Lesson Notes By Weeks and Term v3 - Senior Secondary 1
Nutrition in Animals
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Nutrition in Animals
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Subject: Biology
Class: Senior Secondary 1
Term: 3rd Term
Week: 2
Theme: The Organisation At Work
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Define what foodsubstances are. List types of foodsubstances and statewhat makes a balanceddiet is. List types of heterotrophic nutritionand feedingmechanisms in holozoicorganisms. (i) List types of mammalian teeth.(ii) Describe the structure of amammalian to oth.(iii) State the dentalformula and adaptations of dentitionto mode of nutrition. Describe digestion in Amoeba, Earthworm,Cockroach, grasshopperand birds.
Definition: Food substances are chemical compounds present in food that provide energy, raw materials for growth and repair, and regulate body processes. They are essential for the survival and proper functioning of an organism. Types of Food Substances and their Functions: Carbohydrates: Composition: Carbon, Hydrogen, Oxygen (CHO).
Types: Monosaccharides (glucose, fructose), Disaccharides (sucrose, lactose), Polysaccharides (starch, glycogen, cellulose).
Functions: Primary source of energy for metabolic activities, structural components (e.g., cellulose in plant cell walls, which forms roughage), stored as glycogen in animals. Nigerian
Examples: Yam, rice, garri, cassava, plantain, maize, bread.
Proteins: Composition: Carbon, Hydrogen, Oxygen, Nitrogen (CHON), sometimes Sulphur (S) and Phosphorus (P). Made up of amino acids.
Functions: Body building (growth and repair of tissues), enzyme production (catalyse biochemical reactions), hormone production, antibody formation (immunity), secondary energy source. Nigerian
Examples: Beans, meat (beef, goat meat, chicken), fish (tilapia, catfish), eggs, milk, groundnut.
Fats and Oils (Lipids): Composition: Carbon, Hydrogen, Oxygen (CHO), but with less oxygen than carbohydrates.
Functions: Concentrated source of energy (twice as much as carbohydrates), insulation against heat loss, protection of delicate organs, solvent for fat-soluble vitamins (A, D, E, K). Nigerian
Examples: Palm oil, groundnut oil, butter, margarine, avocado, fatty meat.
Vitamins: Composition: Organic compounds required in small quantities.
Types: Water-soluble (B complex, C) and Fat-soluble (A, D, E, K).
Functions: Act as co-enzymes, regulate metabolism, maintain healthy tissues and organs, boost immunity. Nigerian
Examples: Vitamin A: Carrots, liver, palm oil, green leafy vegetables (ugu, spinach).
Vitamin C: Oranges, guava, tomatoes, pawpaw, mango.
Vitamin D: Sunlight, fortified milk, eggs.
Minerals: Composition: Inorganic elements required in small quantities.
Types: Macro-minerals (calcium, phosphorus, potassium, sodium) and Trace minerals (iron, iodine, zinc, fluorine).
Functions: Building strong bones and teeth (calcium, phosphorus), nerve impulse transmission (sodium, potassium), oxygen transport (iron in haemoglobin), thyroid hormone production (iodine). Nigerian
Examples: Calcium: Milk, fish, leafy greens.
Iron: Liver, red meat, beans, green leafy vegetables.
Iodine: Iodized salt, seafood.
Water: Composition: H2
O. Functions: Solvent for most chemical reactions, transport medium (blood, lymph), regulates body temperature, lubricates joints, essential for digestion and absorption. Nigerian
Examples: Drinking water, water in fruits, vegetables, soups.
Roughages (Dietary Fibre): Composition: Undigested plant material, mainly cellulose.
Functions: Adds bulk to food, aids peristalsis (movement of food through the digestive tract), prevents constipation, helps regulate blood sugar and cholesterol levels. Nigerian
Examples: Whole grains (whole wheat bread, brown rice), fruits (orange, apple with skin), vegetables (cabbage, lettuce), beans.
Balanced Diet: A balanced diet is a meal that contains all the essential food substances (carbohydrates, proteins, fats, vitamins, minerals, water, and roughages) in the correct proportions, sufficient for the body's needs, depending on age, sex, occupation, and physiological state (e.g., pregnancy).
Nigerian Context: A balanced diet can be achieved using locally available foods. For example, a meal of 'eba' (cassava flour) with 'egusi' soup (melon seed soup rich in protein and fat, with leafy vegetables for vitamins, minerals, and roughage) and fish or meat provides a good balance.
Heterotrophic Nutrition Definition: Nutrition in which organisms cannot synthesize their own food and must obtain organic compounds from external sources. All animals are heterotrophs.
Types of Heterotrophic Nutrition: Holozoic Nutrition: Involves the ingestion of solid or liquid organic food materials, which are then digested, absorbed, and assimilated. This is the most common type in animals.
