Although Bryophytes and Pterophytes are both plant divisions with a common ancestor, they have little in common. While Bryophytes (mosses) are generally nonvascular and very short in height, Pterophytes (ferns) are vascular plants that usually grow much taller than mosses. While the dominant generation in mosses is the gametophyte, ferns exhibit the sporophyte generation. The details of their alternations of generation vary as well, although both have diploid and haploid stages. Alteration of generations is defined as a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte.
Meiosis in mosses produces haploid spores. This process occurs in a sporangium, a capsule in fungi and plants in which meiosis takes place and haploid spores develop. After fertilization, the sporophyte zygote grows out of the parent gametophyte. At the end of this stalk is the sporangium. Meiosis occurs and the haploid spores disperse. In ferns, the mature sporophyte (2N) has small spots on the undersides of its leaves. These are clusters of the Pterophyte sporangia, called sori. As in mosses, meiosis occurs in the sporangia, which then release spores, continuing the cycle.
Mitosis in Bryophytes begins germination, or growth. It directly follows meiosis. As mitotic division continues, protonemata (1N) are formed. They grow until they are mature gametophytes. In Pterophytes, mitosis occurs directly after fertilization. The zygote divides and grows until it peeks out of the parent gametophyte, then it matures until it can release its own spores.
Mosses exhibit the embryophyte condition, which means their gametes develop with protective sheaths of cells. This was an adaptation that allowed plants to become hardier. Mosses have two sexes of gametangia; the male gametangium is called an antheridium, and the female is called an archegonium. Eggs are produced in the archegonium and sperm in the antheridium. In order for fertilization to take place, the sperm must swim through moisture to the archegonium. This is why mosses must live in damp environments to survive- they cannot reproduce without moisture. The zygote develops within the archegonial cavity. Ferns are usually homosporous as well (there is a single type of spore; the gametophyte is bisexual). In ferns, the archegonia and antheridia mature at different times, which means there is cross fertilization between gametophytes and thus more genetic variation. Sperm from the antheridia swim to the archegonia where the zygote develops. Like mosses, ferns also need a moist environment for fertilization to occur.
Results obtained in lab as well as scientific research prove that as temperatures increase the percent of crossing over increases as well. Introduction: Sordaria fimicola belongs to the kingdom of fungi and is part of the phylum Ascosmycota. This fungus habitat is in the feces of herbivores. As many fungi, Sordaria have one life cycle which is haploid/ diploid. It is commonly exited as a haploid organism, but when the mycelium of two individuals meets, the result is a diploid zygote.
Sordaria fimicola is a species of microscopic fungus that is an Ascomycete and are used to test for genetic variation in the lab setting (Sordaria fimicola: A Fungus used in Genetics, Volk). These organisms are what are called model organisms, or species that has been widely studied usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages (Sordaria fimicola, Volk). S. fimicola, because it is in the Ascomycota phylum, have a distinguishing reproductive structure called the ascus, which is surrounded by the perithecium. This cylindrical sac-like structure houses 8 haploid spores; created through meiosis to produce 4 haploid spores and then mitosis to make 8 (Lab Manual, pg. 59-68). Based on the genotype they will vary in order and color. There are 3 different ratios that can arise from the 8 ascospores: 4:4, 2:2:2:2, and 2:4:2 (black/wild type and tan coloration). The 4:4 ratio suggests that no crossing over had occurred because there is no difference in order of the color parents that were mated. The two other ratios suggest genetic recombination, or crossing over, because of the
11.2) Asexual reproduction involves a single individual / parent who pass duplicates of all its genes to its offspring without the fusion of gametes. Sexual reproduction involves two parents who give rise to offspring that have unique combination of genes inherited from the two parents.
The gametophytes used in this experiment are of C-ferns. They tend to mature and produce spores at temperature of 28oC and conditions of high humidity. The spores that germinate first are hermaphrodites. Hermaphrodites tend to produce a pheromone called antheridiogen. It is this pheromone that causes later germinating spores to become male.
