Category: Cell Biology Objective Questions

Cell Biology Multiple Choice Questions on “Cytoplasmic Membrane Systems – Studying Endomembrane System”.

1. Which technique was used to study the secretory pathway in acinar cells of the pancreas for the first time?
A. Gel electrophoresis
B. Chromatography
C. Autoradiography
D. ELISA
Answer: C
Clarification: The acinar cells of the pancreas secrete digestive enzyme that reach the small intestine and aid in digestion of food. The steps involved in the synthesis of these proteins, migration to cell surface and the subsequent discharge was studied using autoradiography by James Jamieson and George Palade of Rockefeller University.

2. Which type of molecules are used for labeling the cellular entities in the autoradiography technique?
A. Glycoproteins
B. Radioisotopes
C. Stereoisomers
D. Enantiomers
Answer: B
Clarification: In Autoradiography, cells labeled with radioisotopes are overlaid with a photographic emulsion that contains silver grains. The labeled entities can then be viewed under the microscope by the silver grain.

3. “Pulse-chase” is an experiment related to radioactivity.
A. True
B. False
Answer: A
Clarification: “Pulse-chase” is an experiment that led to elucidation of biosynthetic pathway of the secretory proteins. Pulse was the brief period in which acinar cells were incubated in a solution mixture containing radioactively labeled amino acids and chase is the period when incubation in solution containing unlabeled amino acids is done.

4. Green fluorescent protein (GFP) is observed from which of the following organism?
A. Octopus
B. Jellyfish
C. Drosophila
D. Mouse
Answer: B
Clarification: The green fluorescent protein is a protein synthesized by the jellyfish which is used to tag biological entities; for instance the gene synthesizing GFP can be combined with the gene of test protein and the whole biosynthetic pathway of the protein can be traced.

5. GFP joined at the end of a protein can interfere in its synthesis.
A. True
B. False
Answer: B
Clarification: GFP is a fluorescent protein used to tag the protein whose biosynthetic pathway has to be determined. A chimeric of GFP synthesizing and test protein synthesizing gene is incorporated in the cell. GFP joined at the end the protein has absolutely no effect on the protein’s activity or pathway.

6. After the synthesis of proteins in endoplasmic reticulum, where do they reach before being secreted from the cell?
A. Lysosomes
B. Golgi complex
C. Lysozymes
D. Nucleus
Answer: B
Clarification: After being synthesized in the endoplasmic reticulum, proteins travel through and reach the Golgi complex where they are modified finally reaching the plasma membrane and being discharged from the cell.

7. Which of the following can be used as a temperature-sensitive mutant to study the endomembrane system?
A. Vesicular Stomatitis Virus
B. Human Immunodeficiency Virus
C. Tobacco Mosaic Virus
D. Retrovirus
Answer: A
Clarification: VSVG is a viral gene of the Vesicular Stomatitis Virus, which is fused with the green fluorescent protein (GFP) to study the pathway of VSVG protein. In this case, a VSV with mutant VSVG protein can be used that can only grow at lower temperatures than normal; called the temperature-sensitive mutant.

8. Subcellular fragmentation is a technique to study the endomembrane system, based on _____________ of the cells.
A. homogenization
B. degradation
C. labeling
D. freezing
Answer: A
Clarification: Subcellular fragmentation is a technique that elucidates the molecular composition of an organelle. The cells are first ruptured by homogenization and as a result their membranes and internal structures get fragmented and form vesicles. Since the vesicles derived from different organelles (like ribosome, endoplasmic reticulum etc.) have different properties, they get separated from one another.

9. The microsomal content of a ruptured cell represents how many organelles?
A. 1
B. 2
C. 3
D. 4
Answer: B
Clarification: The heterogeneous similar sized membranous vesicles derived from the endomembrane system of a homogenized cell, primarily represented by the endoplasmic reticulum and Golgi complex, are referred to as microsomes.

10. Which of the following technique was used to study the function of ribosomes and contrast it with the function of ER membrane?
A. Cell-free systems
B. Autoradiography
C. Spectroscopy
D. Microscopy
Answer: A
Clarification: Cell-free systems refer to the isolated organelles of the homogenized cells. These were first used to comprehend the protein synthesizing role of ribosomes and the protein sequestering role of endoplasmic reticulum membrane.

11. A mutant organism or cell encodes normal proteins that can be used for studying the endomembrane system.
A. True
B. False
Answer: B
Clarification: A mutant organism or cultured cell contains chromosomes with on more genes that encode for an abnormal protein. As a result a characteristic deficiency is exhibited by the cell which can be used to study the usual function of the protein.

