Category: Class 11 Biology Objective Questions

Biology Multiple Choice Questions on “Biomolecules – Primary and Secondary Metabolites – 1”.

1. Which of these is a secondary metabolite?
a) Proteins
b) Lipids
c) Vitamins
d) Steroids
Answer: d
Clarification: Primary metabolites are those which are involved in the normal growth and development processes of the body. Proteins, lipids and vitamins are primary metabolites while steroids are secondary metabolites.

2. Which of these statements is false regarding primary metabolites?
a) They have identifiable functions
b) They play a role in normal physiological processes
c) Secondary metabolites are derived from primary metabolites
d) Lipids are primary metabolites
Answer: c
Clarification: Primary metabolites are involved in the normal growth and development processes. They have identifiable functions and take part in normal physiological processes. Lipid is a primary metabolite.

3. Which of these is a pigment?
a) Codeine
b) Ricin
c) Carotenoid
d) Curcumin
Answer: c
Clarification: Pigments are secondary metabolites. Carotenoids are a type of pigment. Ricin is a toxin; codeine is a type of alkaloid while curcumin is a drug. They all are secondary metabolites. Secondary metabolites have important ecological function.

4. What are anthocyanins?
a) Pigment
b) Alkaloid
c) Drug
d) Toxin
Answer: a
Clarification: Anthocyanins are a type of pigment. They are secondary metabolites. Anthocyanins are water soluble and belong to the phenolic group. They are responsible for imparting color to fruits and vegetables.

5. Which of these is an alkaloid?
a) Abrin
b) Morphine
c) Ricin
d) Anthocyanin
Answer: b
Clarification: Morphine is an alkaloid. Alkaloids are a type of secondary metabolite. Secondary metabolites are not involved in the normal growth and development processes. The above substances are all secondary metabolites.

6. Codeine is a(n) _____
a) Lipid
b) Toxin
c) Alkaloid
d) Pigment
Answer: c
Clarification: Codeine is an alkaloid. It is an opiate which is utilized as a central analgesic and sedative to treat pain, coughing and diarrhea. Codeine is a secondary metabolite, along with toxins and pigments.

7. Which of these is a secondary metabolite?
a) Monoterpenes
b) Triacylglycerols
c) Keratin
d) Myosin
Answer: a
Clarification: Triacylglycerols are a type of lipid while keratin and myosin are major proteins of the body. Lipids and proteins are primary metabolites. Monoterpenes are terpenoids which are secondary metabolites.

8. Which of these is a primary metabolite?
a) Diterpene
b) Codeine
c) Anthocyanin
d) Triacylglycerol
Answer: d
Clarification: Diterpenes, codeine and anthocyanin are secondary metabolites. Triacylglycerol is a type of lipid. It is directly involved in the normal growth and development processes. It is hence, a primary metabolite.

9. What is abrin?
a) Alkaloid
b) Pigment
c) Toxin
d) Drug
Answer: c
Clarification: Abrin is a type of toxin. It is a natural poison found in the seeds of a plant. It is a secondary metabolite. This means that that it is not involved in the normal growth and development processes.

10. Essential oils are a secondary metabolite. True or false?
a) True
b) False
Answer: a
Clarification: Essential oils such as lemongrass oil are secondary metabolites. This means that they are not involved in the normal growth and development processes but have other uses in human welfare.

11. Which of these proteins is a secondary metabolite?
a) Myosin
b) Keratin
c) Elastin
d) Ricin
Answer: d
Clarification: Myosin, keratin and elastin are important and major proteins present in the body. They are primary metabolites. However, ricin is a secondary metabolite. It is a toxin which is found naturally in castor beans.

12. Which of these is a lectin?
a) Codeine
b) Monoterpene
c) Concanavalin A
d) Anthocyanin
Answer: c
Clarification: Codeine is an alkaloid, monoterpene is a terpenoid, anthocyanin is a pigment and Concanavalin A is a lectin. They are all secondary metabolites and are not involved in normal growth and development processes.

