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

IB Biology HL C3.1 Integration of body systems Question Bank

[Maximum number: 6]

Auxin can be used to promote the development of roots from stem and leafy cuttings in some plants. In a study into the distribution of auxin in the development of these roots, scientists measured the amount of auxin in different leaves of a shoot tip of Petunia hybrida.

The figure indicates the numbering of leaves on the shoot, from L1 as the youngest and smallest to L6 as the largest and oldest leaf. The developmental stage of L5 and L6 was very similar, so L5 was not analysed. The stem base is the lowest part of the cutting where roots may form.

The graph shows the auxin concentration in the different leaves.

(a)

N-1-naphthylphthalamic acid (NPA) is an inhibitor used to block auxin transport. NPA was sprayed onto the leaves of a set of cuttings for 14 days. Development of the roots in control (non-treated) and NPA-treated cuttings was measured 14 days after taking the cuttings. The table shows the influence of NPA on rooting.

Analyse the effect of NPA on the formation of roots.

[ 2 ]

(b)

The scientists also measured the changes in auxin concentration in L6 and the stem base during the early period of root formation. They recorded the concentration in the control and NPA-treated cuttings for 24 hours after taking the cuttings.

[ 4 ]

(i)

Compare and contrast the changes in auxin concentration in the stem base over time for the control and NPA-treated cuttings.

[ 2 ]

(ii)

Deduce the effect of NPA on auxin transport between L6 and the stem base.

[ 2 ]

[Maximum number: 1]

Though a single nerve cell does not think, millions of them organized as a brain result in thinking. What kind of property does thinking represent?

Anatomical

Adaptive

Extracellular

Emergent

[Maximum number: 3]

Achieving successful rooting of cuttings is difficult in some shrub species. An experiment was undertaken to determine whether juvenile shoots (J) of shrubs root more successfully than mature shoots (M).

Key: ○ mature shoots (M) ○ juvenile shoots (J)

(a)

Auxin is a hormone that can be applied to improve the percentage success of rooting in those study plants with poor rooting success. Explain the effects of auxin on plant cells.

[ 3 ]

[Maximum number: 2]

The diagram shows a section through the melatonin receptor, with melatonin attached to its binding site. Darker grey areas show the surface of the protein and paler areas are internal. The membrane in which this receptor is located is also shown.

(a)

Outline the role of melatonin in humans.

[ 2 ]

[Maximum number: 3]

Synaptic density is the number of synapses per unit volume. The graph shows the synaptic density for a 28 -week-old fetus, and from birth to age 70.

(a)

Label the diagram of the reflex arc with the names of the neurons indicated.

[ 2 ]

(b)

Draw an arrow on the diagram of the reflex arc to show the direction of impulses.

[ 1 ]

[Maximum number: 1]

Hearing loss can range from mild to severe. Cochlear implants have been used in those with profound hearing loss such as children who are born deaf. The image shows a cross section of the ear with a cochlear implant.

(a)

People who are deaf often learn to communicate using sign language. In a study, brain imaging was carried out using functional magnetic resonance imaging (fMRI) of profoundly deaf and hearing people who were processing the same aspects of language. The deaf individuals in the study used either an English sign language or a French sign language.

[ 1 ]

(i)

Compare the general patterns of activation in the brain shown when all of the individuals in the study processed language.

[ 1 ]

[Maximum number: 1]

The images show differences in structure between the brain of a person without Alzheimer's disease (image I) and the brain of a patient with Alzheimer's disease (image II).

(a)

(i)

State one function of the cerebellum.

[ 1 ]

[Maximum number: 1]

The figures below show a human and a sheep brain.

Human brain

Sheep brain

(a)

State the name of the part of the brain that controls breathing rate.

[ 1 ]

[Maximum number: 2]

The drawing shows a vertical section through the brain.

(a)

(i)

State a function of the cerebellum.

[ 1 ]

(b)

On the diagram, label one named structure that produces hormones.

[ 1 ]

(a)

Outline one function for each of the following parts of the brain.

[ 2 ]

(b)

The following diagram shows a section through the spinal cord.

[ 1 ]

(i)

Define the term reflex.

[ 1 ]

0 selected

Question 1

Question 1(c)

Question 1(d)

Question 1(d)(i)

Question 1(d)(ii)

Question 2

Question 3

Question 3(d)

Question 2

Question 2(d)

Question 4

Question 4(b)

Question 4(c)

Question 4

Question 4(b)

Question 4(b)(ii)

Question 5

Question 5(a)

Question 5(a)(ii)

Question 4

Question 4(c)

Question 5

Question 5(a)

Question 5(a)(ii)

Question 5(b)

Question E2

Question E2(a)

Question E2(b)

Question E2(b)(iii)