12. RNAi phenomenon inhibits the synthesis of which biomolecules?
A. RNA
B. DNA
C. Proteins
D. Carbohydrates
Answer: C
Clarification: RNA interference phenomenon wherein cells produce small RNAs called the siRNAs that bind to mRNAs and inhibit the synthesis of proteins. RNAi is a strategy used by the researchers to investigate the function of a missing protein.

Cell Biology Multiple Choice Questions on “Cell Introduction – Viruses and Viroids”.

1. The following diseases is caused by viruses ____________
A. Influenza
B. Measles
C. Typhoid
D. Both Influenza and Measles
Answer: D
Clarification: Measles and Influenza are diseases caused by the infection of viruses. Typhoid is caused by a bacteria known as Salmonella typhi.

2. Which of the following is not true for TMV Virus?
A. It does not contain spikes
B. TMV Virus affects tobacco plants
C. It contains viral coat containing copies of multiple proteins
D. It is a retrovirus
Answer: C
Clarification: TMV or Tobacco Mosaic Virus causes viral infection to the tobbacco plant. It is a rod-shaped helical RNA virus which consists of a single strand of RNA placed centrally enveloped by a protein coat.

3. Which of the following is the largest bacteriophage?
A. T4 bacteriophage
B. T6 bacteriophage
C. Lambda phage
D. T2 bacteriophage
Answer: A
Clarification: T4 bacteriophage is among the largest bacteriophages. It is approximately 90-100 nm wide and 200 nm long. Its double stranded DNA genome is about 169 kb long and encodes 289 proteins.

4. The integrated genetic material of a virus is called __________________
A. Viroid
B. Provirus
C. Virus-like-particle (VLP)
D. Prion
Answer: B
Clarification: The virus infection is caused by the entry of entry of viral DNA into the host cell. After this, the viral DNA is integrated into the host genome. This viral genetic material incorporated into host genome and able to replicate itself is called as provirus.

5. Virus like particles (VLP) are ____________
A. Immunogenic and infectious
B. Immunosuppressive and infectious
C. Infectious but not immunogenic
D. Immunogenic but not infectious
Answer: D
Clarification: An immunogenic organism can evoke the immune response when entered inside a host. Immunosuppressive organism can suppress the host immune response and infectious organism can cause infection to the host. VLP or Virus like particles are the outer protein covering of the virus with no viral genetic material. Hence, they can evoke host immune response but cannot cause infection to the host.

6. Which of the following viruses have DNA as its genetic material?
A. Tobacco Mosaic Virus
B. Potato Mosaic Virus
C. Tomato Mosaic Virus
D. Cauliflower Mosaic Virus
Answer: D
Clarification: Cauliflower Mosaic virus is a DNA virus with a nucleotide sequence of 8024 nucleotides. Tobacco Mosaic Virus, Potato Mosaic Virus and Tomato Mosaic Virus are retroviruses with RNA as its genetic material.

7. HIV antagonizes the ___________ cell in human body.
A. Red Blood Cell (RBC.
B. Cytotoxic T cell
C. B cell
D. Helper T cell
Answer: D
Clarification: HIV or Human Immune deficiency Virus infects the Helper T cells present in the blood. It recognizes the CD4 proteins on the surface of the helper T cells and thus infects it. By doing this, HIV manipulates the very cells which activate both B cells and Cytotoxic T cells.

8. Which of the following has the largest DNA sequence?
A. Pithovirus sibericum
B. Megavirus chilensis
C. TMV
D. T4 bacteriophage
Answer: B
Clarification: Megavirus chilensis has the largest genome length of 1,259,197 base-pair with around 1120 proteins. Pithovirus sibericum is currently the largest known virus with a length of 1500 nm and diameter 500 nm.

9. Which of the following enables a Dengue virus to affect human beings?
A. RNA Polymerase enzyme
B. DNA Polymerase enzyme
C. Reverse Transcriptase enzyme
D. Gyrase enzyme
Answer: C
Clarification: The Dengue Virus is a retrovirus which contains RNA as its genetic material. So, to infect a human being by integrating its genome into the human DNA genome, it is necessary to convert its RNA sequence into DNA. Reverse Transcriptase enzyme catalyzes the reverse transcription of viral RNA into DNA.

