Question

Draw a labelled plant cell diagram. explain any 3 parts of it.
I will Mark as brainlist....​

Answer 1

Answer:

Plant cell: Cells are comparatively larger in size. The cell wall is present. Plastids are present. Vacuoles- generally only one, large vacuole present. Dictyosomes (sub-units of Golgi body) are present. Lysosomes – either absent or very few in number. Centrosome and centrioles are absent; instead, polar caps are present. Structure and functions: 1. Chloroplast: A chloroplast is bounded by two membranes. The inside of chloroplast is clearly marked into a colourless ground matrix, called stroma, and a membranous system called grana (singular-granum). Each granum consists of a stack of membrane-bounded, flattened sacs called thylakoids. Thylakoids contain molecules of green chlorophyll and yellow-orange carotenoid pigments, which take part in trapping solar energy. Stroma contains enzymes (for dark reactions of photosynthesis in chloroplast), DNA, RNA and ribosomes. The latter makes the chloroplasts semiautonomous. Like mitochondria, they can also synthesise some of their own proteins and duplicate themselves. The function of Chloroplast: Chloroplast carries out photosynthesis in plants and synthesises food, by trapping solar energy. So, they are called kitchen of the cell.

2. Endoplasmic reticulum (ER): It consists of an irregular network of channels, which are membrane-bounded and are interconnected with each other. They are seen with the help of an electron microscope only. If ribosomes are seen attached to their surface, then they are called Rough Endoplasmic Reticulum (RER). If ribosomes are not present on ER, they are called Smooth Endoplasmic Reticulum (SER). It performs the following important functions: 1. The endoplasmic reticulum acts as secretory’, storage, circulatory and nervous system of the cell. 2. ER provide channels for quick transport of materials. 3. It provides an ultrastructural skeletal framework of the cell. 4. It provides a surface for attachment of ribosomes. 5. It provides materials, lipids and proteins for biogenesis of membranes. The function of the smooth endoplasmic reticulum is as follows: 1. Formation of visual pigment from Vitamin A in retinal cells. 2. Synthesis of fats inside the cells of adipose tissue. 3. Detoxification of drugs and poison. 4. Synthesis of steroids and hormones. 3. Mitochondria: Structure: 1. Mitochondria are small spherical or rod-shaped, organelles. It is like a bag, whose wall is made up of two membranes. The outer membrane is covered with particles. The inner membrane is thrown into finger-like folds, which project into interspace called matrix. Many respiratory enzymes are present in the matrix and the inner surface of the inner membrane.

2. Function: Mitochondria is the site for respiration of the cell. Enzymes control and regulate the release of energy during oxidation of food molecules in respiration. The chemical energy of food molecules is converted in the form of energy, that can be used by the cell to carry out its various activities. That is why mitochondria are called the “powerhouse” of a cell. 4. Nucleus: Robert Brown in 1831 discovered the nucleus in the cell. Structure: The nucleus is of large size, more dense, spherical or oval and prominent organelle of the cell. The structure of the nucleus can be divided into three parts. 1. Nuclear membrane: Nucleus is enclosed by a double-layered nuclear membrane. In bacteria and blue-green algae, the nuclear membrane is not found. 2. Nucleoplasm: In nucleus is present a thick jelly-like semi-fluid the nucleoplasm. In it, are observed a network of fine thread-like structures, called chromatin network. At the time of cell division, the chromatin takes the form of a thread like structures called chromosomes. The number of chromosomes is fixed for every species of animals and plants. The man has 23 pairs of chromosomes. Wheat has 21 pairs of chromosomes. The two partners of chromosomes pair are called homologous chromosomes.

3. Chromosomes: Chromosomes are composed of specific proteins and a nucleic acid called Deoxy-ribose, Nucleic Acid (DNA). Genes are segments of DNA. Genes control and carry the hereditary characters. 4. Nucleolus: Nucleolus contains RNA, commonly there is a single nucleolus, but two or more may be present. The nucleolus is the seat for the synthesis of cytoplasmic ribosomes. During cell division, nucleolus disappears in early stages and reappears on the same location in the daughter nuclei. The functions of the nucleus are as follows: (i) The nucleus controls the activities of the cell through its DNA molecules. (ii) The main function of the nuclear reticulum is participation in cell-division. (iii) Genes are located in a linear fashion, in chromosomes. The genes are composed of DNA. Genes control and carry the hereditary characters from one generation to another generation. (iv) Nucleolus assists in protein synthesis. Formation of ribosomes takes place in the nucleolus.