13. Vinblastine is a _____
a) Terpenoid
b) Pigment
c) Drug
d) Essential oil
Answer: c
Clarification: Vinblastine is a drug that is used as a chemotherapy medication. It is a secondary metabolite. This means that they are not involved in the normal growth and development processes of the body.

14. Which of these secondary metabolites is useful for human welfare?
a) Curcumin
b) Abrin
c) Ricin
d) Gums
Answer: a
Clarification: Curcumin is a drug and a secondary metabolite. It has anti-inflammatory properties and is mainly found in turmeric. Abrin and ricin are toxins while gums are polymeric substances with no role in human welfare.

15. Which of these is not a primary metabolite?
a) Starch
b) Gum
c) Keratin
d) Myosin
Answer: b
Clarification: Primary metabolites are those which take part in the growth and development processes of the body. Starch, keratin and myosin are primary metabolites while gum is a secondary metabolite.

Biology Assessment Questions for Medical Entrance Exams on “Cell Cycle and Division – M Phase-2”.

1. Which of these events do not take place during metaphase?
a) Chromosomes lie at the equator of the cell
b) One chromatid of each chromosome is attached to the spindle fiber
c) Chromosomes spread throughout the cytoplasm
d) Nuclear envelope starts to disintegrate
Answer: d
Clarification: During metaphase, the nuclear envelope has completely disintegrated. The chromosomes spread out throughout the cytosol and the chromosomes lie at the equatorial plane, attached to spindle fibers.

2. Which phase is marked by the separation of sister chromatids?
a) Prophase
b) Metaphase
c) Anaphase
d) Telophase
Answer: c
Clarification: Anaphase is the third stage of M phase or mitosis. It succeeds metaphase, the phase during which the chromosomes align themselves along the equator of the cell. In anaphase, they start separating towards the poles.

3. In which direction does each chromatid move on separation of sister chromatids?
a) Towards the nuclear envelope
b) Towards the equatorial plane
c) Towards the poles
d) Towards adjacent chromatids
Answer: c
Clarification: Separation of the sister chromatids occurs during the third stage of mitosis or the M phase of the cell cycle, known as anaphase. The chromatids separate from each other and move to the opposite poles of the cell.

4. In which direction are the centromeres directed during separation of chromosomes?
a) Towards the poles
b) Towards the equatorial plane
c) Towards adjacent chromatids
d) Towards the nuclear envelope
Answer: a
Clarification: Separation of the sister chromatids occurs during the third stage of mitosis, known as anaphase. The centromeres of each chromatid are directed towards the poles while the arms of the chromosomes trail behind them.

5. Identify the stage of mitosis.

a) Telophase
b) Anaphase
c) Prophase
d) Metaphase
Answer: b
Clarification: In the given diagram, the sister chromatids have separated from each other at the centromeres and are moving towards the opposite poles of the cell. Thus, the stage is identified to be anaphase.

6. What is the final stage of karyokinesis?
a) Prophase
b) G2 phase
c) Telophase
d) G1 phase
Answer: c
Clarification: Karyokinesis is the division of the nucleus. This proceeds after the genetic material has been replicated and the sister chromatids have undergone separation. Thus, the final stage of karyokinesis is telophase, which is the last stage of mitosis.

7. Which of these events does not take place during telophase?
a) Chromosomes are distinct and clear
b) Chromosomes are present at the poles
c) Chromosomes are decondensed
d) Chromosomes lose their individuality
Answer: a
Clarification: Telophase is the last stage of mitosis or the M phase of cell cycle. During telophase, the chromosomes are present at the poles. They lose their individuality and are decondensed. They cannot be clearly visualized.

8. During which stage of the cell cycle does the nuclear envelope reform?
a) G1 phase
b) Cytokinesis
c) Anaphase
d) Telophase
Answer: d
Clarification: The nuclear envelope reforms after the division of the sister chromatids and their migration to the opposite poles of the cell. Hence, it reforms during the last stage of mitosis, telophase.