10. Viruses can be cultivated in_________________
A. Whole plant
B. Cell lines
C. Chick Embryo
D. All of the mentioned
Answer: D
Clarification: Viruses need a living system to survive and replicate. They complete their life cycle inside the living host but otherwise remain inert. Whole plant, cell lines and chick embryo act as appropriate living systems for the virus.

11. The capsomeres contain small protein subunits known as ___________________
A. Protomeres
B. Capsoproteins
C. Prions
D. None of the mentioned
Answer: A
Clarification: Capsomeres are the subunits of the protein coat enveloping the viral genome known as the Capsid. The Capsomeres assemble to form the capsid and are in turn made up of an assembly of smaller protein subunits known as Protomeres.

12. Which of the following viruses is found in saliva?
A. HIV
B. Dengue virus
C. Hepatitis B virus
D. Epstein-Barr virus (EBV virus)
Answer: D
Clarification: Epstein-Barr virus or EBV is also known as Herpes virus 4. It causes an infection called Mononucleosis, which is a contagious disease. Since the virus is present in the saliva of the host, it can be contracted by a healthy individual by kissing or eating from the same utensils.

13. How many structural and non-structural proteins are there in the dengue virus?
A. 7 ; 2
B. 3 ; 8
C. 3 ; 7
D. 3 ; 9
Answer: C
Clarification: Dengue virus has 3 structural or surface proteins namely the Capsid protein (C., the Membrane protein (M) and the Envelope protein (E). It also has 7 non-structural proteins (NS proteins) namely NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5.

Cell Biology Multiple Choice Questions on “Cellular Membranes – History and Overview”.

1. One of the main functions of plasma membranes is to enclose the contents of _____________
A. cell
B. organism
C. bones
D. tissue
Answer: A
Clarification: The main function of the plasma membrane is compartmentalization, to enclose all the organelles of the cell and thereby separate them from external hydrophilic environment.

2. Cytosol is the same as cytoplasm.
A. True
B. False
Answer: B
Clarification: Cytoplasm is the collective name of the inner fluid of the cell which is surrounded by a plasma membrane. The soluble part of the cytoplasm is called cytosol, which is not held by any of the cell organelles.

3. Which of the following is allowed in context with a plasma membrane?
A. Inversion
B. Transportation
C. Transversion
D. Transformation
Answer: B
Clarification: Plasma membrane is responsible for transportation of solutes across itself. It is a selectively permeable membrane that allows the transport of a number of molecules and prevents it for others.

4. Which type of molecules are involved in responding to external signals received by the cell?
A. Enzymes
B. Nucleic acids
C. Genes
D. Receptors
Answer: D
Clarification: Receptors present on the plasma membrane face outwards in the extracellular environment and are responsible for responding to signals received by cell. These signals are received in the form of small molecules that bind to the receptor consequently generating an orchestration of intracellular action.

5. The specific molecules that bind to receptors are _____________
A. Ligands
B. Co-enzymes
C. Substrates
D. Enzymes
Answer: A
Clarification: Receptors present on the cellular membrane are responsible for receiving the signals that come from extracellular environment. These signals are received and the corresponding action is generated upon binding of specific molecules called ligands on the receptors. The ligands have complementary structure with the receptors.

6. Energy transduction is the underlying process of which of the following?
A. DNA
B. Transcription
C. Translation
D. Photosynthesis
Answer: D
Clarification: Energy transduction is the conversion of one form of energy to another. In photosynthesis, the energy in sunlight is absorbed by the membrane bound photosynthetic pigments, converted into chemical energy and then stored as carbohydrates.

7. The first insights into the chemical nature of plasma membranes date back to __________
A. 1700
B. 1790
C. 1800
D. 1890
Answer: D
Clarification: The first insights into the chemical nature of cell membrane came from Ernst Overton of the University of Zürich during the 1890s. He stated that a substance entering the cell would first have to dissolve in the boundary layer of the cell.

8. Which material was used by Overton in his experiments to conclude the lipid nature of plasma membrane?
A. bacteria
B. yeast
C. plant root hair
D. animal root hair
Answer: C
Clarification: Overton placed plant root hair in different solutions containing different solutes. He concluded that more lipid-soluble the solute, more rapidly it would enter the root hair cells.

9. The fluid mosaic model was proposed in the year __________
A. 1942
B. 1972
C. 2002
D. 1872
Answer: B
Clarification: The fluid mosaic model proposed in 1972 by S. Jonathan Singer and Garth Nicolson of the University of California, San Diego. This model has served as the central dogma of membrane biology for over three decades.

