Consider a plant that grows best in bright sunlight in which seed germination is controlled by phytochromes. Which of the follow
ing statements describe(s) the structure and function of phytochromes in this plant? a. When a phytochrome in the Pfr configuration absorbs far-red light, the phytochrome reverts to the Pr configuration. b. Far-red light stimulates the plant seeds to germinate when the phytochrome is in the Pfr configuration. c. The plant seeds are more likely to germinate after exposure to red light than after exposure to far-red light. d. The effects of red and far-red light on phytochromes are irreversible. e. Phytochromes absorb red light and far-red light equally when the phytochrome is in the Pfr configuration. f. Phytochromes absorb red light maximally when the phytochrome is in the Pr configuration. g. Phytochromes contain photoreceptors.
The answer is c) The plant seeds are more likely to germinate after exposure to red light than after exposure to far-red light
Explanation:
Phytochromes are involved in the biological cycle of the plant, from germination to flowering and tubing. The red light (660 nm) activates the phytochrome, while the ultra-red or far red light (730 nm) inactivates it. In both positive photoblastic seeds (response of the seeds to light) and in the negative photoblastic seeds the red light stimulates germination, while the distant red light inhibits it.
Angiosperms are the most advanced and beneficial group of plants. They can grow in various habitats as trees, herbs, shrubs, and bushes. The angiosperms originated about 250 million years ago and comprise 80% of the earth. They are a major source of food for humans and animals.
