Growth and Development Stages Plant

Growth and Development Stages Plant Growth activity can be measured and expressed quantitatively. In plants, growth speed can be measured using a tool called a growth arc or auxanometer. Plant growth goes through several stages. The stages of plant growth are as follows: 1. Germination Germination occurs due to the growth of the radicle (potential root) and the growth of the plumule (potential stem). Factors that influence germination are water, humidity,oxygen, and temperature.There are two types of seed germination, namely: a. Epigeal germination The hypocotyl extends so that the plumule and cotyledons reach the soil surface and the cotyledons carry out photosynthesis as long as the leaves have not yet formed.Example: germination of green beans. b. Hypogeal germination Epicotyl extends so that the plumule emerges through the seed coat and appears above the soil surface, while the cotyledons remain in the soil. Example: germination of snow peas (Pisum sativum). 2. Primary Growth This is growth that occurs due to the presence of a primary meristem. This growth is caused by the activities of the primary growing points found at the root tips and stem tips starting when the plant is still an embryo. 3. Secondary Growth This is growth that occurs due to the presence of secondary meristems. This growth is caused by the activity of the cambium which is meristematic again.The characteristics of this meristematic tissue are that it has thin walls, small vacuoles or no vacuoles, dense cytoplasm and the cells have not specialized. When growth is active, Meristem cells divide to form new cells. The new cells that are formed initially appear to be the same, but as they mature, the cells differentiate into other tissues. There are two types of meristem tissue, namely: a. Apex meristem tissue This tissue is found at the tips of roots and stems, which functions to realize primary growth. b. Lateral meristem tissue This tissue can form secondary growth. An example that we often find is the cambium, this tissue can produce lateral growth or increase the diameter of a plant part. Cambium is found in dicotyledonous plants and gymnosperms. Another example is cork cambium which is found on the stems and roots of woody plants or on parts of plants that are injured. Cambium activity is influenced by climatic conditions, so that wood cells formed in the rainy season are large, and cells formed in the dry season are small. This growth occurs in Dicotyledoneae and Gymnospermae plants. Secondary growth is caused by secondary meristem activities, which include: a. Cork cambium (phellogen) Phelogen growth produces cork tissue. Cork tissue plays a protective role, namely replacing the function of dead and peeling epidermis. It is also part of the secondary tissue called periderm. b. Fasc cambium Plays a role in forming secondary xylem towards the inside and forming secondary phloem towards the outside, apart from that it also produces living cells which are arranged in rows in the direction of the radius from the xylem to the phloem section which is called the pith radius.The xylem part is thicker than the phloem part due to activitythe cambium towards the inside is greater than the activity towards the outside. c. Interfascicular cambium Its the cambium that forms the pith radius.Monocot plants that do not have cambium grow by thickening. But in general, growth occurs due to an increase in the number and size of cells. Growth in woody dicotyledonous plants involves these two activities, small new cells produced by the cambium and apical meristem, then these cells enlarge and differentiate. 4. Terminal Growth Occurs at the tips of the roots and stem tips of actively growing seed plants. There are 3 areas (zones) of growth and development. a. Division area (meristematic area) This is the area at the very tip and is where new cells are formed. The cells in this area have relatively large nuclei, thin walls, and are actively dividing. b. Elongation area This is the area resulting from the division of meristem cells. The cells resulting from this division will increase in size so that they become part of the elongation area. The cell size increases several tens of times compared to meristematic cells. b. The differentiation area Its an area located below the elongation area. The cells in this area generally have thickened walls and some of them undergo differentiation into epidermis, cortex and pith. Other cells differentiate into parenchyma tissue, supporting tissue, and transport tissue (xylem and phloem). A. Choose the most correct answer by putting a cross (X) on the letters a, b, c, d, or e! 1. The correct definition of growth is . . . . a. increase in the number of individuals b. reversible increase in mass and volume c. irreversible increase in mass and volume d. development towards maturity level e. the ability of plants to produce reproductive organs 2. Growth that occurs due to the activity of growing points located at the root tips and stem tips is called . . . . a. primary growth b. secondary growth c. fascist cambium d. interfasc cambium e. phellogen 3. Tissue that always experiences growth so that the diameter of the plant becomes larger and is only found in dicotyledonous plants, is called tissue. . . . a. cortex b. endodermis c. cambium d. stele e. pith 4. The maturity that rice plants have experienced can be determined by . . . . a. emergence of flowers b. the size of the plant gets bigger c. emergence of branch roots d. the stem is woody e. stems get bigger 5. An auxanometer is a useful tool for . . . . a. find out the amount of auxin produced byplant b. knowing the direction of distribution of auxin in plants c. determine the speed of fruit ripening d. determine the speed of plant growth e. measure the rate of respiration in plants 6. Monocot plants grow by thickening because. . . . a. have wide intercellular spaces b. the transport network is complete and numerous c. does not have cambium d. has a fibrous root system e. the cells always divide thickly 7. In dicotyledonous plants, the role for growth in stem diameter is . . . . a. xylem b. phloem c. epidermis d. cambium e. parenchyma 8. The cambium grows inwards to form . . . . a. xylem b. phloem c. epidermis d. cambium e. parenchyma 9. The cambium grows outward to form . . . . a. xylem b. phloem c. epidermis d. cambium e. parenchyma 10. In growth and development occur successively. . . . a. cell division, cell elongation, and cell differentiation b. cell differentiation, cell elongation, and cell division c. cell division, cell differentiation, and cell elongation d. cell elongation, cell division, and cell elongation e. cell differentiation, cell division, and cell elongation