Plant Growth And Development Test 2: 17/11/12

Auxin is a plant hormone that plays a crucial role in various growth and developmental processes. The growing tips of plants, also known as the apical meristems, contain the highest concentration of auxin. This is because auxin is synthesized in the apical meristems and then transported downwards to other parts of the plant. The high concentration of auxin in the growing tips promotes cell elongation, cell division, and the initiation of new organs, which are essential for plant growth and development.

Ethylene is a naturally occurring gaseous growth hormone or growth inhibitor or growth regulator. It is produced by plants and plays a crucial role in regulating various physiological processes such as fruit ripening, leaf senescence, and flower and root development. Ethylene acts as a signaling molecule, influencing the growth and development of plants by promoting or inhibiting certain processes. It is involved in coordinating responses to environmental stresses, such as drought or pathogen attack. Overall, ethylene is an important regulator of plant growth and development.

Vernalization is the process by which plants require exposure to a prolonged period of cold temperatures in order to transition from the vegetative to the reproductive stage. Vernalin is the hormone responsible for initiating this process. It is produced in response to the cold temperatures and helps to regulate the genetic and physiological changes that occur during vernalization. Therefore, vernalin is the correct answer as it is the hormone specifically associated with the vernalization process.

Photoperiodism refers to the effect of day length on plant growth. It is a phenomenon where plants respond to the duration of light and darkness in a 24-hour period. Different plants have different requirements for light exposure, and photoperiodism influences various aspects of plant growth, such as flowering, fruiting, and dormancy. This response to day length is crucial for plants to adapt to changing seasons and optimize their growth and reproductive strategies.

Florigen is the correct answer because it is a chemical substance that plays a crucial role in the formation of flowers in plants. It is produced in the leaves and then transported to the apical meristem, where it induces the transition from vegetative growth to reproductive growth, resulting in the development of flowers.

Gibberellin or Gibberellic acid is a plant hormone that promotes flowering. In long day plants, flowering is induced when they are exposed to longer periods of light. However, in short day plants, flowering is triggered when they are exposed to shorter periods of light. Therefore, the correct answer is "in long day plants under short day conditions" because gibberellin can be used to induce flowering in long day plants even when they are subjected to shorter periods of light.

Indole butyric acid, also known as auxin, is the growth regulator used for rooting on stem cuttings or leaves of Bryophyllum. Auxin is a plant hormone that promotes root development and stimulates cell elongation. It helps in the formation of adventitious roots, which are roots that form from non-root tissues. By applying indole butyric acid or auxin to stem cuttings or leaves, it enhances their ability to produce roots and establish new plants. Gibberellic acid, carotene, and lycopene are not growth regulators commonly used for rooting on stem cuttings or leaves.

Cytokinin is a plant hormone that promotes cell division and delays senescence, the process of aging in plants. It helps in maintaining the greenness and vitality of leaves by inhibiting the breakdown of chlorophyll and other proteins. Therefore, the presence of cytokinin in plants slows down leaf aging, keeping the leaves healthier and functional for a longer period of time.

Vernalization is the process by which plants are induced to flower by exposure to a prolonged period of cold temperatures. In annual and biennial plants, the stimulus of vernalization is received by the stem apex. The stem apex contains the growing point of the plant, where new shoots and flowers develop. It is sensitive to environmental cues, such as cold temperatures, which trigger the flowering process. The stem apex receives the signal for vernalization, allowing the plant to undergo the necessary physiological changes to initiate flowering.

Auxins (or ethylene) can change the sex of unisexual plants. Auxins are plant hormones that regulate various physiological processes, including the development of reproductive organs. Ethylene is another plant hormone that plays a role in fruit ripening and flower senescence. Both auxins and ethylene can influence the expression of genes involved in sex determination, leading to a change in the sexual characteristics of the plant. Therefore, the application of auxins or ethylene can alter the sex of unisexual plants.