure of a plasma membrane?
- A.
Proteins embedded within two layers of phospholipids.
- B.
Phospholipids sandwiched between two layers of proteins.
- C.
Proteins sandwiched between two layers of phospholipids.
- D.
A layer of proteins on top of a layer of phospholipids.
Correct Answer
A. Proteins embedded within two layers of phospholipids.Explanation
The plasma membrane is composed of two layers of phospholipids, with proteins embedded within these layers. This arrangement is known as the fluid mosaic model, where the phospholipids form a fluid bilayer and the proteins are dispersed throughout, either partially or fully spanning the membrane. The proteins play crucial roles in various cellular functions, such as transport of molecules across the membrane, cell signaling, and structural support.Rate this question:
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- 50.
The movement of sodium ions from an area of higher concentration to an area of lower concentration is called...
- A.
Active transport
- B.
Osmosis
- C.
Diffusion
- D.
Phagocytosis
Correct Answer
C. DiffusionExplanation
Diffusion is the correct answer because it refers to the movement of particles from an area of higher concentration to an area of lower concentration. In this case, the movement of sodium ions follows the principle of diffusion as they move down their concentration gradient. Active transport refers to the movement of particles against their concentration gradient, osmosis specifically refers to the movement of water molecules across a selectively permeable membrane, and phagocytosis refers to the process of engulfing and digesting solid particles by cells.Rate this question:
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Mar 19, 2023Quiz Edited by
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Nov 18, 2010Quiz Created by
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