Chapter 10 Plants (Written Questions)
contrast a pollen grain and a seed
A pollen grain contains the male gametophyte, which is haploid. A seed contains an embryo, which is diploid. Pollen is produced by meiosis; a seed is produced by fertilization.
Explain how double fertilization occurs.
Double fertilization occurs when one sperm cell unites with the egg, forming the embryo (2n), and the other sperm cell fuses with the two polar nuclei, forming endosperm/food supply for the embryo (3n) or the triploid nucleus. The polar nuclei #3 becomes a seed coat to protect the embryo and its endosperm.
How do guard cells prevent a plant from drying out?
Guard cells regulate the size of the openings of the stomata according to the amount of water in the plant. When there is less water in tissues surrounding the guard cells, water leaves the guard cells. The guard cells become shorter and thicker, reducing the size of the pore. The smaller the pores, the less water will leave the plant.
Write a short essay explaining how the structures of roots, stems, and leaves enable them to carry out their functions.
Roots have many branches that help anchor the plant. Root branches make up a large percentage of the plant's total mass, thus providing a large surface area for the plant to absorb water and nutrients from the soil. Stems are composed of bundles of vascular tissue that help to keep the stem upright. Vascular tissue transports water, minerals, and sugars throughout the plant's body. Leaves are usually thin and flat. They have a large surface area for their mass. That large surface area aids them in gathering light, which is used in the process of photosynthesis, which takes place inside the chloroplasts found in leaf cells (and in the cells of herbaceous stems). Leaves also have stomata, which enable gas exchange to occur.
Why are protective structures, such as seed coats, made up of sclerenchyma?
Sclerenchyma is a type of ground tissue in which cells have extremely thick and rigid cell walls. This makes sclerenchyma the ideal material for a seed coat, which protects a developing embryo.
How do animals aid in the reproduction of angiosperms?
Some animals, such as bees, are attracted to flowers. They transfer male gametophytes (pollen grains) to the structures that house female gametophytes. Animals also help to disperse seeds by picking up seeds on their fur or feathers or by eating fruits and the seeds inside them and then passing the seeds out of their bodies, usually some distance from the parent plant.
How do the auxins regulate phototropism?
Stems bend toward light, because the auxins collect in the cells on the shaded side of the stem. The cells on the auxin-rich side grow longer than the cells on the other side. This causes the stem to bend toward the light.
Compare and contrast two vascular tissues - xylem and phloem - in terms of the types of cells they have, direction of flow, substance they transport, if the process requires energy or not, and what is it called.
Use 0.2.28- Plants intro Powerpoint table
Summarize the major morphological differences between monocots and dicots as the primary groups of flowering plants. Use differences in stem (vascular tissue), root, flower, leaves morphology, and number of cotyledons.
Use 0.3.04-05 Powerpoint table