Class 10 Science Chapter 5 Life Processes

Key Concept: Excretion vs. Photosynthesis

a) Photosynthesis
[Solution Description]
During photosynthesis, plants produce glucose and oxygen from carbon dioxide and water using sunlight. The produced oxygen is not needed by the plant during photosynthesis and is released as a waste product into the atmosphere.

Notes:

Excretion is a life process where organisms remove metabolic waste from their bodies. In humans, it involves organs like kidneys, skin, and lungs. Key excretory products include urea, carbon dioxide, and sweat. Excretion helps maintain internal balance by eliminating harmful substances.

Photosynthesis, on the other hand, is a process in green plants where they synthesize food (glucose) using sunlight, carbon dioxide, and water. Chlorophyll in leaves captures sunlight, and oxygen is released as a byproduct.

While excretion eliminates waste, photosynthesis produces essential nutrients, highlighting their opposite but vital roles in maintaining life processes.

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Key Concept:  Blood Clotting

c) Platelets
[Solution Description] Platelets are small cell fragments in the blood that gather at sites of injury, forming clots to stop bleeding. They release chemicals that help the blood coagulate.

Notes:

Blood clotting is a vital process that prevents excessive bleeding when blood vessels are injured. It involves a series of complex steps known as the coagulation cascade. Platelets, or blood cells, aggregate at the site of injury and release chemicals that activate clotting factors. These factors lead to the conversion of fibrinogen (a plasma protein) into fibrin threads, which form a mesh that traps blood cells, creating a clot. This clot seals the wound, preventing further blood loss and protecting against infection. Vitamin K is essential for clotting factor production. The clot eventually dissolves once the tissue is healed.

Key Concept: Source of Water

c) From the soil
[Solution Description] Terrestrial plants absorb water from the soil through their roots. This water serves as a raw material in photosynthesis, providing the hydrogen atoms needed to form glucose.

Notes:

Water is essential for life processes and is obtained from various natural sources. The main sources of water include rivers, lakes, ponds, glaciers, and groundwater. Rainwater is a primary source, replenishing surface and groundwater. Groundwater is stored in underground reservoirs called aquifers. Water from rivers and lakes is commonly used for drinking, agriculture, and industrial purposes. In addition to natural sources, human-made sources like reservoirs and dams also store water for various uses. Conservation of water is crucial, as it is limited and essential for the survival of all living organisms.

Key Concept: WBC Function

b) Fight infections
[Solution Description] White blood cells are part of the immune system and help in fighting against infections.

Notes:

White Blood Cells (WBCs), also known as leukocytes, play a crucial role in the immune system. Their primary function is to protect the body from infections and foreign invaders, such as bacteria, viruses, and fungi. WBCs identify and attack harmful microorganisms through processes like phagocytosis, where they engulf and digest pathogens. They also produce antibodies to neutralize specific pathogens. WBCs are of different types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specialized functions. The number of WBCs increases in response to infections, acting as the body’s defense mechanism to maintain health.

Key Concept: Comparative Analysis

d) Fungi digest externally, while lions digest internally
[Solution Description] Fungi break down food material outside their body using enzymes and absorb nutrients, while lions ingest whole prey and digest it internally.

Notes:

Life processes refer to the essential activities that organisms perform to maintain life. In plants, processes like photosynthesis, respiration, and transpiration are vital for energy production and growth. Animals, on the other hand, rely on processes like digestion, circulation, respiration, and excretion to maintain bodily functions. While both plants and animals carry out respiration, plants primarily use it to convert stored energy, whereas animals use it for immediate energy needs. Additionally, plants have a unique process, photosynthesis, which produces food, unlike animals. Despite these differences, both kingdoms share common processes essential for survival and growth.

Key Concept: Cellular Processes, Advanced Reasoning

d) Since it requires energy input for bond formation
[Solution Description] The synthesis of ATP from ADP and inorganic phosphate requires energy input, making it an endothermic process. However, it is coupled with the exergonic reactions of cellular respiration, where energy is released and made available for ATP synthesis, thus maintaining the energy balance.

Notes:

Cellular processes are essential for maintaining life in organisms. They include metabolic activities like respiration, photosynthesis, and transport mechanisms across cell membranes. Respiration is the process by which cells release energy from glucose, involving glycolysis, the Krebs cycle, and the electron transport chain. Photosynthesis, in plants, converts light energy into chemical energy, producing glucose and oxygen. Transport within cells occurs via passive processes like diffusion and osmosis, and active processes requiring energy, like active transport. The efficiency of these processes is crucial for cell survival and overall organism function. Advanced reasoning involves understanding the regulation and coordination of these processes.