9. During which stage of cell cycle do the major organelles reform?
a) Prophase
b) Anaphase
c) Telophase
d) G2 phase
Answer: c
Clarification: The major organelles of the cell, such as the nucleolus, the Golgi apparatus and the endoplasmic reticulum, are reformed after the sister chromatids have separated and migrated to the opposite poles, during telophase.

10. Chromosomes lose their individuality in anaphase. True or false?
a) True
b) False
Answer: b
Clarification: Chromosomes decondense and lose their individuality during telophase of the M phase or mitosis phase of the cell cycle. It is the last stage of mitosis and is followed by cell division or cytokinesis.

11. Identify the stage of cell division.

a) Prophase
b) Metaphase
c) Anaphase
d) Telophase
Answer: d
Clarification: The diagram shows the presence of nuclear envelope near the opposite poles of the dividing cells. This signifies that prophase, metaphase and anaphase have already taken place. Thus, telophase is depicted.

12. Why do plants not undergo furrowing during cytokinesis?
a) Absence of centrioles
b) Presence of rigid vascular bundle
c) Presence of cell wall
d) Presence of large vacuoles
Answer: c
Clarification: Animal cells undergo furrowing during cell division or cytokinesis. The furrow deepens, ultimately forming two cells. The presence of a relatively inextensible cell wall prevents furrowing in plant cells.

13. From where does wall formation start between two newly formed plant cells?
a) Cell wall
b) Cell membrane
c) Centre of the cell
d) Cytoplasm
Answer: c
Clarification: The presence of a relatively inextensible cell wall prevents furrowing in plant cells. The plant cells instead undergo separation by cell plate formation that starts from the center of the plant cell.

14. The cell-plate of plant cells represents the ______
a) middle lamella
b) primary cell wall
c) secondary cell wall
d) plasmodesmata
Answer: a
Clarification: Plant cells undergo separation by cell-plate formation that starts from the center of the plant cell. It does not undergo furrowing like animal cells. The cell-plate represents the middle lamella.

15. Which of these is an example of syncytium in coconut?
a) Fleshy endosperm
b) Liquid endosperm
c) Endocarp
d) Mesocarp
Answer: b
Clarification: Syncytium is a cytoplasmic mass of cells that are multinucleated. This multinucleate condition arises due to absence of cytokinesis or cell division following karyokinesis or nuclear division.

To practice Biology Assessment Questions for Medical Entrance Exams,

Biology Problems for Medical Entrance Exams on “Mineral Nutrition – Metabolism of Nitrigen-2”.

1. N₂ + A e^– + A H⁺ + B ATP → C NH₃⁺ H₂ + D ADP + D P_i
In the equation given above, C is present in how much quantity?
a) 8
b) 16
c) 2
d) 1
Answer: c
Clarification: As per question, e^– and H⁺ is present 8 in number per N₂ molecule fixed. ATP, ADP and P_i are present in 16 times per N₂ molecule fixed. NH₃ is present two times per N₂ molecule fixed.

2. The bacteria have to modify into rod- shaped bacterium in order to initiate division of inner cortical and pericycle cells.
a) True
b) False
Answer: a
Clarification: The bacteria enter the plant body through root hair with the help of formation of an infection thread. After entering inside the cell, the bacteria change its form to rod-shaped bacterium in order to initiate division of inner cortical and pericycle cells.

3. Statement A: Nitrogenase is a Cu-Mn protein.
Statement B: It catalyses the conversion of atmospheric nitrogen to the form absorbed directly by plants.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: b
Clarification: Nitrogenase is an important enzyme for the process of nitrogen fixation. It is basically a Mo-Fe protein. It catalyses the conversion of atmospheric nitrogen into the first stable form that is ammonia.

4. Which microbe is capable of fixing nitrogen in non-leguminous plants?
a) Bacillus
b) Beijernickia
c) Anabaena
d) Frankia
Answer: d
Clarification: Frankia is a microbe that is capable of fixing nitrogen in non-leguminous plants such as Alnus. It also produces nodules in the roots of plant. It can freely live in soil but fixes nitrogen as a symbiont. Bacillus is a free living anaerobic nitrogen fixer. Beijernickia is an aerobic nitrogen fixer. Anabaena is a microbe among the cyanobacteria that is capable of nitrogen fixation.

