Mr. FAROUK J. T

Meaning of Evolution and Current Concepts Evolution is the development of organisms from pre-existing simple organisms over a long period of time. It is based on the similarities in structure and function that is observed in all organisms. All are…

Comparison of Vertebrate Limbs Limbs of various vertebrates are provided: e.g. fish- Tilapia, amphibian-frog reptiles, lizard; bird – domestic fowl (chicken), mammal- rabbit. Their anatomy can be studied. The following can be noted: Comparison of Wings of bird and insect

Height of Students Discontinuous variations – Ability to Roll Tongue Demonstration of Mitosis and Meisosis Mitosis Plasticene is used to represent number and shapes of various chromosomes e.g. 8 in Drosophila melanogaster. Each stage of mitosis illustrated e.g. interphase. Each…

This is a technology that involves the manipulation of the genotype of an organism to get the desired trait. It also involves the transfer of gene coding for the desired trait from one organism to another. Application of Genetic Engineering…

Study of genetics has been put into a wide variety of uses encompassing plants and animals and in particular humans. Blood transfusion. Blood groups are genetically determined. As discussed earlier a person of blood group A can only get blood…

What is mutations? Mutations are sudden changes in the genotype that are inherited. Mutations are rare in nature and mutated genes are usually recessive to the normal (wild type) genes. Most mutations are generally harmful and some are lethal. A…

LINKAGE.
The term linkage describes the situation where genes or certain characters are located on the same chromosome.
Offspring produced by sexual reproduction show only the parental characteristics and only sometimes few new recombinants.
e. offspring with combinations of characteristics not found in either of the parents due to crossing over in first prophase of meiosis.
Genes are said to be linked when they are located close together on the same chromosome such that they are always inherited together.

Complete Dominance Mendel happened to choose characters that showed complete dominance, the dominant trait completely masked the recessive one in the F1 generation. In man, certain characters are inherited in the same way e.g. colour of the skin; normal colour…

What is structure of DNA? The structure of DNA was first explained in 1953 by Watson and Crick. DNA was shown to be a double helix that coils around itself. The two strands are parallel and the distance between the…

What are chromosomes? These are thread-like structures found in the nucleus. They are normally very thin and coiled and are not easily visible unless the cell is dividing. When a cell is about to divide, the chromosomes uncoil and thicken.…

What is genetics? Genetics is the study of inheritance. The fact that the offspring of any species resemble the parents indicates that the characters in the parents are passed on to the offspring. Factors that determine characters (genes) are passed…

In higher animals, most cells with the exception of the nerve cells retain their power of division. Thus, there is a continued breakdown and replacement of cells. Animal cells undergo rapid cell division and cell differentiation but, unlike plant cells,…

What is plant hornmones? Plant hormones are chemicals produced in very small amounts within the plant body, and play a very important part in regulating plant growth and development. Most growth hormones are produced at the tip of a shoot…

The region of growth in plants is found in localized areas called meristems. A meristem is a group of undifferentiated cells in plants which are capable of continuous mitotic cell division. The main meristems in flowering plants are found at the…

SEED GERMINATION: DEFINITION, TYPES, FACTORS & PROCESS What are the types of germination? The nature of germination varies in different seeds. During germination the cotyledons may be brought above the soil surface. This type of germination is called epigeal germination.…

What are the conditions necessary for seed germination? Seeds can easily be destroyed by unfavourable conditions such as excessive heat, cold or animals. Seeds need certain conditions to germinate and grow. Some of these conditions are external, for example water,…

What is the seed structure? A typical seed structure consists of a seed coat enclosing an embryo. The seed coat is the outer covering which, in most seeds, is made up of the two layers, an outer testa and inner…

Requirements Small plots/boxes, meter rule and seeds of beans (or green grams, peas, maize), Procedure Growth and Development In Plants The main growth and development phase in plants begins with the germination of the mature seed. Seeds are of two…

Concept of Growth and Development Growth is a characteristic feature of all living organisms. Most multicellular organisms start life as a single cell and gradually grow into complex organisms with many cells. This involves multiplication of cells through the process…

Examining the stages of mitosis About 2 mm of a root tip of onion bulb is cut off and placed on a microscope slide. A stain e.g. aceto-orcein is added and the root tip macerated using a scapel. A cover…