Biology

GENETIC: HEREDITARY, TERMINOLOGY, MENDEL’S WORK, GENOTYPE & PRINCIPLES OF HEREDITARY

GENETIC TERMINOLOGY Genetics, the scientific study of heredity and variation in all living organisms, was termed by Dilliam Bateson in 1906. Heredity/Inheritance pertains to the passage and manifestation of traits from parents to offspring, accounting for the common resemblances between them. Variation encompasses the dissimilarities existing among parents, offspring, and siblings. Genes are hereditary units […]

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POLLINATION

This is the transfer of mature pollen grains from the anther of one flower to the mature stigma of the same or another flower of the same plant or another plant of closely related species. Pollination usually precedes fertilization. There are two types of pollination namely, self-pollination and cross-pollination. SELF POLLINATION This is the transfer

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CIRCULATORY SYSTEM | CLOTTING, VESSELS, ARTERY, VEIN, HEART & ORGANS

PROTECTIVE FUNCTION OF BLOOD The blood performs two basic functions in mammals and these are: (1) Transportation of various substances and (2) Protection of the body against diseases The blood defends the body in major ways Antibody production (Clumping): The lymphocytes produce antibodies which are any of a large variety of proteins normally present in

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DIGESTIVE SYSTEM | HYDRA, EARTHWORM, INSECTS, BIRD, MAN

INVERTEBRATES Feeding in Hydra Digestion in Planaria Digestion in Earthworms Digestion in insects (Grasshopper) VERTEBRATES Digestion in Birds Digestion in Rabbits FEEDING IN HYDRA Hydra feeds on small aquatic organisms e.g. crustaceans. It captures its food through its structure called nematocysts found on its tentacles. The food is then passed into the mouth while the

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PRIMARY AND SECONDARY GROWTH

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 tips of shoots and roots, in young leaves, at the bases of the inter-nodes. Zone

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PLANT GROWTH & HORMONES

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 and transported downwards to the root. The root tip produces very small quantities of the

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Animal Growth and Development

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, they undergo very little cell enlargement. In most animals growth occurs throughout their life till

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GENETICS

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 on from parent to offspring through gametes or sex cells. In fertilization the nucleus of

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VARIATION IN POPULATION

Population is a group of organisms of the same specie living in a specified area within a given period of time. Variation refers to the differences which exist between individuals of the same species Types of variations Morphological variation Physiological variation. Morphological variation is the noticeable physical appearance of individuals of the same species. This

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STRUCTURE OF DNA

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 two is constant. Components of DNA What are the components of DNA?  DNA is made

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COMPLETE AND INCOMPLETE DOMINANCE

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 is dominant to albinism (lack of skin pigment). The children are all normal but have

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LINKAGE

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.

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MUTATIONS

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 somatic mutation is a genetic change in somatic cells. Somatic mutations are only inherited if

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THEORIES OF EVOLUTION

ORGANIC EVOLUTION Organic evolution is the sum total of adaptive changes from pre–existing or old forms that has taken place over a long time resulting in diversity of forms, structures and functions among organism. The basis of evolution is that all organisms have pre–existing ancestors. Evidences of evolution Fossil record: A fossil is an impression

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GENETIC ENGINEERING

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 Pharmaceutical industries: Making of hormones e.g. Human insulin and human growth hormone. Enzymes e.g. Alph-Anti-Trypsin

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BIOLOGY PRACTICAL ACTIVITIES

To observe prepared slides of transverse section of stems of herbaceous and woody plants. Permanent slides of transverse sections of: Herbaceous plant and Woody plant are obtained. The permanent slide of an herbaceous plant is placed onto the stage of the microscope. Observations under the low power and medium power objective are made. A plan

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BIOLOGY PRACTICAL ACTIVITIES

BIOLOGY PRACTICAL ACTIVITIES 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: That all limbs have five sets of bones; A single upper bone- the femur in hind limb and the

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