5. Statement A: At physiological pH, NH₃ is protonated to form NH₄⁺ ion.
Statement B: The NH₄⁺ ion is further converted to another form in order to be accumulated.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: a
Clarification: At physiological pH, NH₃ is protonated to form NH₄⁺ ion. Since it is toxic for plants, it is not stored in this form and is further used in the processes of reductive amination and transamination to form amides. The amides obtained are essential parts of protein structure of plants.

6. Statement A: Nodule that arises from root hair cells contains enzyme nitrogenase.
Statement B: The nodule gets it pink color from nitrogenase.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: c
Clarification: Nodules are associations between bacteria and plant roots. It arises from root hair cells and contains enzyme nitrogenase and leghaemoglobin pigment. The nodule gets its pink from leghaemoglobin.

7. Leg-haemoglobin protects nitrogenase enzyme from anaerobic conditions.
a) True
b) False
Answer: b
Clarification: Leg-haemoglobin is a pigment present in root nodules of leguminous plants. It acts as oxygen scavenger. It protects nitrogenase enzyme from aerobic conditions as it is highly sensitive to molecular oxygen.

8. Statement A: In reductive amination, NH₄⁺ reacts with α-ketoglutaric acid to form asparagine.
Statement B: The process takes place in presence of glutamate dehydrogenase.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: d
Clarification: In reductive amination, NH₄⁺ reacts with α-ketoglutaric acid to form glutamic acid. The process takes place in presence of glutamate dehydrogenase. Glutamine contains 2 molecules of nitrogen and 5 molecules of carbon. It is a part of structural protein of the plant cell.

9. Which enzyme catalyses the process of transamination?
a) Lipase
b) Nitrogenase
c) Transaminase
d) Glutamate dehydrogenase
Answer: c
Clarification: Transaminase is the enzyme which catalyses the process of transamination. Nitrogenase is responsible for nitrogen fixation. Glutamate dehydrogenase has role in the process of reductive amination. Lipase is a linking enzyme and has no role to play in nitrogen metabolism.

10. Amides are transported to other parts of the plant through ________
a) phloem parenchyma
b) phloem companion cells
c) xylem vessels
d) phloem fibre
Answer: c
Clarification: Amides contain more nitrogen than amino acids. They are transported to other parts of the plant through xylem vessels. Phloem tissue has no function in relation to translocation of amides.

To practice Biology Problems for Medical Entrance Exams,

Botany Assessment Questions on “Aerobic Respiration – 2”.

1. How many points are there in the TCA cycle where NAD⁺ is reduced?
a) One
b) Two
c) Three
d) Four
Answer: c
Clarification: There are three points in the TCA cycle where NAD⁺ is reduced to NADH + H⁺ and one point where FAD⁺ is reduced to FADH₂. In a coupled reaction GTP is converted to GDP with the simultaneous synthesis of ATP from ADP.

2. Which of the following points are not necessary for the TCA to run continuously?
a) Replenishment of Oxaloacetic acid
b) Regeneration of NAD⁺
c) Regeneration of FAD⁺
d) Regeneration of malic acid
Answer: d
Clarification: The points which are necessary for the TCA cycle to run continuously are:
i. Continued replenishment of Oxaloacetic acid
ii. Regeneration of NAD⁺ from NADH
iii. Regeneration of FAD⁺ from FADH₂

3. What is the full form of ETS?
a) Electrolyte Transport Serum
b) Electrolyte Tissue System
c) Electron Transport System
d) Electron Transmission System
Answer: c
Clarification: ETS stands for Electron Transport System. It is the metabolic pathway where the products of glycolysis and Kreb’s cycle are phosphorylated to form ATP.

4. What is the use of ETS?
a) To release and utilise energy
b) To store energy
c) To transfer energy to the surroundings
d) To take energy from the surroundings
Answer: a
Clarification: The steps in the respiratory process in the ETS are to release and utilise the energy stored in NADH + H⁺ and FADH₂. This system is present in the inner mitochondrial membrane.

