Biology

PROCESS OF PHOTOSYNTHESIS What is photosynthesis? Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds. A general equation for photosynthesis is: Carbon (IV)Oxide+Water light energy—Glucose+Oxygen chlorophyll 6CO2+6H2O light C6H12O+6O2 chlorophyll The reaction occurs in two main […]

Active transport is the movement of solutes such as glucose, amino acids and mineral ions; From an area of their low concentration to an area of high concentration. It is movement against a concentration gradient and therefore energy is required. As such it only takes place in living organisms The energy needed comes from respiration.

CHEMICAL COMPOUNDS WHICH CONSTITUTE LIVING ORGANISMS All matter is made up of chemical elements, each of which exists in the form of smaller units called atoms Some of the elements occur in large amounts in living things These include carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus Elements combine together to form compounds Some of these

COMPARISON BETWEEN ANIMAL CELL AND PLANT CELL Plant Cell & Animal Cell Cell Specialisation Cells are specialised to perform different functions in both plants and animals Example; Palisade cells have many chloroplasts for photosynthesis Root hair cells are long and thin to absorb water from the soil Red blood cells have hemoglobin which transports oxygen

WATER RELATIONS IN PLANT AND ANIMAL CELLS The medium (solution) surrounding cells or organisms is described by the terms hypotonic, hypertonic and isotonic. A solution whose solute concentration is more than that of the cell sap is said to be hypertonic A cell placed in such a solution loses water to the surroundings by osmosis

THE CELL – Cell membrane, Cell wall, Plasma Membrane, Endoplasmic Reticulum & Ribosomes, Goigi Bodies, Mitochondria Introduction What is a cell? The cell is the basic unit of an organism. All living organisms are made up of cells. Some organisms are made up of one cell and others are said to be multicellular. Other organisms

MATERIALS NEEDED FOR COLLECTION OF ORGANISMS Knives to cut portions of plant stem/root or uproot Polythene bags to put the collected plant or specimens Insect collecting jars Insect killing jars Hand gloves Sweep nets Pooters Traps   Observation of Organisms Observe the plant/animal in its natural habitat before collecting Identify the exact place -on surface,

INTRODUCTION TO BIOLOGY What is Biology? Biology derived from Greek words – BIOS meaning LIFE and LOGY meaning STUDY or KNOWLEDGE. Biology means “life knowledge”. It is the study of living things/organisms   BRANCHES OF BIOLOGY Botany – study of plants Zoology – study of animals Microbiology – study’ of microscopic organisms Morphology – study

CHARACTERISTICS OF LIVING THINGS Life defined through observations of activities carried out by living things;   Nutrition Nutrition is the processes by which food/nutrients are acquired/made and utilized by living organisms. Green plants and certain bacteria make their own food. All other organisms feed on complex organic materials.   Respiration This is the breakdown of

CHROMOSOME: THE BASIS OF HEREDITARY  – FULL EXPLANATION   LOCATION AND STRUCTURE OF CHROMOSOMES Chromatin granules (thread – like structures) found in the nucleus of eucaryotic cells are the precursors or raw materials of chromosomes.   Chromosomes occur in pairs known as homologous chromosomes. Each chromosome is made up of two threads called chromatids joined

SEX-LINKED TRAITS   Sex–linked traits are characteristics whose genes are carried on the X chromosome of the sex chromosomes instead of autosomes. Such genes are inherited along with such X chromosomes. They are all controlled by a recessive gene. Examples of Sex-linked traits are: colour blindness, haemophilia, baldness, sickle cell anaemia and albinism. Colour blindness: A

DIHYBRID INHERITANCE   Gregor Mendel crossed plants which differ in two pairs of contrasting characteristics e.g. seed shape (round or wrinkled seeds) and seed colour (yellow or green seeds). He crossed plants having round and yellow seeds with these having wrinkled and green seeds. The F1 seeds were having round and yellow seeds. Self-pollinating F1 plants

DETERMINATION OF THE GENOTYPE OF A DOMINANT PHENOTYPE   A dominant phenotype has the genotypic patterns RR, Rr. The genotype is determined using test cross or back cross Test cross is the crossing of an organisms with an homologous recessive organism Back cross is the crossing of an organism with an homologous recessive organism from the

BIOLOGY OF HEREDITARY AND VARIATION (GENETICS)   DEFINITIONS OF GENETIC TERMS What is Genetics? Genetics is the scientific study of heredity and variation in all living things. The word genetics was coined by Dilliam Bateson (1906). What is hereditary?: Hereditary/Inheritance is the transmission and expression of characters or traits from parents to offspring. It accounts for

HEREDITARY VARIATION AND CAUSES   What is Hereditary? Hereditary variation is the differences among individuals which can be passed from the parents to their offspring (progenies). NOTE: No two offspring inherit exactly the same set of characteristics from parents except in identical twins. Hereditary variation arises because of Genetic reshuffling during meiosis due to independent assortment

MENDELS WORK IN GENETICS   In the study of genetics, Gregor Mendel (1866) worked with the garden pea. (Pisumsativum)  because of three unique properties present in it. These are Peas are self-pollinating They have a very short lifespan They have several unique genetic characteristics e.g. round or wrinkled seeds, tallness or shortness, seeds /pods/ flowers colouration,

SOCIAL ANIMALS – MEANING, CHARACTERISTICS, IMPORTANCE & LIFE HISTORY   Social animals are those in which individuals of the same species live together cooperatively in organized communities known as societies (colonies). Examples of social animals are: social insects (like termites, honey bees or wasps, ants etc), wolves, foxes, baboons etc.   Characteristics of Social Insects

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

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