IB Biology

A Unity and Diversity

A1.1 Water

A1.2 Nucleic acids

A2.1 Origins of cells

A2.2 Cell structure

A2.3 Viruses [HL only]

A3.1 Diversity of organisms

A3.2 Classification and cladistics [HL only]

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B Form and Function

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes and membrane transport

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B3.3 Muscle and motility [HL only]

B4.1 Adaptation to environment

B4.2 Ecological niches

C Interaction and Interdependence

C1.1 Enzymes and metabolism

C1.2 Cell respiration

C1.3 Photosynthesis

C2.1 Chemical signalling [HL only]

C2.2 Neural signalling

C3.1 Integration of body systems

C3.2 Defence against disease

C4.1 Populations and communities

C4.2 Transfers of energy and matter

D Continuity and Change

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutation and gene editing

D2.1 Cell and nuclear division

D2.2 Gene expression [HL only]

D2.3 Water potential

D3.1 Reproduction

D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Stability and change

D4.3 Climate change

Question rangeA1.2.8—Complementary base pairing

[Maximum number: 8]

The image of a nucleosome was obtained using molecular visualization software.

(a)

(i)

Adenine forms hydrogen bonds with the nitrogenous base X . Identify X .

[ 1 ]

(ii)

Suggest one benefit and one disadvantage of using molecular visualization.

Benefit:

Disadvantage:

[ 2 ]

(b)

Describe the structure of the nucleosome.

[ 3 ]

(c)

Explain how methylation of nucleosomes affects DNA transcription.

[ 2 ]

[Maximum number: 1]

What do DNA replication, transcription and translation have in common?

Take place in cell nucleus

Require free nucleotides

Catalysed by polymerase

Complementary base pairing

[Maximum number: 1]

The percentage of thymine in the DNA of an organism is approximately 30 %. What is the percentage of guanine?

70 %

30 %

40 %

20 %

The following diagram shows a short stretch of DNA. What bases are indicated by labels Y and Z ?

thymine

adenine

thymine

guanine

uracil

guanine

uracil

adenine

[Maximum number: 7]

The diagram shows a nucleic acid, with some of the bases indicated.

(a)

Identify the type of nucleic acid shown in the diagram.

[ 1 ]

(b)

Determine with a reason whether the diagram shows transcription or replication.

[ 1 ]

(c)

Deduce the base indicated by X on the diagram.

[ 1 ]

(d)

Identify the terminal indicated by Y on the diagram.

[ 1 ]

(e)

(i)

Identify the type of bond indicated by Z on the diagram.

[ 1 ]

(ii)

Several enzymes can catalyse the formation of this type of bond. Explain how two enzymes catalyse it during the process shown in the diagram.

[ 2 ]

[Maximum number: 8]

The graph shows a sigmoid population growth curve.

(a)

Identify the phases labelled X and Y .
X :
Y:

[ 1 ]

(b)

Outline how fossil records can provide evidence for evolution.

[ 2 ]

(c)

The table summarizes the genome size of several organisms.

[ 3 ]

(i)

Distinguish between the terms genotype and phenotype.

[ 1 ]

(ii)

Outline a structural difference between the chromosomes of Helicobacter pylori and Homo sapiens.

[ 1 ]

(iii)

Deduce the percentage of adenine in Oryza sativa if the proportion of guanine in that organism is 30 %.

[ 1 ]

(d)

The figure shows a pedigree chart for the blood groups of three generations.

[ 2 ]

(i)

Deduce the possible phenotypes of individual X .

[ 1 ]

(ii)

Describe ABO blood groups as an example of codominance.

[ 1 ]