5. Where are the electrons passed in ETS?
a) Oxygen
b) Water
c) Carbon
d) Nitrogen
Answer: a
Clarification: In ETS, NADH and FADH₂ are oxidise through various steps and the electrons from this process are passed on to Oxygen resulting in the formation of water.

6. Which complex oxidises the electrons produced by NADH?
a) Complex I
b) Complex II
c) Complex V
d) Complex IV
Answer: a
Clarification: Complex I oxidises the electrons produced by NADH. Complex I is also known as NADH dehydrogenase. The electrons from the oxidation of NADH to NAD⁺ are passed onto the FMN complex which is located in the inner mitochondrial membrane.

7. Ubiquinone receives electrons from Complex I and Complex IV.
a) True
b) False
Answer: b
Clarification: Ubiquinone receives electrons from Complex I which is NADH dehydrogenase. It also receives reducing equivalents via Complex II which is FADH₂ that is generated during the oxidation of succinate in the citric acid cycle.

8. What is reduced Ubiquinone called as?
a) Ubiquinone
b) Ubiquity
c) Ubiquinol
d) Ubiquinal
Answer: c
Clarification: The reduced ubiquinone which is also known as Ubiquinol is oxidised with the transfer of electrons to cytochrome c via cytochrome bc₁ complex or Complex III.

9. Cytochrome c acts a carrier between which of the two complexes?
a) Complex I and Complex II
b) Complex II and Complex III
c) Complex III and Complex IV
d) Complex IV and Complex V
Answer: c
Clarification: Cytochrome c is a small protein that is attached to the outer surface of the inner membrane and acts as a mobile carrier for transfer of electrons between Complex III and Complex IV.

10. How many copper centres are present in Complex IV?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: Complex IV refers to cytochrome c oxidase complex containing cytochromes a and a₃, and two copper centres. The electrons in ETS pass from one carrier to another via complex I to IV.

11. Complex IV is responsible for the production of ATP.
a) True
b) False
Answer: b
Clarification: When the electrons pass from one carrier to another via complex I to IV in the electron transport chain, they are coupled to ATP synthase or Complex V for the production of ATP from ADP and inorganic phosphate.

12. The number of ATP molecules synthesised depends upon which of the following?
a) Nature of electron donor
b) Nature of electron acceptor
c) Nature of proton donor
d) Nature of atom
Answer: a
Clarification: The number of ATP molecules synthesised depends on the nature of the electron donor. Oxidation of one molecule of NADH gives rise to three molecules of ATP, while that of one molecule of FADH₂ produces two molecules of ATP.

13. Which of the following is the final hydrogen acceptor?
a) Phosphorous
b) Carbon
c) Nitrogen
d) Oxygen
Answer: d
Clarification: Oxygen acts as the final hydrogen acceptor. Oxygen is present in the matrix of the mitochondria and finally accepts the protons and forms water molecules. Oxygen is the molecule which drives the whole process of oxidative phosphorylation.

14. Which of the following energy is utilised for the production of the proton gradient in ETS?
a) Energy of Oxygen
b) Energy of Hydrogen
c) Energy of Phosphorous
d) Energy of Oxidation-Reduction
Answer: d
Clarification: Unlike photophosphorylation, where it is the light energy that is utilised for the production of proton gradient required for phosphorylation, in respiration, it is the energy of the oxidation-reduction utilised for the same process. It is for this reason that the process is called Oxidative phosphorylation.

15. Which of the following complexes in ETS are involved in the transport of protons?
a) Complex I
b) Complex II
c) Complex V
d) Complex IV
Answer: c
Clarification: In the electron transport system, Complex I, II, III and IV are related to the transport of only electrons in the mitochondria. Complex V is the only complex in ETS which is involved in proton transport.

To practice Botany Assessment Questions,

Biology Multiple Choice Questions on “Respiration in Animals”.

