Multiple Choice Question On Respiration-1 - NEET MCQ

To determine which fish has lungs for respiration, let's analyze each option:
A: Scoliodon
- Scoliodon, commonly known as the spadenose shark, is a cartilaginous fish belonging to the class Chondrichthyes. It doesn't have lungs for respiration.
B: Labeo
- Labeo, also known as the carp, is a freshwater fish belonging to the class Actinopterygii. It doesn't have lungs for respiration.
C: Neoceratodus
- Neoceratodus, commonly known as the lungfish, belongs to the class Sarcopterygii. It is the only fish among the given options that possesses lungs for respiration.
D: Torpedo
- Torpedo, also known as the electric ray, is a cartilaginous fish belonging to the class Chondrichthyes. It doesn't have lungs for respiration.
Therefore, the fish that has lungs for respiration is Neoceratodus (option C).

Answer:
The muscles that are involved in changing the volume of the thoracic cavity during respiratory movements in mammals are:
Intercostal muscles:
- These muscles are located between the ribs and play a crucial role in the expansion and contraction of the thoracic cavity.
- The external intercostal muscles are responsible for raising the ribcage during inhalation, which increases the volume of the thoracic cavity.
- The internal intercostal muscles are responsible for lowering the ribcage during exhalation, which decreases the volume of the thoracic cavity.
Sternohyals:
- The sternohyal muscles are not directly involved in changing the volume of the thoracic cavity during respiratory movements.
- These muscles are located in the neck and are responsible for the movement of the hyoid bone.
Thoracic muscles:
- The term "thoracic muscles" is not specific and does not refer to a specific group of muscles involved in respiratory movements.
- The intercostal muscles mentioned earlier are the primary muscles involved in changing the volume of the thoracic cavity.
Laryngeal muscles:
- The laryngeal muscles are located in the larynx and are primarily involved in controlling the position and tension of the vocal cords.
- While these muscles play a role in respiratory movements during activities such as speaking or singing, they are not directly involved in changing the volume of the thoracic cavity.
Therefore, the correct answer is option A: Intercostal muscles.

Structure in Insects Corresponding to Lungs in Higher Animals:
The structure in insects that corresponds to lungs in higher animals is known as the trachea.
Explanation:
- Insects do not have lungs like higher animals, but they have a specialized respiratory system that allows them to obtain oxygen.
- The main component of this respiratory system is the trachea, which is a network of tubes that carry air directly to the insect's tissues.
- The trachea is made up of small tubes called tracheoles, which are responsible for delivering oxygen to individual cells.
- The trachea in insects is similar in function to the lungs in higher animals, as it allows for the exchange of gases (oxygen and carbon dioxide) between the insect's body and the external environment.
- The tracheal system in insects is highly efficient and allows for rapid gas exchange, enabling insects to have a high metabolic rate and perform activities such as flying.
- In addition to the trachea, insects also have small openings called spiracles on the surface of their body, which allow air to enter and exit the tracheal system.
- The spiracles can be opened and closed to regulate the flow of air and prevent water loss in terrestrial insects.
- Some insects, such as spiders and scorpions, have specialized structures called book lungs, which are modified respiratory organs that function similarly to the trachea by facilitating gas exchange.
Therefore, the correct answer is B: Trachea.

Reason for the death of a frog if its mouth remains open:
- The mouth of a frog is essential for respiration and eating. If the mouth remains open for a prolonged period of time, it can lead to the death of the frog due to the following reasons:
1. Inability to respire:
- The mouth of a frog is directly connected to its respiratory system. When the mouth is closed, the frog can effectively breathe through its nostrils and lungs.
- However, if the mouth remains open, the frog will struggle to breathe properly as the air passage will be obstructed. This can result in respiratory distress and eventually lead to the death of the frog.
2. Difficulty in taking food:
- The mouth plays a crucial role in the ingestion of food for a frog. It uses its tongue to catch prey and then swallows it.
- If the mouth remains open, the frog will have difficulty in catching and swallowing its food. This can lead to malnourishment and eventually the death of the frog.
Conclusion:
- In conclusion, if the mouth of a frog remains open, it will be unable to respire properly and take in food, ultimately leading to its death.

Bohr's Effect and the Shifting of Hb-Dissociation Curve

The Bohr effect refers to the phenomenon where the oxygen-hemoglobin dissociation curve shifts to the right. This shift occurs due to certain factors that affect the affinity of hemoglobin for oxygen. The primary factors involved in the Bohr effect are high CO2 levels and high temperature.

