AQA AS Biology B1 Biological Molecules Kerboodle Answers

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1.1Introduction to biological molecules AQA AS Biology B1 Biological Molecules Kerboodle Answers

Question 1: a)Ans: Hydrogen b)Ans: Isotopes c)Ans: 100% d)Ans: Atomic number will not be affected by addition of the new particle. Question 2: a)Ans: It will form positively charged hydrogen ion, written as H⁺. b)Ans: Mass number will remain same.    

1.2 Carbohydrates-monosaccharides AQA AS Biology B1 Biological Molecules Kerboodle Answers

1Ans:  A Yellowish brown B Green C Red D Dark brown E Yellowish green Letter in sequence are B,E, A, D, C 2Ans: Dry the precipitate in each sample and weigh it. The heavier the precipitate the more reducing sugar was present. 3Ans: In Benedict’s test, once all the copper sulfate has been reduced to copper oxide, further amounts of reducing sugar cannot make a difference so it is not possible to distinguish between very concentrated samples.    

1.3 Carbohydrates-disaccharides and polysaccharides AQA AS Biology B1 Biological Molecules Kerboodle Answers

2. Lactose

Ans: Lactose= Glucose+ Galactose

1. Sucrose

Ans: Sucrose= Glucose+ Fructose

1. Starch

Ans: Glucose= Glucose+ (Glucose)_n  

2. Ans: Disaccharides are sugars (carbohydrate molecules) that form when two simple sugars i.e. monosaccharides combine to form a disaccharide. This linkage is known as glycosidic linkage.

This linkage is formed by the loss of a water molecule.  When two monosaccharides are linked together by glycosidic linkage the resulting product is a disaccharide.. Sucrose

• This is the most important disaccharide. It is popularly known as table sugar. The molecular formula of sucroseis C₁₂H₂₂O₁₁.

3. Ans: Enzymes are denatured at higher temperatures/enzymes lower the activation energy required.

   

1.4 Starch, glycogen and cellulose AQA AS Biology B1 Biological Molecules Kerboodle Answers

α-glucose     starch   cellulose  β- glucose  glycogen  

1. Stains deep blue with iodine solution.

Ans: Starch

2. Is known as ‘animal starch’.

Ans: glycogen

3. Found in plants.

Ans: starch, cellulose, α-glucose and β- glucose

4. Are polysaccharides.

Ans: Starch, cellulose and glycogen

5. Monosaccharide found in starch.

Ans: α-glucose

6. Has a structural function.

Ans: cellulose

7. Can be hydrolysed.

Ans: Starch, cellulose and glycogen

8. Easily moves in and out of cells by facilitated diffusion.

Ans: α-glucose and β- glucose    

1.5 Lipids AQA AS Biology B1 Biological Molecules Kerboodle Answers

1. Ans:
   1. Triglycerides
   2. Glycerol
   3. Unsaturated fatty acids
   4. Two
   5. Hydrophobic

2. Ans:

Triglycerides	Phospholipids
A single triglyceride molecule has glycerol and three fatty acids.	Phospholipids have glycerol, two fatty acids and a phosphate.
Triglycerides are a kind of fat found in the bodies of both plants and animals. In plants, triglycerides appear in oils such as peanut oil, while in animals triglycerides live in fat cells. In both plants and animals, triglycerides share the same structure.	Phospholipids are similar to triglycerides, but they do vary slightly in form and function. Phosphates are molecules with charges and have oxygen and phosphorus. Because fats must contain three fatty acids by definition, phospholipids are not fats, as triglycerides are, despite their similarities.

3. Ans: Both carbohydrates and lipids serve as sources of energy, but these compounds contain different capacities for energy storage. Each gram of carbohydrates stores 4 calories of energy, whereas each gram of lipid stores 9 calories. As a result, lipids serve as a more compact way to store energy, since it contains more energy per gram than carbohydrates. As a result, your body tends to use fat to store energy over long periods of time and uses carbohydrates to store energy short-term.

     

1.6 Proteins AQA AS Biology B1 Biological Molecules Kerboodle Answers

1. Ans: Peide bond

2. Ans: Condensation reaction

 

3. Ans: Amino group, carboxyl group, hydrogen atom, r group

   

1.7 Enzyme action AQA AS Biology B1 Biological Molecules Kerboodle Answers

1. Ans: A substance that alters the rate of a chemical reaction without undergoing permanent change

Ans: They are not used up in the reaction so can be used repeatedly.

3. Ans: The changed amino acid may no longer bind to the substrate, which will then not be positioned correctly, in the active site and ultimately it will prevent enzyme from functioning.

