Short & Long Question Answers with Solution: Biomolecules | Science for ACT PDF Download

Short Answer Type Question 

Q1. The functional groups in amino acids are weak bases and acids chemically, the ionization is affected by the pH of the solution. The activity for several enzymes is affected by the ambient pH and is depicted in the curve below, explain in brief.

Ans: Enzymes typically function within a specific pH range, exhibiting their peak activity at a point known as the optimum pH. Their activity diminishes both above and below this optimal pH value. Extreme pH conditions, whether excessively acidic or alkaline, often result in a complete loss of enzyme activity. The graph illustrates the enzymes' maximum activity at their respective optimum pH levels..

Q2. What are monosaccharides? Give examples.
Ans: Monosaccharides are the simplest carbohydrates molecules that cannot be hydrolysed into smaller carbohydrates molecules. The general formula of carbohydrates is Cn H2n OH; their examples are Ribose, Glucose and Fructose.

Q3. Can rubber be classified as a primary metabolite or a secondary metabolite? Write a short note on the rubber.
Ans: Rubber, a secondary metabolite, is derived from the rubber tree, Hevea brasiliensis. The latex responsible for rubber production is generated by specialized phloem cells known as laticifers. Rubber, classified as a terpenoid, is highly valued for its exceptional attributes such as remarkable tensile strength, plasticity, and elasticity, making it indispensable in various industries. This polymeric material also boasts excellent electrical conductivity.

Q4. Why do fats release more energy than carbohydrates in the oxidation process?
Ans: Like carbohydrates, fats are also made up of Carbon, Hydrogen, and Oxygen. Still, as they contain fewer oxygen molecules than carbohydrates, so on oxidation, they consume more oxygen releasing extra energy.

Q5. Justify with the help of an example of why nucleic acids display secondary structure.
Ans: The secondary structure of a nucleic acid molecule pertains to the base-pairing interactions within a single molecule or among a cluster of interacting molecules. It's important to note that the secondary structures of RNA and DNA exhibit differences. For instance, in the case of DNA, its secondary structure involves two complementary strands of polydeoxyribonucleotide, which twist together to form a helix coiled around a shared axis. This double-stranded helical arrangement in DNA is upheld by the presence of phosphodiester bonds, ionic interactions, and hydrogen bonds.

Q6. Explain how the glycosidic bonds are made.
Ans: Formation of the Glycosidic Bonds: A monosaccharide’s aldehyde or ketone group reacts and binds with an alcoholic group of anotherorganic compound to join the two compounds. This bond is known as the glycosidic bond, and this bond may be hydrolysed to give the original compounds. Monosaccharides are also united through glycosidic bonds that give rise to compound carbohydrates.

Q7. The living state is a non-equilibrium steady-state to be able to perform work – Comment.
Ans: Living organisms maintain a dynamic, unchanging state defined by the ongoing metabolic flux and concentration of biomolecules. Any physical or chemical processes within them operate in harmony with this dynamic equilibrium. Since living entities are in constant operation, they never reach a state of true equilibrium. Instead, they exist in a non-equilibrium steady-state, fueled by the energy supplied through metabolism, allowing them to perform work.

Q8. Explain why nucleic acids display a secondary structure.
Ans: The secondary structure of nucleic acid molecules is in the context of base-pairing interactions of a single molecule or a group of interacting molecules. The secondary structure of RNA and DNA varies respectfully. For example, the secondary structure of deoxyribonucleic acid consists of two complementary strands of polydeoxyribonucleotide that are highly coiled on a common axis forming a helical structure. This double-stranded helical structure of the deoxyribonucleic acid is supported by phosphodiester bonds, ionic interactions, and hydrogen bonds.

Q9. What are Esters?
Ans: Esters, in biology, refer to an organic molecules generated after a combination of an acid with an alcohol. The process is done by removing water from both elements and is generally known as ‘esterification’. Esters are commonly found everywhere and may be used as fragrances with low molecular weight. They are also added to essential oils.

