Vascular plants, which account for over 90% of the Earth’s vegetation, all undergo primary growth—which lengthens roots and shoots. Many land plants, notably woody plants, also undergo secondary growth—which thickens roots and shoots.

The Cannon-Bard theory of emotion, proposed by Walter Cannon and Philip Bard, challenges the notion that emotions are solely the result of physiological responses. Instead, this theory suggests that emotional experiences and physiological arousal occur simultaneously but operate through independent mechanisms. This dual response is initiated by the brain, specifically by the thalamus, which plays a critical role in processing sensory information.
Upon perceiving a stimulus, such as a dangerous...

Plant tissue culture is widely used in both primary and applied science. Applications range from plant development studies to functional gene studies, crop improvement, commercial micropropagation, virus elimination, and conservation of rare species.

Gravitropism: Plant Responses to Gravity

Plants grow throughout their lives; this is called indeterminate growth, and it distinguishes plants from most animals. Although certain parts of plants stop growing (e.g., leaves and flowers), others grow continuously—like roots and stems.

Light plays a significant role in regulating the growth and development of plants. In addition to providing energy for photosynthesis, light provides other important cues to regulate a range of developmental and physiological responses in plants.