Table of Contents
Science involves a methodical exploration of both living and non-living entities in our surroundings. The term “Biology” originates from the Greek words “bios,” meaning life, and “logos,” meaning study. Consequently, Biology can be succinctly defined as the study of life, ranging from unicellular organisms to the intricate web of interactions among myriad life forms.
It encompasses the examination of both individual organism life histories and the collective histories of all organisms. Biology is broadly categorized into two branches: Zoology, focusing on animals and their behaviors, and Botany, devoted to the study of various plant types.
Furthermore, Biology encompasses diverse specialized fields such as Morphology, Anatomy, Physiology, Genetics, Ecology, Virology, Bacteriology, Microbiology, Taxonomy, Histology, Mycology, Embryology, and Evolution.
The scientific approach in Biology involves inquiry, providing a systematic means to comprehend the natural world. This process commences with observation, leading to classification, inference, measurement, identification, hypothesis formulation, experimentation, and, ultimately, the establishment of theories, laws, or principles.
Observation employs human senses to describe characteristics and properties, potentially leading to classification, inference, measurement, and identification of problems. Hypothesis is a reasonable assumption subjected to verification. Experimentation, a crucial step, involves an aim, materials, method or procedure, results, and conclusions.
The outcome of an experiment determines the validity of a hypothesis. If disproven, the concept is reconsidered or rejected; if validated through repeated experiments, it evolves into a theory—a tested hypothesis confirmed as true. Extensive testing transforms a theory into a law or principle.
Movement: Living organisms possess the ability to relocate their entire bodies or specific body parts, driven by various motives such as searching for food, escaping danger, seeking mates during reproduction, and responding to external stimuli.
Nutrition: The capability of living organisms to consume and obtain the necessary nutrients for life functions like growth, respiration, and reproduction. Autotrophic nutrition involves the self-production of food through photosynthesis by green plants and some bacteria, while heterotrophic nutrition is exclusive to animals, relying on plant-derived or indirectly acquired food.
Respiration: A process in which the cellular oxidation of food substances occurs in the presence of oxygen, releasing energy for all life processes.
Excretion: The removal of harmful metabolic waste products from the cells or body of living organisms, essential for preventing damage to body cells. Metabolism encompasses all the chemical processes within the cells of an organism’s body.
Growth: The permanent increase in an organism’s body mass or complexity through cell division and differentiation. Adequate feeding supports increased body mass.
Irritability/Sensitivity: The ability of an organism to respond to changes in both internal and external stimuli, including heat, light, pain, water, sound, and chemical substances.
Reproduction: The capacity of living organisms to generate offspring with characteristics similar to their parents. Reproduction ensures the continuity of a species and occurs through sexual or asexual means.
Adaptation: The way in which living organisms adjust to their environments to ensure survival and comfort.
Competition: The struggle among living organisms for essential resources like food, light, space, water, and mates to survive and maintain continuous existence.
Death: All living things have a finite and definite lifespan, leading to eventual death.
Plants:
Animals:
A microscope is an instrument designed for viewing or magnifying organisms smaller than 0.001mm, invisible to the naked eye. It comprises the following parts:
Classification involves grouping living things based on their structural, genetic, and cellular organization, a practice known as taxonomy. The current system of classification, introduced by the Swedish naturalist Carl Von Linne (1707-1778), categorizes living things into various hierarchical levels.
In this system, living things are initially grouped into a broad category called a kingdom. The kingdom is then divided into smaller units known as phyla (or division, in the case of plants).
Phyla are further subdivided into classes, classes into orders, orders into families, families into genera, and genera into species. A species is defined as a population of related organisms capable of interbreeding to produce fertile offspring.
The modern classification system, based on physiology, biochemistry, and embryology, categorizes living things into five kingdoms: Monera, Protoctista, Fungi, Plantae, and Animalia.
Lack organized DNA, with scattered Deoxyribonucleic acid (DNA) in the cytoplasm (prokaryotes).
Absence of mitochondrion in the cytoplasm.
Cell walls made of protein and fatty materials.
Microscopic single-celled organisms, some motile and some non-motile.
Feed both autotrophically and heterotrophically.
Reproduction occurs only through asexual means.
Well-organized DNA in the nucleus (eukaryotes).
Single-celled organisms.
Some motile and some non-motile.
Inhabit water, damp soil, leaf litter, and other moist terrestrial habitats.
Use mitochondrion for cellular respiration.
Form cysts to survive adverse conditions.
Reproduce both sexually and asexually (e.g., Amoeba, Euglena, Chlamydomonas, Plasmodium).
Heterotrophic feeding (lacks chlorophyll and cannot photosynthesize).
Simple multicellular organisms with non-green bodies.
Lack true roots, stems, and leaves.
Composed of thread-like hyphae forming mycelium.
Reproduction through spores.
Carbohydrate storage as glycogen.
Cell walls made of chitin (not cellulose like plants).
Examples: Mucor, Rhizopus, Mushroom, Slime mould.
Multicellular and non-motile organisms.
Cells bounded by rigid cellulose cell walls.
Contain chlorophyll for photosynthesis.
Store carbohydrates as starch or sucrose.
Simple microscopic plants.
Lack true roots, stems, and leaves.
Found in aquatic habitats.
Autotrophic (synthesize their own food).
Reproduce both asexually and sexually.
Cell walls contain cellulose and various pigments.
Non-vascular multicellular plants.
Terrestrial, growing in moist environments.
Differentiated into stem-like and leaf-like structures.
Lack true roots, stems, and leaves.
Asexual reproduction via spores; sexual reproduction in water.
Exhibit alternation of generation.
True roots, stems, and leaves.
Well-developed vascular bundles.
Reproduction by spores and dependent on water for sexual reproduction.
Terrestrial and some aquatic species.
Exhibit alternation of generation.
Well-developed vascular bundles.
Adapted to terrestrial habitats.
Divided into Gymnospermatophyta (Coniferophyta) and Angiospermatophyta.
Large plants with true roots, stems, and leaves.
Needle-like green leaves.
Naked seeds borne in cones.
Possess true flowers for sexual reproduction.
Well-developed roots, stems, and leaves.
Seeds and fruits produced after fertilization, enclosed within the ovary.
Terrestrial and some aquatic species.
Subdivided into two classes:
Leaves with parallel veins.
Dull-colored flowers.
Embryo with one cotyledon.
Leaves with network veins.
Brightly colored flowers.
Embryo with two cotyledons.
Examples: Maize, palm tree, grasses (Monocot); Mango, Orange (Dicot).
Agricultural classification involves categorizing plants based on the purpose for which they are cultivated. The main categories include:
Cereals or Grain Crops:
Cultivated for their grain with high starch content.
Examples: maize, guinea corn, millet, wheat, ryes, barley, and oats.
Leguminous Plants or Pods:
Important plants with high protein content, serve as a source of nitrate in the soil.
Examples: groundnut, beans, melon, flamboyant, crotalaria, etc.
Root Crops:
Tuberous plants specialized for food storage, providing a good source of carbohydrates.
Examples: sweet potatoes, Irish potatoes, yam, cassava, and carrot.
Vegetable Crops:
Herbaceous plants that are vital constituents of a diet, serving as sources of vitamins and mineral salts.
Examples: tomatoes, pepper, onions, cabbage, lettuce, okra, and other vegetables.
Fruits:
Grown for the production of fruits, rich in vitamin A, C, and minerals, usually consumed in their natural form.
Examples: mangoes, pawpaw, guava, bananas, pineapple, etc.
Grown primarily for profit.
Examples: oil-producing plants like oil palm, latex crops like rubber, fiber crops like cotton, and beverage/drug plants like cocoa and spices.
Oil Plants:
Produce oil as a food reserve stored in their fruits or seeds.
Examples: palm oil fruit and kernel, melon seed, cottonseed, groundnut, coconut, and shea butter.
Fibre Crops:
Beverages and Drug Plants:
Produce non-alcoholic beverages (e.g., cocoa, coffee).
Examples of drugs include quinine obtained from the bark of cinchona spp., used as an anti-malaria drug.
