SECTION a Multiple-Choice Questions

NAME……………………………………………….

VCE BIOLOGY UNIT 3

CHAPTER 5&6 TEST

SECTION A – Multiple-choice questions

Instructions for Section A

· Answer all questions by circling the response that is correct for the question.

· A correct answer scores 1, an incorrect answer scores 0.

· No marks will be given if more than one answer is completed for any question.

QUESTION 1

The endocrine system contains ductless glands which secrete their hormones into the

bloodstream before they reach their target cells. A water-soluble hormone of the endocrine

system includes:

A The peptide hormone insulin.

B The thyroid amino acid derivative thyroxin.

C The steroid oestrogen.

D The neurotransmitter acetylcholine.

QUESTION 2

Certain hormones do not travel in the bloodstream to reach their target cells. In some cases,

the hormone travels in extracellular fluid to reach neighbouring target cells. This type of

signalling is known as:

A Autocrine signalling.

B Paracrine signalling.

C Proximal signalling.

D Synaptic signalling.

QUESTION 3

Tiny quantities of a hormone cause profound responses in target cells. In the case of a

signal transduction pathway within a liver cell, for instance, one molecule of adrenalin

causes the release of 100,000,000 molecules of glucose.

The change in the number of molecules involved at most subsequent steps in a signal

transduction pathway is known as:

A Magnification.

B Amplification.

C Translation.

D Reception.

QUESTION 4

Endorphins are neurotransmitters which reduce the chances of impulses travelling along

pain pathways to the brain. The ultimate effect of endorphins would be to:

A Hyperpolarise the membrane of the post-synaptic cell.

B Enhance the effect of excitatory transmitters at the synapse.

C Attach to excitatory neurotransmitters before they reach the post-synaptic membrane.

D Act as competitive inhibitors for the enzymes responsible for digesting

neurotransmitters at the synapse.

QUESTION 5

The bola spider of Australia has a unique technique for capturing its prey. It laces a sticky

globule (a bola) with the scent of a female moth, and dangles and twirls the bola from a silky

thread in order to attract unsuspecting male moths. If the technique has proven unsuccessful

for a period of time, the spider hauls in the bola, only to produce a new one that is laced with

the scent of a female of a different moth species.

The chemical scent used by the spider is:

A A pheromone.

B A hormone.

C Neurohormone.

D A cytokine.

QUESTION 6

Action potentials (nerve impulses) can pass along all neuron membranes. The following

events occur during an action potential:

A Electrons jump from one node of Ranvier to another along myelinated axons.

B Sodium ions rush into the cell via facilitated diffusion.

C Sodium ions actively rush into the cell via sodium-potassium pumps.

D Potassium ions rush into the cell via facilitated diffusion.

QUESTION 7

What type of cell is shown in the diagram?

A A sensory neuron with a receptor.

B An interneuron.

C A sensory neuron with an effector.

D A motor neuron with an effector.

QUESTION 8

A ground squirrel, with a usual body temperature of 38°C, has a hibernation temperature of only 4°C. Body fat is very slowly consumed during hibernation. When compared to their activity at 38°C, the enzymes responsible for the breakdown of body fat cannot be very

active at 4°C as:

A They begin to denature.

B The motion of enzyme and substrate molecules is greatly reduced.

C Competitive inhibitors are activated to prevent excessive respiration.

D Peptide linkages within the enzymes are broken down to provide valuable sources

of energy.

A target cell for both a specific peptide hormone and a particular steroid hormone is

represented in Figure 2 below. A steroid and peptide hormone have both signalled the cell

in the diagram.

QUESTION 9

Structures A, B, C and D represent the following molecules:

A A = receptor, B = steroid hormone, C = hormone-receptor complex, D = peptide

hormone.

B A = G protein, B = receptor, C = hormone-receptor complex, D = cyclic AMP

C A = receptor, B = peptide hormone, C = G protein, D = steroid hormone.

D A = G protein, B = peptide hormone, C = receptor, D = steroid hormone.

QUESTION 10

Signal transduction pathways can involve the response of millions of molecules to a single

chemical messenger molecule. For instance, one molecule of adrenalin causes the

breakdown of 100,000,000 molecules of glucose from the glycogen store in a liver cell.

If the activation of a cytoplasmic receptor initiates a signal transduction pathway, the original

signal could have been provided by:

A A neurotransmitter such as acetylcholine (ACh).

B A steroid hormone such as cortisone.

C A peptide hormone such as insulin.

D A protein hormone such as thyroid stimulating hormone.

QUESTION 11

The following statement is true of plant hormones:

A Auxins cause increased levels of mitosis resulting in phototropic responses.

B Ethylene is a gaseous hormone that is used to prevent stored fruit from ripening.

C With rising temperatures in spring, abscisic acid overrides the inhibitory influence of

gibberellins within seeds, thereby stimulating germination.

D Cytokinins delay leaf death (senescence).

QUESTION 12

The term “hormone” is applied to chemical messenger molecules in both plants and animals.

One difference in the action of plant and animal hormones is that:

A Some plant hormones exert opposite effects on target cells in different parts of the

same organism.

B Plant hormones do not travel in the vascular system.

C Plant hormones are inorganic.

D Animal hormones are exclusively endocrine.

