IB Biology HL B1.1 Carbohydrates and lipids Questions

Practise IB Biology HL B1.1 with molecular diagrams and data questions that connect carbohydrate and lipid structure to digestion, storage, membranes and biological function.

147 questions in this syllabus scope, with question parts counted together.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam analysis

HL · 2010–2025
Papers with this topic38 / 117in the analysed sample
Latest appearanceNovember 2024
Tagged question parts52
Paper types5

Most tested objectives

  1. B1.1.3—Digestion by hydrolysis11 papers
  2. B1.1.5—Polysaccharides as energy storage8 papers
  3. B1.1.10—Fatty acids6 papers
  4. B1.1.6—Cellulose structure and function5 papers
  5. B1.1.4—Form and function of monosaccharides4 papers

Common question formats

  • Definition or recall
  • Structured response
  • Process explanation
  • Diagram interpretation
  • Calculation
  • Comparison

Recent exam appearances

November 2024Paper 2 HL · TZ0Q4(a), 4(b)[ 2 ]
May 2024Paper 2 HL · TZ2Q3(a)[ 1 ]
May 2024Paper 2 HL · TZ1Q8(a)[ 3 ]

117 papers analysed · Tagging incomplete

Exam points

  • Explain how carbon’s four covalent bonds and self-bonding create diverse biological compounds and carbon skeletons, and distinguish molecule classes from carbon, hydrogen and oxygen composition.
  • Explain condensation and hydrolysis in biological molecules, identify disaccharide products, and trace digestive enzymes, substrates, products and absorption.
  • Identify glucose, fructose, galactose and ribose from structures, distinguish alpha- and beta-D-glucose, and relate monosaccharide polarity to transport.
  • Describe starch and glycogen as branched alpha-glucose polymers and compare compact, insoluble carbohydrate and lipid energy stores.
  • Describe cellulose as unbranched beta-glucose chains with 1–4 bonds, hydrogen-bonded microfibrils and plant cell-wall strength.
  • Identify cell-surface glycoproteins as mediators of cell adhesion.
  • Identify non-polar lipids and steroid molecules from hydrophobic structure and fused carbon rings.
  • Identify glycerol, fatty acids, ester bonds and phosphate groups when distinguishing triglyceride and phospholipid structures.
  • Classify fatty acids as saturated, mono- or polyunsaturated, and distinguish cis and trans isomers from double-bond geometry.
  • Identify amphipathic phospholipid heads and tails and explain their orientation in bilayers or surface films.

Covered syllabus points

B1.1.1—Carbon atom propertiesB1.1.2—Macromolecules by condensationB1.1.3—Digestion by hydrolysisB1.1.4—Form and function of monosaccharidesB1.1.5—Polysaccharides as energy storageB1.1.6—Cellulose structure and functionB1.1.7—Glycoproteins in cell-cell recognitionB1.1.8—Hydrophobic properties of lipidsB1.1.9—Formation of triglycerides and phospholipidsB1.1.10—Fatty acidsB1.1.11—Triglycerides functionsB1.1.12—Phospholipid bilayersB1.1.13—Non-polar steroids

Exam points

  • Describe carbon’s four covalent bonds with C, H, O, N, S and P.
  • Identify chain, branched and ring skeletons with single or double bonds.
  • Explain how functional groups give carbon compounds distinctive properties.

Question 1

[Maximum number: 1]

What feature of carbon makes it most suitable as a basis for life?

A

Its abundance in nature

B

Its bonding properties

C

Its reactivity to light

D

Its presence in the early atmosphere of the Earth

Exam points

  • Explain how condensation links monomers by covalent bonds and releases water.
  • Match glycosidic, peptide and phosphodiester bonds to polysaccharides, polypeptides and nucleic acids.

Exam points

  • Explain how hydrolysis uses water to break covalent bonds in polymers, forming monomers.
  • Describe how amylases, proteases and nucleases catalyse hydrolysis of major biomolecules.

Question 1

[Maximum number: 1]

Amylose, amylopectin and glycogen are polysaccharides that are components of human nutrition.

Which molecules are products of the digestion of these molecules?

Amylose

Amylopectin

Glycogen

Alpha glucose

Alpha glucose

Alpha glucose

Beta glucose

Beta glucose

Alpha glucose

Alpha glucose

Alpha glucose

Beta glucose

Beta glucose

Beta glucose

Beta glucose

Exam points

  • Identify ribose as a pentose and glucose as a hexose from their structural diagrams.
  • Explain how glucose's solubility, transportability and stability suit it as a respiratory substrate.
  • Distinguish alpha- and beta-glucose at carbon 1 and link each form to different polysaccharides.

Question 1

[Maximum number: 1]

Which drawing represents beta-D-glucose?

