Class 10 Science Chapter 5 Life Process

What is Alive?

Characteristics of Living Beings:

• Visible movement (e.g., running dog, chewing cow)
• Invisible molecular movements (essential for life).
• Ability to grow, breathe, and maintain order.

Viruses Controversy:

• Do not show molecular movement unless infecting a cell.

Life Processes:

Maintenance processes required for survival.

Examples: Nutrition, respiration, transportation, excretion.

Nutrition

Definition: Process of obtaining and utilizing food.

Type of Nutrition:

1. Autotrophic Nutrition:
   • Organisms prepare their own food (e.g., plants)
   • Process: Photosynthesis.
     • Steps:
       • Abosrption of light by chlorophyll.
       • Conversion of light energy to chemical energy.
       • Splitting of water into hydrogen and oxygen.
       • Reduction of carbon dioxide into carbohydrates.
2. Heteroptrophic Nutrition:
   • Organisms depend on others for food (e.g., animals, fungi).
   • Types:
     • Parasitic: Derive nutrition without killing host (e.g., cuscuta, lice).
     • Saprophytic: Absorb nutriets from decaying matter (e.g., fungi).
     • Holozoic: Intake and digest food (e.g., humans).
   • Exmaples of Heterotrophs:
     • Amoeba: Uses pseudopodia to engulf food.
     • Paramecium: Uses cilia to bring food to a specific spot.

Nutrition in Human Beings

1. Alimentary Canal:
   • A long tube from mouth to anus, specialized for digestion and abosortpiton.
   • Key part: Mouth, esophagus, stomach, small intestine, large intestine, and anus.
2. Digestive Process:
   • Mouth:
     • Food is crushed by teeth and mixed with saliva (contains enzyme salivary amylase) to break down starch into simple sugars.
   • Esophagus:
     • Releases gastric juices (HCl, pepsin, and mucus).
     • HCl: Provides acidic medium for pepsin and sills bacteria.
     • Musus: Protects stomach lining.
   • Small Intestine:
     • Site of complete digestion and nutrient absorption.
     • Enzymes: Pancreatic juice (trypsin for proteins, lipase for fats), bile (emulsifies fats), and intestinal juice.
     • Villi: Increase surface area for absorption and transport nutrients via blood.
   • Large Intestine:
     • Absorbs water and forms feces.
   • Anus:
     • Removes undigested waste via anal sphincter.

Dental Caries:

Bacteria convert sugars into acids, demineralizing enamel.

Plaque formation prevents saliva from neutralizing acid.

Prevent by brushing teeth after meals.

Respiration:

Types of Respiration:

1. Aerobic Respiration: Breakdown of glucose with oxygen into Carbon dioxide, water, and energy (in mitochondria).
2. Anaerobic: Breakdown of glucose without oxygen into ethanol and Carbon dioxide (e.g., yeast) or lactic acid (e.g., muscles during cramps).

ATP (Adenosine Triphosphate):

1. Energy currency of cells.
2. Produced during respiration and fuels cellular processes.

Breathing in Humans:

1. Air enters through nostrils, filtered by hair and mucus.
2. Passes through the throat into lungs, protected by cartilage rings.
3. Lungs: Exchange of oxygen and Carbon dioxide occurs in aveoli.

Aquatic vs. Terrestrial Respiration:

1. Aquatic organisms breathe faster due to low dissolved oxygen in water.
2. Terrestrial organisms use atmospheric oxygen through specialized structures.

Most Important Questions and Answers For Class 10 based on NCERT

Question 1: How do we differentiate between living and non-living things?

Answer: Living things exhibit some form of movement, either visible or at the molecular level. For example, breathing in animals or growth in plants are indicators of life. However, visible movement alone is not sufficient, as some animals can breathe without visible movement, and some plants do not show obvious growth. Molecular movement is essential for life, and it is absent in non-living things.

Question 2: Why are molecular movements necessary for life?

Answer: Molecular movements are necessary because living organisms are well-organized structures that tend to break down over time due to environmental effects. To maintain and repair their structure, living beings must constantly move molecules around, which is essential for sustaining life.

Question 3: Why are viruses not considered truly alive by some biologists?

Answer: Viruses do not show molecular movement unless they infect a host cell. This lack independent molecular movement raises questions about whether viruses are truly alive.

Question 4: What are life processes?

Answer: Life processes are the maintenance functions in living organisms that continue even when they are not performing any specific activity. These processes include nutrition, respiration, transportation, and excretion, which are essential to maintain life and prevent damage or breakdown of the body.

Question 5: What is autotrophic nutrition?

Answer: Autotrophic nutrition is the process by which organisms like green plants and some bacteria synthesize their own food from inorganic substances like carbon dioxide and water using sunlight and chlorophyll. This process, called photosynthesis, produces carbohydrates, which serve as energy sources.

Question 6: What are the steps involved in photosynthesis?

Answer: The steps involved in photosynthesis are:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Question 7: how do guard cells help in photosynthesis?

