BASIC SCIENCE JSS THREE

Basic Science  JSS 3

WEEK 1

                                                               Family  Traits  ( Genetics)

Family traits are transmittable characteristics which are passed from parents to offspring from one generation to another. In other words, this is what makes children to resemble their  parent or grandparents.

  It makes the family linage to continue. Examples of Family traits include:

1.      Shape of the faces, forehead, eyes, mouth, nose and ears.

2.      Colour of the skin, hair and eyes.

3.      Size of mouth, head, eye and nose.

4.      Height of the body.

5.      Method of walking and so on.

6.      Quantity of hair, eyebrow and eyes lashes.

7.      Blood group.

8.      Genotype.

9.      Albinism.

10.  Rhesius factors e t c.

The scientific study of heredity and variation (resemblance and differences) is known as Genetics. Heredity was greatly studied by scientists like Charles Darwin, Gregor Mendel and Francis Galton.

            All living things are made up of cells and chromosomes. Within the nucleus of the cell and  chromosomes, the Chromosome contain genes which are responsible for characters transmission from parents to children.

            Gregor Mendel was a monk and he carried out his experiments in the garden of the monastery where he lived. He used the garden pea plant from the garden for his experiment, the garden pea does not grow well in all part of Nigeria but it grows in plateau State and Surrounding areas. They used short and long stermed garden peas for experiment.

Short stermed peas are about one metre or less tall, while the long stermed variety are about two metre tall. The short variety would never be tall.  Mendel planted separate seeds of the short variety and seeds of the tall variety. When they flowered, he artificially cross pollinated them. He took pollen grains from flowers of the short variety and put on the ripe  stigmer of the tall variety vice versa.

The pollinated Flowers produced seeds. He allowed the seeds to ripe and collected the seeds and stored them.

During the next growing season, he planted all the seeds from the crossed plants, he observed that plants that resulted from the crossing of tall and short plants were  tall. He inferred that  the characteristics of tallness overshadowed that of shortness in the plant.

                                    DOMINANTS AND RECESSIVE TRAITS

            In Gregor Mandel’s experiment, he observed that the characteristics of tallness over shadowed that of shortness when the parental tall plants were crossed with parental short plants.

            When one characteristic overshadows another in the offspring, the characteristics that is observed is called DOMINANT. .When one characteristic is surpressed in the offspring then it is called RECESSIVE

            The table below shows dominant and recessive traits in the garden peas observed by Mendel

	CHARACTERISTICS	DOMINANT	RECESSIVE
1.	Stem height	tall	Short
2.	Seed coat colour	Yellow	Green
3.	Seed  shape	Round	Wrinked
4.	Flower position	Terminal	Axial
5.	Cotyledon colour	Green	Yellow.
6.	Flower colour	Purple	White

                                                                                                                                                                        Due to Mendel’s good results and convincing experiment of pea plant, he is regarded as the father of science of genetics

Generally, scientists use plants, rats, rabbits, chickens and so on for genetics experiments

            Genetics experiments with human being is very difficult. .

REASONS

1.      Experimental closing of human being is authentical

2.      The life of human being is long; so to get specific result is difficult..

3.      If the pea plant had seven pairs of contrasting characteristic, a human being would have many more than that in number.

4.      In human being unlike pea plants many human characteristic show continuous variation from one form to the other for instance;

a.       Intelligence varies continuously from half width to giant

b.      Skin colour; and

c.       Height varies continuously from dwarf to giant

             IMPORTANCE OF FAMILY TRAITS

1.      Tracing family member.

2.      Reducing the occurrence of hereditary diseases e.g. sickle-cell anaemia

3.      Crime –detection

                Assignment

list 7 ways which family traits can be useful.

WEEK 2

ENVIROMENTAL HAZARDS / POLLUTION

     POLUTION is the throwing of waste substances into the environment in quantities that are harmful to human beings.

TYPES OF POLLUTION

The major types of pollution are:

1.      Water pollution

2.      Air pollution

3.      Noise pollution

4.      Land (soil pollution.

WATER POLLUTION

Water pollution is the discharge of chemical substance into water bodies that is rivers, stream, ocean etc  usually by man which may become harmful to plants and animals in the water and makes it unfit for human consumption. Anything that pollutes water is called Water pollutants. Which includes oils, sewage, detergent fertilizers, acids e.g hydro-cyanic acid, sulphuric acid petroleum products, refuse, human faeces and urine.

AIR POLLUTION

This is the discharge of waste substances into the air.  Air  pollution are  dust, smoke, nitrogen dioxide, chlorocarbons and hydrocarbons, sulphur dioxide, wood particles, ammonia, carbon monoxide and so on

LAND (SOIL) POLLUTION

Land pollution is the dumping of rubbish and chemicals on land by man which makes  the land infertile and causing harm to both plants and animals. Some land pollutants are refuse such as paper, plastics, organic matter, meter scraps and old vehicle bodies, glass, plastics, pesticides, crude oil and so on

ASSIGNMENT

Please do research on soil erosion.