Spices: Vegetable plants used to add flavor to modern dishes, such as ginger, cloves, pepper, vanilla, nutmeg.
Plants with one growing season, producing seeds in the first year and then dying off.
Examples: maize, guinea corn, wheat, groundnut, beans, etc.
Plants that grow for two seasons, with the first year devoted to building up food material and seed production in the second year.
Examples: cabbage, carrot, cocoyam, cassava, etc.
Plants that grow for three or more seasons or years.
Examples: shrubs and trees.
Relevance of Biology to Agriculture:
Agriculture, defined as the cultivation of crops and rearing of farm animals, is essential for providing human basic needs like food, shelter, clothing, and materials for industrial purposes.
Kingdom Animalia (Characteristic Features):
Multicellular organisms.
DNA located in the nucleus enclosed with a nuclear membrane.
Cells have no cell walls.
Nervous systems present except in sponges.
True tissues present except in sponges.
Heterotrophic feeding.
Divided into two major groups: Invertebrata (animals without a backbone) and Vertebrata (animals with a backbone).
Radial Symmetry: Body can be cut along its axis anywhere to give two identical halves.
Bilateral Symmetry: Body can be cut along its axis in only one place to give two identical halves.
Sac-like Body Design: Animals with a single opening (mouth) leading to the gut cavity.
Tubular Body Design: Animals with double openings like a tube with gut openings at the anterior (mouth) and posterior (anus).
Acoelomate: Animals without a body cavity.
Pseudocoelomate: Animals with a false body cavity.
Coelomate: Animals with a true body cavity.
Unicellular aquatic animals, often attached to rocks or shells in colonies.
Lack specialized tissues, organs, or systems.
Radial symmetry.
Single opening leading to an internal cavity.
Examples: sponges.
Multicellular organisms, including sea anemones, jellyfish, and corals.
Radial symmetry.
Single body cavity called enteron.
Two distinct body layers (diploblastic): ectoderm and endoderm.
Soft, jelly-like bodies.
Asexual reproduction by budding.
Tentacles and stinging cells (Nematocysts) used for capturing prey.
Flat, unsegmented bodies.
Bilateral body symmetry.
No body cavity or lumen.
Three layers (triploblastic): ectoderm, mesoderm, and endoderm.
Most are hermaphrodites.
Some are parasites in humans and other animals.
Round and cylindrical bodies.
Lack a body cavity (pseudo-coelom).
Bilateral body symmetry.
Some hermaphrodites, some reproduce sexually.
True body cavity or coelom.
Metameric segmentation internally and externally.
Aquatic and terrestrial.
Sexual reproduction; many are hermaphrodites.
Soft, unsegmented bodies.
Tentacles on the head.
Muscular foot adapted for crawling or burrowing.
Body covered by a mantle; some have calcareous shells.
Aquatic and terrestrial.
Oculiferous tentacles for sensitivity.
Segmented bodies with a distinct head and complex muscular system.
Divided into classes: Crustacea, Insecta, Arachnida, Myriapoda.
Hard, rigid exoskeleton made of chitin.
Jointed appendages or legs for various functions.
Molting or ecdysis for growth.
Various means of respiration (gills, trachea, lung book, body surface).
Radial body symmetry.
Mostly marine.
Triploblastic animals.
No brain or eyes.
True feet used for movement.
Bony fish with a bony skeleton or cartilaginous fish with soft bones.
Covered by scales, possess fins for movement.
Gills for gaseous exchange.
Poikilothermic or cold-blooded.
Swim bladder for buoyancy.
Lay eggs externally.
Two pairs of limbs, naked or moist glandular skin.
Dual life: can live in both water and on land.
Gaseous exchange with gills in tadpole stage and with lungs, skin, and mouth in adults.
Oviparous with external fertilization.
Dry skin with scales, lungs for breathing.
Oviparous with internal fertilization.
Homodont dentition.
Some are aquatic, others terrestrial.
Internal jointed skeleton made of bone.
Bilateral symmetry, body divided into head, trunk, and tail.
Two pairs of limbs (pectoral and pelvic limbs).
Well-developed central nervous system with a closed blood system.
Skin covered by scales or feathers.
Warm-blooded.
Internal jointed skeleton made of cartilage or bone.
Bilateral symmetry, body divided into head, trunk, and tail.
Two pairs of limbs (forelimbs and hind limbs).
Well-developed central nervous system, closed blood system.
Skin covered by hair or fur.
Warm-blooded.
This classification provides a comprehensive overview of plant and animal diversity based on agricultural and biological criteria.
Class Aves (Birds):
Birds, belonging to Class Aves, encompass a diverse group adapted to aerial life through wing modifications of the forelimb. Examples include pigeons, domestic fowls, ostriches, and ducks.
Characteristics:
Homoeothermic: Maintaining a constant body temperature, irrespective of environmental changes.
Feathers: Entire body covered except for legs, which are scaled.
Beak: Mouth extended to form a beak for feeding.
Hollow Bones: Rigid, hollow bones with air sacs, aiding lightness during flight.
Internal Fertilization: Reproduction through internal fertilization.
Respiration: Utilization of lungs for respiration.
Wings: Forelimbs modified into wings for flight.
Toothless: Beak used for feeding.
Class Mammalia (All Mammals):
Mammals, the most advanced in the animal kingdom, possess two body cavities separated by a diaphragm.
Characteristics:
Homoeothermic: Maintaining a constant body temperature.
Covering: Bodies covered with hairs or fur.
Heterodont Dentition: Having different sets of teeth in terms of shape and function.
Diaphragm: Thoracic cavity separated from the abdominal cavity by a diaphragm.
Respiration: Lungs used for respiration.
Brain: Well-developed brain.
Pinnae: External ears referred to as pinnae.
Viviparous: Giving birth to live young.
Four-Chamber Heart: Fully developed four-chamber heart.
Mammary Glands: Presence of mammary glands producing milk for young ones.
Internal Fertilization: Reproduction involves internal fertilization.
Agricultural activities impact ecosystems, potentially disrupting the balance through practices like bush clearing, burning, tillage, fertilizer use, and pesticide/herbicide application.
Effects
Exposure of soil to direct sunlight, altering microbial conditions.
Increased risk of erosion without plant cover.
Leaching of nutrients in unprotected soil.
Potential desertification.
Displacement of wildlife.
Setback in plant succession.
Destruction of plant species conservation.
Effects
Loss of animal and microbial life.
Gradual loss of soil fertility.
Alkaline soil from burnt ashes.
Soil exposed to wind and rain erosion.
Delayed return of microorganisms.
Reduced water-retaining capacity.
Non-regeneration of some plant species.
Disruption of balanced ecosystems.
Advantages:
Renewal of grass growth.
Speedy emergence of dormant seeds.
Charcoal and wood for cooking.
Effects
Loosening of soil, increasing erosion risk.
Ecological changes in soil.
Leaching of soil nutrients.
Structural damage and microorganism loss.
Elevated fire and heat risk on soil.
Advantages
Improved soil aeration.
Prevention of different plant appearances.
Enhanced crop yield.
Effects
Loss of organic humus.
Soil crumb structure destruction.
Water pollution if washed into rivers.
Dry, powdery soil susceptible to wind erosion.
Harm to useful soil organisms.
Effects
Loss of organic humus.
Destruction of soil crumb structures.
Water pollution.
Dry, powdery soil prone to wind erosion.
Harm to beneficial soil organisms.
Benefits:
Allows land to fallow.
Prevents erosion.
Increases crop yield.
Prevents disease infestations.
Adds nitrates to the soil.
Avoids nutrient depletion.
Crop rotation involves the systematic planting of different crops in specified plots over multiple years to enhance soil fertility and manage pests effectively.
