Grade 10 Q&A: Chapter 12: Life Processes in Living Organisms Part

Concept Questions

Q1: What are life processes?

Answer: Life processes are the fundamental activities performed by living organisms to maintain their life, grow, and reproduce. These include nutrition, respiration, transportation, excretion, control and coordination, and reproduction.

Q2: Why do living organisms need energy?

Answer: Living organisms need energy for various life processes such as movement, growth, repair of tissues, maintaining body temperature, and performing metabolic activities like synthesis of proteins and other complex molecules.

Q3: What is the primary source of energy for most living organisms?

Answer: The primary source of energy for most living organisms is the food they consume, which is ultimately derived from sunlight through photosynthesis.

Q4: What is cellular respiration?

Answer: Cellular respiration is a metabolic process that occurs in cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.

Q5: Name the two main types of cellular respiration.

Answer: The two main types of cellular respiration are aerobic respiration and anaerobic respiration.

Q6: What is 'ATP'?

Answer: ATP stands for Adenosine Triphosphate. It is the main energy-carrying molecule in cells, often referred to as the "energy currency" of the cell, used to power various cellular activities.

Q7: Where does glycolysis occur in a cell?

Answer: Glycolysis occurs in the cytoplasm of a cell.

Q8: What is the end product of glycolysis in the presence of oxygen?

Answer: The end product of glycolysis in the presence of oxygen is pyruvic acid (or pyruvate).

Q9: Where does the Krebs cycle (citric acid cycle) occur in eukaryotic cells?

Answer: The Krebs cycle (citric acid cycle) occurs in the mitochondria of eukaryotic cells.

Q10: What is the role of the electron transfer chain reaction in energy production?

Answer: The electron transfer chain reaction is the final stage of aerobic respiration where most of the ATP is produced. It involves a series of protein complexes that transfer electrons, releasing energy to pump protons and generate a proton gradient, which is then used to synthesize ATP.

Q11: Name two important nutrients that provide energy to the body.

Answer: Two important nutrients that provide energy to the body are carbohydrates and fats (lipids).

Q12: What is the function of proteins in the body?

Answer: Proteins are essential for growth, repair of tissues, production of enzymes and hormones, and maintaining the body's structure and function.

Q13: Why are vitamins essential for the body, even though they do not provide energy?

Answer: Vitamins are essential for the body because they act as coenzymes or cofactors in various metabolic reactions, regulating body processes and supporting overall health, even though they do not provide direct energy.

Q14: What is the importance of water in life processes?

Answer: Water is crucial for life processes as it acts as a solvent for many substances, participates in metabolic reactions, helps in transport of nutrients and waste, regulates body temperature, and maintains cell structure.

Q15: What is 'cell division'?

Answer: Cell division is the process by which a parent cell divides into two or more daughter cells. It is fundamental for growth, repair, and reproduction in living organisms.

Q16: Name the two main types of cell division.

Answer: The two main types of cell division are mitosis and meiosis.

Q17: What is the primary purpose of mitosis?

Answer: The primary purpose of mitosis is for growth, repair of damaged tissues, and asexual reproduction, resulting in two genetically identical daughter cells.

Q18: What is the primary purpose of meiosis?

Answer: The primary purpose of meiosis is for sexual reproduction, producing four genetically distinct haploid gametes (sperm or egg cells) from a single diploid cell.

Application-Based Questions

Q19: Describe the process of anaerobic respiration in muscle cells during strenuous exercise.

Answer: During strenuous exercise, when oxygen supply to muscle cells is insufficient, they switch to anaerobic respiration. In this process, pyruvic acid (formed from glycolysis) is converted into lactic acid, instead of entering the Krebs cycle. This produces a small amount of ATP quickly, but the accumulation of lactic acid causes muscle fatigue and pain.

Q20: Explain the significance of ATP as the 'energy currency' of the cell.

Answer: ATP is significant as the 'energy currency' because it stores and releases energy in a readily usable form for all cellular activities. When ATP is hydrolyzed to ADP (Adenosine Diphosphate) and a phosphate group, energy is released to power processes like muscle contraction, active transport, and synthesis of macromolecules. Conversely, energy from food breakdown is used to resynthesize ATP from ADP, making it a recyclable energy carrier.

Q21: Differentiate between aerobic and anaerobic respiration based on their requirements and products.

Answer: * Aerobic Respiration: Requires oxygen. It completely breaks down glucose into carbon dioxide and water, producing a large amount of ATP (approximately 36-38 ATP molecules per glucose). Occurs in cytoplasm and mitochondria. * Anaerobic Respiration: Does not require oxygen. It incompletely breaks down glucose, producing products like lactic acid (in animals) or ethanol and carbon dioxide (in yeast), and yields a much smaller amount of ATP (typically 2 ATP molecules per glucose). Occurs only in the cytoplasm.

Q22: Describe the different phases of mitosis and their key events.

Answer: Mitosis consists of four main phases: 1. Prophase: Chromatin condenses into visible chromosomes, nuclear envelope breaks down, spindle fibers begin to form. 2. Metaphase: Chromosomes align at the metaphase plate (equator of the cell). 3. Anaphase: Sister chromatids separate and move to opposite poles of the cell. 4. Telophase: Chromosomes decondense, nuclear envelopes reform around the two sets of chromosomes, and spindle fibers disappear. This is followed by cytokinesis, the division of the cytoplasm.

Q23: How do lipids (fats) contribute to energy production in the body?

Answer: Lipids are a highly concentrated source of energy. When carbohydrates are insufficient, the body breaks down fats into fatty acids and glycerol. Fatty acids are then converted into acetyl-CoA, which enters the Krebs cycle, and glycerol can be converted to pyruvic acid or glucose. This process yields a significant amount of ATP, making fats an important long-term energy reserve.

