Plant Growth and Development

In certain angiospermic herbaceous perennials, like banana and gladiolus, above the ground part of the shoot dies each year after flowering and fruiting, but the underground parts (stem and roots) survive and put out new shoots the next year.

The delay of senescence of leaves and other organs of the plants by cytokinins is called Richmond Lang effect.

 The induction of flowering by prolonged exposure to low temperatures, as during the winter in a temperate climate is called vernalisation.

Phototropins are blue-light receptors which are involved in phototropism. They are basically autophosphorylating protein kinases.

The correct option is 4.

Auxin is synthesised in apical meristems of shoots. 

 The phenomenon of responding to an external stimulus like light is known as phototropism.

An enzyme that can stimulate germination of barley seeds is α-amylase.

Option (2) is correct.

This growth phase is seen in bacteria, not in plants. In this phase, only some bacteria which can tolerate or resist unfavourable conditions will survive in the environment by producing endospores.

The growth in length of the plant is measured with the help of an equipment called auxanometer or auxograph. It is an instrument used for determining and measuring the rate of growth in plants consisting essentially of a lever with a long arm and a short arm which is attached to the plant.

The degree of plant growth is dependent on the environment. Plant development is dependent on the environmental conditions where it is growing. Because light is the energy source for plant growth, plants have evolved highly sensitive mechanisms for perceiving light and using that information for regulating development changes to help maximise light utilisation for photosynthesis.

Abscisic acid is produced during water stress that brings stomatal closure.

Kinetin was isolated from coconut milk.

Photoperiodism in plants is related to the formation of florigen.

Photoperiodism is the ability of plants to measure day length. Lettuce is a long day plant, which flowers after a critical day length is exceeded. Long day plants flower only when photoperiod (day length) is long, that is, summer.

Option (1) is correct.

Cytokinins are the phytohormones that stimulate cell division. They prevent the onset of senescence in tissues. 

High temperature denatures enzymes and retards growth of plants. 

 1-naphthaleneacetic acid, NAA is a synthetic auxin.

It is a gaseous plant hormone playing a key regulatory role in ripening of many types of fruits, including banana, apple, pear and melons. It can be produced naturally by ripening fruits or from synthetic sources such as ethephon. 

Vernalisation is the acquisition of a plant's ability to flower or germinate in the spring by exposure to the prolonged cold of winter. Vernalisation activates a plant hormone called florigen present in the leaves, which induces flowering at the end of the chilling treatment. Florigen or flowering hormone is the hypothesised hormone-like molecules responsible for controlling and/or triggering flowering in plants. Florigen is produced in the leaves and acts in the shoot apical meristem of buds and growing tips.

The chemicals required in smaller quantities are called minor nutrients or trace elements. Among the trace elements are boron, manganese, copper, iron and zinc. Boron is essential for the growth of higher plants. 

Gibberellins are defined as a class of related plant hormones that stimulate growth in the stem and leaves.

Vernalisation is flowering at low temperature (true).