Describe the characteristics of living organisms by describing: (a) movement as an action by an organism or part of an organism causing a change of position or place (b) respiration as the chemical reactions in cells that break down nutrient molecules and release energy for metabolism (c) sensitivity as the ability to detect and respond to changes in the internal or external environment (d) growth as a permanent increase in size and dry mass (e) reproduction as the processes that make more of the same kind of organism (f) excretion as the removal of the waste products of metabolism and substances in excess of requirements (g) nutrition as the taking in of materials for energy, growth and development

Sourav PanNovember 14, 2024

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Characteristics of Living Organisms

(a) Movement

Movement refers to the ability of an organism or a part of an organism to change position or place. This can be observed in various forms:

• Locomotion: Whole organisms, such as animals, move from one location to another (e.g., walking, swimming, flying).
• Growth Movement: Plants exhibit movement as they grow towards light (phototropism) or water (hydrotropism).
• Cell Movement: Within multicellular organisms, cells can move to perform functions such as healing wounds or immune responses.

(b) Respiration

Respiration is a biochemical process that occurs in cells, where nutrient molecules are broken down to release energy. This process is vital for metabolism and can be categorized into two types:

• Aerobic Respiration: Requires oxygen and produces carbon dioxide and water as by-products, releasing a significant amount of energy.
• Anaerobic Respiration: Occurs without oxygen and results in less energy production, along with by-products like lactic acid or ethanol.

(c) Sensitivity

Sensitivity is the ability of an organism to detect and respond to changes in its internal or external environment. This characteristic allows organisms to:

• React to Stimuli: For example, plants may bend towards light, while animals may flee from predators.
• Maintain Homeostasis: Organisms monitor internal conditions (such as temperature and pH) and make adjustments to maintain stable internal environments.

(d) Growth

Growth refers to a permanent increase in size and dry mass of an organism. This characteristic can be measured in several ways:

• Cell Division: Organisms grow through the process of cell division, where cells replicate and increase in number.
• Development: Growth also involves differentiation, where cells develop into specialized types for specific functions.

(e) Reproduction

Reproduction is the biological process through which organisms produce more individuals of the same kind. It can occur in two main forms:

• Asexual Reproduction: Involves a single organism producing offspring that are genetically identical (e.g., binary fission in bacteria).
• Sexual Reproduction: Involves the combination of genetic material from two parents, resulting in genetically diverse offspring.

(f) Excretion

Excretion is the process of removing waste products of metabolism and substances that are present in excess from the body. This is crucial for maintaining internal balance and preventing toxicity. Common excretory products include:

• Carbon Dioxide: Removed during respiration.
• Urea: A nitrogenous waste product eliminated through urine.
• Excess Salts and Water: Regulated through sweat and urine.

(g) Nutrition

Nutrition involves the intake of materials necessary for energy, growth, and development. Organisms obtain nutrients through various means:

• Autotrophic Nutrition: Organisms like plants synthesize their own food using sunlight (photosynthesis).
• Heterotrophic Nutrition: Animals consume organic matter from other organisms for energy and nutrients.