1st Year:
1st Plot: Maize
2nd Plot: Cassava
3rd Plot: Fallow
4th Plot: Groundnut
5th Plot: Yam
2nd Year:
1st Plot: Cassava
2nd Plot: Fallow
3rd Plot: Groundnut
4th Plot: Yam
5th Plot: Maize
3rd Year:
1st Plot: Fallow
2nd Plot: Groundnut
3rd Plot: Yam
4th Plot: Maize
5th Plot: Cassava
4th Year:
1st Plot: Groundnut
2nd Plot: Yam
3rd Plot: Maize
4th Plot: Cassava
5th Plot: Fallow
5th Year:
1st Plot: Yam
2nd Plot: Maize
3rd Plot: Cassava
4th Plot: Fallow
5th Plot: Groundnut
Mixed farming integrates both animal and crop production on the same farm, providing several benefits:
Allows animals to convert plant products into high-quality protein.
Mitigates the risk of single crop failure.
Economically viable, generating income from both crops and animals.
Involves growing more than one type of crop simultaneously on a piece of land, enhancing diversity and reducing the risk of crop failure.
Continuous cropping:
Permanently cultivating a piece of land with potential drawbacks:
Leads to soil mineral exhaustion.
Reduces clearing costs.
May result in low productivity and crop failure over time.
Monoculture or monocropping:
Growing the same crop on the same land annually with adverse effects:
Makes the environment unsuitable for many crops.
Encourages the spread of pests and diseases.
Risks crop failure and soil structure destruction.
Shift cultivation:
Cultivating a piece of land for a few years before abandoning it for a new one, leading to:
Wastage of land.
Soil erosion.
Migration of animals.
Pests, such as insects or small animals, can damage crops and spread diseases to humans and animals.
Harmful insects cause damage to crops in the field and storage.
Examples: crop-eating, sap-sucking, biting and chewing, piercing and sucking insects.
Some subterranean worms feed on plant roots, while others chew leaves, stems, and flowers.
Mammal pests (e.g., monkeys, grass-cutters) and bird pests (e.g., fowls, guinea fowls) that destroy crops.
Destruction of vegetation.
Competition for food.
Reduction in crop quality and quantity.
Financial losses for farmers.
Increased costs for pest control.
Disease transmission to both humans and plants.
Chemical Control: Use of chemical substances like Aldrin, Vertox 85, Gammalin 20, and Didimac 25.
Cultural Methods: Seasonal practices, crop rotation, regular weeding, correct spacing, and early harvest.
Physical Methods: (a) Scaring, killing, collecting pests for mass destruction. (b) Setting traps, shooting, using scarecrows, and farm drums.
Biological Control: Introduction of natural enemies to consume or control pest populations.
The pest bores into yam tubers, with cycles involving eggs, nymphs, larvae, and adults. It contributes to yam tuber destruction.
Found on oil palm trees, this pest’s life cycle includes eggs, larvae, pupa, and adults. It can kill trees and is controlled by burning dead trees.
Diseases are categorized into viral, bacterial, fungal, and protozoal diseases, with general effects including reduced yield, decreased quality, malformation, death, financial losses, increased production costs, unattractiveness, and retarded growth.
Clearing breeding grounds.
Chemical applications.
Vaccination for immunity.
Good sanitation.
Adequate feeding.
Isolation of new stocks.
Rotational grazing.
Regular changing of animal bedding.
Veterinary check-ups.
Disease examples include viral diseases like foot and mouth disease, bacterial diseases like anthrax, fungal diseases like blight, and protozoal diseases like trypanosomiasis. Control methods encompass chemical, cultural, physical, and biological approaches.
This comprehensive overview highlights the importance of integrated farming practices and effective pest and disease management for sustainable agriculture.
The organization of life encompasses a spectrum from single-celled organisms to multicellular entities with intricate structures that perform diverse functions.
The evolutionary progression in plants and animals reveals a gradual complexity in organization, transitioning from unicellular to multicellular forms. The bodies of higher organisms exhibit advanced functionalities with specialized parts composed of tissues, organs, and systems, enhancing their efficiency in various life activities.
Nutrition is the process through which living organisms acquire and utilize food from their external environment for metabolic activities like respiration, growth, excretion, and reproduction.
Photosynthetic or holophytic nutrition involves green plants manufacturing their own organic food from simple inorganic substances—carbon dioxide, water, sunlight, and chlorophyll—resulting in the production of oxygen. The process can be represented by the equation: 6CO2 + 6H2O + Sunlight energy + Chlorophyll → C6H12O6 + 6CO2.
Photosynthesis occurs in two stages: the light reaction and the dark reaction. The light reaction, dependent on light, involves the absorption of light energy by chlorophyll to break water into hydroxyl (OH–) and hydrogen (H+) ions through photolysis. This stage transfers light energy to ATP and produces reduced NADP, which, in the dark, converts into chemical energy in organic compounds.
In the dark reaction, carbon dioxide combines with a five-carbon sugar to form two molecules of phosphoglyceric acid (PGA), which then convert to carbohydrates in the presence of ATP and NADPH2. Other products of photosynthesis include proteins and fats, produced according to the plant’s needs.
The main product of photosynthesis is simple sugar, which is partially used by the plant and the excess is converted to starch for storage and translocation to other plant parts through phloem vessels.
Photosynthesis is crucial for various reasons:
Chemosynthetic nutrition involves certain bacteria manufacturing their own food from simple inorganic substances using chemical energy released during the process. For example, sulfur bacteria oxidize hydrogen sulfide to chemical energy.
Experiments are conducted to test for photosynthesis, including demonstrating the presence of starch in leaves, the necessity of sunlight, carbon dioxide, and chlorophyll for photosynthesis, as well as the production of oxygen as a by-product.
Nutrient cycles involve the circulation of specific elements, such as carbon, sulfur, and water, in the natural environment.
The carbon cycle describes how carbon dioxide is utilized from the atmosphere through photosynthesis and returned to the atmosphere via respiration and decay. The processes involved in the carbon cycle include photosynthesis, respiration, putrefaction, and combustion. Photosynthesis removes carbon dioxide from the atmosphere, while the other three processes release carbon dioxide back into the atmosphere.
Photosynthesis: Carbon dioxide in the air diffuses into leaves, where it is converted into sugars and other complex compounds. When plants are consumed by animals, sugars enter the animal’s body cells.
Respiration: Within the animal body, the breakdown of chemical food substances releases carbon dioxide, water, and energy. Carbon dioxide is released into the atmosphere.
Putrefaction: When plants and animals die, they decay, and bacteria and other microbes involved in the decay process respire, releasing carbon dioxide back into the atmosphere.
Combustion: Burning fuels such as coal, wood, petrol, and kerosene releases carbon dioxide into the atmosphere.
From the sea, more carbon dioxide is liberated when there is a low quantity in the atmosphere, and conversely, more dissolves in the sea when there is an excess of carbon dioxide in the atmosphere.
The water cycle is the process through which water is used and returned to the atmosphere as water vapor, ultimately falling back as rain. It involves two main processes: condensation and evaporation.
When rain falls, some is absorbed by plants, evaporating through transportation. Animals also use water, releasing water vapor during respiration and excretion. Some rain directly enters water bodies, while some filters through soil to form underground water that eventually reaches oceans. Water returns to the atmosphere through evaporation, forming clouds that may precipitate as rain.
Food is a complex, energy-rich organic matter that living organisms consume to obtain essential nutrients for life. These nutrients are classified into six groups:
(i) Carbohydrates
(ii) Proteins
(iii) Fats and Oils
(iv) Mineral Salts
(v) Vitamins
(vi) Water and Roughages.
Carbohydrates are composed of carbon, hydrogen, and oxygen with the general formula (CxH2O)y. They include simple sugars, starches, cellulose, and glycogen, categorized into monosaccharides, disaccharides, and polysaccharides. Common sources are yam, cassava, potatoes, bread, and cereals like rice and maize.
– Polysaccharides: Complex carbohydrates like starch, cellulose, chitin, and inulin.
Proteins are complex molecules composed of amino acids. They need to be digested into amino acids before absorption in the animal’s body. The breakdown during digestion proceeds as follows:
Protein → Peptone → Polypeptide → Amino Acid
Proteins consist of carbon, hydrogen, oxygen, phosphorus, and sulfur. Sources include animal products (milk, eggs, fish, cheese, meat, and chicken) and plant products (beans, groundnut, soya beans, and melon).