Nettie studied Tenebrio molitor beetles and found that unfertilized eggs in female beetles always contain an X chromosome. Sperm from male beetles contain either an X chromosome or a Y chromosome. She found that eggs fertilized by sperm carrying the X chromosome produce female beetles. The combination of egg and Y-chromosome sperm produce male beetles.
As a result of these factors, the flora has adapted to these conditions in a variety of ways including their shape, leaf type, root system, and color. One of the most prominent adapt...
chromosome is called a haploid cell. Meioses produces haploid daughter. cells that are genetically different from each other and from the parent cell. However, mitosis is a form of cell division that produces. daughter cells identical to the parent during repair or growth.
The process of mitosis can take place in either a haploid (23 chromosomes) or a diploid (46 chromosomes) cell. Before a cell can be ready for a mitotic division it must primarily undergo its interphase stage. Following the interphase stage several other stages come into play. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During each specific stage certain sequences of events take place that assist to the completion of the division.
This gave rise to nonvascular plants like, mosses, liverworts, and hornworts. The second period of plant evolution began 425 million years ago was the diversification of plants with vascular tissue allowing plants to grow much taller and rise above the ground. The next period of plant evolution is the origin of seeds, about 360 million years ago. Seeds are embryos packed along with food in a protective covering. Last is flowering plants about 140 million years ago, which is seeds within protective chambers called ovaries. Animal evolution begins when an animals egg and sperm fuse, producing a zygote. The zygote splits by mitosis and forms an blastula, which usually is a hollow ball of cells. One side of the blastula folds in forming a gastrula, which develops into an embryo with a two-layered wall and an opening on one end. After the gastrula stage animals develop into
Meiosis is a special type of cell division that occurs during formation of sperm and egg cells and gives them the correct number of chromosomes. Since a sperm and egg unite during fertilization, each must have only half the number of chromosomes other body cells have. Otherwise, the fertilized cell would have too many.
The differences between the two phases of meiosis are that in meiosis I, while the cell undergoes the phases, prophase I, metaphase I, anaphase I, and telophase I, it causes the cell to divide into two with each of the cells having a double stranded chromosome. But in meiosis II, it is just the division of the the cells from meiosis I. The ending result being that four haploid daughter
In the lab exercise regarding plant structure and function, we examined slides containing the different kinds of roots (monocot, dicot). We labeled the parts and pointed out the different roles of each in the plant structure. Also, we examined monocot stems and dicot stems in order to familiarize ourselves with its external and internal structures. We sketched and labeled the parts of the stem and looked closely at the positions of each part. In the last part of the lab, we classified leaves into different kinds according to their leaf venation, bases of leaves, and apices of leaves. As an additional exercise, we sketched 20 animals and classified them according to phylum and class. We were also able to discover the scientific and common names of the animals. Overall, the exercises we did enabled us to familiarize ourselves with plant structure thus, gaining a better understanding for plant life and its importance.
For many years, nature has cloned organisms. When a plant sends out a stalk and it takes root, the new ...
The process itself is longer than fertilization, timing over 3 to 4 days approximately. The zygote is now a blastocyst. This too will float around for about one or two days. The embryonic disk will form when the blastocyst sticks to one side o...
Asexual propagation is the process through which reproduction without passage through the seed cycle occurs. The advantages of asexual propagation are that it preserves genetic makeup, propagates seedless plants, disease control, rapid production, the plants are identical, cheaper, faster and easier reducing or avoiding juvenility. The disadvantages of asexual propagation are that it increases disease and insect susceptibility, plants are bulky, and the mother plants could become contaminated. The goal of this experiment was to determine the development of adventitious roots and shoots, and observe these plants over a period of five weeks. Due to auxin being produced in the tip, tip cuttings should root faster than any other cuttings. Auxin is a plant hormone that is responsible for cell elongation and enlargement, root formation, and growth. There are two forms of auxins; phototropism, which is produced in the tip and moves downward on the side away from the light and gravitropism, which is where plant roots grow downward and plant shoots grow upward.(Plant Auxin 201...