Q10. What are essential fatty acids?
Ans: Essential fatty acids are the fatty acids that must be consumed as the body needs them to maintain good health and for biological processes; however, it cannot synthesise them. These do not include fats that serve as fuel only. They are called essential, as the body cannot produce them on its own, and they must be consumed as a part of the diet and are key to the right functioning of the body.

Long Answer type Questions

Q1. In catalyzed reactions, the formation of the enzyme-substrate complex is the first step. Explain the other steps until the formation of the product.
Ans: The enzyme action cycle unfolds as follows:

• Initially, the substrate attaches to the enzyme's active site, where it fits perfectly.
• This interaction prompts the enzyme to undergo a conformational change, causing it to wrap tightly around the substrate.
• In close proximity to the substrate, the enzyme's active site catalyzes the breakdown of chemical bonds within the substrate, resulting in the creation of a new enzyme-product complex.
• The enzyme releases the reaction products, making it available to engage with another molecule of the substrate in the subsequent catalytic cycle.

Q2. Explain through the Watson-Crick model, the secondary structure exhibited by the nucleic acids.
Ans: Nucleic acids exhibit diverse secondary structures, such as the well-known Watson-Crick model. In this model, DNA adopts a double helical structure with two polynucleotide strands running in opposite directions. The backbone of this structure comprises a sugar-phosphate-sugar chain, while the nitrogen bases project inward, nearly perpendicular to the backbone. Specifically, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C) on the complementary strand. These base pairings involve two hydrogen bonds for A-T and three for G-C, giving the appearance of a helical staircase. Each complete turn of this helical strand encompasses ten base pairs.

Q3. Describe starch, cellulose, and phospholipids briefly.
Ans:

Chitin: Chitin is distinctly like cellulose in many ways. The only exception is that its basic unit is not glucose but a similar molecule called N-acetyl glucosamine that contains nitrogen. Chitin is a soft and leathery substance that becomes hard when filled with calcium carbonate or certain proteins. Chitin is insoluble in water which helps it retain its form. The retaining of its form also helps in strengthening the structure of organisms.

Starch: It is formed as a product of the photosynthesis process. It is found in large quantities in edible items like rice, wheat, cereals, legumes, potato, tapioca, and bananas. It is the major energy-giving substance as it performs the storage of food.

Phospholipids
Phospholipids are when the two layers of the polar lipids come together to form a double layer. The outer hydrophilic face of every single layer of the phospholipids orients itself towards the solution, through which the hydrophobic part becomes immersed in the core of the bilayer structure.

When exposed to an aqueous solution, these charged heads are attracted to the water phase, while the non-polar tails are repelled from the water phase.

Q4. Explain the different forms of lipids with some examples.
Ans: Lipids are not soluble by water and could exist as simple fatty acids. A fatty acid has a carboxyl group linked to an R-group, which could be methyl or ethyl or higher number of -CH2 groups. For instance, Arachidonic acid has 20 carbon atoms inclusive of the carboxyl carbon, the palmitic acid has 16 carbons inclusive of the carboxyl carbon. These fatty acids could be unsaturated or saturated. Another lipid is trihydroxy propane or glycerol.

Several lipids have fatty acids and glycerol wherein the fatty acids are esterified with glycerol, which results in diglycerides, triglycerides, monoglycerides and are known as oils and fats depending upon the melting point. Few other lipids have phosphorylated organic compound and phosphorous contained in them, which are phospholipids that are found in the cell membrane. Example – Lecithin.

Q5. What are the main functions of carbohydrates?
Ans: The main function of carbohydrates are:

• Regulation of blood glucose.
• Involved in fat metabolism and prevents ketosis.
• Provide energy and food to the body and to the nervous system.
• Functions as the basic component of food including fibre,  starch, and sugars.
• They are the primary source of energy. Therefore involved in the breakdown of starch into glucose, and proteins to produce energy for metabolism.