Fats and oils, also known as lipids, consist of carbon, hydrogen, and oxygen. They are hydrolyzed into fatty acids and glycerol during digestion. Plant sources include groundnut, palm oil, soya beans oil, coconut oil, and melon oil, while animal sources include butter, fish, or cod oil.
Mineral salts are vital substances required in trace amounts for essential body processes. Animals mainly obtain them by feeding on plants or plant products, except for some, like sodium chloride (table salt). Lack of these minerals can lead to nutritional deficiencies.
Vitamins are essential organic food substances required in small quantities for normal growth and healthy development in humans and animals. Inadequate vitamin supply in the diet can result in deficiency diseases.
Groups of Vitamins:
(i) Fat Soluble Vitamins: Soluble only in fat, including vitamins A, D, E, and K.
(ii) Water Soluble Vitamins: Soluble in water, encompassing vitamins B-complex and C, such as B2 (Riboflavin), B3 (Niacin), B5 (Pantothenic), B6 (Pyridoxine), B12 (Cyanocobalamin), and Folic acid, among others.
Vitamin A (Retino): This essential vitamin is found in various sources such as liver, eggs, fish, milk, palm oil, and fresh vegetables. Its functions include supporting the normal growth of cells and skin, as well as contributing to proper vision. A deficiency in Vitamin A may manifest as night blindness and reduced resistance to diseases.
Vitamin B1: Present in yeast, unpolished rice, milk, beans, and palm wine, Vitamin B1 plays a crucial role in normal growth and the formation of co-enzymes involved in cellular respiration. A deficiency in Vitamin B1 can result in slow growth and dermatitis.
Vitamin B2: Yeast, soya beans, egg, milk, and green vegetables are rich sources of Vitamin B2. This vitamin is essential for growth, maintaining healthy skin, and proper functioning of the eyes. Similar to Vitamin B1, a deficiency in Vitamin B2 can lead to slow growth and dermatitis.
Vitamin B3: Found in yeast, beans, milk, palm wine, yam, and various vegetables, Vitamin B3 is necessary for cellular respiration. A deficiency in this vitamin can result in pellagra, characterized by skin problems and digestive issues.
Vitamin B12: Abundant in kidney, liver, fish, and milk, Vitamin B12 is crucial for the formation of red blood cells. A deficiency may lead to pernicious anemia.
Vitamin C (Ascorbic acid): Derived from fresh fruits like oranges and green vegetables, Vitamin C aids in wound healing and helps resist infections. A deficiency can result in scurvy, characterized by bleeding gums, poor wound healing, and low resistance to infection.
Vitamin D (Calciferol): Found in fish, milk, eggs, and liver, Vitamin D is also produced in the skin when exposed to light. It is necessary for the formation of strong bones and teeth. Deficiency may cause conditions such as rickets and osteomalacia.
Vitamin E (Ergo sterol): Present in green vegetables, butter, and liver, Vitamin E is associated with the promotion of fertility in animals. A deficiency can lead to reproductive failure, including issues like sterility and premature abortion.
Vitamin K (Phylloquinone): Found in fresh green vegetables, cabbage, and spinach, Vitamin K aids in blood clotting. A deficiency in Vitamin K may result in hemorrhage.
Water is composed of hydrogen and oxygen. Sources of water include metabolic water from food, drinking water from various sources like rivers, rain, and ponds.
(i) Required for metabolic activities in the body
(ii) Necessary for digestion of food
(iii) Used for maintaining body temperature
(iv) Serves as a medium for transporting nutrients
(v) Assists in excretion of metabolic waste products (e.g., urine)
(vi) Basis for body secretion from endocrine glands
(vii) Maintains the osmotic content of the body
A balanced diet contains the correct proportion of all six essential food substances: carbohydrates, proteins, fats and oils, minerals, vitamins, and water.
Digestive enzymes are organic catalysts, complex protein substances produced by living cells. They accelerate metabolic reactions without altering their composition.
Characteristics of Enzymes:
(i) Specific in their actions
(ii) Only small quantities required for catalyzing a reaction
(iii) Have a specific temperature range for optimal activity
(iv) Do not lose their chemical composition after a reaction
(v) Affected by acidity and alkalinity (pH) of the medium
(vi) Involved in reversible reactions
(vii) Produced by glands specific to the system they support
(viii) Activities can be inhibited by certain substances
(ix) Enhanced by co-enzymes, such as inorganic substances like phosphorus.
Classes of Enzymes:
Proteases – Protein-digesting enzymes found in the stomach (Renin, Pepsin) and small intestine (Trypsin, Erepsin).
Amylase – Enzymes digesting starches and sugars, including Ptyalin (Salivary amylase) in the mouth and Pancreatic amylase in the pancreas.
Lipases – Enzymes converting oils to fatty acids and glycerol, produced in the pancreas and ileum.
Autotrophic Nutrition involves organisms that can independently produce their food. These self-sustaining organisms, known as autotrophs, achieve nutrition through processes like photosynthesis in green plants and chemosynthesis in certain bacteria.
Heterotrophic Nutrition, on the other hand, refers to organisms that are unable to manufacture their own food and rely on other organisms, particularly plants, for their nutritional needs. Heterotrophs include fungi, protozoa, and some bacteria.
Commensalism: This is an association where one partner benefits, and the other neither gains nor suffers harm. An example is the relationship between sharks and remora fish.
Carnivorous Plants: These autotrophic and photosynthetic plants supplement their protein needs by feeding on insects or small animals. Examples include Venus flytrap, sundew plant, pitcher plant, and bladderwort.
Filter Feeding: This feeding mechanism is employed by certain aquatic animals to feed on tiny microorganisms in the water, such as phytoplankton and zooplankton. Animals like mosquito larvae, mussels, ducks, prawns, and lobsters use sieve-like structures to collect organisms from water currents.
Fluid Feeding: Some animals adopt this method, which involves feeding on fluid materials like nectar or blood. Examples include mosquitoes, aphids feeding on plant sap, and larger animals like bees, butterflies, and hummingbirds sucking nectar from flowers.
Ecology involves the examination of living organisms, such as plants and animals, in relation to their surroundings. The field is categorized into two primary branches.
Autecology focuses on studying individual organisms or a single species within its environment. For example, this involves investigating a specific organism and its surroundings.
Synecology, on the other hand, explores the interrelationships among groups of organisms or species coexisting in a particular area. An example would be the examination of diverse organisms in a river in relation to their aquatic environment.
The ecosystem comprises biotic and abiotic components.
Non-living factors in the physical environment essential for the organisms’ survival, including soil, water, temperature, humidity, light intensity, air, minerals, salts, etc. These factors influence and are influenced by the biotic components within the ecosystem.
Growth is the irreversible increase in volume, size, and number of an organism’s parts, length, and weight. It is an organic process that takes time to accomplish.
There are three processes involved in growth:
Mitosis is a cell division process that produces two identical cells with the same chromosome number as the parent cell. It is crucial for growth and occurs in somatic cells (body cells) such as skin, bone marrow, lymph nodes, injured places, and plant meristematic tissues. Mitosis involves stages like interphase, prophase, metaphase, anaphase, and telophase (cytokinesis).
Growth occurs in specific tissues and places in plant bodies, mainly in meristematic tissues. Meristems are tissues capable of mitotic division, and they include root apex, stem or shoot apex, base or internodes, and vascular cambium. Growth in the apical stem and root meristem is termed apical growth, while growth at the meristem base of internodes is called auxiliary growth.
Hormones are biochemical substances produced in small quantities by cells in plant and animal bodies. Plant hormones, such as auxin, gibberellin, cytokinin, abscisic acid, and florigens, play roles in stem elongation, tropism response, root and stem apical division, fruit growth and ripening, flower bud and lateral root initiation. Animal hormones, produced in endocrine glands, control body metabolism, promote animal growth, and stimulate reproduction.
