(a) Differentiate between food contaminants and food adulterants. (b) Enlist major food groups based on nutrients, their functions and sources. (c) What is Artificial Intelligence and how does it differ from traditional programming? Describe the main branches of Artificial Intelligence. (d) What are the advantages of optical fibers in communication system? Draw basic structure of optical fiber and explain propagation of light through it.

(a) Food contaminants and food adulterants

Food contaminants are harmful or unwanted substances that enter food unintentionally during production, processing, storage or handling. Food adulterants are substances deliberately added to food, or valuable components removed, usually to cheat consumers and increase profit.

Examples of contaminants: pesticide residues, aflatoxins, heavy metals, and bacteria such as E. coli. Examples of adulterants: water and urea in milk, brick powder in chilli powder, and cheap oil in ghee. Prevention: contamination is reduced by hygiene, proper storage and good farming. Adulteration is reduced by inspection, testing and legal penalties. Legal view: adulteration is an offence involving intent to deceive, while contamination is treated as a failure of safety, though it can also be penalised.

(b) Major food groups based on nutrients

Carbohydrates: the function is to provide energy. Sources are wheat, rice, potatoes, fruit and sugar. Proteins: the function is growth and repair, and making enzymes and antibodies. Sources are meat, fish, eggs, milk and pulses. Fats: the function is concentrated energy, insulation, and absorbing vitamins A, D, E and K. Sources are oils, butter, nuts and fatty fish. Vitamins: the function is regulating metabolism, immunity and growth. Sources are fruit, vegetables, milk and liver. Minerals: the function is building bones and blood, and supporting nerves. Sources are milk (calcium), red meat and leafy greens (iron), and iodised salt (iodine). Dietary fibre: the function is aiding digestion and preventing constipation. Sources are whole grains, vegetables and fruit. Water: the function is transport, temperature regulation and supporting chemical reactions. Sources are drinking water and water-rich foods.

(c) Artificial intelligence

Artificial intelligence (AI) is the field of computer science that builds systems able to perform tasks normally requiring human intelligence, such as learning, reasoning, understanding language and recognising images.

Difference from traditional programming

Approach: a traditional programmer writes explicit rules, while machine learning systems derive their rules from data. Input and output: traditionally, rules and data produce answers. In machine learning, data and answers are used to produce a model, which then makes predictions. Adaptability: traditional programs do only what is coded, while AI models can improve with more data. Suitable tasks: traditional programming suits clear, fixed logic such as payroll. AI suits complex patterns, such as recognising faces. Predictability: traditional programs are usually exact and easy to trace, whereas AI gives probabilistic results that may be harder to explain.

Main branches of AI

Machine learning: systems learn from data, including deep learning with neural networks. Natural language processing: understanding and producing human language. Computer vision: interpreting images and video. Robotics: machines that sense and act in the physical world. Expert systems: applying encoded specialist knowledge to reach decisions. Planning, search and optimisation: finding effective sequences of action. Speech recognition: converting spoken words into text.

(d) Optical fibres

Advantages in communication: very high bandwidth; low signal loss over long distances; immunity to electromagnetic interference; better security; small size and light weight; and no electrical sparking hazard.

Basic structure (to draw): draw a long horizontal cylinder in cross-section. Label the central strip core (high refractive index, n₁), the layer around it cladding (lower refractive index, n₂), and the outermost layer protective coating. Draw a zigzag ray inside the core, reflecting at the core-cladding boundary.

Propagation of light: light enters one end within a limited cone called the acceptance angle. On reaching the boundary, going from higher to lower refractive index, it strikes at an angle greater than the critical angle, where sin θc = n₂/n₁. It therefore undergoes total internal reflection, and it bounces along the core with little loss, even around gentle bends, until it reaches the far end. In single-mode fibre, light travels essentially straight down a very narrow core, avoiding the spreading seen in multi-mode fibre.