10. According to the fluid mosaic model, the membrane is _____________
A. rigid
B. discontinuous
C. sheet-like
D. fluid-like
Answer: D
Clarification: The fluid mosaic model states that the membrane is a lipid bilayer of fluid nature in which the lipid components are free to move about.

Cell Biology Multiple Choice Questions on “Chloroplast Structure and Function – Light Absorption”.

1. Energy absorbed from sunlight is stored as chemical energy in which of the following biomolecules?
A. ATP, ADP
B. ATP, NADPH
C. NAD, FAD
D. NADH₂, ATP
Answer: B
Clarification: Energy from sunlight is absorbed and saved in the form of chemical energy in two types of biomolecules in plants namely ATP and NADPH. ATP is the cell’s primary source of energy and NADPH is the cell’s primary source of reducing power.

2. Which types of molecules are synthesized in light-independent (dark) reactions?
A. proteins
B. glycolipids
C. carbohydrates
D. nucleic acids
Answer: C
Clarification: The second stage of events involved in photosynthesis is referred to as light-independent (dark) reactions. In these carbohydrates are synthesized from carbon dioxide using energy stored in ATP and NADPH.

3. Photon of light of higher wavelength has _____________ energy.
A. higher
B. lower
C. intermittent
D. dissipated
Answer: A
Clarification: Energy and wavelength are inversely related, therefore photon of higher energy will have lower wavelength and photon of lower energy will have higher wavelength.

4. Pigments absorb light of particular wavelengths.
A. True
B. False
Answer: A
Clarification: Pigments are compounds that appear visibly colored because they only absorb light of particular wavelengths. Chlorophyll is a green colored pigment found in chloroplasts of plants.

5. Which part of the chlorophyll is responsible for absorption of light?
A. hydrophobic phytol chain
B. porphyrin ring
C. thylakoid membrane
D. outer membrane
Answer: B
Clarification: Chlorophyll has two parts; porphyrin ring and hydrophobic phytol chain. Porphyrin ring functions in the absorption of light and the hydrophobic phytol chain maintains the integration of chlorophyll in photosynthetic chain.

6. Which atoms are present in the porphyrin of a chlorophyll molecule?
A. iron
B. magnesium
C. calcium
D. sulphur
Answer: B
Clarification: In myoglobin and hemoglobin the porphyrins contain iron (heme groups) whereas porphyrins present in chlorophyll contain magnesium atom.

7. What are carotenoids?
A. pigments
B. cell organelles
C. terrestrial plants
D. granulated thylakoids
Answer: A
Clarification: Carotenoids are accessory light-absorbing pigments found in terrestrial plants. β-carotene is a carotenoid. These pigments absorb in blue and green regions of the spectrum.

8. Carotenoids dissipate absorbed energy as heat.
A. True
B. False
Answer: A
Clarification: Carotenoids function as secondary light absorbers during photosynthesis and draw excess away from excited chlorophyll molecules (to prevent the formation of singlet oxygen) to dissipate it as heat.

9. Which of the following type of spectrum is a plot of efficiency of different types of wavelengths in bringing about the photosynthesis?
A. absorption spectrum
B. action spectrum
C. efficiency spectrum
D. reflection spectrum
Answer: B
Clarification: Action spectrum is a plot of relative rate of photosynthesis induced by lights of different wavelengths. The spectrum identifies wavelengths that are effective in inducing a physiological response.

10. Which of the following contains a linear system of conjugated double bonds?
A. β-carotene
B. chlorophyll
C. chloroplast
D. thylakoid
Answer: A
Clarification: β-carotene is a carotenoid, a pigment that acts as accessory light absorber during photosynthetic reaction. It has a linear system of conjugated double bonds.

Cell Biology Multiple Choice Questions on “Cytoplasmic Membrane Systems – Endoplasmic Reticulum”.

1. The membranes of rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) are continuous.
A. True
B. False
Answer: A
Clarification: There are two types of endoplasmic reticulum, rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). It has been found that fluorescently labeled proteins and lipids can diffuse from one type of ER to another suggesting that their membranes are continuous.

2. Which of the following biomolecules are not synthesized by the endoplasmic reticulum?
A. Proteins
B. Lipids
C. Nucleic acids
D. Cholesterol
Answer: C
Clarification: The primary function of endoplasmic reticulum is the synthesis of proteins. However certain lipids and cholesterol molecules are also synthesized in ER.

