Tag: science & technology

Common table salt is sodium chloride (NaCl). Baking soda is sodium bicarbonate (NaHCO3), also known as sodium hydrogen carbonate. Option D is correct.

The ozone hole refers to the thinning of the ozone layer in the stratosphere, particularly over Antarctica. It is not an actual hole but a decrease in thickness of the ozone layer in the stratosphere. Option C is correct.

Pollination is the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower. This is the first step in plant fertilization. Option B describes pollen germination, which occurs after pollination. Option C describes fertilization itself. Option D describes pollinator behavior, not the pollination process.

Plants absorb water and dissolved minerals (nitrogen, phosphorus, potassium, etc.) from soil through their roots. While atmospheric CO2 provides carbon and light provides energy for photosynthesis, soil is the primary source of essential nutrients required for growth and development.

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy (ATP). This is the opposite of passive processes like osmosis and diffusion, which move substances down their concentration gradient without energy input.

Photosynthesis occurs primarily in leaves and other chloroplast-containing parts of plants because chloroplasts contain chlorophyll, which captures light energy. Options B and C contain stems/roots which lack chloroplasts or have minimal photosynthetic capacity. Option D includes bark which does not photosynthesize.

Plants synthesize proteins by linking amino acids together through peptide bonds. Amino acids are the building blocks of all proteins. Starch is a carbohydrate storage molecule, sugar provides energy, and fatty acids are used for lipid synthesis - none are direct protein precursors.

Plants absorb nitrates (NO3-) from soil through their roots and reduce them to form free nitrogen (N2) as part of their metabolic processes. They do not convert nitrates to urea (animal waste), ammonia (intermediate form), or directly to proteins (which are built from amino acids).

Bones provide attachment points for muscles (A), protect vital organs like the brain and heart (B), and produce blood cells in bone marrow (D). However, hormone secretion for calcium regulation is done by the parathyroid gland and calcitonin from the thyroid gland, not by bones themselves - though bone tissue responds to these hormones.