Dear Friends, in the previous Blog (Civil Services Preparation - The Introduction), I have mentioned the vast syllabus of General Studies Subject. Now, in this Blog I have mentioned the Subject called General Science. As this subject itself is an vast one, So I will explain it in parts of Blogs. Also it includes the subjects - General Science, Physics, Chemistry and Biology, which will be separated later. The Contents have already been discussed in the Introduction Part. Kindly go through this.
1. Food
1. Food & Its Variety
Food is any substance consumed to provide Nutritional support for the Body. It is usually of plants or animal origin, & contains essential nutrients, such as carbohydrates, fats, proteins, vitamins or minerals. The substance is ingested by an organism and assimilated by the organism's cell in an effort to produce energy, maintain life, or stimulate growth.
The variety of food depends majorly upon following factors:
- Habitat
- Location
- Environmental Conditions
- Weather
- Population, etc.
In India, we have very wide variety of food majorly because of its cultural heritage, weather and various kinds of soil available in India. Food in India varies from location to location.
2. Ingredients of Food
It is defined as the part of food which collectively present in food.
3. Sources of Food
Almost all foods are of Plants or Animal origin. Some of the foods are listed below with their sources:
- Cereals - Plant Origin
- Vegetables - Plant Origin
- Meat, Egg & Fish - Animal Origin
- Mushroom - Edible Fungi
- Baking Soda - Chemical Origin (In-Organic Substance)
Some of the Food requires fungi or bacteria for preparation, like pickle needs to be fermented and bread, etc.
4. Classification of Animals according to the food they eat
- Carnivore - Carnivorous creatures are Meat eaters.
- Herbivore - Herbivorous creatures are Plant eaters.
- Insectivore - These creatures eats insects.
- Frugivore - Frugivorous creatures are Fruit eaters.
- Omnivorous - Omnivorous creatures are just eat almost anything edible.
Note: None of these classifications are exclusive, however. For Example., Herbivorous animals will tend to eat insects and Fruits. Carnivorous may eat plants & plant parts if it helps their digestion.
5. Classification of Living Organisms
Living Organisms can be broadly classified as follows:
- Autotrophs - Those Organisms who make their own food by Photosynthesis, like Green Plants
- Photo-Autotrophs - Those Organisms who make their food by deriving energy from Chemical Reactions, synthesize all necessary organic compounds from CO2. Chemo-Autotrophs use In-Organic energy sources, such as H2S, elemental Sulphur, ferrous Iron, Molecular Hydrogen and Ammonia. Most are Bacteria or archea that live in hostile environments, such as deep-sea vents and are the Primary Producers in such ecosystem.
- Heterotrophs - They are the Organisms that can fix Carbon and uses Organic Carbon for Growth.
- Photo-Heterotrophs - They are those Heterotrophic Organisms that use light for energy, but cannot use CO2 as their sole carbon source. Consequently, they use Organic Compounds from the environment to satisfy their Carbon requirements. Some examples are, Purple Non-Sulfur Bacteria, Green Non-Sulfur Bacteria & Helio-Bacteria.
- Chemotrophs - Chemotrophs are the organisms that obtain energy by the Oxidation of electron donors in their environments. These molecules can be Organic (Chemo-Organotrophs) or Inorganic (Chemo-Lithotrophs). The Chemotropth designation is in contrast to Phototrophs, which utilizes Solar energy. Chemotrophs can be either Autotrophic or Heterotrophic.
- Chemo-Autotrophs - They are also called Chemotrophic Autotrophs. In addition to deriving energy from Chemical Reactions, synthesize all necessary Organic Compounds from CO2. Chemoautotrophs use Inorganic energy sources, such as H2S, Elemental Sulfur, Ferrous Iron, Molecular Hydrogen and Ammonia (NH3). Most are Bacteria or Archea that live in hostile environments such as deep sea vents and are the Primary producers in such ecosystem.
