Free Plant Growth And Development (Weekly Quiz: 1) NEET Biology Questions & Answers with Detailed Explanation & Full Review

Answer: (c)

Flowering in pineapple is promoted by NAA (Naphthalene acetic acid). NAA is a synthetic plant hormone in the auxin family. NAA and 2, 4, D are synthetic auxin plant hormones. All these auxins have been used extensively in agricultural and horticultural practices.

Answer: (c)

Gibberellin is a hormone that replaces vernalisation. Vernalization is a period of cold treatment for plants, usually perennials or trees. Some plants won't bloom without it. In vernalization plants are exposed to low temperature in order to stimulate flowering or to enhance seed production. The biennials form their vegetative body in the first year. Then they pass through a winter season and then produce flowers and fruits in the second year. By exogenous application of gibberellins many biennials can be induced to behave as annuals and they no more require the natural chilling treatment for their flowering.

Answer: (a)

Altering the plasticity allows for permanent changes in cell wall shape. The cell wall must increase in size in order for cell growth to occur.

Answer: (a)

Light and temperature may affect flowering in plants in various ways. The effect of photoperiods or daily duration of light hours (and dark periods) on flowering is called photoperiodism. For example, in short day plants flowering occurs when day length is below critical period, e.g., dahlia, rice, etc. In long day plants, flowering occurs when day length is above critical period, e.g., spinach, lettuce, etc. In short-long day plants, short photoperiod is required for floral initiation and long photoperiod is required for blossoming and vice-versa for long-short day plants. Hence, flowering in certain plants not only depends on a combination of light and dark exposures but also on their relative durations. Similarly, there are plants for which flowering is either quantitatively or qualitatively dependent on exposure to low temperature. This phenomenon is termed as vernalisation. It prevents precocious reproductive development late in the growing season and enables the plant to have sufficient time to reach maturity. Thus, many plants require a warm-cold-warm sequence to complete their annual cycle.