3. All the cells contain the same ratio of rough and smooth endoplasmic reticulum.
A. True
B. False
Answer: B
Clarification: Ribosomes are associated with the cytosolic space of rough endoplasmic reticulum hence they are more actively involved in protein synthesis. In cells that secrete large amount of proteins e.g. the cells of kidneys and salivary glands, more number of RER are present. Hence the ratios of SER and RER vary depending on the cell type.

4. Detoxification of organic compounds like barbiturates and ethanol in the liver is carried out by ________________
A. smooth endoplasmic reticulum
B. sarcoplasmic reticulum
C. rough endoplasmic reticulum
D. nucleus
Answer: A
Clarification: Detoxification of organic compounds is carried out by the smooth endoplasmic reticulum, chronic use of compounds such as barbiturates and ethanol can lead to proliferation of SER in liver cells.

5. Which enzymes are responsible for detoxification of organic compounds carried out by the smooth endoplasmic reticulum?
A. Dehydrogenases
B. Oxygenases
C. Nucleases
D. Ribonucleases
Answer: B
Clarification: Oxygen transferring enzymes – oxygenases (including cytochrome P450) carry out the detoxification of organic compounds and are synthesized in the smooth endoplasmic reticulum.

6. Sarcoplasmic reticulum is found in ________________
A. liver cells
B. kidney cells
C. muscle cells
D. neurons
Answer: C
Clarification: Smooth endoplasmic reticulum sequesters calcium ions within the cytoplasm of the cell and controlled release of Ca²⁺ from the SER of cardiac and skeletal muscle cells triggers contraction. Smooth endoplasmic reticulum (SER) in the aforementioned cells is known as sarcoplasmic reticulum.

7. The signal sequence that determines whether a protein will be synthesized on a free ribosome or ribosome attached to endoplasmic reticulum is located at _______
A. N-terminal
B. C-terminal
C. hydrophobic tail
D. hydrophilic tail
Answer: A
Clarification: There are two locations in a cell where a protein can be synthesized depending upon its type and function. The signal that directs the synthesis of a protein to a free ribosome or ribosome attached to the endoplasmic reticulum is found in the C-terminal of the protein.

8. In the image below, endoplasmic reticulum is depicted by ________

A. a
B. b
C. c
D. d
Answer: A
Clarification: The endoplasmic reticulum is a membranous structure containing sacs called cisternae. The organelle is associated with ribosomes and lies in close vicinity with the nucleus.

9. In yeast cells, protein transport across the endoplasmic reticulum membrane occurs __________
A. perpendicularly
B. discontinuously
C. co-translationally
D. post-translationally
Answer: D
Clarification: Polypeptide is synthesized in the ribosome and if appropriate signal is present in its C-terminal it moves to the ER membrane during the synthesis, this is called co-translational movement. In post-translational movement, the nascent polypeptide reaches the ER membrane after complete synthesis. Unlike mammalian cells post-translational movement of the polypeptides is observed in the yeast cells.

10. In mammalian cells, the signal recognition particle (SRP) consists of ____ distinct polypeptides and one small RNA molecule.
A. 2
B. 4
C. 6
D. 8
Answer: C
Clarification: The hydrophobic signal present in the nascent polypeptide is recognized by the SRP which then binds to the SRP receptor and transports the peptide to the endoplasmic reticulum membrane. The signal recognition particle (SRP) consists of 6 distinct polypeptides and one small 7S RNA.

11. Translocon is a ____________
A. polypeptide
B. protein channel
C. receptor
D. recognition particle
Answer: B
Clarification: Translocon is a protein-lined channel embedded in the membrane of the endoplasmic reticulum. The nascent polypeptide moves through this channel from the ribosome to the ER lumen.

12. Which of the following enzyme present in the rough endoplasmic reticulum removes the signal sequence from nascent polypeptides?
A. signal oxidase
B. signal peptidase
C. olisaccharyltransferase
D. luciferase
Answer: B
Clarification: After the nascent polypeptide reaches the cisterna of endoplasmic reticulum, it is acted upon by a variety of enzymes. One such enzyme is signal peptidase which removes the hydrophobic signal sequence from the peptide.

