Category: Class 11 Biology Objective Questions

Biology Multiple Choice Questions on “Organelles in Eukaryotic and Prokaryotic Cells”.

1. Which among the following is incorrect about endoplasmic reticulum?
a) These are complex network of membrane bounded tubules
b) They are classified as smooth and rough endoplasmic reticulum
c) Smooth endoplasmic reticulum has ribosomes attached to their surface and acts as site of protein synthesis
d) Rough endoplasmic reticulum is connected by nuclear membrane at one end and golgi apparatus on the other end
Answer: c
Clarification: Endoplasmic reticulum is a complex network of membrane bounded tubules. They are classified as smooth and rough endoplasmic reticulum. Rough endoplasmic reticulum has ribosomes attached to their surface and acts as site of protein synthesis. Rough endoplasmic reticulum is connected by nuclear membrane at one end and Golgi apparatus on the other end.

2. Which among the following is incorrect about prokaryotic cell?
a) In prokaryotic cell, cell compartmentalization is absent
b) Genetic material is scattered in the nucleus
c) Protista is an example of prokaryotic cell
d) Prokaryotic cell has a cell membrane
Answer: c
Clarification: In prokaryotic cell, cell compartmentalization is absent. Genetic material is scattered in the nucleus. Protista is an example of eukaryotic cell. Monera and archaebacteria are examples of prokaryotic cells. Prokaryotic cell has a cell membrane along with glycocalyx.

3. Which among the following is incorrect about lysosomes?
a) These are membrane bound vesicles that contain digestive enzymes
b) They are double membraned and are isolated from their neighboring environment
c) The digestive enzymes present include proteases, lipases, nucleases, glycosidases and phosphatases
d) The lysosomes defend against bacterial and viral infection
Answer: a
Clarification: Lysosomes are membrane bound vesicles that contain digestive enzymes. They are single membraned and are isolated from their neighboring environment. The digestive enzymes present include proteases, lipases, nucleases, glycosidases and phosphatases. The lysosomes defend against bacterial and viral infection.

4. Which among the following is not correct about Golgi apparatus?
a) They are absent in RBCs, sperm cell of Pteridophytes and Bryophytes
b) Golgi apparatus is freely distributed in animal cells and in plants fluid filled sac like structures called cisternae that pile parallel to each other to form Golgi bodies
c) There are three main components, namely, cisternae, tubules and vesicles
d) The membrane bound containers which appear dense in the cytoplasm are called vesicles
Answer: b
Clarification: They are absent in RBCs, sperm cell of Pteridophytes and Bryophytes. Golgi apparatus is freely distributed in plant cells and in animal cells fluid filled sac like structures called cisternae that pile parallel to each other to form Golgi bodies. There are three main components, namely, cisternae, tubules and vesicles.

5. Excess alcohol intake leads to fatigue of SER which results in harm to the body.
a) True
b) False
Answer: a
Clarification: Excess alcohol intake leads to fatigue of SER which results in harm to the body. SER helps in detoxification of harmful substances. Since, SER is present in large numbers in the liver, rapid detoxification takes place in this region. At a certain point this results in SER fatigue and finally failure of liver.

6. Which among the following is incorrect about vacuoles?
a) Vacuoles are fluid filled membrane bound sacs
b) They consist of water and sap consisting of minerals, sugars, amino acids and proteins etc.
c) The function of vacuoles differs from one organism to other
d) Vacuoles in plants are not membrane bound and therefore they occupy most of the cell
Answer: d
Clarification: Vacuoles are fluid filled membrane bound sacs. They consist of water and sap consisting of minerals, sugars, amino acids and proteins etc. The function of vacuoles differs from one organism to other. Vacuoles in plants occupy most of the cell because they act as storage units of cells in plants.

7. Which among the following statements is incorrect about mitochondria?
a) Mitochondria is a rod-shaped organelle bounded by two membranes and is also called as the power house of the cell
b) Mitochondria has an outer membrane, an inner membrane, cristae and matrix
c) The inner membrane of the mitochondria is highly folded and these folds provide greater surface area for the generation of ATP molecules
d) Mitochondria can’t synthesize their own proteins and depend on rough endoplasmic reticulum
Answer: d
Clarification: Mitochondrion is a rod-shaped organelle bounded by two membranes and is also called as the power house of the cell. Mitochondrion has an outer membrane, an inner membrane, cristae and matrix. The inner membrane of the mitochondria is highly folded and these folds provide greater surface area for the generation of ATP molecules. Mitochondria can synthesize their own proteins since they have ribosomes and genetic material in them.

