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

B3.2.1—Capillary adaptations

B3.2.2—Artery and vein structure

B3.2.3—Artery adaptations

B3.2.4—Pulse rate measurement

B3.2.5—Vein adaptations

B3.2.6—Coronary artery occlusion

B3.2.7—Water transport in plants

B3.2.8—Xylem vessel adaptations

B3.2.9—Stem tissue distribution

B3.2.10—Root tissue distribution

B3.2.11 (HL)—Tissue fluid in capillaries

B3.2.12 (HL)—Exchange between tissue fluid and cells

B3.2.13 (HL)—Lymph ducts

B3.2.14 (HL)—Single vs. double circulation

B3.2.15 (HL)—Mammalian heart adaptations

B3.2.16 (HL)—Cardiac cycle stages

B3.2.17 (HL)—Root pressure generation

B3.2.18 (HL)—Phloem adaptations

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

IB Biology HL B3.2.17 (HL)—Root pressure generation Question Bank

• Endodermal cells actively pump mineral ions into xylem

• This lowers xylem water potential so water enters by osmosis

• Positive root pressure can push water upward when transpiration is low

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