life processes

• Criteria to decide whether something is alive:

  • Movement is the most important criteria to determine if something is alive
  • All living things move without external help
  • Movements can be visible like body parts or invisible like molecular movements in cells and tissues
• Life processes:

  • Nutrition, respiration, transportation, and excretion are the basic life processes in living organisms
  • Nutrition involves taking in food for growth, repair, and energy
  • Respiration burns food in cells with oxygen to release energy
  • Transportation moves substances within the body
  • Excretion removes waste products
• Modes of nutrition:

  • Autotrophic nutrition: organisms make their own food from inorganic substances like carbon dioxide and water with sunlight and chlorophyll
  • Heterotrophic nutrition: organisms get food from other organisms
  • Types of heterotrophic nutrition: saprophytic, parasitic, and holozoic nutritions
• Nutrition in plants:

  • Photosynthesis: plants prepare food using carbon dioxide and water with sunlight and chlorophyll
  • Chlorophyll is necessary for photosynthesis
  • Stomata are pores for gas exchange in leaves
• Activity to show carbon dioxide is necessary for photosynthesis:

  • Use two plants, one with potassium hydroxide to absorb carbon dioxide, and observe starch presence
• Nutrition in heterotrophs:

  • Amoeba takes in food through pseudopodia and digests it in a food vacuole
  • Human nutrition involves the digestive system with organs like the mouth, stomach, and intestines
• Respiration:

  • Process where food is burnt in cells with oxygen to release energy
  • Types: aerobic (with oxygen) and anaerobic (without oxygen)
• Aerobic respiration:

  • Takes place in the presence of oxygen
  • Produces more energy
  • End products: carbon dioxide, water, and energy
  • Glucose is converted into pyruvate in the cytoplasm and then into carbon dioxide, water, and energy in the mitochondria
• Anaerobic respiration:

  • Takes place in the absence of oxygen
  • Produces less energy
  • End products: lactic acid or ethanol, carbon dioxide, and energy
  • In muscle cells, glucose is converted into pyruvate, then into lactic acid and energy in the absence of oxygen
  • In yeast, glucose is converted into pyruvate, then into ethanol, carbon dioxide, and energy (fermentation)
• Respiration in Humans:

  • Main organs of the respiratory system: nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and diaphragm
  • Mechanism of breathing: diaphragm contracts and moves downward to inhale, relaxes and moves upward to exhale
  • Transportation: circulatory system with blood, arteries, veins, capillaries, and heart
• Transportation in Human beings:

  • Blood transports food, oxygen, and waste products
  • Components of blood: plasma, red blood cells (RBC), white blood cells (WBC), and platelets
  • Arteries carry pure blood, thick-walled without valves
  • Veins carry impure blood, thin-walled with valves
  • Capillaries connect arteries and veins, facilitating exchange of substances
  • Heart pumps blood to all parts of the body, with four chambers
• Working of the heart (Circulation of blood):

  • Double circulation in humans
  • Lymph: colorless fluid in intercellular spaces, transports digested fats and excess fluids back into the blood
• Heart of mammals, birds, amphibians, reptiles, and fishes:

  • Mammals and birds have four-chambered hearts, separated by a septum
  • Amphibians and reptiles have three-chambered hearts
  • Fishes have two-chambered hearts, with blood oxygenated in the gills
• Excretion in plants:

  • Gaseous waste products removed through stomata
  • Excess water removed through transpiration
  • Some waste products stored in leaves, vacuoles, old xylem cells, or removed through roots
• Excretion:

  • Removal of waste products from the body
  • In humans, excretory system includes kidneys, ureters, urinary bladder, and urethra
  • Nephrons in kidneys filter nitrogenous waste and excess substances to form urine
• Transportation in plants:

  • Xylem transports water and minerals
  • Phloem transports food through translocation