The bacteria transform nitrogen into useful forms for the plants; the plants provide carbohydrates.
D. Enzymes increase the rate of the chemical reactions carried out during metabolism.
Image result for Is work done when you carry a book across the room at a constant velocity
Work is not done when you carry an object forward. You may have learnt that carrying an object and moving horizontally at a constant velocity has no work done. The truth is, there is a slight amount of work done due to overcoming air resistance in the horizontal direction.
