Biochemistry / Energy

Question 1

Differentiate between compounds, elements, atoms and molecules.

Answer 1

1. Atom: smallest particle of an element.
2. Element: substance made of one kind of atom.
3. Molecule: two or more atoms covalently bonded, smallest par tile of element or compound.
4. Compound: substance formed by two or more elements chemically combined.

Question 2

What are the four fundamental types of chemical compounds found in living cells?

Answer 2

1. Protein
2. Lipids.
3. Carbohydrates.
4. Nucleic Acid.

Question 3

Define a carbohydrate. What is its function in the human body?

Answer 3

A Carbohydrate is a compound containing carbon, hydrogen, and oxygen in a ration of 1:2:1,

e.g. glucose, fructose, starch, cellulose, and glycogen. Function: Human body’s main energy source.

Question 4

Define a lipid. What is its function in the human body?

Answer 4

A lipid is a compound containing carbon, hydrogen, and oxygen.

Composed of two basic compounds: glycerol and fatty acids,

e.g. fats, oils, waxes. Function: Energy storage cushioning and insulation.

Question 5

Define protein. What is its function in the human body?

Answer 5

Protein, is an organic compound made of one or more polypeptide chains of amino acids.

e.g. enzymes, gelatine, collagen and haemoglobin.

Function: structural components of cells, organic catalysts, antibodies and hormones.

Question 6

Define nucleic acid. What is its function in the human body?

Answer 6

Organic compound made of nucleotides, e.g. DNA, RNA. Function: codes instructions for protein synthesis.

Question 7

What is DNA?

Answer 7

Deoxyribonucleic acid; Nucleic acid that is he hereditary material of more living things; composes the genes.

Question 8

What is an Enzyme?

Answer 8

An enzyme (or part protein) catalysts that speed up the rates of chemical reactions and allow them to occur at temperatures compatible with life.

Question 9

What are the three factors affecting enzyme function?

Answer 9

1. Ph level. 2. temperature. 3. Relative amounts of enzyme and substrate.

Question 10

What is hydrolysis?

Answer 10

Catabolic reaction that splits apart molecules and consumes water.

Question 11

What is dehydration Synthesis?

Answer 11

The process where small molecules are bonded o make a larger molecule and water is released. For example, two glucose (a monosaccharide) molecules are linked to form maltose (a disaccharide)

Question 12

What is an amino acid?

Answer 12

An amino Acid is a building block of protein. Examples are lysine, valine, arginine, alanine, glycine, serene.

Question 13

What is a polypeptide?

Answer 13

A chain of amino acids from which a protein molecule is composed.

Question 14

What is saturate fat?

Answer 14

Saturated fat is am acid carbon chain composed of single bonds. There are about twice as many hydrogen atoms as carbon atoms; usually solid at room temperature e.g. Lard, butter.

Question 15

What is unsaturated fat:

Answer 15

It is a fairy acid chain that contain some double covalent bonds and fewer than twice as many hydrogen atoms as carbon; usually liquid at rom temperate, oil.

Question 16

What is a nucleotide?

Answer 16

It is the building blocks of nucleic acid, and composed of 3 parts: 1. one nitrogenous base. 2. One five- carbon sugar (either ribose or deoxyribose. 3. One phosphate group.

Question 17

Contrast riobse and deoxyribosed.

Answer 17

The sugar portion of a nucleotide. Ribose is present in RNA and deoxyribose is in DNA. Ribose contains one more oxygen atom than dioxyribose.

Question 18

What is a purine?

Answer 18

A purine is a nitrogenous base wit ha double ring structure, e.g. adenine, guanine.

Question 19

What is a pyrimidine?

Answer 19

A nitrogenous base with a single ring structure. e.g. cytosine, thymine, uracil.

Question 20

Which nitrogenous bases pair in DNA? in RNA?

Answer 20

DNA: Adenine and thymine Cytosine and guanine. RNA: Adenine and uracil. Cytosine and guanine.

Question 21

What is a coenzyme?

Answer 21

A non-protein substance (often a vitamin) that assists an enzyme in its functions.

Question 22

What is a substrate?

Answer 22

The substance on which an enzyme acts.

Question 23

What is a mineral?

Answer 23

A naturally occurring element that is important for the body to maintain health, e.g. sodium, potassium, chlorine and calcium.

Question 24

What is a trace element?

Answer 24

An element required by the body in tiny amounts. E.g. magnesium, copper, zinc.

Question 25

What is ATP?

Answer 25

Adenosine Triphosphate: A molecule that is the energy currency of cell metabolism in all living things. Composed of adenine, ribose and three phosphates.

Question 26

Compare aerobic respiration and fermentation (anaerobic respiration). What is the net ATP production? What are the products of reaction?

Answer 26

Aerobic: 36 ATP are produced; carbon dioxide and water are released. Anaerobic: Two ATP’s are produced; carbon dioxide and alcohol are released in alcoholic fermentation; lactic acid released in lactic acid fermentation.

Question 27

What are the three phases of cellular respiration?

Answer 27

1. Glycolysis. 2. Krebs cycle 3. Electron transport chain.

Question 28

What is Glycolysis?

Answer 28

The breakdown of glucose; forms pyruvic acid and ATP; occurs in cytoplasm.

Question 29

What is Fermentation?

Answer 29

Release of stored chemical energy without the use of oxygen. Takes place in yeast and some bacteria.

Question 30

What is Aerobic Respiration?

Answer 30

Release of stored chemical energy and the use of oxygen.

Question 31

Describe the Krebs cycle (also known as the citric acid cycle, tricarboxylic acid cycle.)

Answer 31

A circular series of enzyme reactions during cellular respiration that consumes pyretic acid and releases energy and carbon dioxide. Occurs in the mitochondrial matrix.

Question 32

What is the electron transport chain?

Answer 32

A series of enzymes that pick up and transfer hydrogen to its final acceptor, oxygen, producing water. Leads to synthesis of ATP. The third step of cellular respiration.

Question 33

What is an Autotroph?

Answer 33

An organism that can make its own food from inorganic raw materials. Examples: green plants, some protists.

Question 34

Define photosynthesis reaction. What are the reactants and products?

Answer 34

Conversion of light energy into chemical energy; food making process of autotrophs. Reactants; water, carbon dioxide. Products; glucose, oxygen and water.

Question 35

What is a Heterotroph?

Answer 35

An organism that must feed on other plants or animals in order to obtain energy and nutrients, e.g. mammals, birds, fungi, many protists.

Question 36

What is the general chemical equation that summarises photosynthesis?

Answer 36

6 H₂0 + 6 CO₂ –> C₆H₆O₆ + 6O₂

In the presence of light, chlorophyll, and enzymes.

Question 37

What are light reactions?

Answer 37

First stage of photosynthesis; light energy is absorbed, water is split to produce oxygen gas and ATP and NADPH are produced.

Question 38

What is the Calvin-Benson Cycle

Answer 38

During photosynthesis, the series of enzyme reactions in which carbon dioxide is “fixed” (incorporated) into sugars. Sometimes called “dark reactions”.

Question 39

What are four factors that influence the rate of photosynthesis?

Answer 39

1. Light intensity.
2. temperature.
3. Carbon dioxide concentration.
4. Oxygen concentration.