Which of the following nucleotides is only found in RNA?

The hip joint is an example of a ball-and-socket joint. The hip joint is formed by the articulation of the head of the femur with the acetabulum of the pelvis. The rounded head of the femur (ball) fits into the cup-shaped acetabulum (socket), allowing for a wide range of motion in multiple planes.

Melanocytes are specialized skin cells that produce melanin, which is the protective skin-darkening pigment. They are found mainly in the epidermis, though they occur elsewhere, such as in the hair.

From the heart, blood flows through major arteries, which then branch to give rise to arterioles, which then divide into capillaries that deliver blood to the target organ.

The digestive system breaks down complex food substances into small and less complex absorbable compounds. Proteins, for instance, are broken down to constituent amino acids through a digestion process that combines mastication and enzymatic breakdown.

The kidneys are the primary organs involved in the excretion of nitrogenous wastes. Nitrogenous wastes are mostly products of protein metabolism in the liver. One of the common nitrogenous waste products is urea, which is excreted through the kidneys.

A spectrophotometer is an instrument that measures the intensity of light absorbed after it passes through a sample solution. With the spectrophotometer, the concentration of a chemical substance can be determined by measuring the intensity of light detected.

Rationale

Electrons are subatomic particles that have relatively little mass and are negligible when calculating atomic mass. The atomic number is usually the sum of protons and neutrons in the nucleus of the atom.

a. Water boils to produce steam at 100°C - This is a phase change (from liquid to gas) and not a chemical reaction of water.

b. Water dissolves sugar - This is a physical change, not a chemical reaction of water.

c. Water produces gas with sodium metal - This reaction involves the chemical reaction of water with sodium metal to produce hydrogen gas.

d. Water and oil separate when combined - This is a physical separation, not a chemical reaction of water.

Both prokaryotic and eukaryotic cells have a cell membrane. The cell membrane is a barrier that surrounds the cell and separates its internal environment from the external environment.