Biology: Botany: UPSC Previous Year Questions (Science and Technology)

Explanation

In industrial applications, a wide range of microorganisms are used due to their ability to carry out various biochemical processes that are beneficial for different industries. The following microorganisms are widely used:

Bacteria is used in industries such as fermentation, bioremediation, and food production (e.g., yogurt, cheese, and antibiotics). Microalgae is used in the production of biofuels, aquaculture feed, and nutraceuticals. They are also involved in carbon sequestration. Fungi is widely used in the pharmaceutical industry for the production of antibiotics (such as penicillin) and enzymes. They are also used in fermentation and the production of organic acids.

Explanation

A is matched with 4: Fruit develops from the ovary of the flower after fertilization. The ovary, which contains the ovules, transforms into the fruit as the seeds inside mature. This process is an essential part of the plant’s reproductive cycle. B is matched with 1: Seed originates from the ovule after fertilization. The ovule, located inside the ovary, contains the female gamete (egg cell). Once fertilized by the male gamete (pollen), the ovule develops into a seed, which contains the embryo and stored food for the new plant. C is matched with 3: Wood is produced from the stem of the plant. The stem, with its vascular tissues (xylem and phloem), supports the plant and transports nutrients. The xylem, which is a type of vascular tissue, forms the wood, providing structural support and helping in water transport. D is matched with 2: Starch is primarily produced in the leaf. During photosynthesis leaves use sunlight, water, and carbon dioxide to produce glucose. Some of this glucose is converted into starch, a storage form of sugar, and is stored in the chloroplasts of the leaf.

Explanation

Statement (a) is correct: Starch and cellulose are both found in plants. Starch serves as an energy reserve and cellulose is a structural component of plant cell walls. Statement (b) is correct: Both starch and cellulose are polymers made up of repeating units (monomers) of glucose. Starch and cellulose are polysaccharides Statement (c) is incorrect: While starch gives a blue-black color with iodine, cellulose does not give any significant color reaction with iodine under normal conditions. Starch is a polysaccharide composed of glucose units and gives a blue-black color when iodine is added, which is a characteristic test for starch. Starch occurs in plants in the form of granules, and these are particularly abundant in seeds (especially the cereal grains) and tubers, where they serve as a storage form of carbohydrates. The Cellulose, a fibrous carbohydrate found in all plants, is the structural component of plant cell walls. Cellulose is also a polymer of glucose but its structure differs from starch. Cellulose does not form the characteristic blue-black color with iodine due to the difference in the way glucose molecules are linked in cellulose. Statement (d) is correct: Both starch and cellulose are made up of glucose molecules, but in different forms. Starch consists of alpha-glucose while cellulose consists of beta-glucose.

Explanation

Living organisms require a variety of elements for various physiological functions. Among these, certain elements are required in major quantities (also known as macronutrients). The elements potassium (K), sodium (Na), magnesium (Mg), and calcium (Ca) are macronutrients required in relatively large amounts by living organisms:

Potassium (K) is vital for cell function, maintaining osmotic balance, and nerve transmission. Sodium (Na) is important for maintaining osmotic pressure and fluid balance, as well for nerve function. Magnesium (Mg) is essential for photosynthesis in plants, enzyme function, and the structural component of bones in animals. Calcium (Ca) is crucial for bone and teeth formation, muscle contraction, blood clotting, and nerve function.

Explanation

Seedless tomatoes can be produced through a process called parthenocarpy where fruits develop without fertilization and thus contain no seeds. This is achieved by spraying hormones like gibberellins or auxins on the flowers of the tomato plants. These hormones promote fruit development without the need for fertilization leading to seedless fruits.

Explanation

A is matched with 2: Photosynthesis occurs in the chloroplasts where light energy is converted into chemical energy forming glucose and oxygen. B is matched with 1: Mineral uptake happens at the plasma membrane, where ions and nutrients are absorbed into the cell. C is matched with 3: Respiration takes place in the mitochondria, where glucose is broken down to release energy in the form of ATP. D is matched with 4: Protein synthesis occurs at the ribosomes where mRNA is translated into proteins.

Explanation

The potato is a modified stem known as a tuber. It is an underground stem that stores food and is capable of producing new shoots (vegetative reproduction). The "eyes" on the surface of a potato are actually buds from which new potato plants can grow. The sweet potato is also a modified root (specifically, a storage root) and not a stem. The coconut is a fruit and contains a seed, not a modified stem. Its outer husk is a part of the fruit, not a stem modification.