1. The process which involves the gaseous exchange between the organism and its environment is called as _______
a) Metabolism
b) Photosynthesis
c) Respiration
d) Exchange process
Answer: c
Clarification: Respiration is the process in which gaseous exchange occurs between the organism and its environment. It is also called breathing. The main concept of this process is exchange of CO₂ and O₂.

2. Carbon dioxide is harmful to the body.
a) True
b) False
Answer: a
Clarification: True statement. Carbon dioxide is a by-product in our body which is harmful to beings. It has to be removed systematically, which is carried out through respiration.

3. The respiration mechanism of an organism mainly depends on which of the following?
a) Survival instincts
b) Habitats
c) Levels of situation
d) Habits
Answer: b
Clarification: The mechanism of an organism mainly depends on two things. It is their habitat and level of organization. Small animals have less complex mechanisms, whereas higher organisms have more complex mechanism for respiration. It also depends on where they live.

4. Which of the following organisms undergo respiration through diffusion?
a) Sponges
b) Mammals
c) Bats
d) Whales
Answer: a
Clarification: Sponges are the invertebrates that undergo respiration through diffusion. It mainly occurs between their body surface and surrounding. It is the simplest form of respiration.

5. Earthworms respire through organs called as ______
a) Trachea
b) Cuticle
c) Book lungs
d) Heart
Answer: b
Clarification: Earthworms respire mainly through an organ called cuticle. It is very moist and present on their body segments. It keeps the body moist and prevents drying out. It also has got protective property.

6. Tracheal tubes are present for which type of organisms?
a) Birds
b) Worms
c) Frogs
d) Insects
Answer: d
Clarification: Insects respire using an organ called trachea. Several tubes are present for trachea that is uniformly distributed inside the body of the organism. The trachea divides into tracheoles through which the oxygen is supplied to the body parts.

7. Aquatic arthropods and mollusks use which organ for respiration?
a) Lungs
b) Gills
c) Eyes
d) Nose
Answer: b
Clarification: Since aquatic arthropods and mollusks are mainly in water, they use gills for respiration. These gills are present as outgrowths to their skin, which is covered by the exoskeleton. The exchange of gases takes place through these gills.

8. Which organism classification can breathe through moist skin?
a) Birds
b) Mammals
c) Reptiles
d) Amphibians
Answer: d
Clarification: Amphibians respire through both skin and lungs. The offsprings of amphibians respire through gills. The adults mainly breath through lungs or moist skin. Since their diaphragm is reduced, they mostly respire through their skin. This is applicable mainly to frogs.

9. Which vertebrates have the most well-developed respiratory system?
a) Mammals
b) Reptiles
c) Aves
d) Amphibians
Answer: a
Clarification: Mammals are the most complex form of organism in the classification of vertebrates. Since they are complex organisms, they have a well-developed respiratory system. Lungs are the main respiratory organs of mammals.

10. A fish which is taken and brought to land dies within a few minutes because of _____
a) global warming
b) high temperature
c) pressure absence
d) inability to respire
Answer: d
Clarification: Fishes respire through their gills in water and have no other means for breathing on land. So, when taken out of the water, they die due to the absence of oxygen. Fishes live in water because of the presence of dissolved oxygen present in water bodies.

Biology Multiple Choice Questions on “Excretory System in Animals”.

1. Which of the following is not accumulated by the body of living organisms?
a) Ammonia
b) Carbon dioxide
c) Urea
d) Oxygen
Answer: d
Clarification: Oxygen is not accumulated by the body of living organisms as this is required by the cells to perform respiration. Also, it is not a waste product of the cells. Animals accumulate ammonia, urea, uric acid, carbon dioxide, water, and ions like Na⁺, K⁺, Cl^–, phosphate, sulphate, etc., by certain metabolic activities.

2. Which of the following is not the major form of nitrogenous wastes?
a) Ammonia
b) Urea
c) Carbon dioxide
d) Uric acid
Answer: c
Clarification: Ammonia, urea, and uric acid are the major forms of nitrogenous wastes excreted by the animals. These substances have to be removed totally or partially from the body.

