Test: Respiration - 1 - UPSC MCQ

organism prepare their own food with the help of simple inorganic materials like CO₂,H₂O in sunlight with the help of chlorophyll. Thus, it doesn’t involve oxygen in the process.

Cellular respiration allows organisms to use energy stored in the chemical bonds of glucose. The energy in glucose is used to produce  ATP. Cells use ATP to supply their energy needs. Cellular respiration is therefore a process in which the energy in glucose is transferred to ATP.

Cellular respiration is the process of breaking sugar into a form that the cell can use as energy. This happens in all forms of life. Cellular respiration takes in food and uses it to create ATP, a chemical which the cell uses for energy. Usually, this process uses oxygen, and is called aerobic respiration.

Insects and some other invertebrates exchange oxygen and carbon dioxide between their tissues and the air by a system of air-filled tubes called tracheae. Tracheae open to the outside through small holes called spiracles. Spiracles open into large tracheal tubes. These, in turn, lead to ever-finer branches. The branches penetrate to every part of the body. At their extreme ends, called tracheoles, they may be less than 1 m in diameter and are probably filled with liquid. Every cell in the insect's body is adjacent to, or very close to, the end of a tracheole.

Bronchiole is a fine respiratory tube in the lungs of reptiles, birds and mammals. It is formed by the subdivision of a bronchus. 

A child respires around 26 times per minute. Norman man respires 14-18 times per minute. If the CO₂ concentration in blood increases, the rate of breathing also increases. When CO₂ is dissolved in the blood, then blood becomes slightly acidic. The brain picks up the change and adjusts the breathing to get rid of CO₂ from the blood. Thus, option B is correct.

This is because anaerobic respiration occurs in the absence of molecular oxygen to break down glucose into ethanol or lactic acid, carbon dioxide and energy (2 ATP)

Exchange of gases in a mammal

The exchange of gases, specifically oxygen (O₂) and carbon dioxide (CO₂), in a mammal takes place in the alveoli.

• Trachea: The trachea is responsible for conducting air to and from the lungs, but it does not participate in the exchange of gases.


• Bronchi: The bronchi are the main air passages in the lungs, but they do not directly participate in the exchange of gases.


• Bronchioles: Bronchioles are smaller branches of the bronchi that lead to the alveoli. While they play a role in directing air to the alveoli, they do not directly participate in gas exchange.


• Alveoli: The alveoli are tiny air sacs located at the end of the bronchioles. They are the primary site of gas exchange in the respiratory system. Oxygen from the inhaled air diffuses across the thin walls of the alveoli into the bloodstream, while carbon dioxide diffuses from the bloodstream into the alveoli to be exhaled.

Therefore, the correct answer is d. Alveoli, where the exchange of gases [O₂ and CO₂] takes place in a mammal.

Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and blood cells themselves.

Exhalation is a passive process because of the elastic properties of the lungs. During forced exhalation, internal intercostal muscles which lower the rib cage and decrease thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract.

Structure that prevents the entry of food into the respiratory tract:


The structure that prevents the entry of food into the respiratory tract is the epiglottis.
Explanation:
The respiratory and digestive systems share a common pathway in the throat or pharynx. However, to prevent food from entering the respiratory tract, several structures work together to ensure proper passage of air and food. The epiglottis is one such structure that plays a crucial role in preventing the entry of food into the respiratory tract. Here's how it functions:
- The epiglottis is a flap-like structure located at the base of the tongue.
- During swallowing, the epiglottis moves down and covers the opening of the larynx, which leads to the respiratory tract.
- This movement of the epiglottis ensures that food or liquid is directed towards the esophagus, the passage that leads to the stomach, rather than entering the larynx and trachea.
- The epiglottis acts as a "trapdoor" that closes off the respiratory tract, preventing the aspiration of food or liquids into the lungs.
- Once the food has safely passed through the pharynx, the epiglottis returns to its upright position, allowing normal respiration to resume.
In summary, the epiglottis is the structure that prevents the entry of food into the respiratory tract by covering the opening of the larynx during swallowing.

Respiration rates may increase with fever, illness, and other medical conditions. When checking respiration, it is important to also note whether a person has any difficulty breathing. Normal respiration rates for an adult person at rest range from 12 to 16 breaths per minute.

The lungs of mammals have a spongy and soft texture and are honeycombed with epithelium, having a much larger surface area in total than the outer surface area of the lung itself. The lungs of humans are a typical example of this type of lung.

