Module 15 Study Guide 1. Write the definitions for the following terms. Term Definition Physiology The study of life processes in an organism Nastic movement A plant’s response to stimuli that is preprogrammed and not dependent on the stimulus’s direction Pore spaces Spaces in soil that determine how much water and air it can hold Loam A mixture of gravel, sand, silt, clay, and organic matter Cohesion When individual molecules are so strongly attracted to each other that they stick together Translocation The process of organic substances moving through phloem Hormones Chemicals in multicellular organisms that regulate cellular processes and interact with specific cells Phototropism A plant’s growth response to light Gravitotropism Growth response to gravity Thigmotropism Growth response to touch Perfect flowers Flowers with both stamens and carpels Imperfect flowers Flowers with either stamens or carpels Pollination Process of transfer of pollen grains to carpels Double fertilization Fertilization that requires two sperm to fuse with two other cells Seed A mature plant embryo and its nutrient source encased in an ovule with a protective coating Fruit Mature ovary with seed(s) 2. Name the four processes for which plants require water. Which of these processes can be neglected for a short amount of time? Plants require water for photosynthesis, hydrolysis, turgor pressure, and transport. Turgor pressure can be neglected for a short amount of time. 3. A biologist studies two plants. The flowers of the first plant open each morning and close each night. The second plant’s flowers stay open all of the time. However, if the plant is placed so that one of its sides is in the shade and the other is in the sunlight, the plant will eventually grow so that all of its leaves point towards the sunlight. Which plant is using nastic movement and which is using phototropism? 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. The first plant is using nastic movement, since its movements are preprogrammed and do not depend on the direction of the stimuli. The second plant is using phototropism, since its movement depends on where the light is. Briefly describe the cohesion-tension theory of water transport in plants. The cohesion-tension theory explains how water travels up the plant. When water evaporates through the leaves’ stomata, a deficit of water is created. The water molecules underneath the deficit move up to take their place. Because of cohesion, though, the other water molecules underneath them move up as well. The result is a chain reaction, with all of the water moving up. Do xylem cells need to be alive in order for xylem to do their job? Why or why not? No, xylem cells do not need to be alive in order to do their job. Since the cohesion-tension theory should explain how water travels up a plant, the xylem cells do not have to actively play a role in its transport. Do phloem cells need to be alive in order for phloem to do their job? Why or why not? Yes, phloem cells need to be alive to do their job. They actively direct materials through the plant. What substances do xylem contain? What substances do phloem contain? Xylem contain water and dissolved minerals, and phloem contain sugar and organic materials. Do insectivorous plants really eat insects? Why or why not? Insectivorous plants do not really eat insects. They only digest the insects they catch to use for certain nutrients that they can’t get from the soil. From a genetic point of view, what is the difference between vegetative reproduction and sexual reproduction in plants? Vegetative reproduction leads to genetically identical offspring, but sexual reproduction does not. A gardener says that one limb of his crabapple tree now produces normal-sized apples. What must the gardener have done to make this happen? The gardener must have grafted the limb to his crabapple tree to produce normal-sized apples, because grafting does not mix genetic information. What is the male reproductive organ of a flower? What is the female reproductive organ? The male reproductive organ in a flower is the stamen, and the female reproductive organ is the carpel/pistil. Why are the pollen grains and embryo sacs of flowers sometimes considered the gametophyte generation in an alternation of generations life cycle? The pollen grains and embryo sacs of flowers reproduce using gametes, and they are multicellular. What two types of cells are found in a pollen grain? A pollen grain will have a tube nucleus and at least one sperm cell. Typically, how many cells are in an embryo sac? How many of them get fertilized? Typically, there are seven cells in an embryo sac, but only two are fertilized. What is the difference between pollination and fertilization? Pollination is the transfer of pollen to a stigma, and fertilization is when the sperms fuse with an egg and the large central nucleus in the embryo sac. How many sperm cells are used in plant fertilization? Two sperm cells are used in the fertilization of a plant. Where does the endosperm come from? What is its purpose? 18. 19. 20. 21. 22. The endosperm is created when one of the sperm cells fuses with the large central nucleus in the embryo sac. Its purpose is to act as a source of food for the embryo that develops. The cotyledon or cotyledons help provide food for the plant before and after germination. How do cotyledons accomplish each task? Before germination, the cotyledon(s) either absorb the endosperm or help the embryo absorb nutrients from it. After germination, they sometimes perform the plant’s first photosynthesis. Name the three basic parts of the plant embryo and what each gives rise to in germination. The three basic parts of the plant embryo are the radicle, hypocotyl, and epicotyl. The radicle becomes the plant’s roots, the hypocotyl becomes the plant’s stem, and the epicotyl becomes the plant’s leaves. What is the purpose of a fruit? The purpose of a fruit is to take the seeds away from the parent plant, so that they do not have to compete for resources. Name at least three ways in which pollen is transferred from the stamens of one flower to the carpel of another. Pollen can be transferred from the stamens to the carpels by wind, bees, and birds. Why are cotyledons sometimes called “seed leaves”? Cotyledons are sometimes called “seed leaves” because they form leaflike structures when the seedling first rises out of the ground, and they often perform the plant’s first photosynthesis.