Key Concepts: Concept Application

b) To circulate nutrients and oxygen to different parts

[Solution Description] Multicellular organisms require a transportation system because cells are specialized and not directly in contact with the environment where nutrients and oxygen are available. The transportation system ensures the distribution of nutrients, oxygen, and other essential substances throughout the organism, facilitating effective metabolism and homeostasis.

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Key Concept:  Basic Definition

d) Aerobic respiration
[Solution Description] Aerobic respiration refers to the process where glucose is broken down in the presence of oxygen to produce carbon dioxide, water, and energy. This process occurs in the mitochondria.

Notes:

The process where glucose is broken down in the presence of oxygen to produce carbon dioxide, water, and energy is called aerobic respiration. It occurs in the cells of living organisms to release energy in the form of ATP (Adenosine Triphosphate). The process begins with glycolysis in the cytoplasm, where glucose is converted into pyruvate. In the presence of oxygen, pyruvate enters the mitochondria, undergoing the Krebs cycle and the electron transport chain. The overall reaction is:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP).
Aerobic respiration is highly efficient, producing up to 36 ATP molecules per glucose molecule.

Key Concept: Specialized Tissues

c) Xylem
[Solution Description] In plants, xylem is the specialized tissue that transports water and dissolved minerals from roots to the rest of the plant, including leaves. This process primarily involves capillary action and transpiration pull.

Notes:

Specialized tissues are specific types of cells grouped together to perform a particular function in organisms. In plants, vascular tissues like xylem and phloem are specialized for transporting water, minerals, and food. Xylem carries water and dissolved minerals from roots to other parts, while phloem transports food made in leaves to other parts of the plant. In animals, tissues such as muscle tissues help in movement, and nervous tissues are specialized for transmitting electrical impulses. Epithelial tissue covers body surfaces and organs, while connective tissues support and bind other tissues. These specialized tissues ensure efficient functioning of organisms.

Key Concept: Basic Function

c) To break down food for energy
[Solution Description] The main function of respiration in living organisms is to break down food molecules to release energy in the form of ATP, which is used for various cellular activities.

Notes:

Key Concept: Double Circulation

b) It separates oxygenated and deoxygenated blood efficiently.
[Solution Description] Double circulation in humans ensures that oxygenated and deoxygenated blood are kept separate, which allows for more efficient oxygen supply to body tissues. This separation enhances the ability of the circulatory system to meet high metabolic demands.

Notes:

Double Circulation refers to the two distinct circulatory pathways in the human circulatory system. The heart pumps blood through two separate circuits:

1. Pulmonary Circulation: Blood is pumped from the right side of the heart to the lungs, where it picks up oxygen and releases carbon dioxide. Oxygenated blood returns to the left side of the heart.
2. Systemic Circulation: Oxygenated blood from the left side of the heart is pumped to the body tissues, delivering oxygen and nutrients. Deoxygenated blood returns to the right side of the heart. This separation ensures efficient oxygen supply and waste removal from tissues.

Key Concept: Role of Oxygen

c) It participates in oxidising-reducing reactions to release energy
[Solution Description] Oxygen plays a crucial role in oxidising-reducing reactions, which are common chemical means used by organisms to break down molecules for energy generation. By combining with electrons released from food molecules, oxygen helps release energy stored in those molecules.

Key Concept:  Double Circulation

a) It enables simultaneous pumping of blood to lungs and body.
[Solution Description] A four-chambered heart allows for complete separation of oxygenated and deoxygenated blood, leading to more efficient oxygen delivery to tissues. The left side pumps oxygen-rich blood to the body, while the right side handles deoxygenated blood returning from the body.

Notes:

Double circulation refers to the two separate circulatory circuits in the human heart: pulmonary and systemic. The heart has two halves, each responsible for one circuit.

1. Pulmonary Circulation: Deoxygenated blood from the body enters the right atrium, flows into the right ventricle, and is pumped to the lungs through the pulmonary artery. In the lungs, blood gets oxygenated.
2. Systemic Circulation: Oxygenated blood returns to the left atrium, moves to the left ventricle, and is pumped to the body via the aorta. This circuit delivers oxygen and nutrients to body tissues.

Double circulation ensures efficient oxygenation and nutrient supply.

Key Concept: Energy Efficiency, Chemical Pathways

c) Anaerobic respiration, due to insufficient oxygen.
[Solution Description] During intense physical activity, muscle cells may lack sufficient oxygen supply and temporarily favor anaerobic respiration, converting pyruvate to lactic acid. This allows ATP generation without oxygen, though less efficient and leads to lactic acid buildup.

Notes:

Energy efficiency in living organisms refers to how effectively energy is used to perform biological functions. In cellular respiration, energy is produced through chemical pathways that break down glucose. Two main pathways are aerobic respiration (requires oxygen) and anaerobic respiration (occurs without oxygen). Aerobic respiration produces more energy, yielding 38 ATP molecules from one glucose molecule, whereas anaerobic respiration produces only 2 ATP molecules. The efficiency of energy production in cells is crucial for sustaining life processes. Different organisms utilize these pathways based on the availability of oxygen in their environment, ensuring survival and energy balance.

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Key Concept: Process Application

b) Carbon dioxide
[Solution Description] Aerobic respiration is a process where glucose is broken down in the presence of oxygen to produce energy, carbon dioxide, and water. It occurs in the mitochondria. The reaction can be summarized as follows:
$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$
Therefore, carbon dioxide is a by-product of aerobic respiration.

Notes:

Life processes in organisms involve various chemical and biological activities necessary for survival, growth, and reproduction. These processes include nutrition, respiration, transportation, excretion, and control and coordination. The application of life processes can be seen in various fields such as medicine, agriculture, and biotechnology. For instance, understanding respiration helps in treating respiratory diseases. Knowledge of nutrition is applied in designing balanced diets. Biotechnology applications, like genetic engineering, depend on processes like DNA replication and protein synthesis. Understanding excretion helps in the development of dialysis for kidney patients. Thus, life processes are crucial for advancing health and technology.

Key Concept: Basic Transport

c) Assertion is true, but Reason is false.
[Solution Description]
The assertion states that blood is responsible for transporting oxygen in human beings, which is true. However, the reason provided is incorrect because it claims that oxygen is carried by the plasma. In reality, oxygen is primarily transported by red blood corpuscles, not plasma. Plasma mainly carries nutrients and waste products. Therefore, while the assertion is true, the reason given is false.

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Key Concept: Direct Fact

b) To break down food for energy
[Solution Description] The role of respiration in life processes is to break down food molecules to release energy needed for various cellular functions. Oxygen is utilized in this process to efficiently convert glucose into ATP, the energy currency of cells.

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Key Concept:  Nutrition Process

b) Nutrition
[Solution Description] Nutrition is the process that involves transferring energy from consumed food into the body, allowing organisms to access the energy required for life processes.

Notes:

Nutrition is the process of obtaining and using food for growth, energy, and repair. In plants, nutrition occurs through photosynthesis, where chlorophyll absorbs sunlight and converts carbon dioxide and water into glucose and oxygen. This is a form of autotrophic nutrition. In animals, nutrition involves ingestion, digestion, absorption, and assimilation. Animals are heterotrophs and obtain food from plants or other animals. The digestive system breaks down food into simpler forms for absorption into the bloodstream, which delivers nutrients to cells for energy and growth. The process of digestion differs in various organisms but serves the same basic purpose.

Key Concept: Role of Potassium Hydroxide

b) To absorb carbon dioxide
[Solution Description] Potassium hydroxide is used to absorb carbon dioxide from the surrounding air, preventing it from participating in the photosynthesis process within the experiment.

Notes:

Potassium Hydroxide (KOH) plays an important role in the process of photosynthesis. It is used in the experiment to demonstrate the presence of oxygen during photosynthesis. KOH is commonly placed in a setup where a plant is submerged in water and exposed to light. The KOH absorbs carbon dioxide (CO₂) from the air, creating a low-carbon dioxide environment around the plant. This enables the plant to carry out photosynthesis, producing oxygen (O₂) in the process. The presence of oxygen is then measured, confirming the occurrence of photosynthesis.

Key Concept: Comparative Analysis

c) Autotrophs require sunlight, chlorophyll, carbon dioxide, and water; heterotrophs require pre-formed organic compounds.
[Solution Description] Autotrophic nutrition involves organisms that can prepare their own food using inorganic substances like carbon dioxide and water, typically through photosynthesis, while heterotrophic nutrition involves organisms that obtain energy by consuming other organisms or organic matter because they cannot make their own food.

Notes:

Life processes are essential biological functions performed by living organisms to sustain life. These include nutrition, respiration, transportation, and excretion.

• Nutrition: Autotrophic (plants) synthesize food via photosynthesis, while heterotrophic (animals) depend on other organisms.
• Respiration: Aerobic respiration occurs in the presence of oxygen, yielding more energy, while anaerobic respiration occurs without oxygen, producing less energy.
• Transportation: Plants use xylem (water) and phloem (food), whereas animals rely on a circulatory system.
• Excretion: Plants excrete through stomata and other pathways; animals excrete via specialized organs like kidneys.

These differences reflect adaptations for diverse environments and survival strategies.

Key Concept: Water Source

a) Through their roots
[Solution Description] Plants primarily obtain water from the soil through their roots. This water is transported up to the leaves where it is used in the process of photosynthesis to produce glucose and oxygen.

