1: What do scientists mean when they say a fungus is imperfect? This refers to fungi that do not fit into the common classifications due to the fact that they have not been observed to reproduce sexually and that the only form of reproduction that is known is asexual. 2: Plants are said to have an alternation of generations. What does this mean? Distinguish between the sporophyte and gametophyte. Alteration of generations refers to the process in a life cycle in which a multicellular diploid phase alternates with a multicellular haploid phase.
This cycle, is the way in which all land plants and algae perform sexual reproduction. A gametophyte is the multicellular structure that is haploid, or contains a single set of chromosomes and uses mitosis to produce male or female gametes (or both). Sporophytes develop from the fusion of male and female gametes which produce a diploid zygote developed by repeated mitotic cell divisions into a multicellular sporophyte. Due to it being the product of the fusion of two haploid gametes, its cells are diploid- containing two sets of chromosomes.
3: What adaptations have allowed plants to successfully invade land? Plants often shade one another and have evolved the ability to tolerate any light situation from direct sunlight to shade. For example photosynthesis in shade versus photosynthesis in direct sunlight, shows a lower light compensation point and saturation point. There is often a lower concentration of Rubisco and increased concentration of chlorophyll. Since cooler temperatures in shade lead to reduced rate of respiration (and this to the lowering of the light compensation point) leaves are broader and thinner.
Tolerance to sun and shade varies with shade tolerant plants showing less reduction in photosynthetic rate when moved from sunlight to shade than do shade intolerant plants Temperatures can increase water stress in plants thus producing adaptation behaviors such as closing stomata during the hottest times of day and changing the turgor pressure in order to curl leaves. Adaptations to prolonged water stress situations include sinking stomata into pits, dropping leaves at the beginning of dry seasons and covering photosynthetic areas with hairs. 1.
Describe the differences you observe between the sexual spore producing structures of the divisions Zygomycota, Ascomycota and Basidiomycota. The sexual reproductive structures of the Zygomycota are called zygospores are produced when to mating strands join which produce a thick black wall. Ascomycota reproductive structure is made up of sterile hyphae and consists of thousands of spore producing sacs giving the fungi a distinctive cup shape. Basidiomycota reproductive structure consists of small spikes that project from the end of a club and which contain four basiodospores
2. What features of the moss plant prohibit them from growing larger? A moss plant body has no roots ; instead it uses tiny cellular threads to serve as anchors. Although it has an appearance of leaves, they are actually thin sheets of cells, usually a single layer. These structures will curl up and dry out when water is unavailable and then revive once again when they obtain water. These water-absorbing cells cannot reach more than 2 centimeters into the ground.
When enough moisture is not available, the top layer of soil dries out and the mosses either die or stop growing until it rains. This prohibits growth of any larger formations. 3. The fern gametophyte is much smaller than the fern sporophyte. What prohibits the gametophyte from growing larger? The fern gametophyte is dependent on water for reproduction, thus lack of moisture who prohibit the growth of a gametophyte. 4. Most members of the Coniferophyta do not lose their leaves seasonally, they are evergreen.
What advantages and disadvantages could this have for the plant? The advantage of the evergreen is the ability to photosynthesize year round which means they do not have to expend large amounts of energy to produce new leaves all at once. \ The disadvantage to this is dry weather can tax the trees system as they do not drop leaves to help balance water loss. While the long, thin, waxy needles pines have are there to limit the water loss problem the surface area is much less than broad deciduous leaves which likely inhibits photosynthesis when conditions are good. ,Sample Essay of RushEssay.com