Access comprehensive solutions to the Biochemistry exercise from Punjab Textbook Board. Simplified answers, detailed explanations, and helpful notes designed for college students to excel in their chemistry studies.
Short Answer Questions:
- How plants synthesize carbohydrates?
- Plants synthesize carbohydrates through the process of photosynthesis, where carbon dioxide (CO₂) from the air and water (H₂O) from the soil react in the presence of sunlight and chlorophyll to form glucose (C₆H₁₂O₆) and oxygen (O₂). The general equation is:
[ 6CO₂ + 6H₂O + sunlight →{chlorophyll} C₆H₁₂O₆ + 6O₂ ]
- Give the characteristics of monosaccharides.
- Monosaccharides are the simplest form of carbohydrates, consisting of a single sugar unit. They are crystalline, water-soluble, and sweet-tasting. Examples include glucose, fructose, and galactose.
- What is the difference between glucose and fructose?
- Glucose is an aldohexose (contains an aldehyde group), while fructose is a ketohexose (contains a ketone group). Although they have the same molecular formula (C₆H₁₂O₆), their structural arrangements differ.
- Give an example of a disaccharide. How is it hydrolyzed into monosaccharides?
- An example of a disaccharide is sucrose. It is hydrolyzed into glucose and fructose in the presence of an enzyme (sucrase) or dilute acid by breaking the glycosidic bond.
- Give the characteristics of polysaccharides.
- Polysaccharides are complex carbohydrates composed of long chains of monosaccharide units. They are generally insoluble in water, tasteless, and serve as energy storage (e.g., starch, glycogen) or structural components (e.g., cellulose).
- Where are the proteins found?
- Proteins are found in various sources, including animal products (meat, dairy, eggs), plant sources (legumes, nuts, seeds), and are also present in every cell of living organisms.
- Describe the uses of carbohydrates.
- Carbohydrates serve as a primary source of energy for the body, act as dietary fiber for digestion, and are used in the formation of cell structures (e.g., cellulose in plant cell walls).
- Lactose is disaccharide; which monosaccharides are present in it?
- Lactose is composed of glucose and galactose.
- Why are the ten amino acids essential for us?
- The ten essential amino acids cannot be synthesized by the human body and must be obtained from the diet to support protein synthesis and overall metabolism.
- How are proteins formed?
- Proteins are formed by the polymerization of amino acids, linked together by peptide bonds to form polypeptide chains, which then fold into specific three-dimensional structures.
- How is gelatin obtained?
- Gelatin is obtained by the hydrolysis of collagen, a protein found in the skin, bones, and connective tissues of animals.
- Give the general formula of the lipids.
- The general formula for simple lipids (triglycerides) is RCOOR’, where R and R’ are fatty acid chains.
- Name two fatty acids with their formulae.
- Palmitic acid (C₁₆H₃₂O₂)
- Oleic acid (C₁₈H₃₄O₂)
- Give the types of vitamins.
- Fat-soluble vitamins: A, D, E, K
- Water-soluble vitamins: B-complex, C
- What is the significance of vitamins?
- Vitamins are essential nutrients that the body needs in small amounts to maintain health, support metabolic processes, and prevent deficiency diseases.
- Describe the sources and uses of vitamin A.
- Sources: Carrots, liver, dairy products, and leafy green vegetables.
- Uses: Essential for vision, immune function, and skin health.
- Justify that water-soluble vitamins are not injurious to health.
- Water-soluble vitamins (e.g., vitamin C, B-complex) are not stored in the body in large amounts and are easily excreted through urine, reducing the risk of toxicity.
- What do you mean by the genetic code of life?
- The genetic code refers to the sequence of nucleotides in DNA that dictates the sequence of amino acids in proteins, thus determining the traits and functioning of living organisms.
- What is the function of DNA?
- DNA serves as the genetic material, carrying instructions for the development, functioning, growth, and reproduction of all living organisms.
- How do you justify that RNA works like a messenger?
- RNA acts as a messenger by transcribing genetic information from DNA and translating it into proteins during the process of protein synthesis.
Long Answer Questions:
- What are carbohydrates? How monosaccharides are prepared? Give their characteristics.
- Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen, usually in the ratio 1:2:1. They serve as a major energy source and structural material in living organisms.
- Monosaccharides are prepared through hydrolysis of disaccharides or polysaccharides. For example, hydrolyzing starch can yield glucose.
- Characteristics: Monosaccharides are sweet-tasting, crystalline solids, and soluble in water.
- Explain oligosaccharides.
- Oligosaccharides consist of 2-10 monosaccharide units linked together. They are found in various natural sources and play a role in cell recognition and immune response.
- What are polysaccharides? Give their properties.
- Polysaccharides are long chains of monosaccharide units. They are generally insoluble in water, non-sweet, and serve as energy storage (e.g., glycogen, starch) or structural materials (e.g., cellulose).
- Explain the sources and uses of proteins.
- Sources: Animal products (meat, fish, eggs), legumes, nuts, and seeds.
- Uses: Proteins are essential for growth and repair, enzyme formation, immune function, and transport of molecules in the body.
- Explain that amino acids are building blocks of proteins.
- Amino acids link together through peptide bonds to form polypeptide chains, which fold into functional proteins. They are considered the fundamental units in protein synthesis.
- Explain the sources and uses of lipids.
- Sources: Animal fats, vegetable oils, nuts, and seeds.
- Uses: Lipids serve as an energy reserve, structural component of cell membranes, and precursors of hormones.
- Give the importance of vitamins.
- Vitamins are critical for metabolic processes, preventing deficiency diseases, supporting immune function, and maintaining healthy skin, bones, and eyes.
- Describe the sources, uses, and deficiency symptoms of water-soluble vitamins.
- Sources: Fruits, vegetables, whole grains, and legumes.
- Uses: Support energy metabolism, nerve function, and collagen formation.
- Deficiency symptoms: May include fatigue (vitamin B deficiency), scurvy (vitamin C deficiency), neurological problems (vitamin B12 deficiency).
