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 C2.1 Chemical signalling [HL only] Question Bank

[Maximum number: 1]

In an experiment to determine the effect of diet on response to leptin, mice were fed a control diet or a high fructose diet for six months and then either injected with a saline (salt) solution or injected with leptin. The food intake of both groups was then monitored over a 24 hour period.
Removed for copyright reasons

(a)

Leptin is a hormone. Hormones are chemicals produced in one part of the body that have an effect in another part of the body. State the

[ 1 ]

(i)

Leptin is a hormone. Hormones are chemicals produced in one part of the body that have an effect in another part of the body. State the target that leptin normally acts on.

[ 1 ]

(a)

Blood transports molecules throughout the body. State where the blood absorbs

[ 1 ]

(i)

Blood transports molecules throughout the body. State where the blood absorbs hormones.

[ 1 ]

[Maximum number: 2]

Vibrio fischeri is a bioluminescent (light-producing) bacterium in the Pacific Ocean. V. fischeri grown in the laboratory often has less luminescence. An investigation was carried out to look at the effect of the external osmolarity (in mOsmol) on the bacterium's luminescence, at different densities of bacteria. V. fischeri cultures were grown in three different concentrations of artificial seawater. Relative luminescence is the total luminescence divided by the density of bacteria.

Key: osmolarity
- 1300 mOsmol
- 810 mOsmol
- 570 mOsmol

(a)

Comment on the effects of osmolarity on the luminescence of the bacterium V. fischeri.

[ 2 ]

[Maximum number: 1]

The electron micrograph shows part of a pancreas cell that secretes digestive enzymes.

(a)

The pancreas secretes other chemicals as well as enzymes. State an example of a chemical and the type of pancreatic cell that secretes it.

[ 1 ]

[Maximum number: 1]

What is an example of quorum sensing?

Expression of incomplete dominance by Mirabilis jalapa flowers

Spring growth of the Arctic mouse-ear chickweed Cerastium arcticum

Bioluminescence in the marine bacterium Vibrio fischeri

Biochemical control of lactase synthesis in Escherichia coli bacteria

[Maximum number: 1]

The graph shows changes in blood plasma glucose concentration before exercise, during exercise and during recovery with and without epinephrine (adrenaline) infusion. Epinephrine infusion was started 30 minutes into the exercise routine.

E949-57. https://doi.org/10.1152/ajpendo.2000.278.5.E949. Reference redacted. Source adapted.]

Which action of epinephrine would result in the observed changes to plasma glucose concentration?

Second messenger is deactivated.

A G protein is activated, and cyclic AMP (cAMP) is produced.

Second messenger stimulates the production of ATP.

Cyclic AMP (cAMP) deactivates the G protein.

[Maximum number: 1]

What is an example of negative feedback in the menstrual cycle?

High levels of estrogen inhibit FSH secretion.

High levels of LH stop progesterone secretion.

High levels of FSH delay ovulation.

High levels of progesterone make follicles less receptive to FSH.

[Maximum number: 1]

Atropine drops are used by opticians to dilate the pupil, so that a thorough examination of the retina can be performed. Atropine binds to acetylcholine receptors in synapses.

What is the effect of atropine binding in synapses?

Inhibits the binding of acetylcholine at the presynaptic membrane

Inhibits the release of acetylcholine from the presynaptic neuron

Prevents binding of acetylcholine at the postsynaptic membrane

Prevents transport of acetylcholine through the postsynaptic membrane

[Maximum number: 1]

Leptin helps to regulate body mass in humans and mice. The image shows an obese mouse (O) and a normal mouse (N).

What hypothesis could account for the differences between the mice?

The hypothalamus of mouse O stopped producing leptin.

Adipose cells of mouse O are continuously producing leptin.

Mouse N has a defective leptin receptor.

Leptin binds to receptors in the hypothalamus of mouse N.

[Maximum number: 1]

What releases leptin?

Thyroid gland

Hypothalamus

Pineal gland

Adipose tissue

0 selected

Question 2

Question 2(c)

Question 2(c)(ii)

Question 3

Question 3(a)

Question 3(a)(i)

Question 2

Question 2(b)

Question 2

Question 2(e)

Question 17

Question 18

Question 24

Question 24

Question 25

Question 25