Notes:

water is a crucial component for all living organisms. It acts as a solvent, transport medium, and regulator of temperature. In plants, water is absorbed through roots and transported to leaves, where it is used in photosynthesis. In animals, water helps in digestion, circulation, temperature regulation, and waste elimination. Water sources include natural reservoirs like rivers, lakes, and groundwater. Conservation of water is vital due to its limited availability and the increasing demand. Sustainable practices like rainwater harvesting, reducing wastage, and maintaining healthy water cycles are essential for preserving water resources.

Key Concept: Energy Source

c) ATP
[Solution Description] During cellular respiration, the energy released is used to synthesize ATP, which then powers various cell functions.

Notes:

During cellular respiration, the energy released is used to synthesize Adenosine Triphosphate (ATP) molecules. ATP is often called the “energy currency” of the cell as it stores and supplies energy for various biological processes. Cellular respiration occurs in three main stages: glycolysis, Krebs cycle, and electron transport chain. In this process, glucose is broken down into carbon dioxide (CO₂) and water (H₂O), releasing energy. This energy is captured in the form of ATP molecules. ATP provides energy for cellular activities like muscle contraction, protein synthesis, and active transport across cell membranes, making it vital for sustaining life processes.

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Key Concept:  Comparative Physiology, Environmental Influence

b) Increased glycogen storage
[Solution Description] Marine animals, such as some fish species, can endure hypoxic conditions (low oxygen) by developing adaptations like increased glycogen storage. This allows them to store energy sources that can be rapidly mobilized through anaerobic metabolic pathways to sustain cellular function when oxygen is scarce.

Notes:

Comparative physiology studies the functions of living organisms and their systems across different species. It helps in understanding how different organisms perform similar life processes (such as respiration, digestion, circulation) despite having different anatomical structures. Environmental factors like temperature, humidity, and light influence the physiological processes of organisms. For instance, cold-blooded animals (ectotherms) rely on external temperatures to regulate body heat, while warm-blooded animals (endotherms) maintain a constant body temperature. Adaptations like hibernation in cold climates or migration for resource availability are examples of how organisms respond to environmental challenges.

Key Concept: Complex Pathways, Real-world Application

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that the efficiency of aerobic respiration can be measured by assessing ATP production which involves the complete breakdown of pyruvate into carbon dioxide and water in the mitochondria, providing substantial energy output. This measurement indeed provides insight into how effectively the oxidative processes are occurring.

The reason suggests that under high-intensity exercise conditions, lactic acid formation occurs due to insufficient oxygen supply, causing the body to partially rely on anaerobic pathways. While this statement is true, it doesn’t directly explain the method of determining aerobic respiration efficiency through ATP measurement; rather, it indicates a condition where aerobic respiration might not fully occur.

Therefore, both statements are true, but they are not conceptually tied as cause and effect regarding measuring the efficiency of aerobic respiration through ATP levels.

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Key Concept:  Filtration Unit

a) Nephron
[Solution Description] The nephron is the basic structural and functional unit of the kidney. It is responsible for filtering blood to form urine.

Notes:

The filtration unit of the kidney is known as the nephron. Each kidney contains around 1 million nephrons. The nephron consists of the Bowman’s capsule, glomerulus, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct.

Blood enters the glomerulus under pressure, where it is filtered in the Bowman’s capsule. The filtrate, which includes water, salts, glucose, and urea, passes through the PCT, loop of Henle, and DCT. Useful substances like glucose and water are reabsorbed, while waste products like urea are excreted as urine through the collecting duct.

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Key Concept: Simple Comparison

d) Lactic acid
[Solution Description] During anaerobic respiration in human muscle cells, when oxygen supply is limited, pyruvate is converted into lactic acid.

Notes:

Life processes are essential functions that occur in living organisms to maintain life. The key processes include nutrition, respiration, transport, excretion, and reproduction.

• Nutrition: The process of obtaining and utilizing food (autotrophic or heterotrophic).
• Respiration: The process of releasing energy from food (aerobic or anaerobic).
• Transport: Movement of substances like oxygen, nutrients, and waste in organisms.
• Excretion: Removal of waste products from the body.
• Reproduction: Biological process for the production of offspring.

These processes ensure growth, energy production, and survival of organisms.

Key Concept: Capillary Function

c) Capillaries
[Solution Description] The exchange of gases between blood and tissues happens mainly through capillaries due to their thin, one-cell-thick walls that facilitate diffusion.

Notes:

Capillaries are the smallest blood vessels in the body, connecting arterioles and venules. They play a crucial role in the exchange of gases, nutrients, and waste products between the blood and tissues. Due to their thin walls, which are only one cell thick, capillaries allow for the diffusion of oxygen, carbon dioxide, nutrients, and waste materials. Oxygen and nutrients pass from the blood into the surrounding tissues, while carbon dioxide and waste products move from the tissues into the blood. This exchange is vital for maintaining homeostasis and supporting cellular functions.