Concept explainers
Introduction:
Phototropism is a mechanism that is mostly seen in the plants. In this mechanism, the plant responds to the light stimulus.
Answer to Problem 1TYK
Correct answer:
Phototropism is the growth of an organism toward a light source (positive phototropism) or away from a light source (negative phototropism). In phototropism, the cells located on the shaded side of a stem elongate more than cells on the illuminated side of a stem.
Explanation of Solution
Explanation/Justification for the correct answer:
Option (c) is given that cells on the shaded side of a stem elongate more than the cells on the illuminated side of a stem during phototropism. The plant tip cells when exposed to light source sense light and release a chemical known as auxin. This results in the process of phototropism. It leads to the elongation of the cells that are far from the light. The shoot bends toward light and cells present in the shaded region of the stem elongate more. Hence, Option (c) is correct.
Explanation for incorrect answers:
Option (a) is given that cells on the illuminated side of a stem elongate more than the cells on the shaded side in phototropism. The cells present on the illuminated side, that is, those cells that are receiving the light, do not extend more. Actually, the cells that are present in the shaded region and are far from the light elongate more than those on the illuminated side due to the chemical auxin released by the cells, which causes phototropism. So, it is a wrong answer.
Option (b) is given that phototropism is triggered by red/far-red light. The bending of the plant occurs only toward the light that includes blue wavelength. Plants have a phototropic response when the blue wavelength is available, which falls in the visible range. Therefore, it is not necessary that phototropism is triggered due to the red or far-red light. So, it is a wrong answer.
Option (d) is given that phototropism is triggered by phytochrome. Phototropism is triggered by a chemical named auxin. This chemical is produced by the cells that are present in the shaded region of the stem, thereby inducing phototropism. So, it is a wrong answer.
Hence, options (a), (b), and (d) are incorrect.
Phototropism refers to the orientation of the plant in response to the light. Cells that are present on the shaded side of the stem extend more than cells that are present on the illuminated side of the stem.
Want to see more full solutions like this?
Chapter 37 Solutions
BIOLOGICAL SCIENCE VOL. 2 >IC<
- Which of the following statements is false? a. Auxin and gibberellin promote stem elongation b. Cytokinin promotes cell division in shoot tips c. Abscisic acid promotes water loss and dormancy d. Ethylene promotes fruit ripening and abscission.arrow_forwardPhytochrome is a plant pigment protein that: a. mediates plant infection b. promotes plant growth c. mediates morphological changes in response to red and far-red light d. inhibits plant growtharrow_forwardStems and roots, respectively, exhibit a. a positive phototropic response and no phototropic response. b. a negative phototropic response and no phototropic response. c. no phototropic response and a positive phototropic response. d. no phototropic response and a negative phototropic response.arrow_forward
- A plant lacking the WOODEN LEG gene will likely a. be incapable of transporting water to its leaves. b. lack xylem and phloem. c. be incapable of transporting photosynthate. d. All of the choices are correct.arrow_forwardStomata (a) help prevent desiccation of plant tissues (b) transport water and minerals through plant tissues (c) allow gas exchange for photosynthesis (d) strengthen cell walls (e) produce male gametesarrow_forwardWhich of the following statements is/are FALSE for CAM plants? a.The dark reaction uses less ATP and NADPH than other plants. b.Succulents and tropical plants growing under semi-arid condition. c.C4 pathway occurs at night and C3 pathway occurs at daytime. d.Scotoactive stomata are open during daytime but close at nighttime.arrow_forward
- If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering? (A) 16 hours light/8 hours dark (B) 14 hours light/10 hours dark (C) 4 hours light/8 hours dark/4 hours light/8 hours dark (D) 8 hours light/8 hours dark/light flash/8 hours darkarrow_forwardTo which of the two lighting conditions would you expose seedlings if you wanted to maximize the rate of photosynthesis in the plants as well as minimizing your costs for electricity to light the plants in the greenhouse? A. Low light only. B. Moderate light only. C. Low light for the first 12 hours and then moderate light afterwards. D. Moderate light for the first 12 hours and then low light afterwards.arrow_forwardTranslocation mainly involves the movement of products from the leaves where they are synthesized, to other plant parts like the roots, where photosynthesis does not occur. Which of the following cells make up the tissue that is involved in the process of translocation? * A. companion cells B. vessels C. tracheids D. sieve tubesarrow_forward
- Which of the following adaptations allows plants to pause their life cycle until environmental conditions are optimal? a. Stomata b. Phloem and xylem c. Seeds d. Flowersarrow_forwardChoose the incorrect statement: a. Fusiform and ray initials are formed by the vascular cambium. b. The cork cambium produces the periderm layer, a thicker tougher outer layer that replaces the epidermis. c. Wood is composed of secondary xylem. d. The vascular cambium separates the xylem on the outside of the stem and the phloem on the inside.arrow_forwardwhich of the following best describes the seeds of dicots? a. the seeds produce only one cotyledon with no endosperm b. the seeds contain two cotyledons with endosperm c. the seeds contain two cotyledon and very little endosperm d. an example is bean e. c and darrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning