Life Processes Compulsory Test Class 10 - Class 10 MCQ

Introduction:
ATP (adenosine triphosphate) is a molecule that stores and provides energy for cellular processes. It is synthesized during respiration and serves as the primary energy currency of cells. The energy derived from ATP molecules is used to drive various cellular reactions.
Energy Utilization:
The energy derived from ATP molecules synthesized during respiration is used to drive endothermic reactions. Endothermic reactions are those that require an input of energy in order to proceed. The energy released from the hydrolysis of ATP (breaking it down into ADP and inorganic phosphate) provides the necessary energy for these reactions to occur.
Examples of Endothermic Reactions:
The energy derived from ATP is utilized in a variety of cellular processes, including:
1. Active Transport: ATP powers the movement of molecules across cell membranes against their concentration gradient, such as in the sodium-potassium pump.
2. Protein Synthesis: ATP is required for the formation of peptide bonds during protein synthesis.
3. Muscle Contraction: ATP provides the energy for muscle fibers to contract and generate force.
4. Biosynthesis: ATP is used in the synthesis of macromolecules like DNA, RNA, and proteins.
Conclusion:
In summary, the energy derived from ATP molecules synthesized during respiration is primarily used to drive endothermic reactions in cells. These reactions are essential for various cellular processes, including active transport, protein synthesis, muscle contraction, and biosynthesis.

Explanation:
Stomatal pore:
- Stomatal pores are tiny openings found on the surface of leaves and stems of plants.
- They are surrounded by two specialized cells called guard cells.
Opening of stomatal pore:
- The stomatal pore opens to allow the exchange of gases, such as carbon dioxide and oxygen, between the plant and its surroundings.
Role of guard cells:
- Guard cells control the opening and closing of stomatal pores.
- They regulate the movement of gases, water vapor, and other molecules in and out of the plant.
Changes in guard cells:
- When the guard cells swell up, the stomatal pore opens.
- Swelling of guard cells occurs due to the absorption of water by osmosis.
- As a result, the inner walls of the guard cells are pulled apart, opening the stomatal pore.
Choices:
A: Chloroplast of guard cells shrink
- The shrinkage of chloroplasts in guard cells does not directly affect the opening of stomatal pores.
C: Guard cells shrink
- The shrinkage of guard cells does not lead to the opening of stomatal pores.
D: Chloroplast of guard cells swell up
- Swelling of chloroplasts in guard cells does not directly affect the opening of stomatal pores.
Correct answer:
B: Guard cells swell up
- Swelling of guard cells causes the stomatal pore to open.
- This allows the exchange of gases and regulates transpiration in plants.

Respiration in Humans
Introduction:
Respiration is a vital process in living organisms, including humans, to generate energy. In humans, the breakdown of glucose during respiration occurs through several pathways, including the alternative pathway where pyruvate is converted into lactic acid.
Location of the Alternative Pathway:
The alternative pathway of respiration, also known as anaerobic respiration, is found in muscle cells. This pathway is activated when there is an insufficient supply of oxygen to meet the energy demands of the muscle cells. The breakdown of glucose in muscle cells through the alternative pathway allows for the production of ATP (adenosine triphosphate) in the absence of oxygen.
Process of Lactic Acid Formation:
The conversion of pyruvate into lactic acid occurs through a process called lactic acid fermentation. Here are the key steps involved in this process:
1. Glycolysis: The first step of glucose breakdown, known as glycolysis, occurs in the cytoplasm of the cell. During glycolysis, glucose is converted into pyruvate, producing a small amount of ATP.
2. Conversion of Pyruvate: In the absence of oxygen, pyruvate is converted into lactic acid. This conversion is catalyzed by the enzyme lactate dehydrogenase.
3. Regeneration of NAD+: Lactic acid fermentation is necessary to regenerate NAD+ (nicotinamide adenine dinucleotide) from NADH (reduced form of NAD+). NAD+ is required for the continuation of glycolysis, which produces ATP.
Significance of Lactic Acid Formation:
The alternative pathway of respiration plays a crucial role in supplying energy to muscle cells during intense physical activity when oxygen supply is limited. Lactic acid accumulation in the muscles can cause fatigue and muscle soreness. However, once oxygen becomes available, lactic acid is converted back into pyruvate and further metabolized through aerobic respiration.
In conclusion, the alternative pathway of respiration, where pyruvate is converted into lactic acid, is found in muscle cells. This pathway allows for the production of ATP in the absence of oxygen, providing energy for muscle contraction during intense exercise.