8. Which among the following is incorrect about plastids?
a) These are the organelles present only in plant cell and bear color imparting pigments
b) Plastids are of three kinds, namely, leucoplasts, chromoplasts and chloroplasts
c) Chromoplasts contain carotenoid pigments and provide red to orange color to the flowers and fruits
d) Chloroplast is a single membrane bound organelles with stroma which contains a stack of thyllakoids called grana
Answer: d
Clarification: Plastids are the organelles present only in plant cell and bear color imparting pigments. Plastids are of three kinds, namely, leucoplasts, chromoplasts and chloroplasts. Chloroplast is a double membrane bound organelles with stroma which contains a stack of thyllakoids called grana.

9. Which among the following is incorrect about ribosomes?
a) Ribosomes are granule like structures without any membrane that act as site for protein synthesis
b) The size of the ribosomes are expressed using their sedimentation coefficients and is denoted by S, where S denotes to sub – units
c) Eukaryotic and prokaryotic ribosomes are 80S and 70S respectively
d) Eukaryotic ribosome further contains two unequal sub-units, 40S and 60S
Answer: a
Clarification: Ribosomes are granule like structures without any membrane that act as site for protein synthesis. The size of the ribosomes are expressed using their sedimentation coefficients and is denoted by S, where S denotes to Svedberg unit. Eukaryotic and prokaryotic ribosomes are 80S and 70S respectively. Eukaryotic ribosome further contains two unequal sub-units, 40S and 60S.

10. Which among the following is incorrect about cytoskeleton, cilia and flagella?
a) Cytoskeleton is the network of minute proteinaceous structure in the cytoplasm and which mainly contains microfilaments and micro tubules
b) Microtubules are composed of protein actin and microtubules are composed of protein tubulin
c) Cilia is present in large numbers of the body and only one or two flagella are present in an organism
d) Both flagella and cilia help in movement of the organism
Answer: b
Clarification: Cytoskeleton is the network of minute proteinaceous structure in the cytoplasm and which mainly contains microfilaments and micro tubules. Microtubules are composed of protein tubulin and microtubules are composed of protein actin.

Biology Multiple Choice Questions for Medical Entrance Exams on “Biomolecules – Primary and Secondary Metabolites – 2”.

1. Based on which of the following, amino acids are classified?
a) Based on the number of hydrogen
b) Based on the number of carbon atoms
c) Based on the number of ions
d) Based on the number of amino and carboxyl groups
Answer: d
Clarification: Based on the number of amino and carboxyl groups, there are acidic (e.g., glutamic acid, aspartic acid), basic (lysine, arginine) and neutral (valine) amino acids. Similarly, there are aromatic amino acids like phenylalanine, etc.

2. Which of the following is a peculiar property of amino acids?
a) Basic nature
b) Acidic nature
c) Ionisable nature
d) Neutral nature
Answer: c
Clarification: A peculiar property of amino acids is the ionisable nature of –NH₂ and –COOH groups. Hence, in solutions of different pHs, the structure of amino acid changes.

3. What does the given structure represent?

a) Glycine
b) Serine
c) Thymine
d) Lysine
Answer: a
Clarification: The given structure represents glycine. Glycine is a neutral amino acid. It is the only optically inactive amino acid. It is also responsible for the heme formation.

4. How many fractions do we obtain while straining a thick slurry of living tissue through the cheesecloth?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: When we strain thick slurry through a cheesecloth or cotton we would obtain two fractions. One is called the filtrate or the acid-soluble pool, and the second, the retentate or the acid-insoluble fraction.

5. All the elements present in a sample of earth’s crust are also present in a sample of living tissue.
a) True
b) False
Answer: a
Clarification: All the elements present in a sample of earth’s crust are also present in a sample of living tissue. However, a closer examination reveals that the relative abundance of carbon and hydrogen with respect to other elements is higher in any living organism than in earth’s crust.

6. What are the primary metabolites?
a) Compounds formed in every kind of cells
b) Compounds present in only plants
c) Compounds formed only in animals
d) Compounds formed only by fungus
Answer: a
Clarification: The compounds which are involved in the metabolic or the physiologic activities of the cell and which are formed in all kinds of cells are called primary metabolites.