A
Figure for Question 1 — IB Biology HL — Option A
B
Figure for Question 1 — IB Biology HL — Option B
C
Figure for Question 1 — IB Biology HL — Option C
D
Figure for Question 1 — IB Biology HL — Option D

Exam points

  • Compare amylose and amylopectin in plant starch with more highly branched glycogen.
  • Explain how insolubility, compactness and easy hydrolysis make starch and glycogen effective glucose stores.

Question 1

[Maximum number: 1]

What describes the structure of glycogen?

A

Unbranched polymer of alpha-D-glucose linked by 1,4 glycosidic linkages

B

Branched polymer of alpha-D-glucose linked by 1,6 glycosidic linkages with branches linked by 1,4 glycosidic linkages

C

Unbranched polymer of alpha-D-glucose linked by 1,6 glycosidic linkages

D

Branched polymer of alpha-D-glucose linked by 1,4 glycosidic linkages with branches linked by 1,6 glycosidic linkages

Exam points

  • Explain how alternating beta-glucose units joined by 1,4 glycosidic bonds form straight, unbranched cellulose chains.
  • Relate hydrogen-bonded fibrils and fibres to the strength of plant cell walls.

Question 1

[Maximum number: 3]

The element carbon is an essential component of living matter, representing approximately 50 % of all dry biomass, and is present in a wide range of compounds.

Describe how cellulose is formed from monosaccharides.

Exam points

  • Identify cell-surface glycoproteins as mediators of cell adhesion.

Question 1

[Maximum number: 1]

Animal cells often secrete glycoproteins as extracellular components. What is a role of these glycoproteins?

A

Adhesion

B

Additional energy reserve

C

Membrane fluidity

D

Water uptake

Exam points

  • Explain why lipids are sparingly soluble in water but dissolve in non-polar solvents.
  • Classify fats, oils, waxes, phospholipids and steroids as lipids, not true polymers.

Question 1

[Maximum number: 1]

What characteristic shows that this steroid molecule is a lipid?

Figure for Question 1 — IB Biology HL
A

It is made of carbon rings.

B

It has a very low proportion of oxygen to carbon.

C

It contains OH groups as do fatty acids.

D

It is made only of nitrogen, oxygen and hydrogen.

Exam points

  • Explain how condensation links glycerol to three fatty acids through ester bonds in a triglyceride.
  • Identify a phospholipid as glycerol with two fatty acids and an ionized phosphate group.

Question 1

[Maximum number: 2]

A triglyceride is shown.

Figure for Question 1 — IB Biology HL

Question (a)

(a)

State the two types of molecules that combine to make a triglyceride.

[ 1 ]

Question (b)

(b)

Annotate the diagram, using an arrow to show where a condensation bond has formed during formation of the triglyceride.

[ 1 ]

Exam points

  • Classify saturated, monounsaturated and polyunsaturated fatty acids by their number of C=C bonds.
  • Explain how double-bond kinks lower melting points and affect membrane or storage properties.

Question 1

[Maximum number: 1]

Which molecule can have cis and trans isomers?

A
Figure for Question 1 — IB Biology HL — Option A
B
Figure for Question 1 — IB Biology HL — Option B
C
Figure for Question 1 — IB Biology HL — Option C
D
Figure for Question 1 — IB Biology HL — Option D

Exam points

  • Explain why insoluble triglycerides in adipose tissue suit concentrated, long-term energy storage.
  • Relate fat stores to insulation, protection, buoyancy and avoiding osmotic effects.
  • Compare energy and metabolic water released by oxidising equal masses of fat and carbohydrate.

Question 1

[Maximum number: 1]

The table shows the approximate energy stores in a man with an average mass.

Table for Question 1 — IB Biology HL

What can be concluded from the data?

A

The brain contains no short-term stored energy.

B

The liver contains less long-term than short-term stored energy.

C

The adipose tissue provides for most of the long-term energy storage.

D

Carbohydrates provide more energy per gram than lipids or proteins.

Exam points

  • Identify the hydrophilic phosphate heads and hydrophobic tails that make phospholipids amphipathic.
  • Explain how phospholipid tails turn away from water in monolayers or bilayers that form stable membrane barriers.

Question 1

[Maximum number: 1]

Which features of phospholipids give them their amphipathic properties?

A

Basic phosphate groups and acidic lipids

B

Acidic phosphate groups and basic lipids

C

Hydrophobic phosphate groups and hydrophilic fatty acids

D

Hydrophilic phosphate groups and hydrophobic fatty acids

Exam points

  • Identify oestradiol and testosterone as cholesterol-derived steroids with four fused carbon rings.
  • Explain how non-polar steroids pass through the hydrophobic core of phospholipid bilayers.

Question 1

[Maximum number: 1]

Oestradiol is a steroid hormone.

Figure for Question 1 — IB Biology HL

How does oestradiol cross plasma membranes?

A

It can move between phospholipids because it is non-polar.

B

It can pass either between phospholipids or through channel proteins because it is amphipathic.

C

It can only pass through hydrophilic pores as its polar ends can form H bonds.

D

It must pass through channel proteins due to its large size.