- Chemo-Heterotrophs - They are also called Chemotrophic Heterotrophs. They are unable to fix Carbon and form their own Organic Compounds. Chemoheterotrophs can be Chemo-Litho-Heterotrophs, utilizing Inorganic energy sources such as Carbohydrates, Lipids and Proteins.
- Radiographic Fungus - Radiographic Fungii are Fungii which appear to use the pigment melanin to convert Gamma Radiation into Chemical energy for Growth. However, whether melanin containing fungii employ a similar multi step pathway as Photosynthesis, or same Chemosynthesis, is unknown. These were first discovered in the year 2007 as Black Molds growing inside and around the Chernobyl Nuclear Power Plant. Examples of these Fungii are: Cladosporium Sphaerospermum, Wangiella Dermatidis & Cryptoccus Neoformans.
5. Food Distribution
Food Distribution is a method of distributing or transporting food or drink from one place to another, is a very important factor in Public Nutrition, where it breaks down famine, malnutrition or illness can occur. During Same Periods of Ancient Rome, food distribution occurred with the policy of giving free bread to its citizens under the provision of a common good. These are the three components of food distribution.
- Transport Infrastructure, such as Roads, Vehicles, Rail-Transports, Airports and Sea Ports.
- Food handling technology & regulation, such as refrigeration, storage and warehousing.
- Adequate source & supply logistics, based on demand & need.
2. Components of Food
1. Nutrient
Nutrient is a Chemical that an Organism needs to live and grow or a substance used in an Organism's metabolism which must be taken in from its environment. They are used to be taken in from its environment. They are used to build and repair tissues, regulate body processes & are converted to and used as energy. Organic nutrients includes Carbohydrates, Fats, Proteins (or their building blocks, Amino Acids) and Vitamins. Inorganic chemical compounds includes dietary minerals, water and Oxygen may also be considered nutrients. A nutrient is said to be essential if it must be obtained from an external source, either because the organism cannot synthesize it or produces insufficient quantities. Nutrients needed in very small amounts are called Micro-Nutrients and those that are needed in larger quantities are called Macro-Nutrients. The effects of over dose of nutrients are called dose dependents and shortages are called deficiencies.
2. Types of Nutrients
We can classify nutrients broadly in two types, which are as follows:
- Substances that provide energy.
- Substances that supports metabolism.
Substances that provide Energy - In this category there are three major parts of Nutrients, these are further explained below:
- Carbohydrates - These are the compounds made up of types of sugars. Carbohydrates are classified by their number of sugar units: Mono-Saccharides (such as Glucose and Fructose), Di-Saccharides (such as Sucrose & Lactose), Oligo-Saccharides (such as Fructo-Oligo-Saccharides & Galacto-Oligo-Saccharides GOS), and Poly-Saccharides (such as Starch, Glycogen & Cellulose).
- Proteins - These are the Organic Compounds that consists of the Amino Acids joined by peptide bonds. The body cannot manufacture some of the Amino Acids (termed as Essential Amino Acids); the diet must supply these. In Nutrition, Proteins are broken down through digestion by Proteases back into free Amino Acids.
- Fats - Fats consists of Glycerin molecule with three fatty acids attached. fatty acids are unbranched hydrocarbon chains connected by single bonds alone (called Saturated Fatty Acids) or by both Double and Single Bonds (called Unsaturated Fatty Acids). Fats are needed to keep cell membranes functioning properly, to insulate body organs against shock, to keep body temperature stable and to maintain healthy skin and hair. The body does not manufacture certain fatty acids (termed as Esseantial Fatty Acids) & the diet must supply these.
Note:- Fat has an energy content of 9 KCal/gm (~37.7 KJ/gm)
Proteins & Carbohydrates has an enrgy content of 4KCal/gm (~16.7 KJ/gm)
Ethanol (Grain Alcohol) has an energy content of 7 KCal/gm (29.3 KJ/gm)
Substances that supports Metabolism
- Dietary Minerals - Dietary minerals are generally trace elements, salts or ions such as Copper and Iron. Some of these minerals are essential to human metabolism.
