the answer is <em>a} physical and chemical changes</em>
Answer:
This question lacks options, the options are;
A. Absorption of heat
B. A chemical change
C. A physical change
D. Formation of a new compound
The answer is C. A physical change
Explanation:
A physical change is a type of change that does not involve the chemical composition of the substance(s) involved. Physical changes affect the form but not the chemical content of a substance. Examples of physical changes are freezing, change of state, boiling etc.
In this question, a liquid is cooled during an investigation causing it to solidify. The cooling of this liquid represents a PHYSICAL CHANGE because the liquid state of the substance is only changed to a solid state but does not involve changing the chemical composition of the substance.
The capability to do work is said to be energy. It can neither be created nor be destroyed according to law of conservation of energy. Energy exist in different forms depends upon the work to be done such as potential energy, kinetic energy, mechanical energy, heat energy etc.
Now, when the guitarist plucks the guitar strings to make sound, he uses mechanical energy and when guitarist plucks the guitar strings guitar produces sound energy also.
Thus, option (d) is the correct answer.
Answer:
1) thiamine pyrophosphate -activation of aldehydes
2) coenzyme A -acyl group transfer
3) biotin -CO2 activation/transfer
4) NAD -oxidation/reduction
Explanation:
1. Thiamine pyrophosphate: This is a derivative of Vitamin B1 also known as thiamine. It contains a pyrimidine group linked to the thiazole ring. This connection is further linked to the pyrophosphate group. It functions as a coenzyme in all reactions involving alpha-keto acids. This produces activated aldehydes that could be subject to oxidation.
2. Coenzyme A: This cofactor is a thiol that reacts with carboxylic acids to form thioesters. In so doing, it carries the acyl group. In this condition, it can also be referred to as acyl CoA.
3. Biotin: Also known as Vitamin B7, biotin consists of an ureido ring merged with tetrahydrothiophene. The ureido ring contains the CO2 that can be transferred or activated. Five carboxylase enzymes use biotin as a cofactor in processes such as fat synthesis, glucose generation and the breakdown of sugar.
4. NAD: Nicotinamide adenine dinucleotide consists of two dinucleotides connected to each other at their phosphate groups. NAD exists in two states which are the NAD+ and NADH states. These two states serve as oxidizing and reducing agents respectively. The oxidizing agent becomes reduced to NADH after accepting electrons from other compounds. NADH donates an electron and becomes oxidized to NAD+.