Normal Blood Pressure in Humans
Systolic Pressure:
- Systolic pressure refers to the maximum pressure in the arteries during the contraction of the heart.
- It represents the force exerted by the heart to pump blood into the arteries.
- The normal systolic blood pressure in humans is around 120 mmHg.
Diastolic Pressure:
- Diastolic pressure refers to the minimum pressure in the arteries during the relaxation of the heart.
- It represents the pressure when the heart is at rest between beats.
- The normal diastolic blood pressure in humans is around 80 mmHg.
Normal Blood Pressure Range:
- Blood pressure is usually expressed as a ratio, stating the systolic pressure first and then the diastolic pressure.
- The normal blood pressure range in humans is typically stated as 120/80 mmHg.
- This means that the systolic pressure is 120 mmHg and the diastolic pressure is 80 mmHg.
Correct Answer:
- The correct answer is D: 120 and 80 mmHg, which represents the normal systolic and diastolic blood pressure in humans.
- This answer aligns with the commonly accepted range of 120/80 mmHg.

Digestion of proteins starts in the stomach.
Explanation:
The process of protein digestion involves several steps and begins in the stomach. Here is a detailed explanation of each step:
1. Mouth: While the digestion of proteins does not begin in the mouth, the process of mechanical digestion starts here as food is chewed and broken down into smaller pieces.
2. Pancreas: The pancreas plays a role in protein digestion by producing enzymes, such as trypsin and chymotrypsin, which are released into the small intestine. These enzymes further break down proteins into smaller peptides.
3. Stomach: The stomach is where the initial digestion of proteins takes place. It secretes gastric juice, which contains hydrochloric acid and the enzyme pepsin. Pepsin breaks down proteins into smaller polypeptides.
4. Small Intestine: After the stomach, the partially digested proteins move into the small intestine. Here, the pancreas releases additional enzymes, such as proteases, which further break down the polypeptides into smaller peptides and amino acids.
In conclusion, while protein digestion involves multiple organs and enzymes, the process begins in the stomach where pepsin breaks down proteins into smaller polypeptides.

Key Points:
- Lymph is a clear fluid that circulates through the lymphatic system.
- Lymph is derived from interstitial fluid, which is the fluid that surrounds cells in the body.
- Lymph contains a variety of cells, including white blood cells (WBCs) and a few red blood cells (RBCs).
- The main function of lymph is to transport immune cells and proteins throughout the body to help fight off infections and remove waste products.
Detailed Explanation:
Lymph is a clear fluid that circulates through the lymphatic system, which is a network of vessels and organs that helps the body fight off infections and remove waste products. Lymph is derived from interstitial fluid, which is the fluid that surrounds cells in the body.
Composition of Lymph:
Lymph contains a variety of cells, including white blood cells (WBCs) and a few red blood cells (RBCs). The presence of these cells differentiates lymph from blood, which contains a higher number of RBCs and fewer WBCs.
Function of Lymph:
The main function of lymph is to transport immune cells and proteins throughout the body. WBCs in lymph play a crucial role in the body's immune response by identifying and eliminating foreign substances, such as bacteria and viruses. The few RBCs present in lymph are not the main component and do not play a significant role in its function.
In summary, lymph differs from blood as it contains a higher number of white blood cells (WBCs) and no red blood cells (RBCs). The primary function of lymph is to transport immune cells and proteins to fight off infections and remove waste products.

