Biology Keypoints; Nutrition

Biology Keypoints; Nutrition; Nutrition is the process by which organisms obtain energy and essential nutrients from food. There are two main modes of nutrition: autotrophic and heterotrophic.

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Autotrophic Nutrition:

Autotrophic nutrition is a type of nutrition in which organisms synthesize their own food from inorganic substances such as carbon dioxide and water. Autotrophs are capable of using light energy (phototrophs) or chemical energy (chemotrophs) to synthesize organic compounds.

Photosynthesis is the most common form of autotrophic nutrition, in which chlorophyll-containing cells capture light energy and use it to convert carbon dioxide and water into glucose and oxygen. Photosynthesis occurs in plants, algae, and some bacteria.

Chemosynthesis is another form of autotrophic nutrition in which organisms use the energy from chemical reactions to produce organic compounds. Chemosynthesis occurs in some bacteria and archaea living in extreme environments such as deep-sea hydrothermal vents.

Heterotrophic Nutrition:

Heterotrophic nutrition is a type of nutrition in which organisms obtain organic compounds from other organisms. Heterotrophs are incapable of synthesizing their own food and must consume other organisms or their by-products to obtain energy and essential nutrients.

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There are several types of heterotrophic nutrition:

1. Holozoic nutrition: This type of nutrition involves the ingestion of complex organic compounds such as proteins, carbohydrates, and lipids, which are broken down into smaller molecules by digestive enzymes before being absorbed by the organism. Holozoic nutrition is seen in animals such as humans, dogs, and sheep.
2. Parasitic nutrition: Parasites are organisms that live on or inside another organism (the host) and obtain their nutrients from the host. Parasites can be unicellular or multicellular and can cause a variety of diseases in their hosts. Examples of parasitic nutrition include tapeworms, roundworms, and the Loranthus plant.
3. Saprophytic nutrition: Saprophytes are organisms that obtain their nutrients from dead and decaying organic matter. These organisms play an important role in the decomposition and recycling of organic material. Examples of saprophytic nutrition include fungi such as Rhizopus and mushrooms.
4. Carnivorous nutrition: Carnivorous plants are plants that capture and digest insects and other small animals to obtain nutrients that are lacking in their environment. Examples of carnivorous plants include the sundew and bladderwort.

In conclusion, understanding the modes and types of nutrition is crucial in understanding how organisms obtain their energy and essential nutrients to carry out metabolic activities. Autotrophic and heterotrophic nutrition are the two main modes of nutrition, and the types of heterotrophic nutrition include holozoic, parasitic, saprophytic, and carnivorous nutrition.

Types of Nutrition:

Plant Nutrition:

Plants are classified as autotrophs since they are capable of producing their food. They synthesize organic food materials from inorganic raw materials, mainly carbon dioxide, and water, in the presence of sunlight. This process is called photosynthesis.

i. Photosynthesis:

Photosynthesis is a process by which green plants manufacture their food using sunlight, carbon dioxide, and water. The process takes place in chloroplasts, which are found in the mesophyll cells of leaves. Chloroplasts contain a pigment called chlorophyll, which absorbs light energy and converts it into chemical energy that is stored in glucose.

Photosynthesis occurs in two stages:

a. Light-dependent reactions:

During light-dependent reactions, light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). The oxygen molecule is also released during this stage, as it is a byproduct of water splitting.

b. Light-independent reactions:

During the light-independent reactions, also known as the Calvin cycle, carbon dioxide is fixed into organic compounds using the ATP and NADPH produced in the light-dependent reactions. The organic compounds produced during this stage are used by the plant as a source of energy and building materials.

ii. Mineral requirements (macro and micro-nutrients):

Plants require various minerals to grow and function properly. These minerals are classified as either macro-nutrients or micro-nutrients.

a. Macro-nutrients:

Macro-nutrients are required in large amounts by plants. These include nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

• Nitrogen is required for the production of chlorophyll, amino acids, and nucleic acids. It is often a limiting factor in plant growth.
• Phosphorus is required for the production of ATP and nucleic acids. It is also involved in the formation of cell membranes and cell walls.
• Potassium is involved in the regulation of water balance in cells and the activation of enzymes.
• Calcium is required for the formation of cell walls and the regulation of membrane permeability.
• Magnesium is required for the production of chlorophyll and the activation of enzymes.
• Sulfur is required for the production of amino acids and the formation of proteins.

b. Micro-nutrients:

Micro-nutrients are required in smaller amounts by plants. These include iron, manganese, zinc, copper, boron, molybdenum, and chlorine.