7. What are the secondary metabolites?
a) Compounds formed in all kinds of cells
b) Compounds formed only in plants
c) Compounds formed only in animals
d) By-products of the cell
Answer: d
Clarification: Secondary metabolites are not involved in metabolic reactions. We do not understand the role or functions of all the secondary metabolites in the host organism. Secondary metabolites are the by-products of various cells.

8. Which of the following cells are not responsible for the formation of secondary metabolites?
a) Plant cells
b) Fungal cells
c) Animal cells
d) Bacterial cells
Answer: c
Clarification: Secondary metabolites are not the by-products of animal cells. These metabolites have ecological importance. Plant cells, Fungal cells and bacterial cells are responsible for the formation of secondary metabolites.

9. Which of the following is not a secondary metabolite?
a) Amino acids
b) Gum
c) Perfume
d) Spices
Answer: a
Clarification: Rubber, drugs, spices, gum, perfumes and pigments are some of the secondary metabolites. Many of these secondary metabolites are useful to human welfare. Glucose, amino acids, fructose, vitamins, cholesterol are some of the primary metabolites.

10. Which of the following is not a polymeric substance?
a) Rubber
b) Gum
c) Cellulose
d) Morphine
Answer: d
Clarification: Rubber, gum and cellulose are polymeric substances. Morphine, codeine, etc. are some of the alkaloids. Both the alkaloids and polymeric substances are some of the secondary metabolites.

11. Carotenoids and anthocyanins are some of the primary metabolites.
a) True
b) False
Answer: b
Clarification: Carotenoids and anthocyanins are some of the types of pigments. Pigments are included in the secondary metabolites. For example, chlorophyll is the major pigment responsible for trapping light.

12. Which of the following is an essential oil?
a) Monoterpene
b) Lemongrass oil
c) Vinblastin
d) Abrin
Answer: b
Clarification: Lemongrass oil is an essential oil. Monoterpenes, Diterpenes are some examples of terpenoids. Vinblastin, curcumin are examples of some drugs. Abrin and ricin are examples of toxins. All of these are examples of secondary metabolites.

13. Mitochondria are rich in which of the following ions?
a) Manganese
b) Molybdenum
c) Copper
d) Nitrogen
Answer: a
Clarification: Mitochondria are rich in manganese. Molybdenum is necessary for fixation of nitrogen, catalysed by the enzyme nitrogenase. Copper occurs in cytochrome oxidase.

14. Which of the following is the most abundant element in the cell?
a) Oxygen
b) Iron
c) Magnesium
d) Copper
Answer: a
Clarification: The most abundant element in the cell or living matter is oxygen. Fe²⁺ and Cu²⁺ are found in cytochromes. Magnesium is essential for a large number of enzymes, particularly those utilising ATP.

15. Which of the following is incorrect regarding sodium and potassium ions?
a) Responsible for maintenance of extracellular and intracellular fluids
b) Responsible for transmission of electrical impulses
c) Responsible for the maintenance of membrane potential
d) Responsible for nitrogen fixation in animals
Answer: d
Clarification: Sodium and Potassium are responsible for the maintenance of extracellular and intracellular fluids through the osmotic effects of the concentration of these two ions. These two ions are also responsible for the maintenance of membrane potential and the transmission of electrical impulses in the nerve cells.

To practice Biology Multiple Choice Questions for Medical Entrance Exams,

Biology Multiple Choice Questions on “Cell Cycle and Division – Meiosis-1”.

1. Which of these statements is not true about fertilization?
a) The gametes are haploid
b) Gametes develop from diploid cells
c) It involves the fusion of two gametes
d) Gametes have an incomplete set of chromosomes
Answer: d
Clarification: Fertilization involves the fusion of two gametes to produce an offspring. These gametes develop from diploid cells and are haploid. However, they possess the complete set of chromosomes.

2. Which of these processes ensure the haploid phase of life cycle?
a) Fission
b) Mitosis
c) Meiosis
d) Fertilization
Answer: c
Clarification: The haploid phase of life cycle occurs when the total chromosome number inside the cell is reduced to half. It occurs by the process of meiosis. Fertilization restores the diploid phase of life cycle.

3. Which of these processes involve meiosis?
a) Atherogenesis
b) Organogenesis
c) Gametogenesis
d) Embryogenesis
Answer: c
Clarification: Gametogenesis is the formation of gametes from some specialized diploid cells. Since gametes are haploid, gametogenesis involves in the reduction of chromosome number by half through meiosis.