Answer:
During digestion, fats are broken down into fatty acids and glycerol through a process called lipolysis. This process occurs in several stages and involves the action of various enzymes. Here is a detailed explanation of how fats are broken down during digestion:
1. Emulsification:
- Fats are initially present as large globules in the digestive system.
- Bile salts produced by the liver and stored in the gallbladder help in emulsifying these fat globules, breaking them down into smaller droplets.
- Emulsification increases the surface area of fats, making it easier for enzymes to act on them.
2. Lipase action:
- Once emulsified, fats are acted upon by pancreatic lipase, an enzyme secreted by the pancreas.
- Pancreatic lipase breaks down the triglycerides (the main type of fat) into fatty acids and monoglycerides.
- The fatty acids and monoglycerides are then transported to the surface of the fat droplets.
3. Micelle formation:
- Fatty acids and monoglycerides combine with bile salts to form micelles.
- Micelles are small spherical structures that have hydrophilic (water-loving) and hydrophobic (fat-loving) regions.
- The hydrophobic regions of the micelles contain the fatty acids and monoglycerides, while the hydrophilic regions face outward.
4. Absorption:
- The micelles move to the surface of the intestinal epithelial cells.
- The fatty acids and monoglycerides are then absorbed into the cells lining the small intestine.
- Once inside the cells, the fatty acids and monoglycerides are reassembled into triglycerides.
5. Chylomicron formation:
- Triglycerides combine with proteins to form chylomicrons.
- Chylomicrons are large lipoprotein particles that transport fats through the lymphatic system and eventually into the bloodstream.
In summary, fats are broken down into fatty acids and glycerol through the processes of emulsification, lipase action, micelle formation, absorption, and chylomicron formation during digestion.

The chemical responsible for muscle cramping is a:
There are several factors that can contribute to muscle cramping, including dehydration, electrolyte imbalances, and muscle fatigue. However, the chemical responsible for muscle cramping is not specifically mentioned in the given question. Therefore, it is not possible to determine the exact chemical responsible for muscle cramping based on the information provided.
- The question does not provide any specific information about the chemical responsible for muscle cramping.
- Muscle cramping can be caused by a variety of factors, including dehydration, electrolyte imbalances, and muscle fatigue.
- It is important to maintain proper hydration and electrolyte balance to prevent muscle cramping.
- Stretching and warming up before physical activity can also help prevent muscle cramps.
- If muscle cramps persist or are severe, it is recommended to seek medical attention for further evaluation and treatment.
In summary, while muscle cramping can be caused by various factors, the specific chemical responsible for muscle cramping is not mentioned in the given question. It is important to address hydration, electrolyte balance, and muscle fatigue to prevent muscle cramping. If muscle cramps persist or are severe, it is advisable to consult a healthcare professional for further evaluation and treatment.

Anaerobic respiration in yeast is also called fermentation.

• Definition: Anaerobic respiration is a type of cellular respiration that occurs in the absence of oxygen. It is the process by which cells break down organic molecules to produce energy in the form of ATP.


• Yeast: Yeast is a type of fungus that can undergo anaerobic respiration.


• Fermentation: Fermentation is the specific type of anaerobic respiration that occurs in yeast. It is a metabolic process that converts sugar into alcohol, carbon dioxide, and energy (in the form of ATP).


• Steps involved in yeast fermentation:
  
  
  
  • Yeast cells take in glucose and break it down into pyruvate through a process called glycolysis.
  
  
  • During glycolysis, a small amount of ATP is produced, and pyruvate is converted into ethanol (alcohol) and carbon dioxide.
  
  
  • This conversion of pyruvate into ethanol and carbon dioxide is the defining characteristic of yeast fermentation.
  
  
  • The carbon dioxide produced during fermentation is responsible for the bubbling and foaming often observed in fermenting yeast.
  