Irritability is an organism’s ability to perceive and respond to changes in the internal and external environment or stimuli. Stimuli can be external or internal, and organisms respond through tactic, nastic, and tropic responses.
Movement is the ability of living organisms to change location, motivated by reasons such as searching for food, escaping danger, responding to stimuli, or reproducing.
Cyclosis, or cytoplasmic streaming, involves the rotational movement of the cytoplasm and its contents within cells. Different organisms use various organelles and mechanisms for movement, such as pseudopodia in amoeba, cilia in paramecium, flagellum in Euglena, tentacles in Hydra, and limbs in animals like earthworms, fishes, toads, and frogs.
Reproduction refers to the capacity of an organism to generate new individuals of the same species, ensuring the continuity of life.
Natural vegetative propagation is a fascinating process in the realm of botany, relying on various vegetative parts of plants to proliferate and reproduce. These vegetative parts, encompassing stems, leaves, roots, or buds, serve as the building blocks for generating new individuals. Within this intricate system, several organs of vegetative propagation play crucial roles, each with its unique characteristics and mechanisms.
Bulbils, miniature bulb-like structures found on certain plants, harbor the potential for new growth and serve as a means of propagation. They often develop along the stems or in the axils of leaves, ready to sprout into independent plants when provided with the right conditions.
Runners or stolons, elongated stems that run horizontally along the ground, are adept at producing roots and shoots at various intervals. As they spread out, they facilitate the establishment of new plant colonies, effectively expanding the plant’s reach and influence.
Rhizomes, underground stems with nodes and internodes, possess the ability to produce new shoots and roots from their nodes. This underground network enables plants to efficiently spread and colonize diverse environments, ensuring their survival and persistence.
Corms, solid underground storage structures resembling bulbs but lacking fleshy scales, serve as reservoirs of nutrients and energy. Through the development of new buds, corms give rise to offspring, perpetuating the plant’s lineage and ensuring its genetic continuity.
Stem tubers, modified underground stems swollen with stored nutrients, are vital organs of propagation for numerous plant species. Sprouting from the eyes or nodes of these tubers, new shoots emerge, heralding the emergence of a new generation.
Suckers, shoots arising from underground roots or stems, function as natural propagules capable of independent growth. Often seen in species such as fruit trees, suckers contribute to the expansion of plant populations and the rejuvenation of aging individuals.
Bulbs, specialized underground storage organs consisting of layers of fleshy leaves, serve as repositories of nutrients and water. Through the development of offsets or daughter bulbs, they propagate and perpetuate the genetic heritage of the parent plant, ensuring its legacy continues.
In essence, these organs of vegetative propagation embody the resilience and adaptability of plants, enabling them to multiply and thrive in diverse environments. Through the utilization of stems, leaves, roots, and buds, nature orchestrates a symphony of growth and renewal, perpetuating the cycle of life.
Artificial propagation, a cornerstone of horticulture, encompasses a diverse array of techniques aimed at multiplying plants by harnessing the reproductive potential of parent specimens. Through strategic manipulation and intervention, various methods are employed to propagate plants, ensuring genetic continuity and diversity. These methods include:
These methods of artificial propagation not only facilitate the rapid multiplication of plants but also enable the preservation and dissemination of desirable genetic traits, contributing to the cultivation of diverse and resilient botanical populations.
There are two forms of sexual reproduction: conjugation and fusion of gametes.
In conjugation, the simplest type of sexual reproduction compared to asexual reproduction, certain unicellular organisms like paramecium, fungi such as rhizopus, and algae like spirogyra exhibit this process. Two similar organisms, known as conjugants, come together and exchange genetic material from their nuclei. Following the exchange, the organisms separate, and the resulting zygote or zygosphere has the potential to develop into a new organism.
Fusion of Gametes occurs in higher organisms, where male and female sex cells (gametes) are produced in specialized structures through gametogenesis involving meiotic cell divisions. Fertilization, the fusion of haploid male and female sex cells, results in a single diploid cell (zygote) that develops into an adult organism.
Meiosis is a reduction division method leading to the formation of four haploid daughter cells. Unlike mitosis, meiosis involves two consecutive cell divisions, and genetic material in chromosomes is not duplicated during the second meiotic division. While mitosis produces identical daughter cells, meiosis randomly combines chromosomes, generating unique chromosome combinations in each daughter cell. Meiosis ensures that the chromosome number remains constant from generation to generation.
Meiosis comprises two successive divisions:
Meiosis facilitates the formation of:
Amoeba undergoes asexual reproduction through binary fission and multiple fission (sporulation) in adverse conditions.
In binary fission, when Amoeba reaches full size, it ceases movement and divides into two equal parts, starting from the nucleus. Subsequently, the cytoplasm undergoes division, resulting in the formation of two daughter amoebae.
During multiple fission, Amoeba becomes rounded and secretes a cyst around itself. Inside the cyst, the nucleus undergoes multiple divisions. When conditions become favorable, the cyst bursts, and each nucleus, surrounded by a portion of the parent cytoplasm, gives rise to very small amoebae.
Reproduction In Paramecium
Paramecium reproduces asexually through binary fission and sexually through conjugation.
Under favorable conditions, binary fission occurs as the micronucleus undergoes mitosis, dividing into two halves. Each half moves to opposite sides of the cell, the meganucleus elongates, and the cytoplasm constricts, resulting in the production of two young paramecia.
Sexual reproduction in Paramecium involves conjugation between two individuals of different descent lines. Conjugation stages include the fusion of mature paramecia through their oral grooves, micronucleus division through meiosis, exchange of smaller micronuclei, fusion of migratory and stationary micronuclei to form a zygote, and subsequent division to produce new paramecia.
Spirogyra reproduces asexually via fragmentation and sexually through conjugation.
In fragmentation, when a filament reaches a certain length, parts break away, growing into new filaments.
Conjugation in Spirogyra involves two filaments lying side by side, forming a conjugation tube. One filament’s cells act as male gametes, and the other as female gametes. The male gamete passes through the conjugation tube, fusing with the female gamete to form a zygote. The zygote secretes a resistant wall, forming a zygospore, which, after a period of rest and favorable conditions, grows into a new filament.
Earthworms, being hermaphrodites, have both male and female sex organs, and reproduction occurs through sexual means.
During copulation, two earthworms come together with their ventral surfaces touching. Copulation takes place at night, outside burrows, with reproductive organs located anteriorly. After copulation, eggs are laid and fertilized in a cocoon secreted by the clitellum. Embryo development occurs inside the cocoon, and a worm hatches from a batch of eggs in each cocoon.
Cockroaches undergo sexual reproduction with internal fertilization. Mating occurs between male and female cockroaches, with the male introducing sperm into the female’s genital opening. Sperm is stored in a pouch until eggs are released from the ovaries. Fertilized eggs are then laid in a protective egg case (ootheca), which the female carries before depositing it in a secure location. After a period of 30–100 days, the eggs hatch into wingless, small, whitish nymphs. Metamorphosis is incomplete, requiring 11–20 months for development from eggs to adults.
Houseflies undergo sexual reproduction and complete metamorphosis.
After mating, female houseflies lay 2–7 batches of eggs in a moist, dirty environment, with 100–150 eggs in each batch. The eggs hatch into white larvae within 8–24 hours, developing into maggots with segmented bodies and spiny pads for movement. The larvae molt several times and last about 5–14 days before moving to a dry place to enter the pupal stage. The pupa, or puparium, eventually gives rise to a young adult housefly through a sac-like organ (ptilinum), which breaks open the puparium. The adult housefly, or imago, emerges and flies away when its wings are dry.
Reproduction in land snails is hermaphroditic and involves internal fertilization. The female snail has a fertilization pouch for sperm to travel into, and spermatophores are transferred to the epiphallus. The sperm is then transported to the bursa duct, where fertilization occurs. Snail development involves a 180o twist called torsion, bringing the anus and mantle cavity forward above the head.
Irritability denotes the capacity of organisms to react to stimuli, where stimuli refer to alterations in external or internal environmental conditions capable of influencing the activity of the entire organism or specific parts.