• Iron is required for the production of chlorophyll and the activation of enzymes.
• Manganese is involved in the production of chloroplasts and the activation of enzymes.
• Zinc is involved in the production of enzymes and the regulation of gene expression.
• Copper is involved in the production of chlorophyll and the activation of enzymes.
• Boron is involved in the formation of cell walls and the regulation of membrane permeability.
• Molybdenum is required for the production of enzymes involved in nitrogen metabolism.
• Chlorine is involved in the regulation of water balance in cells and the production of oxygen during photosynthesis.

In summary, plants require various minerals, both macro-nutrients, and micro-nutrients, to grow and function properly. These minerals are obtained from the soil through the roots and are transported to the rest of the plant through the xylem and phloem. Photosynthesis is the process by which green plants manufacture their food using sunlight, carbon dioxide, and water. The process takes place in chloroplasts, which contain a pigment called chlorophyll.

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Animal Nutrition

i. Classes of Food Substances

Animals require a variety of nutrients to maintain their body functions, including carbohydrates, proteins, fats and oils, vitamins, mineral salts, and water.

• Carbohydrates: provide energy and include sources such as sugars, starches, and cellulose (a structural component of plant cells that cannot be digested by all animals).
• Proteins: are needed for the growth, repair, and maintenance of tissues, as well as for enzyme and hormone production. They are found in meat, fish, eggs, beans, and nuts.
• Fats and oils: are a concentrated source of energy and are important for the insulation and cushioning of organs. Sources include meats, fish, oils, and nuts.
• Vitamins: are required in small amounts to aid in various body functions. Examples include vitamin C (found in fruits and vegetables) and vitamin D (obtained through sunlight exposure or in some foods).
• Mineral salts: are needed for various body functions such as bone formation, nerve function, and fluid balance. Examples include calcium, iron, and sodium.
• Water: is essential for life and makes up the majority of an animal’s body weight.

ii. Food Tests

There are various tests that can be conducted to identify the presence of different types of nutrients in food. Some examples include:

• Starch test: using iodine solution to identify the presence of starch in a food sample. Starch will turn the solution blue-black.
• Reducing sugar test: using Benedict’s solution to identify the presence of reducing sugars (such as glucose and fructose) in a food sample. The solution will change from blue to green, yellow, orange, or red, depending on the amount of reducing sugar present.
• Protein test: using Biuret reagent to identify the presence of proteins in a food sample. The solution will turn purple if proteins are present.
• Oil/fat test: Use a paper towel or filter paper to test for the presence of oil or fat. A translucent spot will appear on the paper if oil/fat is present.

iii. The Mammalian Tooth

Mammals have different types of teeth that are specialized for different functions. These include:

• Incisors: front teeth used for biting and cutting food.
• Canines: pointed teeth used for tearing and gripping food.
• Premolars: used for crushing and grinding food.
• Molars: larger teeth used for heavy grinding of food.

Each type of tooth has a different structure that is adapted to its function. For example, incisors are sharp and flat, while molars have large, flat surfaces with ridges for grinding.

iv. Mammalian Alimentary Canal

The alimentary canal, also known as the digestive tract, is a long, muscular tube that runs from the mouth to the anus. It is responsible for processing food and extracting nutrients for the body to use. The alimentary canal includes the following parts:

• Mouth: where food is ingested and mechanical digestion (chewing) begins.
• Esophagus: a muscular tube that moves food from the mouth to the stomach.
• Stomach: where food is broken down by acid and enzymes.
• Small intestine: where nutrients are absorbed into the bloodstream.
• Large intestine: where water is absorbed from the remaining material and waste products are formed.
• Rectum: where waste products are stored.
• Anus: where waste products are eliminated from the body.

v. Nutrition Process

The nutrition process in animals involves four main stages: ingestion, digestion, absorption, and assimilation of digested food.

1. Ingestion: The first step in the nutrition process is ingestion, which involves the intake of food. Ingestion can occur through various mechanisms such as capturing, filtering, or grazing. Animals have different adaptations to carry out ingestion, for example, carnivorous animals have sharp teeth to tear and cut meat while herbivorous animals have flat teeth for grinding plants.
2. Digestion: After the food is ingested, it is broken down into smaller molecules by the process of digestion. Digestion can be divided into two types, mechanical and chemical. Mechanical digestion involves the physical breaking down of food into smaller pieces, while chemical digestion involves the use of enzymes to break down food molecules into their component parts.
3. Absorption: After the food is digested, the nutrients are absorbed into the bloodstream. The nutrients are transported by the bloodstream to different parts of the body where they are needed. The absorption of nutrients occurs mainly in the small intestine, which has a large surface area due to the presence of finger-like projections called villi.
4. Assimilation: The final stage of the nutrition process is assimilation, which involves the use of the absorbed nutrients by the body. The assimilated nutrients are used to build new tissues, repair damaged ones, and produce energy. The excess nutrients are stored in the body for later use.

Overall, the nutrition process is a complex series of steps that ensures that animals get the necessary nutrients from their food to carry out their life processes.