OCR A Level Biology

Topic Questions

A LevelBiologyOCRTopic Questions2. Foundations in Biology2.2 Biological Molecules

2.2 Biological Molecules

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1
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Which of the following is not a property of water?

  • High specific heat capacity

  • Excellent solvent

  • Low latent heat of vaporisation

  • High surface tension

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2
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Which of the following best describes the bonding between amino acids in the tertiary structure of a protein?

  • Hydrogen and ionic bonds, disulfide bridges and hydrophobic interactions.

  • Glycosidic, peptide and hydrogen bonds.

  • Ionic and glycosidic bonds, and disulfide bridges.

  • Peptide and glycosidic bonds, hydrophobic interactions and disulfide bridges.

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3
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Which of the following is an example of a fibrous protein?

  • Elastin

  • Haemoglobin

  • Enzymes

  • Insulin

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4
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Carbohydrates, such as starch, are made from monosaccharides joined together. Which of the following types of bond joins monosaccharides together?

  • Peptide

  • Ester

  • Glycosidic

  • Phosphodiester

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5
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Which biological molecule is tested for using the emulsion biochemical test?

  • Lipid

  • Protein

  • Reducing sugars

  • Starch

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1
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Some of the properties of water make it a vital component of certain organelles such as the matrix in mitochondria. 

Which of the following statements does not describe a useful property of water in the mitochondria?

  • Water is adhesive.

  • Water is a liquid.

  • Water is a substrate for reactions

  • Water is a polar solvent.

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2
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Fibroin, the protein found in silk, mainly consists of amino acids in anti-parallel beta-sheets.

Which of the following statements explains why haemoglobin has a more complex structure than fibroin?

1 Fibroin has a basic, repeating structure.
2 Interactions between R-groups when forming haemoglobin are within and between protein molecules.
3 The quaternary structure of haemoglobin is formed from folding of the secondary structure.
4 In fibroin, hydrogen bonds only form between the amino group and R group of the amino acids.

  • All 4 statements.

  • Statements 1, 2 and 3.

  • Statements 1, 2 and 4

  • Statements 1 and 2 only.

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3
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Chitin is a structural polysaccharide that is found in the cell walls of fungi. The chemical structure of chitin is shown below, it shares some similarities with the structure of cellulose.

ocr-a-2-2h-mcq-chitin-structure

Which of the following statements accurately compares the structures of cellulose and chitin?

  • Chitin contains α-glycosidic bonds, cellulose contains β-glycosidic bonds.

  • Chitin contains nitrogen, cellulose does not.

  • Chitin contains 1-4 glycosidic bonds, cellulose contains 1-6 glycosidic bonds.

  • Chitin does not have branching, cellulose has branching.

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4
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A patient is experiencing the following symptoms:

  • Muscle cramps
  • Seizures
  • Headaches
  • Increased urine production.

Which of the following ions is likely to be deficient in this patient?

  • Na+

  • HCO3-

  • NH4+

  • H+

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5
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Sickle cell anaemia is a genetic disease affecting red blood cells which is caused by base substitution in the haemoglobin protein which results in a polar amino acid being replaced with a non-polar amino acid in the globin subunits.

The diagram below shows the difference between a normal red blood cell and a sickle cell.

ocr-a-2-2h-mcq-q5-red-blood-cell-diagram

Which of the following statements correctly explain the impact of the amino acid substitution?

  • The haemoglobin becomes less soluble.

  • The haemoglobin subunits lose their prosthetic groups.

  • The disulfide bonds holding the subunits together break.

  • The haemoglobin becomes less compact.

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1
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Which of the following reactions, A to D, describes the conversion of a polymer to a monomer?q10-paper-2-nov-2020-ocr-a-level-biology

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2
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Collagen is found in tendons. Tendons attach muscles to bones.

Which of the following lists of properties, A to D, makes collagen suitable for this role?

  • strong, inflexible, insoluble

  • strong, flexible, soluble

  • strong, inflexible, soluble

  • strong, flexible, insoluble

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3
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The following are a series of organic molecules and the chemical processes that occur to convert them into different molecules.

Which of the rows, A to D, is correct?

_vJ4sJUh_question

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The following table describes the approximate percentage mass of different chemical elements in organic polymers. 

  Polymer N
(%)		 C
(%)		 O
(%)		 H
(%)		 P
(%)
A nucleic acid 20.0 30.0 20.0 10.0 20.0
B carbohydrate 0.0 33.3 33.3 33.3 0.0
C protein 30.0 10.0 10.0 0.0 50.0
D lipid 0.0 50.0 49.0 1.0 0.0

Which of the rows, A to D, is correct?

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5
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Which of the following processes involves the formation of ester bonds?

1   synthesis of polynucleotides
2   synthesis of triglycerides
3   synthesis of polypeptides

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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6
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Which of the following could not be an amino acid?

q5-paper-2-june-2018-ocr-a-level-biology

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7
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Lipids are a diverse group of chemicals that are neither polar nor charged and hence are insoluble in water. The ___(1)___ nature of the heads of phospholipids allows them to form membranes. ___(2)___ also contain fatty acids and form part of the membrane. Lipids can be used for energy storage in the form of ___(3)___. Some hormones are also lipids and they are similar in structure to ___(4)___.

Which row shows the correct sequence of missing words?

  1 2 3 4
A hydrophilic glycolipids triglycerides cholesterol molecules
B hydrophilic triglycerides cholesterol molecules glycolipids
C hydrophobic cholesterol molecules triglycerides bile
D hydrophilic cholesterol molecules triglycerides glycolipids

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8
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Which of the statements, A to D, correctly describes the process of adhesion?

  • attraction of water molecules to the impermeable walls of xylem tissue

  • attraction of water molecules to other water molecules in the xylem tissue

  • active transport of water molecules into phloem tissue

  • attraction of water molecules to other water molecules in the phloem tissue

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9
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Which of the statements, A to D, about amylopectin is correct?

  • it contains 1-4 and 1-6 glycosidic bonds between α-glucose monomers

  • it is an unbranched chain of α-glucose monomers

  • it contains α 1-4 and β 1-6 glycosidic bonds

  • it is made up of β-glucose monomers and is uncoiled

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10
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An unknown solution of a single sugar was tested. The results were recorded in Table 9.1.

Colours observed after testing
Benedict’s test for reducing sugars Benedict’s test for non-reducing sugars
blue brick red

Table 9.1

Identify the unknown sugar.

  • fructose

  • lactose

  • sucrose

  • glucose

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