B. Metagenesis
B. Metagenesis
The physical change of generations, of ferns, or metagenesis is quite a unique phenomenon. There are two different phases in one life cycle of organisms which experience metagenesis. In one phase, spores are produced. In the other phase, sexual cells or gametes are produced. The spore-producing phase is called the sporophyte phase, and the gamete-producing phase is called the gametophyte phase. The spores produced have a 2n or diploid chromosome composition and the gametes produced have an n or haploid chromosome composition.
When you observe ferns, you will see that there are groups of sporangia on the lower surface of the leaves (See Figure 1.8.). It means that the plant is in the sporophyte stage. The fern plants you are observing are members of a sporophyte generation. If the spores in the sporangia fall on a moist place, each will grow and be flatten into a heart-shaped structure called prothallium. it will produce male and female gametes.
In one lifecycle an alternation occurs sbetween the sporophyte stage, in which spores with diploid chromosomes are produced, and the gametophyte stage, in which gametes with haploid chromosomes are produced. The alternation of the two stages is known as the alternation of generations or metagenesis.
The growth areas of plants
Different species of plants grow differently. Some species grow into short plants with soft stems. They live for only a few weeks or a few months. Some other species grow tall and large, have wooden trunks, and live for years. What part of the plants controls their growth?
How do plants become longer? Observe the stem of a plant in Figure 1.11. On the stem you see two types of buds. At the tip there is a terminal bud, which is also known as an apical meristem. It determines the increase of plant length. Along the stem there are lateral buds, which are also known as side buds or axillary buds. They can finally grow into branches, leaves, or flowers. Buds are the start of new growth and the points where they appear are nodes of growth. Some plant species have stems that keep becoming larger. In fact, some large stems like those found in wooden trees ( teak trees, and some forest trees) are even 1 to 2 meters in diameter. Why do they become so large? Stem enlargement is determined by the presence of a cambium. The cambium is located between the xylem and phloem and its function is to form new xylem and phloem .
Figure illustrates the increasing size of the diameter of the stern stem. It is because the quantity of xylem and phloem increases in the same direction. It means that the cambium keeps producing new xylem and phloem. The stem tip is protected by epidermis on the outside. In any enlarged part of the stem the epidermis become damaged due to the newly produced phloem. To replace it, a new protection is formed in the shape of cork tissues Why new xylem and phloem arae continously produced? Do you know their function? They are vascular tissues for transport. Xylem transports water and mineral solutions from the roots to the sleaves. Phloem transports photosynthesis products from leaves to all plant organs. Because their function is important, these tissues are continuously produced. The larger the size of the stem, the more xylem and phloem there are. Besides the stem, the roots’ also grow longer penetrate the soil. Where are the zones that determine root growth? To answer this question.
A. Growth and Development of Organisms
A.Growth and Development of Organisms
Growth is an increase in size of an organism. It is a quantitatively measurable change. For example, leaves increase in length and width. It means that the length and width of leaves can be measured in centimeters or meters. We can say that they grow.Another change observable in the previous observation was the change of a seed that sprouted into a seedling. Such a change belongs to both growth and development.
B. Metagenesis More
What kind of changes happen to animals during their life? Compare the changes that happen to a chicken and a butterfly. Both animals change differently as they grow. Which animal appears to change more? Have you ever observed the changes that happen to a corn seed as it grows? If you compare the germinating phase and the maturing phase that follows, which phase shows more growth, or which phase changes more? . Every organism experiences changes during its life. The changes include changes in size, a small one becoming larger, a short one becoming longer, a light one becoming heavier, and so on.
Growth is an increase in size of an organism. It is a quantitatively measurable change. For example, leaves increase in length and width. It means that the length and width of leaves can be measured in centimeters or meters. We can say that they grow.Another change observable in the previous observation was the change of a seed that sprouted into a seedling. Such a change belongs to both growth and development.
An example of development is the change that happens to an adult hen. When it reaches its reproductive phase, it has the capacity to lay eggs. There is no increase in its physical size but there is an important change in the hen’s life: its reproductive capacity. In the developmental process, the change that happens is called a qualitative change, which cannot be measured. When an egg is about to hatch, there is no increase in its size but there is an important process of development: the egg hatches. See also Figure showing a newly-born butterfly coming out of its cocoon.
Some Factors that Influence Growth and Development
Growth and development of living thing are influenced by various factors, booth external and internal. Factor are from inside the body of the organism and from the environments.