The term “response” characterizes the changes in the organism’s activity. Three primary response types exist: taxis (tactic movement), nastism (nastic movement), and tropism (tropic movement).
This involves directional movement or responses of entire organisms from one location to another in reaction to external stimuli like light, temperature, water, and specific chemicals. Examples include Euglena or Chlamydomonas swimming away from high light intensity (negative phototaxis) and moss plant sperm moving toward the chemical produced by the egg cell (positive chemotaxis).
Non-directional sleep movement or responses of a plant part to non-directional stimuli like light intensity, temperature, and humidity. Examples include the folding of mimosa plant leaflets when touched and the closing of morning glory flowers in low light intensity.
Unilateral growth and directional movement of a plant part in response to directional stimuli, controlled by plant hormones known as auxins. Examples include shoots bending towards light (positive phototropism) and roots bending away from light (negative phototropism).
Organisms move in search of food, water, mates, or to escape predators or harsh weather conditions.
Cyclosis, or cytoplasmic streaming, involves the rotational movement of the cytoplasm and its contents within cells. This facilitates substance transportation and material exchange between cell organelles, occurring in protozoa like amoeba (amoeboid movement) and chloroplasts of some plants adjusting their position for optimal sunlight exposure during photosynthesis.
Animals generally lack the ability to produce their own food and depend either directly or indirectly on plants for sustenance, classifying them as heterotrophs. Animals are categorized into three groups based on their dietary preferences:
Animal nutrition involves seven primary classes of food:
Carbohydrates, derived from foods like bread, yam, and rice, consist of carbon, hydrogen, and oxygen. They are classified into three types:
Importance of Carbohydrates:
Proteins are complex molecules composed of amino acids and include carbon, hydrogen, oxygen, nitrogen, and sometimes phosphorus and sulfur. Protein sources include eggs, meat, fish, and beans. Enzymes like pepsin, rennin, trypsin, and erepsin break down proteins into amino acids.
Importance of Proteins:
Fats are solid at room temperature, while oils are liquid. They consist of carbon, hydrogen, and a small amount of oxygen. Digestion results in fatty acids and glycerol. Sources include palm oil, groundnut, and soybeans. Lipids are broken down by lipase enzymes.
Importance of Fat and Oil:
Mineral salts, except for sodium chloride (table salt) and iron tablets, are consumed in small quantities through food. Essential minerals include calcium, magnesium, potassium, phosphorus, sulfur, chlorine, iron, iodine, fluorine, manganese, copper, cobalt, and sodium.
Importance of Mineral Salts:
Vitamins are organic substances required in small quantities for normal growth and development. They are grouped into water-soluble (B complex, C) and fat-soluble (A, D, E, K) vitamins.
Vitamins And Their Roles
Vitamins play crucial roles in maintaining overall health and well-being, contributing to various physiological functions within the body. Here is an overview of different vitamins, their sources, functions, and the potential symptoms associated with their deficiency:
Vitamin A:
Vitamin B1:
Vitamin B2:
Vitamin B3:
Vitamin B12:
Vitamin C:
Vitamin D:
Vitamin E:
Vitamin K:
Understanding the sources, functions, and potential deficiencies of these vitamins is crucial for maintaining a balanced and nutritious diet to support optimal health. Incorporating a variety of vitamin-rich foods into one’s diet ensures a well-rounded and comprehensive intake of essential nutrients.
Water, composed of hydrogen and oxygen, is crucial for all organisms. It can be obtained from various sources such as food, rivers, streams, and ponds, constituting 75% of the human body.
Importance Of Water
Roughages refer to indigestible fibrous materials derived from vegetables, fruits, carbohydrates, and proteins. They play a role in aiding digestion, and their absence can lead to constipation.
A balanced diet consists of a correct proportion of all essential food substances. In general, a balanced diet comprises 15% protein, 15% fat and oil, 10% vitamins, minerals, and water, and 60% carbohydrates. Consuming food in these proportions promotes normal growth and development in the body.
Functions Of Balanced Diet
Enzymes, organic catalysts produced by living cells, accelerate or decelerate chemical reactions. Digestive enzymes aid in breaking down complex food substances into simpler, soluble forms. Characteristics of enzymes include:
Digestive enzymes are categorized based on the type of food they act upon:
Biomes are extensive natural terrestrial ecosystems distinguished by their predominant vegetation. The composition of plant life, including factors like densely packed tall trees in a forest biome or scattered shrubs in a savanna biome, characterizes these terrestrial ecosystems. The type of vegetation present in a biome is determined by climatic elements such as rainfall, relative humidity, temperature, wind, and light.
Local biomes specific to Nigeria encompass the mangrove swamp, tropical rainforest, and various savanna types (northern and southern Guinea savanna, Sudan savanna, and Sahel savanna).
Located in tropical coastal regions and river mouths, mangrove swamps consist of small, evergreen, broad-leaved trees growing in shallow, brackish water or wet soil. Notable in Nigeria’s delta region, these swamps experience a hot and wet climate with an annual rainfall exceeding 250cm and temperatures around 26°C.
Situated between the equator and latitudes 5-10°N and S, tropical rainforests in Nigeria (e.g., Edo, Delta, Ondo, Imo, Lagos, Rivers) exhibit characteristics such as lowland terrain, hot and wet climates, broad-leaved evergreen trees, and a rich diversity of epiphytes and wood climbers. Annual rainfall and temperatures hover around 200cm and 27°C, respectively.
Tropical grasslands in Africa, savannas are flat expanses dominated by grasses. In Nigeria, there are various types:
Temperature and rainfall play pivotal roles in determining world biomes, which encompass tropical rainforests, temperate forests, coniferous forests, temperate shrublands, savannas, temperate grasslands, deserts, tundras, and mountain vegetation.
Characterized by broad-leaved deciduous trees shedding leaves in winter, temperate forests have a moderately wet climate with dry or cold seasons.
Defined by needle-leaved evergreen conifers like pines and firs, coniferous forests have few trees, a tall upper storey, and a forest floor covered in conifer needles. They experience cool temperatures, light rainfall, and snow.
Comprising drought-resistant shrubs and dwarf trees (e.g., marquis), temperate shrublands have a temperate climate with low rainfall.
Featuring perennial grasses on fertile soil supporting grazing mammals, temperate grasslands have a moderately dry climate with cold winters and hot summers.
Tropical grasslands with scattered trees, often on infertile soil, savannas experience a moderately dry climate with a warm dry season and a hot rainy season.
Characterized by very sparse vegetation and succulent perennials with deep root systems, deserts occur in tropical, temperate, and afro-alpine regions with less than 25 cm annual rainfall.
Treeless marshy vegetation consisting mainly of dwarf shrubs, grasses, lichen, and moss characterizes the tundra, with a cold climate featuring long icy winters and very short summers.
Evergreen rainforests on mountain slopes are less luxuriant than tropical rainforests. Afro-alpine vegetation occurs at heights above 3000m, featuring heath, grasses, and sedges.
Population characteristics encompass various factors such as population size, density, frequency, percentage cover, and distribution.
These ecological factors can be quantified using various instruments:
Living organisms rely on obtaining energy and nutrients from their environment to survive, categorizing them into feeding relationships. This categorization results in three major groups within a biotic community: producers (autotrophs), consumers (heterotrophs), and decomposers.
Autotrophs, such as grasses, trees, and seaweeds, serve as a food source for organisms within terrestrial and aquatic habitats. Heterotrophs, including herbivores, carnivores, and omnivores, consume these autotrophs, with examples like cows, lions, and water fleas. Decomposers, such as termites and bacteria, break down dead organic matter, releasing simple compounds for reuse.
Among these biotic groups, consumers generally have a higher chance of survival in an ecosystem.
In ecosystems, energy and nutrients move through organisms in a step-by-step manner along feeding pathways. These pathways share a common pattern:
Trophic levels, representing each step in a feeding pathway, are numbered in ascending order, indicating the flow of energy.