4. Meiosis involves one cycle of ______
a) DNA replication
b) cytokinesis
c) karyokinesis
d) separation of chromosomes
Answer: a
Clarification: Meiosis is divided into two stages- meiosis I and meiosis II. In each stage, the cell undergoes separation of chromosomes during anaphase I and anaphase II, cytokinesis and karyokinesis.

5. Which of these undergo recombination?
a) Homologous chromosomes
b) Non-homologous chromosomes
c) Non-sister chromatids
d) Sister chromatids
Answer: b
Clarification: Non-sister chromatids of homologous chromosomes undergo recombination during meiosis, during which their genetic material is exchanged. This increases the genetic diversity of the species.

6. How many cells are formed at the end of meiosis I?
a) 2 haploid cells
b) 4 diploid cells
c) 2 diploid cells
d) 4 haploid cells
Answer: c
Clarification: Meiosis 1 involves one round of cell division in which the tetrad is separated into two daughter cells. Hence, from 4n of tetrad, two daughter cells each having 2n chromosomes are formed.

7. Arrange the phases of prophase I in order.
a) Leptotene → Zygotene → Pachytene → Diplotene
b) Zygotene → Leptotene → Pachytene → Diplotene
c) Leptotene → Pachytene → Zygotene → Diplotene
d) Zygotene → Leptotene → Diplotene → Pachytene
Answer: a
Clarification: Prophase 1 is the first stage of meiosis. It is the first step of meiosis 1. It is divided into four sub-phases-namely, Leptotene, Zygotene, Pachytene and Diplotene. Diplotene is followed by diakinesis.

8. Compaction of chromosomes occurs during ______
a) zygotene
b) pachytene
c) diplotene
d) leptotene
Answer: d
Clarification: Chromosomes have to become decondensed and compact before they can undergo cell division. Hence, chromosomal compaction occurs during the leptotene stage of prophase I of meiosis I.

9. What is the chromosomal association process in zygotene called?
a) Zygote
b) Tetrad
c) Synapsis
d) Chiasmata
Answer: c
Clarification: Zygotene is the second stage of prophase I of meiosis I. The compact chromosomes begin to associate with each other during this phase, and this association process is known as synapsis.

10. The duration of zygotene is shorter than that of pachytene. True or false?
a) True
b) False
Answer: a
Clarification: Zygotene is the second stage of prophase I while pachytene is the third stage. Tetrad formation takes place during zygotene while crossing over and recombination take place during pachytene stage.

11. During which stage of prophase I does synapsis occur?
a) Pachytene
b) Leptotene
c) Diplotene
d) Zygotene
Answer: d
Clarification: Synapsis is the process of association of compact chromosomes after the first phase of prophase I, leptotene. It occurs in the second phase known as the zygotene phase. The chromosomes pair with each other during synapsis.

12. Which of these following statements is false about synapsis?
a) Pairs of homologous chromosomes are formed
b) It occurs during zygotene
c) It results in tetravalent formation
d) It is accompanied by synaptonemal complex formation
Answer: c
Clarification: Synapsis is the process of chromosomal association that takes place in the zygotene stage of prophase I. It results in pairing of homologous chromosomes and involves synaptonemal complex formation. It results in bivalent formation.

13. During which stage do the chromatids of a bivalent become distinct?
a) Leptotene
b) Zygotene
c) Pachytene
d) Diplotene
Answer: c
Clarification: Bivalent or tetrad formation takes place during the zygotene stage of prophase I, after synapsis has occurred and homologous chromosomes form pairs. However, the bivalent is distinct only in the next stage, pachytene.

14. Crossing over takes place during _____
a) pachytene
b) zygotene
c) leptotene
d) diplotene
Answer: a
Clarification: Crossing over takes place after tetrad or bivalent formation by the process of synapsis during zygotene. Hence, crossing over takes place during pachytene. Crossing over leads to genetic diversity.

15. Which of these is true regarding crossing over?
a) Exchange occurs between non-homologous chromosomes
b) It involves recombination nodules
c) It is not mediated by enzymes
d) It occurs during zygotene
Answer: b
Clarification: Crossing over takes place during the pachytene stage of prophase I. It is enzyme mediated and involves recombination nodules. Exchange of genetic material occurs between homologous chromosomes.

Biology Multiple Choice Questions on “Photosynthesis Basics – 1”.

