Describe the process of mitosis and meiosis.
2 answers:
The process of dividing the pre-existing cell into two or more daughter cells is called cell division.
Mitosis
Mitosis is defined as the division of the cell in which a single cell divides to form two daughter cells, having the equal number of chromosomes as present in the mother cell. In mitosis cell division, chromosomes duplicate and equally distribute into two diploid cells. Thus as a result, all the daughter cells come to have the same number of chromosomes compared to the mother cell. It occurs in somatic or vegetative cells.
Meiosis
Meiosis is a types of cell division in which a mother cell divides into four daughter cells and each daughter cell having only the half number of chromosomes as compared to mother cell. Meiosis cell division comprises two divisions: Meiosis I and Meiosis II
The meiosis I division is also known as reduction division. This is because it involves the formation of two daughter nuclei with just half number of chromosomes as that present in the another cell. more over, in the prophase stage of meiosis, crossing over ( interchange of chromosome segments between two homologous chromosomes) takes place. This causes the variation in the off-spring and gas a role in evolution.
The meiosis II is also called equational division because the number of chromosomes remains the same in the daughter nuclei as after meiosis I. In this way, four daughter haploid nuclei formed. Then the divison of cytoplasm of the cell ( cytokinesis) takes place and all nuclei get their own cytoplasm and form four haploids.
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Angiosperms belong to the plant kingdom. Flowers are the organs needed for sexual reproduction, carrying feminine and masculine structures.
<h3>What are the parts of the flowers?</h3>Flowers are reproductive structures in charge of sexual reproduction through the production of seeds.
⇒ Feminine reproductive structures
- The central structure is the carpel, also recognized as the pistil.
- The base of the carpel forms the ovary, in which the eggs are produced and where the zygote develops.
- The opposite extreme of the carpel is the stigma, in the superior part.
- The stigma is a sticky surface where the pollen grains get attached.
- The style is the filament structure that connects the ovary and the stigma.
⇒ Masculine reproductive structures
- The pollen grains, or male sex cells, are produced in the stamens.
- The stamen has an anther where the pollen is produced, and a filament that provides support.
⇒ External non-reproductive structures
Flowers also have external structures known as petals and sepals. These are modified leaves whose principal function is to protect the flower's fertile parts and attract pollinators.
Petals characterize as having many different colors that make the flower more attractive to insects and other animals. When they visit a flower searching for their recompense, the flower's pollen grains transfer to the insect's body.
The insect transports the pollen to the next visited flower, leaving it in the stigma of the second flower.
<h3>What happens during the fertilization process?</h3>1) The mature pollen grains are driven to the stigma of the same flower or other flowers of the species, where they stick.
2) Once in the stigma, the pollen grain germinates.
3) A pollinic tube forms. It goes from the stigma along the style and ends in the flower ovary.
4) The pollen grains move along the tube forward to the ovary.
5) Once in the ovary, the pollen grains get in touch with the ovule. They have double fertilization.
6) The zygote develops in the ovary.
Now, let us answer the questions,
1) Flower Dissection ⇒ you will find and scheeme in the attached files
2) Characteristics of the plant kingdom
- eukaryotic multicellular organisms,
- photosynthetic organisms,
- cells with chloroplasts, a big vacuole, and cell wall.
- sexual and asexual reproduction
3) Stomata regulate water vapor flow through transpiration.
Desert plants have fewer stomata than tropical plants as an adaptation to avoid losing water.
4) Having fewer stomata help protect the health of a plant by preventing excessive water loss under extreme conditions.
5) The vascular system of plants is composed of
- The xylem ⇒ takes water and nutrients from the soil to the aerial part of the plant.
- The phloem ⇒ transports photosynthetic products to different tissues of the plant.
If the xylem gets damaged, the plant will not be able to take water and nutrients from the ground. If the phloem gets damaged, the plant will not be able to use photosynthetic products in different tissues. In any case, the plant will dye.
6) Because plants and human dermal tissues vary in the number of layers and functions.
- Plants have one dermal layer and have a cuticle to avoid dehydration and provide protection.
- Human skin is multilayered and the immune system protects it.
7) Ground tissues are not meristematic, dermal, or vascular tissues. However, among their functions, we can mention photosynthesis, storage, regeneration, and healing capability. All of them are necessary to survive. If the ground tissues are damaged, the plant can not survive.
8) Flowering plants can reproduce sexually or asexually. During sexual reproduction, pollen grains fertilize the eggs in the ovary.
9) During pollination, insects and other animals get a recompense -nectar-. Flowers provide a source of food and prime matter to different pollinator agents. Also, flowers might be a shelter for many species.
10) The stamen where the pollen is produced. The ovary is where eggs are produced and where the zygote develops. Pollen gets to the egg in the ovary and fertilizes it (description above).
11)
The embryo is formed after the double fecundation. It composes of growing cotyledons, an epicotyl, and a hypocotyl.
The tegument and endosperm of the seed protect the embryo from dehydration and denutrition.
Germination is the process of development and the emergence of the embryo. These are a series of steps that must occur in the seed from the moment the embryo begins to develop until a newly emerged plantule is formed. For germination to occur, there must be appropriate environmental conditions.
12) Flowers are bright and colored because this is how they attract pollinator agents such and insects and other animals.
You can learn more about flowers and sexual reproduction at
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