Food chains depict the linear transfer of energy from producers to consumers. Examples include terrestrial and aquatic chains involving grass, zebra, lion, spirogyra, tadpoles, and kingfish.
Food webs are complex relationships formed by interconnecting two or more food chains, involving numerous organisms. Consumers in food webs have a better chance of survival due to their ability to feed on various plants or animals.
Pyramids (number, energy, biomass) represent ecological concepts.
Energy is lost in ecosystems due to respiration and heat transfer along the food chain. Only a small percentage of solar energy is available to photosynthetic producers.
Mutualism or symbiosis occurs when both populations benefit, and at least one is so dependent on the other for a critical resource or function that it cannot survive in the given environment without the other species. Examples include:
Protocooperation is an association between organisms of different species in which both benefit but can also survive individually. Examples include:
Commensalism is an association where one organism benefits, and the other is neither harmed nor benefited. Examples include:
Amensalism is an association where one species is inhibited or killed, and the other is unaffected. Examples include:
Parasitism is a close association where one organism (parasite) lives on or in another (host), benefiting at the host’s expense. Examples include:
Predation involves one organism (predator) killing and feeding on another (prey). Examples include:
Micro-organisms, also known as microbes or germs, are living entities that cannot be observed with the naked eye but require microscopes for visibility. They are omnipresent, inhabiting various environments such as water, air, soil, surfaces of objects, and within living organisms. Air currents carry them from the Earth’s surface to the upper atmosphere, and they thrive where there is sufficient food, moisture, and a suitable temperature for growth.
The invention of the microscope by Dutchman Anthony Leeuwenhoek (1632-1723) revealed the existence of these tiny organisms. Leeuwenhoek, using a simple microscope, made the surprising discovery that rainwater collected from pools was teeming with microorganisms.
Micro-organisms encompass viruses, bacteria, protists, cyanobacteria, certain fungi, and algae. Bacteria, minute unicellular organisms or simple associations of similar cells, multiply by binary fission. They lack a well-defined nucleus, making them prokaryotic organisms. Various types of bacteria exhibit different shapes, such as cocci (spherical), bacilli (rod-shaped), spirilla (spiral), and vibrios (comma-shaped). Examples include streptococci, staphylococci, diplococci, and bacilli, each causing specific conditions like sore throat or typhoid fever.
Viruses, a group of pathogens, become noticeable only when in contact with living cells. They are extremely small, with a diameter ranging between 0.1µ-0.25µ. Viruses consist of nuclear material (DNA or RNA) enclosed within a protein coat.
Protists are single-celled animals visible only through microscopes, commonly found in fresh water and moist soils. Examples include Euglena, Paramecium, Trypanosoma, and Plasmodium.
Fungi, diverse in form, manifest as blue and green growth on fruits or the white/grey growth on bread. Common fungi include Mucor, Rhizopus, Penicillium, and Aspergillus.
Algae, mostly unicellular and small, contain chlorophyll and are abundant in water, moist soils, bark of trees, and stones. Phytoplanktons are free-floating microscopic algae and serve as a major food source for aquatic animals.
The cultivation of microbes under laboratory conditions, known as culturing, is essential for studying them. Culture mediums, such as agar, provide a platform for microbial growth. Identification methods involve microscopy, stains, colony types, food requirements, and oxygen needs.
Micro-organisms exist in air, water, soil, and sewage, with examples like viruses, bacteria, fungi, and protists. In our bodies, microbes form a normal population without harm, but under certain conditions, they can become pathogenic, causing diseases when body resistance is low.
Carriers of microorganisms can be living or non-living agents. Non-living carriers include air, water, and food, while animals like houseflies, mosquitoes, rats, and cats serve as living carriers. Vectors or carriers can transmit diseases such as malaria, sleeping sickness, cholera, typhoid fever, and yellow fever.
Bacteria undergo reproduction through a process known as binary fission, where a single cell divides into two. This method is referred to as asexual reproduction. The time it takes for a cell to divide into two is termed the generation time, which varies among different organisms based on factors such as nutrient availability, temperature, gaseous requirements, and pH.
Bacterial growth consists of distinct phases, including the lag phase, logarithmic or exponential phase, stationary phase, and decline or death phase. Various methods, such as turbidity, serial dilution, and squared transparent paper or cellophane, can be employed to measure microbial growth.
Beneficial Effects:
Harmful Effects:
Chickenpox:
Chickenpox is caused by the Varicella Virus, and its symptoms include fever, tiredness, and an itchy rash. The transmission occurs through contact, and the control measures involve isolating the patient and administering appropriate drugs.
Cholera:
Cholera, induced by Vibrio Cholerae, manifests as watery diarrhea, vomiting, and leg cramps. Transmission occurs through flies, food, faeces, and carriers, emphasizing the importance of personal hygiene as a control measure.
Common Cold:
Rhino Virus is the culprit behind the common cold, leading to symptoms like cough, runny nose, and shivering. Its transmission is primarily through contact, and controlling it involves taking appropriate medications and avoiding contact.
Dengue:
Dengue, caused by the Dengue Virus, results in severe headache, eye pain, joint pain, and rash, among other symptoms. Aedes Mosquitoes transmit it, prompting control measures such as draining water and clearing bushes to reduce mosquito habitats.
Diarrhoea:
Giardia intestinalis causes diarrhea with symptoms like frequent passing of watery faeces, cramps, and nausea. The transmission is through contaminated stools, making personal hygiene crucial for control.
Diphtheria:
Corynebacterium diphtheriae causes diphtheria, characterized by sore throat, difficulty breathing, and fever. It spreads through contact, and control involves using antibiotics and avoiding contacts.
Leprosy:
Leprosy, caused by Mycobacterium leprae, results in disfiguring skin sores and muscle weakness. Long and close contact contribute to transmission, and control measures include antibiotics, avoiding contacts, and isolating patients.
Measles:
Measles, caused by the Measles virus, presents symptoms like high temperature, cough, and diarrhea. The transmission is through contact, and control measures include appropriate medication and avoiding contact.
Pneumonia:
Diplococcus pneumonia causes pneumonia with symptoms like high fever and difficulty breathing. Bacteria transmission through contact highlights the importance of using antibiotics and avoiding contact for control.
Poliomyelitis:
Poliomyelitis, caused by Polio Virus or Enterovirus, induces symptoms like fever and muscle weakness. Houseflies, food, and water contribute to transmission, and control involves good hygiene and appropriate medication.
Rabies:
Rabies, caused by the Rhabdovirus, results in fever, cough, and sore throat. Its transmission occurs through mad dog bites, and control measures include treating dogs and seeking urgent medical attention for bites.
Septic Sore Throat:
Streptococcus Bacteria cause septic sore throat, leading to fever and difficulty swallowing. Transmission is through contact, and control involves using antibiotics and avoiding contact.
Sleeping Sickness:
Tryponosoma Brucei causes sleeping sickness, featuring anxiety, fever, and swollen lymph nodes. Transmission through fly bites underscores the need to clear vegetation, use insecticides, and administer medication.
Smallpox:
Smallpox, caused by the Variola Virus, exhibits symptoms like high fever and vomiting. The transmission occurs through contact, and control measures involve appropriate medication and avoiding contact.
Tuberculosis:
Mycobacterium tuberculosis causes tuberculosis, leading to symptoms like malaise and weight loss. Bacteria transmission through cough emphasizes the need to isolate patients and use appropriate antibiotics.
Tetanus:
Clostridium tetani causes tetanus, resulting in muscle spasms and breathing problems. Transmission through bacteria in soil highlights the urgency of treating wounds.
Typhoid:
Salmonella Typhi induces typhoid with symptoms like abdominal tenderness and confusion. Flies, food, and other means contribute to transmission, and control involves treating water, maintaining hygiene, and using antibiotics.
Whooping Cough:
Hameophilius Pertussis causes whooping cough, featuring coughing and breathing difficulties. Transmission occurs through coughing and sneezing, and control measures involve isolating patients and using appropriate antibiotics.