1. The process in which green plants synthesize organic food by utilizing carbon dioxide and water as raw materials, in the presence of sunlight is called as ______
a) Respiration
b) Food synthesis
c) Photosynthesis
d) Light synthesis
Answer: c
Clarification: The process in which green plants synthesize organic food by utilizing carbon dioxide and water as raw materials, in the presence of sunlight is called Photosynthesis. This is the pure definition. Oxygen is a byproduct which is advantageous for all living organisms.

2. Which is correct regarding photosynthesis?
a) Carbon dioxide is obtained from the atmosphere
b) Water is absorbed from the soil through the stem system
c) Sunlight is trapped by pigments called xanthophyll
d) Chlorophyll absorbs green light
Answer: a
Clarification: The carbon dioxide is obtained from the atmosphere whereas water is absorbed from the soil through the root system. Sunlight is trapped by pigments present in the leaf called chlorophyll and it absorbs violet, blue, and red lights and reflects green light.

3. The half leaf experiment showed that _____ is important for photosynthesis.
a) O₂
b) CO₂
c) Sunlight
d) Chlorophyll
Answer: b
Clarification: This experiment showed that CO₂ is important for photosynthesis. It was experimented by a scientist named Molls. It was named half leaf experiment because half of the leaf was enclosed in a test tube.

4. A compound was used in the half leaf experiment to absorb CO₂. This compound is ______
a) KMNO₄
b) HCl
c) NaOH
d) KOH
Answer: d
Clarification: KOH was the compound used in half leaf experiment to absorb CO₂. The part of the leaf enclosed in test tube contained some KOH soaked cotton while the other half was exposed to air. KOH has got the capability to absorb CO₂.

5. Chlorophyll b is the major pigment associated with photosynthesis.
a) True
b) False
Answer: b
Clarification: It is a wrong statement as chlorophyll a is the chief or main pigment associated with photosynthesis. Whereas chlorophyll b, carotenoids, and xanthophyll all are accessory pigments.

6. Which scientist showed that only the green part of the plants will release oxygen?
a) Jan Ingenhousz
b) Joseph Priestly
c) C. Van Neil
d) T. W. Engelmann
Answer: a
Clarification: Jan Ingenhousz showed that sunlight is essential for the plant process as it purifies the fouled air due to pollution or breathing animals. He found out the presence of bubbles in the green part of the plant whereas it was absent during dark. These bubbles were later termed as oxygen.

7. Who found the presence and properties of glucose in green plants?
a) T. W. Engelmann
b) C. Van Neil
c) Julius Von Sachs
d) Jan Ingenhousz
Answer: c
Clarification: Julius Von Sachs found out the production of glucose in plants growth. He also found out that green parts of the plant store glucose and it is usually in the form of starch. Glucose was not stored in plants as it increases the osmotic pressure.

8. The first action spectrum based on photosynthesis was given by ______
a) Jan Ingenhousz
b) Joseph Mathew
c) Cornelius Van Neil
d) T. W. Engelmann
Answer: d
Clarification: T. W. Engelmann discovered the first action spectrum based on photosynthesis. He split light into its spectral components VIBGYOR by using a prism. A green alga i.e. Cladophora was used to detect the sites of O₂ evolution.

9. Joseph Priestley did his experiments with which organism?
a) Chlorella
b) Mint plant
c) Green sulfur bacteria
d) Cladophora
Answer: b
Clarification: Joseph Priestly did his experiments with a mint plant. He placed a mint plant in a bell jar containing a mouse and candle. Presence of just a candle or animal in the jar removed the air in it. But due to the presence of the mint plant, the air was restored.

10. Which of the following is the correct equation of photosynthesis?
a) 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂
b) 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂
c) 6CO₂ + 6O₂ → C₆H₁₂O₆ + 12H₂O
d) 6CO₂ → C₆H₁₂O₆ + 6H₂O + 6O₂
Answer: a
Clarification: The correct equation is 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂. This occurs in the presence of sunlight. Six molecules of CO₂ react with twelve molecules of H₂O to produce one molecule glucose. The byproducts are six molecules of H₂O and O₂.

11. The method by which leaf pigments of any green plants can be separated is called as _____
a) condensation
b) centrifugation
c) paper chromatography
d) distillation
Answer: c
Clarification: Paper chromatography is used to remove or separate leaf pigments of any green plants. With the proper mobile and stationary phase, the pigments such as chlorophyll, xanthophyll, etc. can be converged. The remaining methods cannot separate the leaf pigment from the plants as it will only destroy its pigments.