Answer: Guard cells control the opening and closing of stomatal pores on leaves. When water flows into the guard cells, they swell, causing the stomata to open, allowing the intake of carbon dioxide necessary for photosynthesis. When guard cells shrink, the stomata close to prevent water loss.

Question 8: How do heterotrophs differ from autotrophs in their mode of nutrition?

Answer: Heterotrophs obtain their food by consuming other organisms, as they cannot sysnthesize their own food. They rely on autotrophs directly or indirectly. Examples include animals and fungi. In contrast, autotrophs synthesize their food using inorganic substances and sunlight.

Question 9: How do Amoeba and Paramecium their nutrition?

Answer:

Amoeba: Amoeba engulfs food using temporary finger-like extensions called pseudopodia, forming a food vacuole. Inside the vacule, food is broken down, and the nutrients diffuse into the cytoplasm.

Paramecium: Paramecium uses cilia to move food to a specific spot in its cell where it is ingested.

Question 10: What experiment demonstrates the importance of chlorophyll in photosynthesis?

Answer: The experiment involves:

1. Taking a plant with variegated leaves and keeping it in the dark for three days.
2. Exposing it to sunlight for six fours.
3. Testing the leaf for starch by boiling it in water, then alcohol, and adding iodine solutio.
4. The areas containing chlorophyll turn blue-black, showing that chlorophyll is essential for photosynthesis.

Question 11: What is the role of potassium hydroxide in the experiment to test the role of carbon dioxide in photosynthesis?

Answer: Potassium hydroxide absorbs carbon dioxide. In the experiment, the plant exposed to potassium hydroxide shows no starch formation, proving that carbon dioxide is essential for photosynthesis.

Question 12: What is the role of saliva in digestion?

Answer: Saliva contains an enzyme called salivary amylase that breaks down starch into simple sugars. It also moistens the food to aid in smooth passage through the alimentary canal.

Question 13: What are peristaltic movements, and why are they necessary?

Answer: Peristaltic movements are rhythmic contractions of the muscles in the alimentary canal. They help push food forward through the digestive system for proper processing.

Question 14: How does stomach aid in digestion?

Answer: The stomach aid in digestion?

Answer: The stomach releases gasstric juices containing hydrochloric acid, pepsin, and mucus. Hydrochloric acid creates an acidic environment for pepsin to digest proteins, while mucus protects the stomach lining form acid damage.

Question 15: Why is bile important in digestion?

Answer: Bile, produced by the liver, neutralizes the acidic food from the stomach and emulsifies fats into smaller globules, making them easier to digest by enzymes like lipase.

Question 16: What is the function of villi in the small intestine?

Answer: Villi are finger-like projections in the small intestine that increase the surface area for absorption. They are richly supplied with blood vessels to transport absorbed nutrients to the rest of the body.

Question 17: What happens to unaborbed food in the digestive system?

Answer: Unabsorbed food enters the large intestine, where water is reabosorbed. The remaining material is expelled from the body through the anus as waste.

Question 18: What causes dental caries, and how can they be prevented?

Answer: Dental caries are caused by acids produced by bacteria acting on sugars in food. These acids demineralize enamel and dentine. Brushing teeth after meals helps remove plaque and prevents tooth decay.

Question 19: What is aerobic respiration, and where does it occur?

Answer: Aerobic respiration is the process of breaking down glucose into carbon dioxide and water in the presence of oxygen. It occurs in the mitochondria of cells and releases a large amount of energy.

Question 20: How is anaerobic respiratin different from aerobic respiration?

Answer: Anaerobic respiration occurs in the absence of oxygen. It breaks down glucose into ethanol and carbon dioxide (in yeast) or lactic acid (in muscles) and releases less energy compared to aerobic respiration.

Question 21: What is the role of ATP in the body?

Answer: ATP (Adenosine Triphosphate) is the energy currency of cells. It stores energy and releases it during cellular processes like muscle contraction, protein synthesis, and nerve cnoduciton.

Question 22: Why do aquatic organisms breathe faster than terrestrial organisms?

Answer: Aquatic organisms breathe faster because the amount of dissolve oxygen in water is much lower than the oxygen in the atmosphere.

Question 23: How is air filtered in the human respiratory system?

Answer: Air entering through the nostrils is filtered by fine hairs and mucus lining the nasal passage. This traps dust and other particles.

Question 24: What is the function of cartilage rings in the respiratory tract?

Answer: The cartilage rings in the resptiratory tract prevent the air passage from collapsing, ensuring uninterrrupted airflow to the lungs.

Quesiton 25: What happens in the alveoli during respiration?

Answer: In the alveoli, oxygen from inhaled air diffuses into the blood, and carbon dioxide from the blood diffuses out to be exhaled.

Question 26: What is the significance of lime water turning milky in respiration experiments?

Answer: Lime water turns milky due to the presence of carbon dioxide, indicating its higher concentration in exhaled air compared to inhaled air.