Which of the following must be visually studied using microscopy?
Multiple choice.

Choice A rationale: Density of media affects the rate of diffusion because it influences the frequency of collisions between the diffusing molecules and the molecules of the medium. The denser the medium, the slower the diffusion rate, and vice versa.

Choice B rationale: Size of molecules affects the rate of diffusion because it determines how easily the molecules can move through the spaces between the molecules of the medium. The smaller the molecules, the faster the diffusion rate, and vice versa.

Choice C rationale: Concentration gradient affects the rate of diffusion because it is the difference in concentration of the diffusing molecules between two regions. The higher the concentration gradient, the faster the diffusion rate, and vice versa.

Choice D rationale: Membrane permeability affects the rate of diffusion because it is the ability of the membrane to allow the diffusing molecules to pass through it. The more permeable the membrane, the faster the diffusion rate, and vice versa.

Choice E rationale: pH affects the rate of diffusion because it is the measure of acidity or alkalinity of the medium. pH can affect the charge and shape of the diffusing molecules, which can affect their ability to cross the membrane or interact with the molecules of the medium. pH can also affect the membrane permeability by altering the charge and shape of the membrane proteins.

Photosynthesis is the process by which plants, algae, and some bacteria use light energy to convert water and carbon dioxide into organic molecules, such as glucose, that can be used as food or building blocks for other molecules. Photosynthesis also releases oxygen as a by-product, which is essential for aerobic respiration in animals and other organisms.

Photosynthesis is the primary source of energy and organic matter for most living organisms on Earth, either directly or indirectly. Directly, photosynthesis provides food for the primary producers, such as plants and algae, that make their own food. Indirectly, photosynthesis provides food for the consumers, such as animals and fungi, that eat the primary producers or other consumers.

Photosynthesis also affects the global climate and the carbon cycle by removing carbon dioxide from the atmosphere and storing it in organic matter. Therefore, photosynthesis is the most important metabolic pathway of living organisms because its products have a significant impact on the biosphere.