Biology Multiple Choice Questions on “Plants Respiration – Amphibolic Pathway”.

1. How many major components are there in Complex V of ETS?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: The energy released during the electron transport system is utilised in synthesising ATP with the help of ATP synthase-Complex V. This complex consists of two major components F₁ and F₀.

2. What kind of protein is F₁ that is present in Complex V?
a) Peripheral protein
b) Embedded protein
c) Integral protein
d) Membrane less protein
Answer: a
Clarification: The F₁ headpiece that is present in the Complex V is a peripheral membrane protein complex and contains the site for synthesis of ATP from ADP and inorganic phosphate.

3. What kind of compound is F₀ particle?
a) Peripheral protein
b) Cutaneous protein
c) Embedded protein
d) Integral protein
Answer: d
Clarification: Fo is an integral membrane protein complex that forms the channel through which protons across the inner membrane. It is a component of Complex V of ETS.

4. For each ATP produced, how many protons pass through the intermembrane space?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: The passage of protons through the channel is coupled to the catalytic site of the F₁ component for the production of ATP. For each ATP produced, two protons pass through the F₀ from the intermembrane space to the matrix down the electrochemical proton gradient.

5. Which of the following is the favoured substance for respiration?
a) Sucrose
b) Lactose
c) Glucose
d) Mannose
Answer: c
Clarification: Glucose is the favoured substrate for respiration because glucose is a carbohydrate and is readily available in the cells through the food that cell intakes. It also releases a large amount of energy on its oxidation.

6. For the fats to be respired, what are they broken into?
a) Glycerol and fatty acids
b) Glycerol and ethanol
c) Fatty acids only
d) Glycerol only
Answer: a
Clarification: Fats would need to be broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded to acetyl CoA and enter the pathway.

7. Glycerol would enter the pathway after being converted to malic acid.
a) True
b) False
Answer: b
Clarification: Glycerol would enter the pathway after being converted to PGAL which is 3-phosphoglyceraldehyde. Apart from glucose, other substances can be respired but then they do not enter the respiratory pathway at the first step.

8. Which of the following are responsible for the degradation of proteins?
a) Lipases
b) DNase
c) RNase
d) Proteases
Answer: d
Clarification: Proteases are the enzymes which are responsible for the degradation of proteins. These enzymes break the bonds between the proteins and release amino acids which then enter the respiratory pathway.

9. Which pathway was respiration traditionally considered as?
a) Anabolic pathway
b) Catabolic pathway
c) Amphibolic pathway
d) Bolic pathway
Answer: b
Clarification: Since respiration involves the breakdown of substrates, the respiratory process has traditionally been considered as a catabolic process and the respiratory pathway as a catabolic pathway.

10. What would happen if organisms need to synthesise fatty acids which had already broken down into acetyl CoA?
a) Acetyl CoA would be withdrawn from the pathway
b) Acetyl CoA would be further broken down
c) Ethanol would be released
d) Glycerol would be released
Answer: a
Clarification: When fatty acids are to be used as substrates, then they would be broken down to acetyl CoA before entering the respiratory pathway, but when organisms need to synthesise fatty acids, acetyl CoA would be withdrawn from the respiratory pathway for it.

11. The respiratory pathway comes into the picture in both the breakdown and synthesis of fatty acids.
a) True
b) False
Answer: a
Clarification: The respiratory pathway comes into the picture in both the breakdown and synthesis of fatty acids. Similarly, during breakdown and synthesis of proteins too, respiratory intermediates form the link.

12. What is catabolism?
a) Joining of substances
b) Breaking down processes
c) Continuous processes
d) Discontinuous processes
Answer: b
Clarification: Catabolism refers to the breaking down processes that occur within the living organisms. Catabolic reactions include glycolysis, the tricarboxylic citric acid cycle, breakdown of fatty acids, etc.

13. What is meant by anabolism?
a) Synthesis of some molecules
b) Breaking down of molecules
c) Joining of bonds
d) Shifting of bonds
Answer: a
Clarification: Anabolism refers to the synthesis of some new molecules, for example, the reaction of glycerol with fatty acids to make lipids, photosynthesis, etc.

14. In mitochondria, which of the following is the site for the oxidation-reduction reaction?
a) Inner membrane
b) Outer membrane
c) Matrix
d) Cristae
Answer: d
Clarification: In mitochondria, cristae re the sites for oxidation-reduction reaction. They produce cellular energy in the form of ATP, hence they are called as powerhouse of the cell.

