Biology Quiz Chapter 21

Indoleacetic acid is the most naturally occurring auxin. Auxins are a group of plant hormones that regulate various aspects of plant growth and development. Indoleacetic acid is produced in the tips of plant shoots and promotes cell elongation, root development, and fruit growth. It plays a crucial role in phototropism, geotropism, and apical dominance. Indoleacetic acid is synthesized from the amino acid tryptophan and is transported throughout the plant to regulate various physiological processes.

Apical dominance refers to the phenomenon where the terminal bud of a plant inhibits the growth of lateral buds. The terminal bud releases a hormone called auxin, which travels downwards and suppresses the growth of lateral buds. This allows the plant to focus its energy on growing upwards, promoting vertical growth. By inhibiting the growth of lateral buds, apical dominance helps maintain the plant's shape and directs its growth towards the top.

The correct answer is "in the shoot meristem and is found in young leaves and in flowers and fruits." This answer specifies that the most naturally occurring auxin is produced in the shoot meristem and can be found in young leaves, flowers, and fruits.

Auxin is a plant hormone that plays a crucial role in phototropism. Phototropism is the growth or movement of a plant in response to light. Auxin helps in this process by redistributing itself in response to light, causing the plant to bend towards the light source. This hormone is responsible for elongating cells on the shaded side of the plant, causing it to grow towards the light and optimize its exposure to sunlight for photosynthesis. Therefore, auxin is involved in phototropism and helps in plant growth by facilitating light perception and directional growth.

The correct answer is Abscisic acid, Auxins, Cytokinins, Ethylene, and Gibberellins. This answer lists the 5 major plant hormones in alphabetical order, providing a comprehensive and accurate response to the question.