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 from another one of A or O. In case of emergencies and unavailability of blood, […]
PRACTICAL APPLICATIONS OF GENETICS Read More »
EVOLUTION 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 made up of cells, and similar chemical compounds are present. This indicates that all
EVOLUTION – WELL EXPLAINED Read More »
Height of students Students should work in pairs, use chalk and metre rule to mark level of top of head onto the wall. Or door as one student stands straight without shoes, next to the wall or door. The height for each student is recorded on chalk board. The frequency distribution of height is recording
PRACTICAL ACTIVITIES TO DEMONSTRATE CONTINUOUS VARIATIONS Read More »
The structures involved in detecting the changes may be located far away from the ones that respond. There is need for a communication system within the body. The nervous system and the endocrine system perform this function, i.e. linking the parts of the body that detect changes to those that respond to them. Irritability Living
PLANTS – RECEPTION, RESPONSE AND CO-ORDINATION Read More »
What is Gestation Period? The period between conception and birth is called gestation. In humans gestation takes nine months (40 weeks). The embryo differentiates into tissues and organs during this period. Week 1 to 3: Zygote divides to form blastocyst. Implantation takes place. The three germ layers form endoderm, mesoderm and ectoderm. Nervous system starts
What is hydrophytes (water plants)? Water plants are submerged, emergent or floating. Submerged Plants The leaves have an epidermis with very thin walls and a delicate cuticle. They have no stomata. Water is excreted from special glands and pores at the tips. Other adaptations include the following: Presence of large air spaces and canals (aerenchyma)
HYDROPHYTES (WATER PLANTS) Read More »
Ecology is best studied outdoors. Students identify a habitat within or near the school compound, e.g. a flower bed. The quadrat method is used. Observation and recording of the various animals as well as their feeding habits is done. Birds that feed on the plants or arthropods in the area studied are noted through observation
BIOLOGY PRACTICAL ACTIVITIES Read More »
Multicellular fungi are made of thread-like structures called hyphae (singular hyphae) that form a mycelium. e.g. Saccharomyces cereviseae (bread yeast). Others include Penicillium, Rhizopus, and edible mushroom Economic Importance of Fungi Beneficial Effects of Fungi Some fungi are used as food e.g. mushrooms. Some are decomposers which enhance decay to improve soil fertility – recycling
Classification is the science that puts organisms into distinct groups to make their study easy and systematic. Modern scientific classification is based on structure and functions. Organisms with similar anatomical and morphological characteristics are placed in one group while those with different structures are grouped separately. Modern studies in genetics and cell biochemistry are used
GENERAL PRINCIPLES OF CLASSIFICATION Read More »
General Characteristics Unicellular and microscopic Some single cells ,others colonial Nuclear material not enclosed within nuclear membrane-prokaryotic Have cell wall but not of cellulose. Have few organelles which are not membrane bound Mitochondria absent Mostly heterotrophic, feeding saprotrophically or parasitically,some are autotrophic. Reproduction mostly asexual through binary fission Most of them are anaerobes but others
The relationships between organisms in a given ecosystem is primarily a feeding one. Organisms in a particular habitat have different feeding levels referred to as trophic levels. There are two main trophic levels: Producers: These organisms that occupy the first trophic level. They manufacture their own food hence are autotrophic. Consumers: These are the organisms
INTER-RELATIONSHIPS BETWEEN ORGANISMS Read More »
Most animals move from place to place in search of food. Major phyla are: Platyhelminthes (Tapeworm). Nematoda (Ascaris). Annelida (Earthworm). Mollusca (Snails). Arthropoda Chordata Phylum Arthropoda Distinguishing Characteristics of Phylum Arthropoda They have jointed appendages, which are specialised for various functions. Their body is covered by a hardened exoskeleton made of chitin. It is shed
KINGDOM PROTOCTISTA Examples include; Algae such as spirogyra, Chlamydomonas, euglena, Sargassum And protozoa such as amoeba, paramecium and Trypanosoma. General Characteristics They are said to be eukaryotic since their nucleus is bound by a membrane Most are mobile, and use flagella, cilia and pseudopodia. Some are sessile. They reproduce mainly asexually, by binary fission, fragmentation
KINGDOM PROTOCTISTA Read More »
The term disease denotes any condition or disorder that disrupts the steady state of wellbeing of the body. Health is a state of physical, mental and emotional wellbeing in the internal environment of the body. Some of the causes of diseases are due to entry of pathogens and parasites. Pathogens include bacteria, viruses, protozoa and
HUMAN DISEASES – BACTERIAL DISEASES Read More »
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 one, the legmen. The testa is thick; the tegmen is a transparent membrane tissue. The
The water lily, Salvia and Wolfia whose stems remain in water are permeable to air and water. Oxygen dissolved in the water diffuses through the stem into the cells and carbon (IV) oxide diffuses out into the water. Gaseous Exchange in Roots Terrestrial Plants Gaseous exchange occurs in the root hair of young terrestrial plants.
AQUATIC PLANT STEMS Read More »
STRUCTURE OF A FRUIT What is a fruit? A fruit is a matured fertilized ovary of a flower containing one or more seeds. Contrary to this, some plants do not undergo fertilization for the formation of their fruit. Such fruits are called parthenocarpic fruits e.g. banana and pineapple. Such fruits are seedless. A typical fruit
FRUIT – STRUCTURE, TYPES, DISPERSAL OF SEEDS & FEATURES Read More »
COMPETITION Competition is the process by which living organisms in the habitat struggle with one another for limited essential needs in the environment. Such scarce resources in plants include; light, space, nutrient and water while animals complete for food, space or mate. Competition finally results in survival of the fittest and elimination of the unfit.
ADAPTATION FOR SURVIVAL Read More »
What is the nervous system? The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body Components of the nervous system in humans Every organ is the human body is connected to nerves. The nervous system is made
NERVOUS SYSTEM – TYPES, FUNCTIONS AND STRUCTURES Read More »
The Central Nervous System (CNS) consists of the brain and the spinal cord. The CNS co-ordinates body activities by receiving impulses from sensory cells from different parts of the body. It then sends the impulses to the appropriate effectors. The brain is enclosed within the cranium or braincase. It is covered and protected by membranes
HUMAN BRAIN – FUNCTIONS AND MAJOR PARTS OF THE HUMAN BRAIN Read More »