Organisms exhibit diversity across Earth’s ecosystems. Plants and animals, both complex multicellular life forms, have evolved different survival strategies. These differences are evident in their basic biological processes and structures.
Energy Acquisition
Plants acquire energy through photosynthesis, converting light into chemical energy. Chloroplasts within plant cells capture sunlight to synthesize sugars from carbon dioxide and water. Plants are autotrophs, producing their own food. Animals are heterotrophs, obtaining energy by consuming other organisms. They digest organic compounds from other organisms, breaking them down for metabolic activities and growth.
Cellular Architecture
Plant and animal cells have distinct structural features. Plant cells have a rigid cell wall, primarily composed of cellulose, providing structural support and protection. They also contain chloroplasts for photosynthesis and a large, central vacuole that maintains turgor pressure. Animal cells, in contrast, lack cell walls and chloroplasts. They have a flexible cell membrane and may have smaller, temporary, or no vacuoles, relying on other mechanisms for storage and waste removal.
Locomotion
Most animals are motile, exhibiting various forms of movement to navigate their environment. They utilize specialized structures like muscles, flagella, or cilia to move in search of food, mates, or to escape predators. This ability to relocate is important for their survival. Plants are generally sessile, meaning they remain rooted in one location. While they cannot move their entire body, they rely on growth mechanisms and external factors like wind or animals for the dispersal of pollen and seeds.
Growth and Development
Plants exhibit indeterminate growth, meaning they grow throughout their lives. This continuous growth occurs from meristems, areas of active cell division, allowing plants to add new organs like leaves, stems, and roots. In contrast, animals typically display determinate growth. They reach a genetically predetermined mature size and shape, after which growth largely ceases, with cellular activity focused on tissue repair and maintenance rather than increasing overall body size.
Environmental Interaction
Animals often have complex nervous systems and specialized sensory organs, including eyes, ears, and noses. These systems enable rapid information processing and quick responses to environmental stimuli, such as detecting prey or avoiding danger. Plants lack nervous systems and sensory organs comparable to animals. Their responses to environmental cues like light, gravity, or touch are typically slower, mediated by hormones, and lead to growth-related movements known as tropisms, such as a stem bending towards light.