It is evaluation of the effect of a substance on a living organism under controlled conditions. Two bioassays used to examine auxin activity in plants are:
1. The Avena Curvature Test
2. Root growth inhibition test

Yes, we can alter the rate of growth by making variations in the factors affecting growth, these are light and temperature. A plant grows quicker during the night then during the day. During the night retarding or inhibiting action of light is absent and rate of growth of a plant gradually increases until dawn while during the day the rate of growth gradually decreases until about sunset.

Ethylene.

When seed dormancy is because of internal causes, it is called inherent seed dormancy.

The first step in the process of plant growth is seed germination. The seed germinates when favourable conditions for growth exist in the environment. In absence of such favourable conditions the seeds do not germinate and goes into a period of suspended growth or rest.

Development is a term that includes all changes that an organism goes through during its life cycle from germination of the seed to senescence.

They promote cell division, cell enlargement, flowering, fruiting and seed formation. Examples are auxins, gibberellins and cytokinins.

Abscisic acid is also known as the stress hormone because it is found to induce various types of responses in plants against stress conditions like the closure of the stomata during drought, seed dormancy and it also ensures germination of seed during favorable conditions.

A - Lag phase, B - Log phase and C- Steady phase.

Abscisic acid (ABA) and cytokinin antagonistically regulate many developmental processes and environmental stress responses in plants.

The compound, which can be converted into auxin are called auxin precursors. The compounds, which inhibit the actions of auxins, are termed anti-auxins. The auxins, which can easily be extracted, are called free auxins. And auxins, which are hard to extract and need the use of organic solvents, are reffered to as bound auxins.

Spraying of sugar plants with gibberellin can increases the length of internodes and increased or lengthy internodes will produce more sugar. Thus,gibberelins can increase sugar yield.

Callus (i.e., undifferentiated mass of cells) proliferates only when nutrient medium containing auxin was supplemented with coconut milk because it contains kinetin (a cytokinin) which stimulates growth of plants tissues.

Meristematic cells are actively dividing cells which show mitotic divisions, ie.each chromosome is split lengthwise into two homologous chromatids, which pass equally into daughter cells. These possess thin cell wasll and a dense cytoplasm.
Mature cells are incapable of divisions becauses inthese cells differentiation has take place. Also mature cells do not possess thin cell wall in and a dense cytoplasm.

Higher concentration of auxins inhibit growth of the plants. In normal course in nature, self produced auxin in plants inhibits the growth and development of lateral buds and as a result lateral bud remains dormant.