What is the magnification of a standard ocular lens on a light microscope?

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid cycle, takes place in the mitochondrial matrix. Mitochondria are the powerhouses of the cell, responsible for generating ATP through aerobic respiration. The Krebs cycle is a key metabolic pathway occurring in the matrix of mitochondria, where acetyl-CoA molecules derived from the breakdown of carbohydrates, fats, and proteins are further oxidized to produce ATP, NADH, FADH2, and carbon dioxide. These energy-rich molecules serve as substrates for the electron transport chain, leading to the production of additional ATP molecules.

The mitochondria are often referred to as the powerhouse of the cell because they are the primary site of ATP (adenosine triphosphate) production through aerobic respiration. ATP is the primary energy currency of the cell, providing energy for various cellular processes such as muscle contraction, active transport, biosynthesis, and cell division. Mitochondria contain their own DNA and ribosomes, enabling them to produce some of the proteins required for their function. However, their most critical role is in ATP production through the electron transport chain and oxidative phosphorylation, processes that occur within the inner mitochondrial membrane.

Water is the major component of blood plasma, making up approximately 90-92% of its composition by volume. Blood plasma is the liquid portion of blood, composed mostly of water along with dissolved solutes, such as ions, nutrients, gases, hormones, and waste products. Water in blood plasma serves as the solvent for carrying nutrients, hormones, and other molecules throughout the body, facilitates gas exchange in the lungs and tissues, helps regulate body temperature, and maintains blood volume and pressure. The remaining components of blood plasma, including ions (such as sodium, potassium, and calcium), proteins (such as albumin, globulins, and fibrinogen), and other solutes, contribute to various physiological functions in the body.

Passive transport refers to the movement of molecules across a biological membrane without the expenditure of cellular energy. This process occurs down the concentration gradient, meaning molecules move from areas of higher concentration to areas of lower concentration until equilibrium is reached. It includes simple diffusion, where small, non-polar molecules like oxygen and carbon dioxide can pass directly through the lipid bilayer of the membrane, as well as facilitated diffusion, where larger or polar molecules move across the membrane with the help of transport proteins, such as channel proteins or carrier proteins. Overall, passive transport is essential for maintaining the balance of molecules within cells and between different cellular compartments.