Life Processes in Organisms

Life Processes

• Life processes define characteristics of living organisms, which are called organisms.
• Seven essential life processes determine whether something is living or non-living.

Movement

• Both animals and plants exhibit movement; animals move quickly while plants move slowly as they grow.
• Plant movements include roots growing downward and stems reaching toward light.

Respiration

• Respiration refers to energy extraction from food, taking place in the mitochondria.
• Essential for growth, replacement of worn parts, and movement.

Sensitivity

• All living organisms are sensitive to environmental changes, responding to stimuli like heat, light, and sound.
• Animals generally react quickly, while plant responses are slower.

Growth

• All living organisms experience growth; plants continue to grow throughout their lives, while animals stop growing at adulthood.
• Replacement of materials occurs in the bodies of animals even after growth halts.

Excretion

• Living organisms produce waste that must be expelled to avoid harm, known as excretion.
• Plants remove waste through fallen leaves, while animals excrete carbon dioxide and waste products via urine and sweat.
• Egestion, the removal of undigested food, is not classified as excretion.

Reproduction

• Organisms must reproduce to ensure species survival.
• Plants produce seeds for new plants, while animals reproduce through eggs or offspring.
• Reproduction occurs in two forms:
  • Sexual (involving two parents)
  • Asexual (single parent reproduction)

Nutrition

• Nutrition is crucial for energy and growth; plants are autotrophs that produce their own food via photosynthesis, while animals are heterotrophs relying on other organisms for nutrition.
• Autotrophs convert inorganic substances into organic ones, while heterotrophs depend on consuming complex organic matter.

Autotrophic Nutrition

• Organisms synthesize organic materials from inorganic sources, primarily using sunlight for energy.
• Photosynthesis involves several steps: light absorption by chlorophyll, conversion to chemical energy, and carbon dioxide reduction to carbohydrates.

Heterotrophic Nutrition

• Heterotrophs rely on autotrophs for nutrition, categorized into three types:
  • Holozoic: Involves ingestion and digestion of complex food (e.g., humans, amoeba).
  • Saprophytic: Involves feeding on dead organic matter (e.g., fungi).
  • Parasitic: Organisms take nutrients from hosts without benefiting them (e.g., ticks, tapeworms).