Higher-Order Thinking Questions

Q24: Explain the importance of 'fibers' in the human diet, even though they are not digested for energy.

Answer: Fibers (roughage) are crucial for the human diet despite not being digested for energy because: 1. Digestive Health: They add bulk to stool, preventing constipation and promoting regular bowel movements. 2. Blood Sugar Control: Soluble fibers can slow down glucose absorption, helping to regulate blood sugar levels, which is beneficial for diabetics. 3. Cholesterol Reduction: Some fibers can help lower blood cholesterol levels. 4. Weight Management: Fiber-rich foods provide a feeling of fullness, aiding in weight control. 5. Gut Microbiome: Certain fibers act as prebiotics, feeding beneficial gut bacteria, which are vital for overall health.

Q25: Why is meiosis considered a crucial process for sexual reproduction and maintaining species chromosome number?

Answer: Meiosis is crucial for sexual reproduction and maintaining species chromosome number for two main reasons: 1. Halving Chromosome Number: It reduces the chromosome number by half, producing haploid gametes (sperm and egg) from diploid parent cells. This ensures that when two gametes fuse during fertilization, the resulting zygote restores the diploid chromosome number characteristic of the species. Without meiosis, chromosome numbers would double with each generation, leading to genetic instability. 2. Genetic Variation: Meiosis introduces genetic variation through processes like crossing over and independent assortment of chromosomes. This variation is vital for the adaptability and evolution of a species, allowing it to survive in changing environments and resist diseases.

Q26: How does the body ensure a continuous supply of energy (ATP) even during periods of fasting or intense activity?

Answer: The body ensures a continuous supply of energy (ATP) through a sophisticated system of energy reserves and metabolic pathways: 1. Glycogen Stores: Glucose is stored as glycogen in the liver and muscles. During fasting or activity, glycogen is broken down to glucose, which then enters glycolysis. 2. Fat Stores: When glycogen stores are depleted, the body turns to fat (lipid) reserves. Fats are broken down into fatty acids and glycerol, which can be metabolized to produce a large amount of ATP. 3. Protein Utilization: In prolonged fasting or starvation, proteins can be broken down into amino acids, which are then converted into glucose or intermediates of the Krebs cycle to generate ATP. 4. Metabolic Regulation: Hormones like insulin, glucagon, and adrenaline regulate these pathways, ensuring that energy is mobilized and utilized efficiently based on the body's needs.

Q27: Discuss the role of the nucleus and cytoplasm in controlling cell division.

Answer: Both the nucleus and cytoplasm play critical roles in controlling cell division: 1. Nucleus: The nucleus houses the cell's genetic material (DNA) organized into chromosomes. It contains the instructions for cell division and regulates the entire process. Key events like DNA replication and chromosome segregation occur within or are initiated by signals from the nucleus. Regulatory proteins (e.g., cyclins, CDKs) that control the cell cycle are also encoded by genes in the nucleus. 2. Cytoplasm: The cytoplasm provides the necessary machinery and environment for cell division. It contains organelles, enzymes, and structural components (like microtubules that form the spindle fibers) essential for chromosome movement and cytokinesis. Cytoplasmic factors can also influence the progression of cell division, ensuring that the cell is ready to divide and that the daughter cells receive appropriate cytoplasmic components.

Q28: Why is it crucial for DNA to replicate accurately before cell division? What happens if errors occur?

Answer: It is crucial for DNA to replicate accurately before cell division to ensure that each daughter cell receives a complete and identical set of genetic information. This fidelity is vital for maintaining genetic stability, proper cell function, and the overall health of the organism. If errors (mutations) occur during DNA replication: 1. Altered Proteins: The altered DNA sequence can lead to the production of incorrect or non-functional proteins, disrupting cellular processes. 2. Cellular Dysfunction: This can cause cells to malfunction, leading to various diseases. 3. Cancer: Accumulation of specific mutations can lead to uncontrolled cell division, which is a hallmark of cancer. 4. Genetic Disorders: Mutations in germ cells (sperm or egg) can be passed on to offspring, leading to inherited genetic disorders. Cells have repair mechanisms to correct many errors, but some persist.

Q29: How do different types of nutrients (carbohydrates, proteins, fats, vitamins, minerals, water, fibers) contribute to the overall energy efficiency and functioning of the body?

Answer: All nutrients play interconnected roles in the body's energy efficiency and functioning: 1. Carbohydrates: Primary and immediate source of energy. 2. Fats (Lipids): Concentrated long-term energy storage, also vital for cell membranes and hormone production. 3. Proteins: Essential for building and repairing tissues, forming enzymes, hormones, and antibodies. Can be used for energy in dire situations. 4. Vitamins and Minerals: Act as cofactors and regulators for almost all metabolic reactions, including those involved in energy production. They don't provide energy directly but are crucial for its efficient release and utilization. 5. Water: The medium for all biochemical reactions, transports nutrients and waste, and regulates body temperature. Essential for nutrient absorption and waste excretion. 6. Fibers: Aid in digestion, regulate blood sugar, and contribute to gut health, indirectly supporting nutrient absorption and overall metabolic efficiency. Together, they ensure that the body has the raw materials for energy, growth, repair, and regulation, allowing all life processes to function optimally.

References

1. MSBSHSE Class 10 Science and Technology Textbook Part 2 (2021-22 English) - Chapter 2: Life Processes in Living Organisms Part - 1
2. Maharashtra State Board 10th Standard Science Syllabus 2025-26
3. Balbharati Science and Technology Part 2 Textbook
4. Shaalaa.com Balbharati solutions for Science and Technology 2