Examination of a typical dicotyledon seed reveals that it a. is made mostly of meristematic tissue used for the storage of food. b. can be stimulated to germinate by the application of abscisic acid. c. forms from the union of a microscopic mother cell with a meagspore mother cell. d. shows the presence of a well-developed coleoptile. e. contains the first-foliage plumule formed at the apical meristem.

Flowering in plants such as tobacco and cocklebur and the germination of certain lettuce seeds are induced primarily by a. photoperiodism. b. temperature. c. negative feedback. d. circadian rhythms. e. lunar phases.

Gibberellic acid stimulates the cells of germinating grass seeds to produce mRNA molecules that code for hydrolytic enzymes. In this case the role of gibberellic acid can best be described as that of a. a regulator of gene activity. b. a stimulator of hydrolase secretion. c. a stimulator of DNA replication. d. an allosteric activator of hydrolase. e. an activator of translation.

All of the following are plant growth regulators EXCEPT a. ethylene. b. indoleacetic acid. c. abscisic acid. d. cytokinins. e. anthocyanin.

Auxins are responsible for many plant growth responses, including all of the following EXCEPT a. phototropism. b. formation of adventitious roots. c. apical dominance. d. detection of photoperiod. e. none of these

Movement of plants that is independent of the direction of the stimulus is known as a. tropism. b. nastic movement. c. auxic movement. d. all of these e. none of these

In order to flower, what does a short day plant need? a. a burst of red light in the middle of the night b. a burst of far red light in the middle of the night c. a day that is longer than a certain length d. a night that is longer than a ceratin length e. none of these

In nature, poinsettias bloom in early March. Research has shown that these plants are triggered to flower three months before they actually bloom. The trigger is the length of the light-dark cycle. In order to get poinsettias to bloom in December, florists change the length of the light-dark cycle in September. Given the information and clues above, which of the following is FALSE? a. Poinsettias are short day plants. b. Poinsettias require a light period shorter than some maximum. c. Poinsettias require a longer night period than is available in September. d. The dark period can be interrupted without affecting the flower. e. all are correct

A botanist exposed 2 groups of plants (of the same species) to two photoperiods. One with 14 hours of light and 10 hours of dark and the other with 10 hours of light and 14 hours of dark. Under the first set of conditions, the plants flowered, but they failed to flower under the second set of conditions. Which of the following conclusions would be consistent with these results? a. The critical night length is 14 hours. b. The plants are short day plants. c. The critical day length is 10 hours. d. The plants flower in spring. e. all of these

If a plant is mechanically stimulated, it will grow shorter, thicker stems. This response is a. caused by an increase in turgor. b. an adaptation to windy environments. c. both a and b d. neither a nor b

One effect of gibberrellins is to stimulate the aleurone layer of certain seeds to reproduce a. RuBP carboxylase. b. lipids. c. abscisic acid. d. starch. e. amylase.

We know from experiments of the past that plants bend toward light because a. the sum stimulates cell growth. b. cell expansion is greater on the dark side of the stem. c. its warmer in the direction of the sun. d. auxin is inactive on the dark side of the stem.

The application of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant dwarf plants? a. IAA b. cytokinin c. gibberellin d. abscisic acid e. ethylene

Biological clocks cause organisms to perform daily activities on a regular basis. Which of the following is a FALSE statement about this kind of “circadian rhythm”? a. It may have the same signal-transduction pathway in all organisms. b. It must be reset on a daily basis. c. It may help to cause photoperiod responses. d. It is independent of day and night length.

As flowers develop, which of the following transitions occur? a. The microspores become pollen grains. b. The ovary becomes a fruit. c. The petals are discarded. d. The ovules become seeds. e. All of these are correct.

The gametophyte is the dominant generation in which of the following plants? a. dicots b. monocots c. gymnosperms d. ferns e. mosses

Which of the following is mismatched? a. polar nuclei- plumule b. egg and sperm- zygote c. ovule- seed d. ovary- fruit

Phytochrome a. is a plant pigment. b. is present as Pfr during the day. c. activates regulatory proteins. d. all of these