Plant hormones

A(An) ______ is an organic molecule synthesized by a plant that has physiological and/or developmental effects.

• enzyme

• plant hormone

• nutrients

• cotyledon

Which of the following plant hormones is NOT a growth promoter?

• auxins

• cytokinins

• gibberellins

• abscisic acid

Which of the following plant hormones acts to cause a leaf and/or fruit to drop?

• auxin

• cytokinin

• gibberellins

• ethylene

Which of the following plant hormones affects stem elongation?

• gibberellin

• cytokinin

• ethylene

• abscisic acid

Violets and tulips flower in the spring; asters and goldenrods flower in the fall. This indicates that flowering is controlled by ______ .

• temperature

• day length

• sunlight

• gravity

A response based on the proportion of light to darkness in a 24-hour cycle is called ______ .

• photoperiodism

• translocation

• transpiration

• alternation of generations

______ plants initiate flowering when the days get shorter than a critical length.

• Long day

• Short day

• Day-length neutral

• short-day neutral

A particular plant does not flower when the day is shorter than a critical length. However, when the day is longer than a critical length, it will flower. If a long night is interrupted by a flash of light, the plant will also flower. Such a plant is classified as a ______ plant.

• long day plants

• short day plants

• day-length neutral

• short-length neutral

______ is a pigment that is part of a biological clock system that helps control flowering.

• Gibberellin

• Auxin

• Phytochrome

• Chlorophyll

The photoperiod of a plant refers to the relative periods of light and dark that controls their flowering response.

• True

• False

• Neither correct

• Maybe true