13. The cysteine residues present in the reduced form in peptides that enter the endoplasmic reticulum lumen are converted into ____________ when they leave the compartment.
A. hydrolyzed bonds
B. hydrophobic bonds
C. disulfide bonds
D. hydrophilic bonds
Answer: C
Clarification: Disulfide bonds play an important role in the stability of proteins. When the proteins enter ER lumen they contain cysteine residues in the reduced form (-SH) which is converted to oxidized disulfide bonds (-SS-) when they leave the ER, a reaction catalyzed by protein disulfide isomerase (PDI).

14. Hydrophobic transmembrane segments of which proteins are not synthesized in the endoplasmic reticulum?
A. integral membrane proteins
B. lysosomal proteins
C. steroids
D. secretory proteins
Answer: A
Clarification: Unlike secretory and lysosomal proteins, integral membrane proteins are not completely synthesized in the endoplasmic reticulum. One more or hydrophobic segment of these proteins are shunted directly from the translocon to the phospholipid bilayer.

15. Glycolipids are synthesized in the ER and ____________
A. Nucleus
B. Golgi complex
C. Mitochondrion
D. Plasma membrane
Answer: B
Clarification: Most membrane lipids are synthesized entirely in the endoplasmic reticulum with a few exceptions, one being glycolipids. The synthesis of glycolipids begins in the ER and completes in the Golgi complex.

Cell Biology Multiple Choice Questions on “Chemical Basis of Life – Acids, Bases and Buffers”.

1. Which of the following is released when a Hydrogen atom loses an electron?
A. Nucleus
B. Proton
C. Charge
D. Ion
Answer: B
Clarification: Whenever a hydrogen atom releases a shared electron in solution, a proton is also released. For example, acetic acid undergoes dissociation reaction to release acetate ion and a proton.

2. Which of the following is an example of amphoteric molecule?
A. Acetic acid
B. Malic acid
C. Sugars
D. Water
Answer: D
Clarification: Water is an example of both an acid and a base, and is therefore an amphoteric molecule. It can accept a proton thereby acting as a base and can also donate a proton acting as an acid.

3. Acids that lose a proton easily are weak acids.
A. True
B. False
Answer: B
Clarification: The strength of an acid is measured by the relative ease by which it loses a proton. The more readily the proton is lost, more strong is the acid. An example of a strong acid is Hydrogen Chloride which readily transfers its protons to water.

4. What is the full form of pH?
A. Positive hydrogen
B. Potential Hydrogen
C. Positron
D. Proton of hydrogen
Answer: B
Clarification: The acidity of a compound is measured by the concentration of hydrogen ions and is expressed in terms of pH- potential hydrogen. pH equals negative logarithmic concentration of protons.

5. A solution having a pH of 6 has a proton concentration of _______
A. 10^-6 M
B. 10⁶ M
C. 6 M
D. 0.6 M
Answer: A
Clarification: pH equals negative logarithmic concentration of protons. Since the pH scale is logarithmic, an increase of one pH unit corresponds to ten-fold decrease in hydrogen ion/ proton concentration.

6. What is the concentration of pure water?
A. 55.51 M
B. 25.51 M
C. 55 M
D. 25 M
Answer: A
Clarification: The concentration of pure water is always 55.51 Molar. On the basis of this universal value ion-product constant Kw for water is calculated, which is a constant value at 25℃.

7. In presence of an acid, amino group can be ____________
A. Polarized
B. Washed away
C. Protonated
D. Replaced
Answer: C
Clarification: In presence of an acid, amino group can be Protonated because an acid release proton, thereby increasing the hydrogen ion concentration in its vicinity and this can result in disruption of the protein activity to which amine group is attached.

8. Buffers react with _______________ ions.
A. hydrogen, hydroxyl
B. magnesium, calcium
C. potassium
D. sodium
Answer: A
Clarification: Buffers react with free hydrogen and free hydroxyl ions resisting changes in the pH and protecting cells and solutions from destroying. Buffers are also routinely used in laboratories.

9. Buffers usually contain ________________ with its conjugate ____________
A. weak base, acid
B. strong base, acid
C. weak acid, base
D. strong acid, base
Answer: C
Clarification: Buffers are used for resisting changes in the pH. A buffer usually contains a weak acid and its conjugate base. Even slight changes in pH can halt biological reactions.

10. Carbonic acid and bicarbonate ions buffer which of the following?
A. Cytosol
B. Cytoplasm
C. Blood
D. Lymph
Answer: C
Clarification: Carbonic acid and bicarbonate ions buffer the blood and hold its pH at 7.4. Carbonic acid is a weak acid and bicarbonate ions are basic in nature. A change in pH of the blood can lead to abnormalities.