  
  
  


• Applications of yeast fermentation:
  
  
  
  • Fermentation by yeast is used in the production of alcoholic beverages such as beer and wine.
  
  
  • Yeast fermentation is also utilized in the baking industry to make bread rise. The carbon dioxide produced during fermentation creates air pockets in the dough, causing it to expand and become light and fluffy.
  
  
  • Yeast fermentation is also responsible for the production of other fermented foods and beverages such as yogurt, sauerkraut, and kimchi.
  
  
  
  

In conclusion, anaerobic respiration in yeast is commonly referred to as fermentation. It is a metabolic process that converts sugar into alcohol, carbon dioxide, and energy in the form of ATP. This process has various industrial and culinary applications.

The breakdown of the pyruvate molecule using oxygen takes place in the mitochondria during aerobic respiration.
Explanation:
During aerobic respiration, the breakdown of the pyruvate molecule occurs in the mitochondria, which are known as the powerhouses of the cell. The process can be further explained in the following steps:
1. Glycolysis: The initial step of aerobic respiration occurs in the cytoplasm, where glucose is broken down into two molecules of pyruvate through a series of chemical reactions. This step does not require oxygen and is known as glycolysis.
2. Pyruvate transport: The pyruvate molecules formed during glycolysis are then transported across the mitochondrial membrane into the mitochondrial matrix.
3. Pyruvate decarboxylation: Once inside the mitochondria, the pyruvate molecules undergo decarboxylation, where a carbon atom is removed in the form of carbon dioxide. This step produces acetyl CoA, which enters the next stage of aerobic respiration.
4. Citric Acid Cycle (Krebs cycle): Acetyl CoA enters the citric acid cycle, a series of chemical reactions that occur in the mitochondrial matrix. During this cycle, acetyl CoA is further broken down, releasing carbon dioxide and producing energy-rich molecules such as NADH and FADH2.
5. Electron Transport Chain: The energy-rich molecules (NADH and FADH2) generated in the previous steps are then used in the electron transport chain, which is located in the inner mitochondrial membrane. This chain transfers electrons from NADH and FADH2 to oxygen, generating ATP (adenosine triphosphate), the energy currency of the cell.
In summary, the breakdown of the pyruvate molecule takes place in the mitochondria during aerobic respiration, involving processes such as pyruvate decarboxylation, the citric acid cycle, and the electron transport chain.

The movement of the ribs during inhalation:
- During inhalation, the diaphragm contracts and moves downward, causing the volume of the thoracic cavity to increase.
- As the thoracic cavity expands, the ribs move up and outwards, allowing for more space for the lungs to expand.
- This movement of the ribs is facilitated by the intercostal muscles, which contract and lift the ribs.
- The ribs also rotate slightly, which further increases the thoracic cavity volume.
- The expansion of the thoracic cavity and the movement of the ribs create a negative pressure within the lungs, causing air to rush in and fill the lungs.
Why the other options are incorrect:
- Digestion: The movement of the ribs is not directly involved in the process of digestion.
- Exhalation: During exhalation, the ribs move downwards and inwards, decreasing the thoracic cavity volume.
- Excretion: The movement of the ribs is not directly involved in the process of excretion.
- Inhalation: This is the correct answer as explained above.

The seeds swell when placed in water because of imbibition. Imbibition is the process when solid surfaces absorb water and swells.

The brain stem, at the bottom of the brain, connects the cerebrum with the spinal cord. It includes the midbrain, the pons, and the medulla. It controls fundamental body functions such as breathing, eye movements, blood pressure, heartbeat, and swallowing.

This build-up of lactic acid in our muscles during sudden activity causes cramps. The energy released during cellular respiration is immediately used to synthesise a molecule called ATP which is used to fuel all other activities in the cell.

Respiration is considered as exothermic reaction because energy is released in this process. Glucose combines with oxygen present in our cells to form carbon dioxide and water along with energy.