class10 chapter5 notes

                                                     SCORE CBSE

1. Introduction to Life Processes

• Life processes are the essential activities that living organisms perform to stay alive. These processes include nutrition, respiration, transportation, excretion, and regulation.

2. Nutrition

• Nutrition is the process by which living organisms obtain and utilize food for energy, growth, and maintenance of body functions.

(a) Types of Nutrition

• Autotrophic Nutrition: Organisms like plants make their own food using sunlight, carbon dioxide, and water through the process of photosynthesis. Green plants and some bacteria exhibit this form of nutrition.
  • Photosynthesis equation:
    $6CO_2 + 6H_2O + \text{light energy} \longrightarrow C_6H_{12}O_6 + 6O_2$
• Heterotrophic Nutrition: Organisms like animals and fungi depend on other organisms for food. This includes:
  • Holozoic Nutrition: Involves ingestion, digestion, absorption, and assimilation of food. Humans, animals, and most fungi exhibit this type of nutrition.
  • Saprophytic Nutrition: Organisms like fungi and some bacteria obtain food from dead and decaying organic matter.
  • Parasitic Nutrition: Some organisms obtain food from living organisms (hosts) at the host's expense (e.g., lice, tapeworms).

(b) Human Digestive System

• The human digestive system is responsible for breaking down food into simple molecules that can be absorbed into the bloodstream.
  • Organs involved: Mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.
  • Key Processes:
    • Ingestion: Intake of food.
    • Digestion: Breakdown of food into simpler molecules by physical and chemical means.
    • Absorption: Nutrients are absorbed into the bloodstream primarily in the small intestine.
    • Assimilation: The absorbed nutrients are used by cells for energy and growth.
    • Egestion: Removal of undigested food from the body.

3. Respiration

• Respiration is the process by which cells obtain energy by breaking down food molecules (like glucose) in the presence of oxygen.

(a) Types of Respiration

• Aerobic Respiration: This occurs in the presence of oxygen. It is the most efficient way of obtaining energy from glucose.
  • Equation:
    $C_6H_{12}O_6 + 6O_2 \longrightarrow 6CO_2 + 6H_2O + \text{energy}$
• Anaerobic Respiration: This occurs in the absence of oxygen. It is less efficient and produces less energy. In animals, it produces lactic acid; in yeast, it produces ethanol and carbon dioxide.
  • Equation in yeast (fermentation): $C_6H_{12}O_6 \longrightarrow 2C_2H_5OH + 2CO_2 + \text{energy}$

(b) Respiratory System in Humans

• The human respiratory system involves the intake of oxygen and the release of carbon dioxide. Key components include:
  • Nasal cavity: Air enters through the nose, where it is filtered, warmed, and moistened.
  • Trachea: A tube that carries air to the lungs.
  • Lungs: The site of gas exchange, where oxygen is absorbed and carbon dioxide is released.
  • Alveoli: Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

4. Transportation

• Transportation refers to the movement of substances (like nutrients, gases, and waste) within an organism.

(a) Circulatory System in Humans

• The human circulatory system involves the heart, blood, and blood vessels.
  • Heart: Pumps blood throughout the body.
  • Blood vessels: Arteries carry oxygenated blood away from the heart, veins carry deoxygenated blood back to the heart, and capillaries facilitate the exchange of gases, nutrients, and waste between blood and tissues.
  • Blood: Composed of plasma, red blood cells, white blood cells, and platelets. Red blood cells carry oxygen through the body, and white blood cells are involved in immune responses.

(b) Xylem and Phloem in Plants

• In plants, xylem is responsible for the transport of water and minerals from roots to other parts of the plant, while phloem transports food (mainly sugars) produced in the leaves to other parts of the plant.

5. Excretion

• Excretion is the process of removing waste products produced by metabolism.

(a) Excretory System in Humans

• The human excretory system involves the kidneys, ureters, urinary bladder, and urethra.
  • Kidneys filter blood, remove excess water, salts, and urea, and produce urine.
  • Ureters carry urine from the kidneys to the urinary bladder.
  • Urinary bladder stores urine before it is expelled through the urethra.

(b) Excretion in Plants

• Plants excrete excess oxygen, water (through transpiration), and waste products (mainly in the form of resins or gums).