15. What is an amphibolic pathway?
a) Breaking down processes
b) Another name for catabolic processes
c) Both anabolic and catabolic processes
d) Another name for anabolic processes
Answer: c
Clarification: As the respiratory pathway is involved in both anabolism and catabolism, it is better to consider the respiratory pathway is an amphibolic pathway. Therefore, according to new studies, respiration is treated as an amphibolic pathway and not as a catabolic pathway as according to traditional studies.

Biology Multiple Choice Questions on “Human Respiratory System – 1”.

1. Which of the following is not part of the human respiratory system?
a) Pharynx
b) Alveoli
c) Trachea
d) Lumen
Answer: d
Clarification: Lumen is not a part of the human respiratory system whereas it belongs to the digestive system. Lumen increases the surface area for the absorption of food. Pharynx, alveoli, and trachea are part of respiratory system.

2. The common passage for both food and air is called the esophagus.
a) True
b) False
Answer: b
Clarification: It is a wrong statement. The pharynx is a common passage for both food and air. Esophagus also is known as food pipe is part of the digestive system, that allows passage of food from mouth to stomach.

3. Which of the following part is known as the soundbox of our body system?
a) Vocal gland
b) Pharynx
c) Larynx
d) Nasopharynx
Answer: c
Clarification: Larynx is known as the soundbox of our body system. It is made of cartilage and helps in production of sound, hence the name soundbox. The larynx is guarded by epiglottis. Also, larynx helps in regulation of our pitch and volume.

4. ________ prevents the food from entering into the glottis during swallowing.
a) Larynx
b) Peri glottis
c) Post glottis
d) Epiglottis
Answer: d
Clarification: Epiglottis prevents the food from entering into glottis during swallowing. It is a thin elastic cartilaginous flap. And if the food enters into the glottis, then it can lead to severe coughing or choking.

5. At which thoracic vertebrae does the trachea branch?
a) Sixth
b) Fourth
c) Fifth
d) Second
Answer: c
Clarification: The trachea is a straight tube that extends up to the mid-thoracic cavity. It divides at the fifth thoracic vertebra into left and right bronchi. The first division of the respiratory system occurs through trachea.

6. Trachea, bronchi, and bronchioles are all supported by _______
a) incomplete cartilaginous rings
b) complete cartilaginous rings
c) in-cartilaginous rings
d) bones
Answer: a
Clarification: Trachea, bronchi, and bronchioles are all supported by incomplete cartilaginous rings. They are actually hyaline cartilage and this is strong enough to hold the mentioned parts. They are also supported by a small smooth muscle at the end of the trachea.

7. Which of the following is not a characteristic of alveoli?
a) Thick
b) Thin
c) Irregular walled
d) Vascularized
Answer: a
Clarification: Alveoli is a thin, irregular walled and vascularized bag-like structure. It is the main site for diffusion of gases. Terminal bronchioles give rise to alveoli. Lungs without alveoli is a dead lung as they play a major role in respiration.

8. Which network comprises the lung?
a) Bronchi and bronchioles
b) Trachea, tracheoles
c) Bronchi, bronchioles, and alveoli
d) Trachea only
Answer: c
Clarification: Bronchi, bronchioles, and alveoli together comprise the lung. They are the main vital organs compared to other secondary parts. They have a perfect network for respiration to take place.

9. Trachea is a straight tube extending up to the ________
a) end of pharynx
b) middle of larynx
c) posterior of the thoracic cavity
d) anterior of the thoracic cavity
Answer: d
Clarification: Trachea is a straight tube extending up to the anterior part of the thoracic cavity. It is also known as the windpipe. The trachea connects the soundbox to the bronchi. Also, it provides the passage for air.

10. Pleura is _______ layered.
a) Not
b) Single
c) Double
d) Triple
Answer: c
Clarification: Pleura is doubled layered. It protects the lungs. Also, there is a fluid called pleural fluid present between the pleura. It reduces the friction between the surfaces of the lungs.

11. In which respiratory part does the diffusion of gas take place?
a) Alveoli
b) Bronchi
c) Bronchioles
d) Trachea
Answer: a
Clarification: Alveoli is the part where the diffusion of gases takes place. It exchanges oxygen and carbon dioxide between the bloodstream. They are arranged as small balloon clusters throughout the lungs.