4. Ans: The changed amino acid may be one that forms hydrogen bonds with other amino acids. If the new amino acid does not form hydrogen bonds the tertiary structure of the enzyme will change, including the active site, so that the substrate may no longer fit.

   

Banner 2 1.8 factors affecting enzyme action AQA AS Biology B1 Biological Molecules Kerboodle Answers

1. Ans: To function enzymes must physically collide with their substrate. Lower temperatures decrease the kinetic energy of both enzyme and substrate molecules, which then move around less quickly. They hence collide less often and therefore react less frequently.
2. Ans: The heat causes hydrogen and other bonds in the enzyme molecule to break. The tertiary structure of the enzyme molecule changes, as does the active site.
3. Ans: High temperatures denature the enzymes and so they cannot spoil the food.
4. Some foods, such as onions, are preserved in vinegar.

Ans: Vinegar is very acidic and the low pH will denature the enzymes and so preserve the food.

4. Ans: pH = -log[H+]

Here it helps to rewrite the concentration as 1.0 x 10-4 M, because if you understand how logarithms work, this makes the formula: pH = – (-4) = 4 Or, you could simply use a calculator and take: pH = – log (0.0001) = 4

Banner 2 1.9 Enzyme inhibition AQA AS Biology B1 Biological Molecules Kerboodle Answers

 

1. The structure of inhibition molecule is similar to that of the substrate.
2. The inhibitors get attached to the active site of the enzyme.
3. It competes with the substrate molecule or for the enzyme.
4. It does not alter the structure of the enzyme.
5. The reaction can be reversed by increasing the substrate concentration.
6. Example: Sulpha drugs given to bacteria complete with para-amino benzoic acid (PABA) and folic acid synthesis is inhibited.

Non-competitive inhibition

1. The Structure of the inhibitor molecule is entirely different.
2. The inhibitor forms complex at a point other than the active site.
3. It does not complete with the substrate.
4. It alters the structure of the enzyme in such a way that the substrate may get attached to the active site but products are not formed.
5. The reaction goes on decreasing as more and more inhibitors contact the enzyme till saturation is reached.
6. Example: Cyanide combines with the prosthetic group of cytochromo oxidase and inhibits the election transport chain.

Ans: Increase the substrate concentration. If the degree of inhibition is reduced it is a competitive inhibitor, if it stays the same, it is a non competitive inhibitor.    

Banner 3 Practice questions: chapter 1

1. (a)

STATEMENT	SUBSTANCE
	STARCH	GLYCOGEN	DEOXYRIBOSE	DNA helicase
Substance contains only the elements carbon, hydrogen and oxygen	√	√
Substance is made from amino acid monomers				√
Substance is found in both animal cells and plant cells			√	√

(b)   https://slideplayer.com/slide/2399455/9/images/8/Condensation+Reaction+between+2+glucose+monomers.jpg (c)  (i) Ans: 1. Holds chains / cellulose molecules together / forms cross links between chains / cellulose molecules / forms microfibrils, providing strength / rigidity (to cellulose / cell wall);

1. Hydrogen bonds strong in large numbers’

(ii)                                                                                                Ans: Compact / occupies small space / tightly packed; “good for storage”, “easily stored” or “small” are insufficient.

2. (a)

Ans:  Unsaturated fats fall into two categories, monounsaturated and polyunsaturated. Monounsaturated and polyunsaturated fats are considered to be more health beneficial than saturated fats or trans fats. Monounsaturated fatty acids (MUFAs) are fatty acids that are missing one hydrogen pair on their chain. These fats are usually liquid at room temperature. Polyunsaturated fatty acids (PUFAs) are missing 2 or more hydrogen pairs on their fatty acid chains. These fats are usually liquid at room temperature. (b) Ans: Graph shows negative correlation; however correlation does not mean causation; and may be due to another factor (c)

1. i) Ans: Glycosidic Bond

1. ii) Ans: Contains three fatty acids.

iii) Ans:  Two water molecules https://www.thestudentroom.co.uk/attachment.php?attachmentid=327707&stc=1

4. Ans: Mixing speed of the enzyme and substrate.

Ans: Rate of the reaction is uniformly increasing at 25⁰C as the concentration of the product is linearly increasing.

1. Ans: Concentration of the product increasing linearly at 25⁰C and hence graph at this temperature is linear. But concentration of the product increases exponentially at high rate in the initial 90 minutes and later concentration of the protein become almost stationary after 90 minutes to 240 minutes at 35⁰

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