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

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.