Factors affecting the Bohr effect:

1. High CO2 levels:

• Increased levels of carbon dioxide in the blood lead to the production of carbonic acid, which lowers the pH.


• The decrease in pH causes a conformational change in hemoglobin, reducing its affinity for oxygen.


• As a result, oxygen is released more readily from hemoglobin, shifting the dissociation curve to the right.

2. High temperature:

• Increased temperature also leads to a decrease in the affinity of hemoglobin for oxygen.


• The higher temperature promotes the release of oxygen from hemoglobin, facilitating oxygen delivery to the tissues.


• Thus, an increase in temperature further shifts the dissociation curve to the right.

3. High O2 and alkalinity:

• High oxygen levels and alkalinity do not directly contribute to the Bohr effect.


• However, high oxygen levels can result in increased oxygen saturation of hemoglobin, leading to a leftward shift of the dissociation curve.


• Alkalinity, or high pH, can also cause a leftward shift of the curve.

Therefore, the correct answer is:

Answer: A - High CO2, high temperature

During aerobic metabolism, one glucose molecule undergoes several metabolic reactions in order to produce energy. The process involves the breakdown of glucose to produce carbon dioxide, water, and energy in the form of ATP.
Here is a detailed explanation of the process and the number of hydrogen molecules released:
1. Glycolysis:
- In the cytoplasm, glucose is converted into two molecules of pyruvate.
- During this process, two molecules of NADH (Nicotinamide adenine dinucleotide) are produced by the reduction of NAD+.
- Each NADH molecule carries two hydrogen atoms.
- Therefore, a total of 4 hydrogen atoms (2 NADH x 2 hydrogen atoms) are released during glycolysis.
2. Krebs cycle:
- Each pyruvate molecule from glycolysis enters the mitochondria and is converted into Acetyl-CoA.
- Acetyl-CoA undergoes the Krebs cycle, also known as the citric acid cycle.
- During each turn of the Krebs cycle, three molecules of NADH are produced by the reduction of NAD+.
- Each NADH molecule carries two hydrogen atoms.
- Therefore, a total of 6 hydrogen atoms (3 NADH x 2 hydrogen atoms) are released during one turn of the Krebs cycle.
- Since two molecules of pyruvate are produced from one glucose molecule, the Krebs cycle will turn twice, resulting in a total of 12 hydrogen atoms (6 hydrogen atoms x 2 turns) released.
3. Electron transport chain:
- The NADH and FADH2 (Flavin adenine dinucleotide) produced in glycolysis and the Krebs cycle donate their electrons to the electron transport chain (ETC) located in the inner mitochondrial membrane.
- The ETC consists of several protein complexes that transfer electrons from NADH and FADH2 to oxygen.
- As electrons are transferred, hydrogen ions (H+) are pumped across the membrane, creating an electrochemical gradient.
- The hydrogen ions then flow back through ATP synthase, which generates ATP.
- During this process, each NADH molecule releases two hydrogen atoms, while each FADH2 molecule releases two hydrogen atoms.
- Since a total of 10 NADH and 2 FADH2 molecules are produced from one glucose molecule, the ETC will release a total of 24 hydrogen atoms (10 NADH x 2 hydrogen atoms + 2 FADH2 x 2 hydrogen atoms).
Overall:
- Glycolysis: 4 hydrogen atoms
- Krebs cycle: 12 hydrogen atoms
- Electron transport chain: 24 hydrogen atoms
- Total number of hydrogen atoms released during aerobic metabolism from one glucose molecule = 4 + 12 + 24 = 40
Therefore, the correct answer is B: 40 hydrogen atoms.

The ATPase activity in muscle is located in Myosin A-HMM. Here's a detailed explanation:
ATPase Activity:
- ATPase activity refers to the ability of an enzyme to hydrolyze ATP (adenosine triphosphate) into ADP (adenosine diphosphate) and inorganic phosphate.
- In muscle cells, ATPase activity plays a crucial role in muscle contraction and relaxation.
Myosin A-HMM:
- Myosin is a protein that forms thick filaments in muscle fibers and is responsible for muscle contraction.
- Myosin is composed of two major subunits: the heavy chain and the light chain.
- The heavy chain of myosin can be further divided into the A-band (A) and B-band (B) regions.
- The A-band region can be further divided into the light meromyosin (LMM) and heavy meromyosin (HMM).
Location of ATPase Activity:
- Studies have shown that the ATPase activity in muscle is primarily present in the Myosin A-HMM region.
- The ATPase activity of myosin is responsible for the hydrolysis of ATP, which provides the energy required for muscle contraction.
- The ATPase activity in Myosin A-HMM allows the myosin heads to detach from actin filaments after cross-bridge formation, leading to muscle relaxation.
Therefore, the correct answer is option B: Myosin A-HMM.

