Characteristics of Living Organisms

Characteristics of Living Organisms

• Understanding Living Organisms

  • All living organisms share certain characteristics, crucial for classification as 'living'.

  • These eight characteristics must be present:

  • Movement

  • Respiration

  • Sensitivity

  • Homeostasis

  • Growth

  • Reproduction

  • Excretion

  • Nutrition

  • Mnemonic: The acronym Mrs. H Gren is commonly used to remember these characteristics.

Movement

• Animals often move their entire bodies to navigate and find food.

  • Example: Cheetah can reach speeds of up to 70 mph to catch prey.

• Plants also exhibit movement, such as:

  • Leaves moving towards sunlight to optimize photosynthesis.

  • Roots growing towards mineral ions in the soil.

Respiration

• Both plants and animals perform aerobic respiration using oxygen to convert glucose into energy.

  • Equation: \text{OXYGEN} + \text{GLUCOSE} \rightarrow \text{CARBON DIOXIDE} + \text{WATER} + \text{ENERGY}

• This energy powers essential life processes:

  • Movement, Growth, Excretion, Reproduction

Sensitivity

• Living organisms respond to changes or stimuli in their environment.

  • Plants may respond to seasonal changes.

  • Animals detect temperature and pressure changes and respond accordingly.

  • Example: Human fingertips contain millions of receptors to sense touch and changes in the environment.

Homeostasis

• Homeostasis refers to the ability to maintain stable internal conditions.

  • Coordinated response mechanisms include:

  • Nervous system

  • Hormonal system in animals

  • Some plants have hormone-like chemicals for regulation.

• Homeostasis maintains optimal conditions for enzymatic reactions to occur.

Growth

• Growth is defined as an increase in cell size, number, or complexity.

  • Example: Infants grow into adolescents and then adults.

  • In plants, seedlings grow into mature plants.

• Growth enhances survival rates, as maturity implies better defense mechanisms against threats.

Reproduction

• All living organisms engage in reproduction to produce offspring, ensuring species survival.

  • Animals reproduce either sexually or asexually.

  • Example: Mammals typically reproduce sexually, while many bacteria reproduce asexually (binary fission).

  • Plants can reproduce through pollination or self-fertilization, often aided by pollinators like bees.

Excretion

• Metabolic processes generate waste that must be removed to avoid toxicity.

  • Both plants and animals have specific excretory organs:

  • Kidneys in mammals filter waste and produce urine.

  • Stomata in plants expel excess oxygen produced during photosynthesis.

Nutrition

• Energy is necessary for cell growth, repair, and maintenance.

• Animals obtain energy through consumption (heterotrophy), while plants synthesize their food through photosynthesis (autotrophy).

  • Examples:

  • Carnivores eat other animals, while herbivores consume plants.

• A balanced diet, particularly including fruits and vegetables, is essential for optimal nutrition in humans.