The internal factors are coming from inside the body. There are determined by genes. The work of genes is seen in the work of hormones and enzymes. A hormone, auxin, for example increases the number and the size of the cells of a tree trunk. It causes the tree grow taller and bigger. An enzyme for example, digestive enzymes in mammals enable food to be digested and a bsorbed by the body. The absorbed food is used to compose new cells to grow and develop.
Environmental factors are related to anything in the environment such as air, water, soil, and sunlight. The sunlight plays an important role in the growth and development of plants. It affects quantity of chlorophyll, formation of young plants, period of fruition, and the ability to form and store food.
The organisms consist mostly of water. Water is a solvent, or a substance that dissolves various other substances. All nutrients can be utilized by the body of organisms because they dissolve in water. Similarly, all substances that must be disposed from the body must also be soluble, or able to dissolve, in water.
Growth of animals
Animals are performing growth during their life cycle. Their life cycle starts from their birth, and then continues to grow, mature, produce and die.
Animals need food for their growth. Food gives them with energy to grow. But there are animals that do not move, for example, corrals that cling to rocks for the rest of their life.
Based on their food, animals can be classified into three groups, namely herbivorous, carnivorous, and omnivorous. Animals’ foods normally consist of organic materials.
Below are some examples of animals’ growth and development processes.
Metamorphosis
Metamorphosis
Some animals such as butterflies and frogs undergo metamorphosis phases of different appearances. Figure 1.4 illustrates the metamorphosis phases of a frog.
A frog starts its life cycle as a zygote from a fertilized egg. The egg then hatches and a tadpole comes out. A tadpole is able to swim to find food. It continues to grow and then change shapes. The growth starts with limbs (or legs), lungs, and teeth that grow inside the mouth. Changes that will support the tadpole’s life on land begin at this time.
What happens to the tail of a tadpole? After its limbs grow, the tadpole does not need a tail to move about. Does the tail come off the body? It does not. It becomes smaller and smaller so that it gradually merges withs the body of the young frog. After a few months the body of the young frog has completed its metamorphosis process. Metamorphosis is the change of an organism in one life cycle. When the metamorphosis is completed, the animal gains its adult shape. The pattern of change is complete and the cycle may occur in any new individual
of the species.
Butterflies are actually adult forms of organisms that have experienced a complete metamorphosis through the phases of being a larva, a pupa, and an imago (adult individuals) At a given moment a larva becomes inactive and it is called a pupa. In this phase pupa has a coccoon. The pupa changes into an adult butterfly in a completely different shape. It does not look like a caterpillar anymore.
of the species.
Butterflies are actually adult forms of organisms that have experienced a complete metamorphosis through the phases of being a larva, a pupa, and an imago (adult individuals) At a given moment a larva becomes inactive and it is called a pupa. In this phase pupa has a coccoon. The pupa changes into an adult butterfly in a completely different shape. It does not look like a caterpillar anymore.
Grasshoppers have different types of a metamorphosis . Their metamorphosis is incomplete and it involves three phases, namely egg, nymph, and adult.
Nymph are smaller than that of an adult grasshoppers but it has no wings . But on the whole they have the shape as adult grasshoppers . Gradually the wings and a system of reproduction keep growing until they are fully ready to continue their life cycle. They mate and reproduce young grasshoppers of their own. Another animal that has an incomplete metamorphosis is a mosquito .
Some organisms can resist extinction because they reproduce and can adapt well. Various changes may occur during the process of producing a new generation. An alternating succession from one generation to another generation many change physically different characteristics occurs in some organisms. This process is called metagenesis.
LESSON PLAN 1
Unit : Junior High School 1 Batu
Grade/Semester : VIII / 1
Subject : Biology
Topic : Growth and development
Time allocation : 8 x 40 minutes
A. Standard of Competence:
1. To understand the various systems in human body.
B. Basic Competence:
1.1. To analyze the importance of growth and development of organism
C. Indicators to achieve the competence:
1. To distinguish between growth and development.
2. To explain the growth and development of plants.
3. To mention the factors that influence growth and development.
4. To mention the phases of growth and development in animal.
5. To compare metamorphosis between meta-genesis.
D. Objectives Learning
The students are able to:
1. Distinguish between growth and development.
2. Explain the growth and development of plants.
3. Mention the factors that influence growth and development.
4. Mention the phases of growth and development in animal.
5. Compare metamorphosis between meta-genesis.
E. Teaching Materials: More
Mapping Basic Compentens Lesson : Sains Grade: VIII
Mapping Basic Compentens
Lesson : Sains
Grade: VIII
Semester | Standard Competence | Basic competence | Structur Task Independent Aktivities Unstructured Task |
I | 1. To Comprehend the System of Human life | 1.1. To Analyze the importance of the growth of living things | TT: · Plant nut for 1 week |
1.2. To Describe some steps of human growth | TT: · Searching of growth feature data human | ||
1.3. To Describe the human motion system and its relations to the health | TT: · perceive human body framework · show form of human bone | ||
1.4. To describe the human digest system & its relation to heath | TT: · differentiate chemistry digestion and mechanic · test enzyme activity ptealin KMTT: · count breakfast energy | ||
1.5. To describe human respiratory system and its relations to health | TT: · prove substance that produced in process of human respiration · measure volume of respiration air KMTT: · make physic of stomach respiration | ||
1.6. Describe the circulatory system in human and the relation to immunity and healthy | TT: · count pulse at different activity · perceive heart chicken | ||
I | 2. Explaining items particle concept. | 2.1 To explain the concept of atomic, molecule | TT: · make atomic model picture · differentiate electrolyte sollution and not electrolyte |
2.2. To compare the element molecule and compound molecule | TT: · differentiate elementary body molecule and compound molecule | ||
2.3. To connect the concept of atom, ion, & molecule with the daily chemistry products | TT: · make model of elementary molecule and compound molecule | ||
I | 3. Comprehending role of energy, force, and energy in everyday life. | 3.1 Analysis of rectilinear motion experiment data and rectilinear motion changes and its applying in daily file | TT: · conduct perception of motion object |
3.2.Explain the connection between energy forms and the conservation, the “work and energy principles” and also the application in daily life | TT: · make its form of energy data and change | ||
3.3.conduct experiment about simple plane and its applying in daily file | TT: · conduct experiment of lever activity | ||
3.4.Applying Newton law to explain various event in everyday life | TT: · searching of activity example that use newton law | ||
3.5.To identify kinds of force, force quantifying & the effect of one particular object with force | TT: · count resultant two different styles | ||
3.6.To search the pressure on solid, liquid and gas thing and its application in life | TT: · conduct perception of solid substance pressure | ||
II | 4.Comprehending system in life of plant. | 4.1 To identify the structure & function of plant cell | TT: · draw structure of root organ , trunk and leaf |
4.2 To describe the process of nutrition gathering & energy transforma-tion on green plant | TT: · conduct photosynthesis experiment | ||
4.3 To identify kinds of plant movement | TT: · perceive flora motion | ||
4.4 To identify plant pest & plant organs diseases found in daily life | TT: · searching of pest data information and flora disease | ||
II | 5.Comprehend of concept and the application of vibration, wave and optical in life thecnology product | 5.1 To discribe the concept of vibration and wave and the parameters | TT: · conduct perception kinds of vibration and wave |
5.2.Describ process the happening of earthquake and sunami | TT · Finding the information about earthquake and tsunami | ||
5.3.To describe the concept of sounds in life | TT: · conduct resonance perception | ||
5.4.To search the light characteristics and its connection with kind of mirrors and lens form | TT: · depict the way light at mirror and lens | ||
5.5.To describe the optical instruments and its application in life | TT: · portray some eye handicaps | ||
II | 6. Comprehending usefulness of chemicals in life. | 6.1. To find information about the uses of chemicals and their side effects in everyday life | TT · Finding the information about earthquake and tsunami |
6.2.To communicate the information about the uses of chemicals and their side effects. | TT · data searching about usefulness and chemicals side effects | ||
6.3.To descry be the natural and artificial chemical substances found in food substance packages | TT · searching of chemicals example experiences of and brand that existed in food | ||
6.4.To describe character and influence of addictive and psycotropica To describe character and influence of addictive and psycotropica | KMTT: · make article about substance influence adiktif and psikotropika | ||
6.5.To avoid from the effect o additive and psychotropic substance | TT · Finding the information about how to avoid from addictive and psychotrophica substances KMTT · Make a data about addictive and psychotrophica substances that used in medict |
Acknowledge
by Principal Teacher Batu, July 2011
الاشتراك في:
الرسائل (Atom)