3. Which of the following is the most toxic form of nitrogenous waste?
a) Guanine
b) Ammonia
c) Urea
d) Uric acid
Answer: b
Clarification: Ammonia is the most toxic form of nitrogenous waste as it is corrosive. Also, it requires large amounts of energy for its elimination. Ammonia also needs a huge amount of water for its removal from the body.

4. Ammonia is generally excreted through which of the following?
a) Kidneys
b) Gills
c) Lungs
d) Skin
Answer: b
Clarification: Ammonia is generally excreted through the gills. It is generally excreted by the diffusion across the body surfaces or through the gill surfaces as it is readily soluble. Kidneys do not play a significant role in the elimination of ammonia.

5. The process of excreting ammonia is called as ureotelism.
a) True
b) False
Answer: b
Clarification: The process of excreting ammonia is called as ammonotelism while the process of excreting urea is known as ureotelism. Many bony fishes, aquatic amphibians and aquatic insects are known to be ammonotelic. Ureotelic organisms include cockroaches, humans, etc.

6. Which of the following organisms is not ureotelic?
a) Bony fishes
b) Mammals
c) Terrestrial amphibians
d) Marine fishes
Answer: a
Clarification: Mammals, many terrestrial amphibians, and marine fishes mainly excrete urea and are called as ureotelic animals. Terrestrial adaptations necessitated the production of lesser toxic nitrogenous waste like urea.

7. In ureotelic organisms, ammonia is converted into which of the following?
a) Uric acid
b) Carbon dioxide
c) Remains as such
d) Urea
Answer: d
Clarification: In ureotelic organisms, ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered and excreted out by the kidneys.

8. Which of the following is not a uricotelic organism?
a) Mammals
b) Reptiles
c) Birds
d) Land snails
Answer: a
Clarification: Those organisms which secrete uric acid as a nitrogenous waste are known as uricotelic organisms. Some uricotelic organisms are reptiles, birds, land snails, and insects. They excrete uric acid in the form of a pellet or paste to conserve water and to reduce the weight of the body because removal of uric acid requires a minimum amount of water.

9. Which of the following is not a guanotelic organism?
a) Spiders
b) Scorpions
c) Starfish
d) Marine birds
Answer: c
Clarification: Guanotelic organisms are those organisms whose main excretory product is guanine in the urine. These include spiders, scorpions, and some marine birds like an arctic tern, etc.

10. Excretion of which of the following is for the adaptation of water conservation?
a) Ammonia
b) Urea
c) Uric acid
d) Carbon dioxide
Answer: c
Clarification: Excretion of uric acid is an adaptation for water conservation as uric acid is least soluble in water and is formed by nucleic acid metabolism.

11. In most of the invertebrates, kidneys are present for excretion.
a) True
b) False
Answer: b
Clarification: In most of the invertebrates, kidneys are not present for excretion. Their excretory structures are simple tubular forms like nephridia, flame cells, etc. It is the vertebrates who have complex tubular organs called kidneys.

12. Which of the following organism has flame cells for excretion?
a) Flatworms
b) Roundworms
c) Hookworms
d) Pinworms
Answer: a
Clarification: Flame cells are also known as protonephridia. These are the excretory structures of flatworms like planaria, rotifers, some annelids and some cephalochordates like the Amphioxus. Flame cells are the primitive forms of nephridia.

13. Which of the following phyla have nephridia as an excretory structure?
a) Arthropods
b) Annelids
c) Platyhelminthes
d) Ctenophora
Answer: b
Clarification: Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance.

14. Malpighian tubules are the excretory structures of which of the following?
a) Insects
b) Flatworms
c) Roundworms
d) Crustaceans
Answer: a
Clarification: Malpighian tubules are the excretory structures of most of the insects including cockroaches. Malpighian tubules help in the removal of nitrogenous wastes and osmoregulation.

15. Which of the following are the excretory structures of crustaceans?
a) Nephridia
b) Protonephridia
c) Malpighian tubules
d) Antennal glands
Answer: d
Clarification: Antennal glands or green glands perform the excretory function in crustaceans like prawns. Protonephridia are the excretory structures which are primarily concerned with ionic and fluid volume regulation.