Answer:
The correct answer is A: Pharynx.
Explanation:
The lung arises from the ventral wall of the pharynx. Here is a detailed explanation:
- The pharynx is a muscular tube that connects the nasal cavity and mouth to the larynx and esophagus.
- It is divided into three parts: the nasopharynx, oropharynx, and laryngopharynx.
- The lung, on the other hand, is an organ responsible for respiration, located in the thoracic cavity.
- The lung develops from the ventral wall of the pharynx during embryonic development.
- As the embryo grows, the lung buds emerge from the ventral wall of the pharynx and continue to develop into the respiratory system.
- The lung buds undergo branching and further development to form the bronchial tree, which includes the bronchi, bronchioles, and alveoli.
- The lungs are connected to the pharynx through the trachea, which carries air from the pharynx down to the lungs.
In summary, the lung arises from the ventral wall of the pharynx during embryonic development.

The function of swim bladder found in bony fishes may be:
There are four options given as possible functions of the swim bladder in bony fishes. Let's discuss each option in detail:
A: Acts as hydrostatic organ:
- The swim bladder acts as a hydrostatic organ, meaning it helps in maintaining the fish's buoyancy at a particular level in the water column.
- It adjusts the fish's position in the water by altering the amount of gas present in the swim bladder.
- When the fish wants to rise in the water, it increases the gas volume in the swim bladder, making it less dense and more buoyant.
- Similarly, when the fish wants to sink, it decreases the gas volume, making the swim bladder more dense and less buoyant.
B: To increase body surface:
- This statement is incorrect. The swim bladder is not involved in increasing the body surface area of the fish.
C: Related to buoyancy:
- The swim bladder is indeed related to buoyancy control in fishes.
- It helps the fish in maintaining its position in the water column and conserving energy while swimming.
- By adjusting the gas volume in the swim bladder, the fish can achieve neutral buoyancy, where it neither sinks nor rises in the water.
D: A & C both:
- This option is correct as both options A and C are true.
- The swim bladder acts as a hydrostatic organ and is related to buoyancy control in bony fishes.
In conclusion, the correct answer is option D: A & C both. The swim bladder in bony fishes acts as a hydrostatic organ and is related to buoyancy control. It helps the fish maintain its position in the water column and conserve energy while swimming.

Transportation of CO₂ in Blood
CO₂ is produced as a waste product during cellular respiration and needs to be transported from the tissues to the lungs for elimination. The majority of CO₂ in the blood is transported in the form of bicarbonate ions (HCO₃^-) in a reaction catalyzed by the enzyme carbonic anhydrase. Sodium (Na) and potassium (K) are the major cations involved in this process.
Transportation of CO₂ as Bicarbonate
1. Carbon Dioxide Dissolution: CO₂ diffuses from the tissues into the red blood cells (RBCs) and dissolves in the plasma.
2. Carbonic Anhydrase Reaction: Inside the RBCs, carbonic anhydrase catalyzes the reaction between CO₂ and water (H₂O) to form carbonic acid (H₂CO₃).
CO₂ + H₂O ⇌ H₂CO₃
3. Bicarbonate Formation: Carbonic acid (H₂CO₃) dissociates into bicarbonate ions (HCO₃^-) and hydrogen ions (H⁺).
H₂CO₃ ⇌ HCO₃^- + H⁺
4. Chloride Shift: To maintain electrochemical balance, chloride ions (Cl^-) move from the plasma into the RBCs in exchange for bicarbonate ions (HCO₃^-).
5. Bicarbonate Transport: Bicarbonate ions (HCO₃^-) are transported out of the RBCs into the plasma, where they are carried to the lungs for elimination.
Percentage of Bicarbonate Transport
The major part of CO₂ in the blood is transported as bicarbonate ions. The percentage of bicarbonate transport can be estimated as follows:
- The total CO₂ content in the blood can be divided into three forms: dissolved CO₂, bicarbonate ions, and carbamino compounds (CO₂ combined with hemoglobin).
- Among these forms, the bicarbonate ions contribute the most to CO₂ transportation.
- The percentage of bicarbonate transport is estimated to be around 75%.
Therefore, the correct answer is option A: 75%.