91影视

A plant鈥檚 response to the relative amounts of daylight and darkness is (a) apical dominance (b) bolting (c) gravitropism (d) photoperiodism (e) phototropism.

Pfr, the active state of ______________ , forms when red light is absorbed. (a) photosystem I (b) phytochrome (c) far-red light (d) phototropin (e) cryptochrome.

Which of the following represents the correct order in the phytochrome signal transduction pathway? (1) red light (2) lightresponsive gene is switched on (or off) (3) movement of Pfr to nucleus (4) conversion of Pr to Pfr (5) formation of PFr-PIF3 complex that is bound to promoter region (a) 1-3-5-4-2 (b) 1-5-3-2-4 (c) 1-2-3-4-5 (d) 1-4-3-2-5 (e) 1-4-3-5-2.

Which of the following statements about phytochrome is incorrect? (a) Phytochrome is the main photoreceptor for photoperiodism. (b) Phytochrome is a family of about five blue-green pigment proteins, each coded by a different gene. (c) Most of our knowledge of phytochrome function is based on mutant corn (Zea mays) plants. (d) Each member of the phytochrome family exists in two forms: Pr and Pfr. (e) Phytochrome helps plants sense the presence of nearby plants with which they must compete for light.

Which photoreceptor(s) is/are implicated in resetting the biological clock? (a) phytochrome only (b) cryptochrome only (c) gibberellin only (d) cryptochrome and gibberellin (e) phytochrome and cryptochrome.

In ______________, leaves or other plant organs track the sun鈥檚 movement across the sky. (a) heliotropism (b) thigmotropism (c) phototropism (d) bolting (e) photoperiodism.

The orientation of the growth of a plant according to the direction of light is called ______________, whereas the twining of tendrils is an example of ______________. (a) heliotropism; gravitropism (b) photoperiodism; nastic movements (c) phototropism; gravitropism (d) phototropism; thigmotropism (e) photoperiodism; thigmotropism.

When you prune shrubs to make them 鈥渂ushier鈥濃�攖hat is, to prevent apical dominance鈥攜ou are affecting the distribution and action of which plant hormone? (a) auxin (b) jasmonic acid (c) systemin (d) ethylene (e) abscisic acid.

A synthetic ______________ known as 2,4-D is used as a selective herbicide. (a) auxin (b) gibberellin (c) cytokinin (d) ethylene (e) abscisic acid.

Research on a fungal disease of rice provided the first clues about the plant hormone (a) auxin (b) gibberellin (c) cytokinin (d) ethylene (e) abscisic acid.