Respiratory Pathway:
The correct answer is B: Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchiole → Lungs.
Explanation:
The respiratory pathway involves the movement of air from the external environment into the lungs. It can be summarized as follows:
1. Nasal Cavity: The process begins in the nasal cavity, where air enters the respiratory system through the nostrils. The nasal cavity is lined with cilia and mucus that help filter and warm the inhaled air.
2. Pharynx: From the nasal cavity, the air moves to the pharynx, also known as the throat. The pharynx serves as a common passage for both air and food.
3. Larynx: Next, the air enters the larynx, commonly known as the voice box. The larynx contains the vocal cords and plays a crucial role in producing sound.
4. Trachea: The air then passes through the trachea, a tube-like structure commonly known as the windpipe. The trachea is reinforced with C-shaped cartilage rings to keep it open and prevent collapse.
5. Bronchi: The trachea divides into two branches called bronchi, one leading to each lung. The bronchi further divide into smaller branches called bronchioles.
6. Bronchioles: The bronchioles are tiny tubes that continue to divide within the lungs, eventually leading to the alveoli.
7. Lungs: Finally, the air reaches the lungs, where gas exchange takes place. The alveoli, small sacs within the lungs, are responsible for the exchange of oxygen and carbon dioxide between the air and bloodstream.
This respiratory pathway ensures that the inhaled air is properly filtered, warmed, and reaches the lungs for efficient gas exchange.

The alveoli are the final branchings of the respiratory tree and act as the primary gas exchange units of the lung. Inhaled oxygen enters the lungs and reaches the alveoli. 

The majority of carbon dioxide is transported as part of the bicarbonate system. Carbon dioxide diffuses into red blood cells. Inside, carbonic Anhydrase converts carbon dioxide into carbonic acid, which is subsequently hydrolyzed into bicarbonate. 

Cellular Respiration and Photosynthesis are almost opposite processes because photosynthesis removes carbon dioxide from the atmosphere while cellular respiration puts back carbon dioxide.

For the experiment where CO₂  is given out during respiration, KOH solution are taken in a test tube and placed kn the conical flask KOH absorbs carbon dioxide and prevents it from being utilized by the plant for the process of photosynthesis.

The highest rate of respiration are found in the actively growing root and stem tips, cambium and embryos of germinating seeds and lowest rates in dormant seeds or spores. As, the growing tips are generally rich in meristematic tissues the rate of respiration is also high.

• Root and stem tips: These regions are actively growing and require energy for cell division, elongation, and differentiation.
• Buds: Buds are also actively growing and undergo rapid cell division and differentiation, requiring significant energy.
• Germinating seeds: During germination, seeds are metabolically active as they undergo processes like hydration, enzyme activation, and growth of the embryo, all of which require substantial energy through respiration.

Correct option is B)

• The plant cell can do respiration and photosynthesis.
• The plants get energy through the process of respiration in which glucose food breaks down in the presence of oxygen to form carbon dioxide and water with the release of energy.
• In plants, photosynthesis takes place in the cell organelle called chloroplast. A plant cell cannot breathe because in a plant body lungs are absent.

So the correct answer is 'Respiration and photosynthesis'.

Respiration is constitutive process that occurs in all tissues. Unlike photosynthesis that can happen only in the presence of sunlight, respiration in plant occurs all time. So, the answer is - both light and dark.

Because in alveoli( richly supplied with blood vessels), where oxygenated blood is present, is absorbed by haemoglobin, present in the RBC(Red Blood Cell). With the help of haemoglobin, the oxygenated blood is diffused in the whole body. Where on the other side, deoxygenated blood, which is present in the plasma, is reached to the alveoli and it absorbs by our lungs then finally the deoxygenated blood is exhaled by our nostrils. This is how alveoli helps for respiration with the help of diffusion in our lungs.

the hemoglobin increases the oxygen carrying capacity of blood. In humans and most other vertebrates, the most common respiratory pigment is a protein called hemoglobin.

Haemoglobin is the iron containing protein found in red blood cells. It is responsible for the transportation of oxygen and carbon dioxide. It consists of four protein chains and each chain has a haem group attached to it. Each haem group has an iron molecule. The oxygen binds to the iron molecule. Since there are four iron molecules, each haemoglobin is capable of carrying four oxygen molecules.

The rate of cellular respiration is directly affected by the concentration of oxygen available to the cells. Oxygen is a critical substrate in aerobic respiration, as it acts as the final electron acceptor in the electron transport chain, facilitating the production of ATP. Therefore, a sufficient supply of oxygen is essential for optimal cellular respiration.