Influenza Flu:
Orthomixovirus causes influenza flu, presenting symptoms like fever and sore throat. Transmission is through contact, and control involves taking appropriate medication and avoiding contact.
Malaria:
Malaria, caused by Plasmodium and transmitted through female Anophelex mosquitoes, leads to symptoms like chills and muscle aches. Control measures include using drugs, insecticides, and other preventive measures.
Sexually Transmitted Infections (STIs), also known as venereal diseases, are contracted through sexual intercourse. Examples include syphilis, gonorrhea, herpes, thrush, AIDS, etc. The following information outlines various STIs, their causative organisms, symptoms, and prevention/control measures.
Causative Organism: Bacterium (Neisseria gonorrhea)
Symptoms:
Prevention/Control:
Causative Organism: Human immune-deficiency virus (HIV)
Symptoms:
Prevention/Control:
Symptoms:
Prevention/Control:
HIV (Acquired Immune Deficiency Virus) causes AIDS, a sexually transmitted disease that breaks down the immune system. HIV belongs to a group of RNA viruses called retroviruses, capable of converting RNA to DNA. They attack and destroy helper T cells or CD4 (lymphocytes).
Mode Of Transmission
Apart from sexual intercourse, HIV can be transmitted through:
The management of harmful microbes involves employing physical agents/processes and chemical agents or antibiotics to achieve removal, growth inhibition, or killing. Common methods to control harmful microorganisms for the maintenance of good health include:
A vector, an animal transmitting disease-causing organisms, can be controlled through various measures:
To maintain good health, practices such as proper refuse disposal, sewage disposal, protection of water, and protection of food are essential:
Refuse disposal:
Sewage disposal:
Protection of water:
Protection of food:
The administration of health services in Nigeria involves various organizations, including:
International health organizations play a crucial role in disease prevention and providing aid to needy areas. Some of these organizations include:
Plants exhibit diverse forms and types, necessitating classification based on various criteria. The following are the bases for plant classification:
The principle of binomial nomenclature subdivides the plant kingdom into divisions, classes, orders, families, genera, and species, based on structures, functions, and evolutionary trends. Plants are generally grouped into three broad categories:
Tracheophytes further branch into pteridophytes (D) and spermatophytes (E). Spermatophytes include gymnosperms (F) and angiosperms (G), which are further subdivided into dicots (H) and monocots (I).
Plants are classified agriculturally based on:
Agricultural classifications encompass:
Plants are categorized based on life cycle (annuals, biennials, and perennials) and size (herbs, shrubs, and trees).
Size categories include:
Various agricultural practices impact ecological systems. Examples include:
A pest is an organism that hosts disease organisms or causes damage to other organisms. There are crop pests, such as insects like grasshoppers, mealy bugs, myriads, beetles, birds, and mammals (such as rodents), and livestock pests, including ectoparasites like ticks and mites, and endoparasites like liver flukes, roundworms, and tapeworms. Additionally, there are plant pests known as weeds or animal pests like insects, birds, rodents, monkeys, humans, or nematodes.
Insect pests are arthropods that carry diseases or cause damage to plants and animals, such as ticks, lice, grasshoppers, and cotton stainers. Non-insect pests are vertebrates and mollusks that commonly cause disease to plants and animals or destroy crops, such as rodents, worms, nematodes, and monkeys.
A parasite is an organism that lives in or on another organism, known as a host, and has harmful effects on the host due to the association. There are endoparasites, such as tapeworms, roundworms, and liver flukes, that live inside the host, and ectoparasites, such as ticks, lice, and mites, that live on or outside the host.
Ticks:
Liver fluke (Fasciola hepatica):
Roundworm (Ascarissuum):
Lice:
Tse-tse fly:
Pests can lead to a reduction in crop and plant yield, a decrease in the quality of farm produce, an increase in production control costs, a reduction in farmers’ income, unattractive and unmarketable farm produce, malformation in plants and animals, and the death of plants and animals.
A disease is a deviation from the normal state of health in plants or animals, presenting visible symptoms. Disease pathogens include bacteria, viruses, fungi, nematodes, and protozoa.
Maize rust:
Groundnut rosette:
Rice blasts:
Cassava mosaic:
Cocoa black pod:
Cassava wilt:
Cocoa swollen shoot:
Newcastle Disease (Poultry)
Rinderpest (Cattle)
Anthrax (Cattle, Goat, Sheep)
Coccidiosis (Poultry)
Trypanosomiasis (Cattle)
Food production relies on various factors, including the government’s role in agricultural activities, environmental conditions essential for food production, methods to enhance crop yield, and the consequences of food shortage on population size.
The role of government encompasses the provision of agro-chemicals, financial assistance, high-quality planting materials, tractors, extension services, river basin authorities, storage and processing facilities, efficient transportation networks, quarantine measures, and research work.
Environmental factors affecting food production include both biotic and abiotic elements. Biotic factors comprise rainfall, temperature, wind, sunlight, relative humidity, solar radiation, and edaphic factors such as soil pH, texture, and structure. Biotic factors involve soil organisms, pests, parasites, diseases, weeds, and predators.
Methods for improving food production include crop improvement techniques, strategic plant timing, adoption of superior cultivation methods, weed control, use of quality crop varieties, application of resistant varieties, utilization of manures and fertilizers, pest and disease control.
Food shortage directly impacts population size, leading to consequences such as increased food costs, competition, cannibalism, emigration, and higher mortality rates.
Food preservation methods involve salting, drying, smoking, refrigeration/freezing, pasteurization, canning/bottling, irradiation, and the use of chemicals. Each method employs specific principles to inhibit microbial growth and extend the shelf life of food.
Food storage has positive effects, including preventing hunger and famine, maintaining stable prices, reducing the impact of natural disasters, and providing employment opportunities in food processing companies.
The eyes are remarkable sensory organs that grant us the ability to see, offering a rich perception of the world around us.
The eyes are not only essential for daily activities but also convey emotions and non-verbal communication. Maintaining optimal eye health through regular check-ups, protection, and healthy habits is crucial for clear and comfortable vision throughout life.
The human eyes operate in a complex manner to gather, process, and interpret visual information. Here’s a simplified overview:
This intricate process enables us to see and understand our surroundings, combining anatomy, optics, and neurology to provide the gift of sight.
Solution: Glasses, contact lenses, or refractive surgery like LASIK.
Solution: Reading glasses or multifocal lenses.
Solution: Cataract surgery involving the removal of the cloudy lens.
Solution: Medications, laser surgery, or traditional surgery to lower intraocular pressure.
Solution: Anti-VEGF injections or laser therapy.
Solution: Controlling blood sugar, anti-VEGF injections, or laser therapy.
Solution: Artificial tears, prescription medications, or lifestyle changes.
Solution: Antibiotics for bacterial conjunctivitis, antihistamine drops for allergic conjunctivitis.
Solution: Emergency surgery to reattach the retina.
Solution: Antibiotics or antifungal medication, pain management.
Solution: Ptosis repair surgery to lift the drooping eyelid.
Solution: No cure, but color vision aids may help.
Symptoms: Blurred vision, eye strain, headaches.
Symptoms: Cloudy vision, faded colors, glare, poor night vision.
Symptoms: Often asymptomatic; signs include increased intraocular pressure and peripheral vision loss.
Symptoms: Blurred central vision, difficulty recognizing faces.
Symptoms: Blurred vision, floaters, vision loss.
Symptoms: Dryness, redness, itching, burning, sensitivity to light.
Symptoms: Redness, itching, tearing, discharge.
Symptoms: Sudden floaters, flashes of light, curtain-like shadow in vision.
Symptoms: Pain, redness, blurred vision, sensitivity to light.
Symptoms: Drooping eyelid, impaired vision in severe cases.
Symptoms: Difficulty distinguishing certain colors.
Conclusion:
Understanding the complexity, functions, and care of the eyes is crucial for maintaining optimal vision and eye health. Regular eye check-ups, protective measures, and a healthy lifestyle contribute to long-lasting visual well-being. Whether appreciating the beauty of the world or expressing emotions through gaze, our eyes play a central role in the human experience.
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