social science and philosophy.pdf

HEREDITY – is the transmission of genetic characters from parents to offspring. It is the process And the result of the process by which the characteristics, or traits of a living organism, plant or animal are produced and transmitted from parent to offspring. GENETICS – the branch of biology deal...

HEREDITY – is the transmission of genetic characters from parents to offspring. It is the process And the result of the process by which the characteristics, or traits of a living organism, plant or animal are produced and transmitted from parent to offspring. GENETICS – the branch of biology dealing with the scientific investigations of the Mechanism of heredity. DOMINANT TRAITS – are those traits phenotypically manifested. Certain traits have greater biochemical activity than others. RECESSIVE TRAITS – the traits that will not be produced when paired with the dominant gene. DOMINANT TRAITS RECESSIVE TRAITS Brown eyes Blue eyes Curly hair Straight hair Normal hair Baldness Normal sight Night blindness Normal color vision Color blindness Normal coloring Albinism Extra finger or toes Normal number Dwarfed limbs Normally-proportional limbs HOMOZYGOUS – when identical characteristics are found in the genes. HETEROZYGOUS – different characteristics in the genes EUGENICS – the science dealing with methods for improving the heredity of the species. EUTHENICS – a branch of applied science which attempts at improvement by regulating the environment. Both the sciences of Eugenics and Euthenics can be applied to man and animals. George Mendel – an Augustinian monk and Austrian botanist made a genetic experiment regarding The inheritance of various traits in different kinds of plants and animals, laid the foundation for the study of heredity. MENDELLIAN LAWS OF HEREDITY 1. Law of Unit Characters – that various characters are transmitted as distinct, individual entities. 2. 3. Law of Dominance – that if two contrasting traits in two purebred organisms are crossed, like tallness or shortness, only one character will appear in the hybrid, the dominant one; the invisible one, the recessive. 4. 3. Law of Segregation – that the character’s segregate and recombine independently in each generation, in the crossing of hybrids, the dominant and the recessive traits being inherited in ratios worked out by Mendel in different instances which sometimes result in incomplete dominance. THE MECHANISMS OF HEREDITY 1. The process of reproduction – an average fertile man produces about 200 million 2. Or more of spermatozoa every week while an average fertile female produces about 400,000 eggs (ova) Every 28 days or more. The mitochondria in the spiral body of the sperm contains 23 pairs of chromosomes. Only one sperm succeeds in fertilizing the egg and the moment this happens, a thick wall encloses the zygote so that no sperms may further penetrate. The biological heredity of the newly formed zygote is fixed at the moment of such fertilization. 2. Chromosomes and Genes - Each child receives an equal number of chromosomes from each parent. When the sperm enters the egg, it releases its chromosomes which duplicate by meiosis or the process of reduction division resulting in every germ cell containing 23 pairs. Genes are chemical packets contained in chromosomes and are too small to be seen under the microscope. They are the carriers of hereditary units and they are able to duplicate themselves. They are also able to control the chemical processes of a cell, determining the kind of tissue to be formed. Genes work in pairs, directing the development of some particular behavior or characteristics of the body. The law of dominance and Recessiveness determine which characteristics will be manifested. The outer surface of each ovary is covered by a layer of cells (germinal epithelium) these surround the immature egg cells, which are present in the ovaries from the time of birth. If an egg does not become fertilized it begins to Degenerate. After the egg is fertilized in undergoes a series of cell divisions. If at an early stage of its development if the fertilized egg splits into two parts that continue to grow, identical twins will result, incomplete division will result in Siamese twins, born physically joined. Fraternal twins result when two separate eggs are released and independently fertilized. THE MATURATION PROCESS Definition of Development, Growth and Maturation 1. Development is a sequence of continuous change in a system extending over a considerable time, specifically, 2. Such change or related and enduring particular changes, as follows one another in an organism from its origin to maturity and death. Changes may be in structure, function or organization, or in size, differentiation, complexity, Integration and efficiency. 3. Growth and development are sometimes use synonymously. Formerly, development referred to qualitative changes while growth referred to quantitative changes. Now this differentiation has disappeared. 4. 3. Maturation refers to the process of change (usually growth) of an individual which occurs primarily as a function 4. Of aging or time. It excludes the effects of practice and experience. Example: Young birds learn to fly when their wings are fully matured irrespective of exercise or practice. CONDITIONS OF GROWTH AND DEVELOPMENT  1. Physical change – involves a change in size and proportion in relation to height, weight, breadth and to the 2. Different parts and organs of the body. It includes change of features like the lengthening of facial muscles at maturity, the sagging of eye muscles, the loss of elasticity of the skin, etc. 3. Functional change – involves a slowing down of mental processes like the ability to perceive things, the 4. Ability to reason, the increase in vocabulary, ability, etc. Conditions for growth and development vary. These may influence not only the rate but also The amount reached. Among these factors are: a. Heredity – the gene structure controls and limits the amount of variations in the structure of the body. b. c. Environmental: d. i. Food – in prenatal development, for instance, substances necessary for growth must be present to insure a relatively normal development. ii. Endocrine actions of glands influence development. For example: thyroxine, secreted by the thyroid gland may slow down or impede growth altogether. An excess of the hormone leads to premature maturation. C Exercise speeds up the metabolic rate of the body processes, thus increasing heartbeat, blood pressure, respiration, etc.