The cell carries out the metabolic processes and it grows during interphase.

The cell cycle has three phases that must occur before mitosis, or cell division happens. These three phases are collectively known as interphase. They are G1, S, and G2.

The given number series 2, 19, 0, 21, –2, ? follows a pattern,

2

2 + 17 = 19

19 - 19 = 0

0 + 21 = 21

21 - 23 = -2

-2 + 25 = 23

Hence, the next number in the series is 23.

The kidneys deactivate vitamin D and stimulate the activity of osteoclasts is wrong among the functions of kidneys.

The kidneys are two bean-shaped organs in the renal system. They help the body pass waste as urine. They also help filter blood before sending it back to the heart.

The kidneys perform many crucial functions, including:

• maintaining overall fluid balance.
• regulating and filtering minerals from the blood.
• filtering waste materials from food, medications, and toxic substances.
• creating hormones that help produce red blood cells, promote bone health, and regulate blood pressure.

After falling it bruises, similarly after knocking it bumps.

Hence, Bruise : Fall :: Bump : Knock.

World Wide Web is being standard by W3C.

The World Wide Web Consortium (W3C) is an international community where Member organizations, a full-time staff, and the public work together to develop Web standards. Led by Web inventor and Director Tim Berners-Lee and CEO Jeffrey Jaffe, W3C's mission is to lead the Web to its full potential.

Ratio of efficiencies of P, Q and R = 2 : 3 : 4

From the given data,

Number of working days of P, Q, R = 5 : 10 : 5

Hence, ratio of amount of p, Q, R = 2x5 : 3x10 : 4x5 = 10 : 30 : 20

Amounts of P, Q, R = 200, 600 and 400.

A traffic light.

It has three 'eyes' (the red, orange and green lights) and the leg is the pole holding it up. Many people beg the light to stay green as they’re approaching.

Natural gas is primarily composed of methane, but also contains ethane, propane, and heavier hydrocarbons.

Natural gas is a colorless, tasteless, odorless, and non-toxic gas. Because it is odorless, mercaptan is added to the natural gas, in very small amounts to give the gas a distinctive smell of rotten eggs. This strong smell can alert you of a potential gas leak.

It also contains small amounts of nitrogen, carbon dioxide, hydrogen sulphide and trace amounts of water.