Answer: C) the chemical properties of their R groups Explanation: Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid.   Depending on the nature of the side chain groups, three classes of aminoacids can e distinguished: 1. Amino acids with H ond donor and acceptor groups. Histidine, lysine, aspartic acid, threonine,... 2. Amino acids with donor grups only. Arginine, tryptophan and cysteine. 3. Amino acids with acceptor groups only. Asparagine and glutamine.

Answer: A) a wave reflects upon itself Explanation: A standing wave also known as a stationary wave, is a wave in which its peaks or any other point on the wave do not move spatially. This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions. The most common cause of standing waves is the phenomenon of resonance, in which standing waves occur inside a resonator due to interference between waves reflected back and forth at the resonator's resonant frequency.   Hence, standing wave occurs when a wave reflects upon itself.

Answer: C) Synaptic cleft Explanation: A neuron or nerve cell is a cell that carries electrical impulses. Neurons are the basic units of the nervous system and its most important part is the brain. Every neuron is made of a cell body (also called a soma), dendrites and an axon. Dendrites and axons are nerve fibres.   The gap between two communicating neurons is termed Synaptic cleft.

Answer: C) Petrology Explanation: The scientific study of rocks is called petrology, which is an essential component of geology.

Answer: C) 9 & 21 Explanation: Let the two numbers be x and y Given x : y = 3 : 7 .....(1) Now, x+6 : y+6 = 5 : 9 .....(2) From (1), x = 3y/7 From (2), 5y - 9x = 24 => 5y - 9(3y/7) = 24 => y = 21 => From(1), x = 9 Hence, the two numbers be 9 and 21

Answer: A) No alcohol Explanation: The temperance movement of the late nineteenth and early twentieth centuries was an exception in many ways: "Temperance" refers to the moderate consumption of alcoholic beverages.   However, in the context of the temperance movement, the term usually indicated complete abstinence, which means drinking no alcohol at all. The goal of the temperance movement in the United States was to make the production and sale of alcohol illegal. Supporters believed that prohibiting alcohol would solve a number of society's problems, making people safer, healthier, and more productive.

Answer: B) -2 Explanation: The sum of the oxidation numbers in a compound must equal zero. In the compound hydrogen sulfide, H2S, the two hydrogen atoms have an oxidation number of +1, for a total of +2. Therefore, the oxidation number of sulfur in the compound is -2, and the sum of the oxidation numbers is 0.

Answer: B) Flimsy Explanation: Durable means able to withstand wear, pressure.   Antonyms for Durable are Delicate, Flimsy, Short-lived.