- Vitamins - Vitamins are organic compounds essential to the body. They Usually act as co-enzymes or co-factors for various proteins in the body.
- Water - Water is an essential nutrient and is the solvent in which all the chemical reactions of life takes place.
3. Essential and Non-Essential Nutrients
Nutrients are frequently categorized as essential or non essential nutrients.
- Essential Nutrients - These are the Nutrients which are unable to synthesized internally (either at all, or in sufficient quantities), and so must be consumed by an organism from its environment.
- Non-Essential Nutrients - These are the Nutrients that can be made by the body, they may often also be absorbed from consumed food. The majority of animals ultimately derive their essential nutrients from plants, though some animals may consume mineral based soils to supplement their diet.
4. Deficiencies and Toxicity
An adequate amount of a nutrients is a deficiency. Deficiencies can be due to a number of causes including inadequacy in nutrient intake called dietary deficiency, or conditions that interfere with the utilization of a nutrient within an organism. Some of the conditions that can interfere with nutrient utilization include problems with nutrient absorption, substances that cause a greater than normal need for a nutrient, conditions that cause nutrient destruction, and conditions that cause greater nutrient excretion. Nutrient toxicity occurs when an excess of a nutrient does harm to an organism.
In Plants five types of deficiency or toxicity symptoms are common:
- Chlorosis - which is the yellowing of plant tissue caused by a shortage of Chlorophyll Synthesis.
- Necrosis - which is the death of Plant Tissue.
- Accumulation of Anthocyanin - which produces a purple or reddish colorization of foilage and/or stems.
- Lack of new growth.
- Stunting or reduced growth - where new growth is stunted or reduced.
Oversupply of Plant nutrients in the environment can cause excessive plant or Algae growth. This Process is called Eutrophication, which may cause imbalances in population numbers and other nutrients that can be harmful to certain species.
For Example, an Algal bloom can deplete the Oxygen available for fish to breathe, causes include water pollution from sewage or run off from farms (carrying excess agricultural fertilizer). Nitrogen and Phosphorus are most commonly the limiting factor in growth, and thus the most likely to trigger Eutrophication when introduced artificially.
5. Vitamins
Vitamin is an Organic Compound required as a Nutrient in tiny amounts by an Organism. In other words, an Organic Chemical Compound (or related set of compounds) is called a Vitamin, when it cannot be synthesized in sufficient quantities by an organism.
For Example, Ascorbic Acid (Vitamin C) is a Vitamin for Humans, but not for most other animals. Vitamins are Classified as either Water-Soluble or Fat-Soluble. In Human, there are 13 Vitamins: 4 Fat Soluble, (A, D, E and K) and 9 Water Soluble, (8 B-Vitamins & Vitamin C). Water soluble vitamins dissolve easily in water and in general, are readily excreted from the body, to the degree that Urinary Output is a Strong Predictor of Vitamin Consumption. Because they are not readily stored, consistent daily intake is important. Many types of water soluble vitamins are synthesized by bacteria. Fat-Soluble Vitamins are absorbed through the intestinal tract with the help of lipids (Fats). Because they are more likely to accumulate in the body , they are more likely to lead to hypervitaminosis than are Water-Soluble Vitamins. Fat-Soluble Vitamin regulation is of particular significance in cystic fibrosis.
List of Vitamins
- Vitamin-A - Its Chemical name is Retinol, this is a Fat Soluble Vitamin. Deficiency diseases includes, and the overdose Disease is Hyper-Vitaminosis-A. Good Sources are Orange Vegetables, Carrots, Pumpkin, Squash, Spinach, etc.
- Vitamin-B1 - Its Chemical name is Thiamine, this a Water Soluble Vitamin. The Deficiency diseases includes, Beri-Beri, Wernicke Korsakoff Syndrome, and the Overdose disease is Drowsiness or Muscle relaxation with large doses. The good sources are Oatmeal, Rice, Vegetables, Cauliflower, Potatoes, Liver and eggs.
- Vitamin-B2 -