Stages: Ingestion, Digestion, Absorption, Assimilation, Egestion.
Sub-types based on diet: Herbivores: Feed on plants (e.g., goat, cow, rabbit).
Carnivores: Feed on other animals (e.g., lion, dog, eagle).
Omnivores: Feed on both plants and animals (e.g., human, pig, bear).
Detritivores: Feed on dead organic matter (e.g., earthworm, millipede).
Saprophytic Nutrition: Organisms (e.g., fungi, bacteria) secrete digestive enzymes onto dead organic matter externally and then absorb the digested nutrients. (While primarily associated with fungi/bacteria, some animals, like carrion beetles, exhibit similar absorption of decaying matter products, though often involving some form of ingestion).
Parasitic Nutrition: Organisms (parasites) live in or on another living organism (host) and obtain nutrients directly from the host, often harming it in the process.
Examples: Ectoparasites: Live on the host's surface (e.g., tick on cattle, mosquito feeding on humans, lice on humans).
Endoparasites: Live inside the host (e.g., tapeworm in human intestine, Plasmodium (malaria parasite) in human blood, liver fluke in sheep).
Feeding Mechanisms in Holozoic Organisms: These are the diverse ways animals acquire and ingest food.
Filter Feeding (Suspension Feeding): Organisms filter small food particles (plankton, detritus) suspended in water.
Mechanism: Specialized structures (e.g., gills, baleen plates) create water currents and strain food.
Examples: Tadpoles, clams, oysters, flamingos, baleen whales.
Fluid Feeding: Organisms feed on liquid food.
Mechanism: Piercing-sucking mouthparts (e.g., proboscis) to draw blood, nectar, or plant sap.
Examples: Mosquito (blood), butterfly (nectar), tsetse fly (blood), aphid (plant sap).
Deposit Feeding: Organisms ingest sediments (soil, mud) and extract organic matter.
Mechanism: Ingesting large quantities of substrate.
Examples: Earthworms, sea cucumbers.
Mass Feeding: Ingestion of large chunks of solid food.
Mechanism: Biting, chewing, swallowing. Most common type.
Examples: Humans, dogs, lions, goats, birds of prey.
Capture and Swallow: Organisms capture prey whole and swallow it without significant chewing.
Mechanism: Often involves large, extensible mouths and backward-pointing teeth.
Examples: Snakes, frogs, some fish (e.g., catfish). gap between the incisors/canines and the premolars/molars. This allows the tongue to manipulate food and store freshly cut grass while chewing.
Jaws: Strong jaw muscles, but articulation allows for extensive side-to-side grinding motions. Carnivores (e.g., Lion, Dog): Incisors: Small, sharp, and pointed, used for gripping and stripping flesh from bone.
Canines: Long, sharply pointed, and well-developed for piercing, tearing flesh, and holding prey.
Premolars and Molars: Often blade-like and pointed, with sharp cusps. The last upper premolar and first lower molar are often modified into large, shearing carnassial teeth for slicing meat and crushing bone.
Jaws: Strong, with powerful jaw muscles. Articulation allows for strong up-and-down shearing movements, but limited side-to-side motion. Omnivores (e.g., Human, Pig): Incisors: Chisel-shaped for biting.
Canines: Pointed but not as developed as in carnivores, for tearing.
Premolars and Molars: Relatively flat with cusps, suitable for both crushing plant material and grinding meat. Generalized dentition allowing for a varied diet. * Jaws: Articulation allows for a combination of up-and-down, side-to-side, and some forward-and-backward movements, facilitating versatile chewing. (i)
Types of Mammalian Teeth: Mammals typically have heterodont dentition, meaning different types of teeth specialized for different functions.
1. Incisors (I): Location: Front of the mouth.
Structure: Chisel-shaped, sharp edges.
Function: Cutting, biting, gnawing food.
2. Canines (C): Location: Next to incisors.
Structure: Pointed, conical, often long.
Function: Tearing, piercing food, holding prey. Reduced or absent in herbivores.
3. Premolars (P): Location: Between canines and molars.
Structure: Broader than canines, often with two cusps (bicuspid), sometimes called grinding teeth.
Function: Crushing, grinding, shearing food.
4. Molars (M): Location: Rear of the mouth.
Structure: Largest teeth, broad, flat surfaces with multiple cusps.
Function: Grinding, crushing, pulverizing food. (ii)
Structure of a Mammalian Tooth: A typical mammalian tooth consists of three main parts:
1. Crown: The visible part of the tooth, projecting above the gum.
2. Neck (Cervix): The constricted region where the crown meets the root, usually covered by the gum.
3. Root: The part embedded in the jawbone, anchoring the tooth.
Internal Structures: Enamel: The hardest substance in the body, covers the crown. It protects the tooth from wear and tear and chemical degradation.
Dentine: A bone-like material forming the bulk of the tooth, under the enamel and cement. It is less hard than enamel but harder than bone. It contains microscopic tubules that connect to the pulp cavity.
Pulp Cavity: The central cavity within the dentine, extending into the root canals. It contains soft connective tissue, blood vessels (supply nutrients), and nerves (for sensation).
Cement (Cementum): A bone-like tissue covering the root surface. It helps anchor the tooth to the jawbone by attaching to the periodontal ligament.
Periodontal Ligament: Fibrous connective tissue that connects the cementum of the tooth root to the alveolar bone of the jaw, holding the tooth in place and acting as a shock absorber. (iii) Dental Formula and Adaptations of Dentition to Mode of Nutrition: Dental Formula: A concise way to represent the number and arrangement of teeth in one half of the upper and lower jaws.
It is written as: I C P M / I C P M Where I=Incisors, C=Canines, P=Premolars, M=Molars. The numbers above the line represent teeth in the upper jaw, and below the line for the lower jaw. The total number of teeth is found by summing all numbers and multiplying by two.
Human (Adult - Omnivore): I 2/2 C 1/1 P 2/2 M 3/3 = 16 x 2 = 32 teeth. (This indicates 2 incisors, 1 canine, 2 premolars, and 3 molars in each half of the upper jaw, and similarly for the lower jaw).
Dog (Carnivore): I 3/3 C 1/1 P 4/4 M 2/3 = 21 x 2 = 42 teeth.
Sheep/Goat (Herbivore - Ruminant): I 0/3 C 0/1 P 3/3 M 3/3 = 16 x 2 = 32 teeth. (Note the dental pad in the upper jaw instead of incisors and canines, and the presence of only a single canine in the lower jaw often resembling an incisor). Adaptations of Dentition to Mode of Nutrition: Dentition is highly adapted to an animal's diet. Herbivores (e.g., Cow, Goat, Sheep): Incisors: Often absent in the upper jaw, replaced by a tough, cartilaginous dental pad against which lower incisors bite to shear off vegetation. Lower incisors are sharp and shovel-shaped.
Canines: Usually absent or indistinguishable from incisors.
Premolars and Molars: Broad, flat surfaces with complex ridges (cusps) for grinding tough plant material. The jaw moves sideways (ruminants) for efficient grinding.
Diastema: A significant gap between the incisors/canines and the premolars/molars. This allows the tongue to manipulate food and store freshly cut grass while chewing.
Jaws: Strong jaw muscles, but articulation allows for extensive side-to-side grinding motions. Carnivores (e.g., Lion, Dog): Incisors: Small, sharp, and pointed, used for gripping and stripping flesh from bone.
Canines: Long, sharply pointed, and well-developed for piercing, tearing flesh, and holding prey.
Premolars and Molars: Often blade-like and pointed, with sharp cusps. The last upper premolar and first lower molar are often modified into large, shearing
Health and Nutrition Education: Balanced Diet: Emphasize the importance of consuming a balanced diet using readily available and affordable Nigerian food items to prevent malnutrition (e.g., Kwashiorkor from protein deficiency, Marasmus from general calorie deficiency, Vitamin A deficiency causing night blindness). Students can learn to plan healthy meals for their families.
Dental Hygiene: Understanding tooth structure and function highlights the need for proper dental care (e.g., regular brushing, avoiding excessive sugary foods, use of chewing sticks as a traditional practice) to prevent dental caries and gum diseases, which are prevalent in communities.
Agriculture and Livestock Management: Animal Feed: Knowledge of animal nutrition helps farmers understand appropriate feeding strategies for different livestock (e.g., cattle as herbivores, poultry as omnivores) to optimize growth and productivity. This includes understanding the role of roughage for ruminants and concentrated feed for others.
Pest Control: Understanding the feeding mechanisms of insects (e.g., grasshoppers, cockroaches, mosquitoes) is crucial for developing effective pest control strategies in agriculture (e.g., using pesticides that interfere with chewing mouthparts) and public health (e.g., targeting mosquito fluid feeding for malaria prevention).
Environmental Awareness and Food Security: Food Web Dynamics: By studying different feeding mechanisms (herbivory, carnivory, omnivory), students can better understand how energy flows through local ecosystems and the interconnectedness of species in their environment (e.g., the impact of overfishing on local communities).
Sustainable Food Systems: Discussions on diverse diets and food sources can lead to a deeper appreciation of biodiversity and the need for sustainable farming practices to ensure food security for Nigeria's growing population.