QUESTION 13

Neurotransmitter molecules have a very short lifespan once they have attached to a receptor

on a postsynaptic membrane. Enzymes will rapidly degrade the neurotransmitter molecules,

and the breakdown products may be returned to the presynaptic cell.

Some insecticides act as competitive inhibitors on the enzymes responsible for the

breakdown of excitatory neurotransmitters. The insecticide kills the insect by:

A Preventing impulses from being generated in the postsynaptic cells.

B Preventing the release of more neurotransmitter across the synapses.

C Overstimulating the postsynaptic cells.

D Interfering with the release of inhibitory neurotransmitters of pain control pathways.

QUESTION 14

Interneurons occur within the grey matter of animal nerve tissues. An interneuron:

A Is the most common type of neuron in the human body.

B Only produces myelin when part of a reflex arc.

C Contains many dendrites and axons.

D Uses nodes of Ranvier to speed up impulse transmission.

QUESTION 15

The most accurate description of the difference between hormones and pheromones is

A. pheromones are small, volatile molecules whereas hormones are not.

B. pheromones are signals that function between organisms, whereas hormones communicate within an organism.

C. pheromones use neurons as their means of transmission, whereas hormones use chemicals as their means of transmission.

D. pheromones are involved in reproduction, whereas hormones are not.

Explanatory notes

• A is incorrect. Both pheromones and hormones are small molecules.

• B is correct. Pheromones are signals that function intraspecifically, whereas hormones communicate within an organism.

• C is incorrect. Pheromones are released into the external environment and interact chemically; they do not use neurons as their means of transmission.

• D is incorrect. Both pheromones and hormones are involved in reproduction.

QUESTION 16

Epinephrine is a hormone produced in humans. When it binds to the muscle cells of the small intestine, contraction of the muscles is inhibited. In contrast, when it binds to heart muscle, it speeds up the contraction. Epinephrine can have different effects on muscle cells because

A. small intestine muscle is not as strong as heart muscle and has a weaker response to epinephrine.

B. the cells in small intestine muscle and heart muscle have different signal transduction pathways for epinephrine, producing different cellular responses.

C. there are more receptors for epinephrine in heart muscle cells than there are in small intestine muscle cells.

D. epinephrine circulates to the heart first and the higher concentration around heart muscle cells results in a stronger response.

Explanatory notes

• A is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the signal transduction pathway of epinephrine, it is not related to the strength or weakness of the muscle.

• B is correct. Cellular responses to hormones can be different depending on the nature of the signal transduction pathway in the cell.

• C is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the signal transduction pathway of epinephrine. It is not related to the number of receptors in the plasma membrane of the cells.

• D is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the signal transduction pathway of epinephrine. It is not related to the order of circulation of epinephrine around the body.

QUESTION 17

A signal molecule that binds to a plasma membrane protein functions as a

A. protein kinase.

B. receptor protein.

C. second messenger.

D. ligand.

Explanatory notes

• A is incorrect. A protein kinase is an enzyme that transfers phosphate groups from ATP to a protein. It does not bind to a plasma membrane protein.

• B is incorrect. A receptor protein is found embedded in the plasma membrane. Signal molecules are not incorporated in the plasma membrane; they are produced in endocrine cells and travel in the bloodstream.

• C is incorrect. A second messenger is a small, non-protein, water-soluble molecule or ion that relays a signal within a cell in response to a signalling molecule; it does not bind to a plasma membrane protein.

• D is correct. A ligand is a molecule that specifically binds to another molecule. Ligand binding causes a receptor protein to undergo a change in shape, and is what occurs when a signal molecule binds to a plasma membrane protein.

Section A total marks /17

SECTION B – Short-answer questions

Instructions for Section B

· Answer all questions in the spaces provided.

QUESTION 1

In animals, homeostasis is a term used to describe a relatively stable internal environment.

(a) What is the internal environment of the body?

______

I mark

Type 1 diabetes mellitus is characterised by loss of the insulin-producing beta cells of the

islets of Langerhans in the pancreas, leading to insulin deficiency. A common treatment has

been NPH insulin but recently the activity of a new type of insulin, called LANTUS insulin,

has been tested and compared with NPH insulin.

Participants in the test were divided into two groups. One group received NPH insulin. The

second group received LANTUS insulin. All participants received the same amount and

concentration of the appropriate insulin.

The following graph shows the average results for participants in each of the two groups:

Insulin is regarded as being effective when the glucose uptake by cells is above 0.4

mg/kg/min.

(b) After the injections, for how long was each kind of insulin effective?

______

2 marks

______

1 mark

(d) Explain what events may occur to regulate the uptake of glucose in a non diabetic.

______

2 marks

Total 6 marks

answers

(a) The internal environment of the body is the extracellular fluid that surrounds the cells.

(b) NPH was effective for 12.5 hours. AND Lantus was effective for 24 hours.

administered once over a 24 hour period. The glucose uptake is also maintained within

a more narrow limit, creating less stress on the homeostatic mechanisms of the

patient.

(d) Blood glucose regulation relies on negative feedback systems. If the glucose levels of

blood slightly overshoots the optimal as a result of effector action, the counter negative

feedback system will respond to correct the overshoot (1). These actions occur

continuously in the body of a normal person so that optimal levels of blood glucose are

continually fine-tuned (1).

QUESTION 2

The concentration of an unknown protein (X) increased dramatically after depriving a

particular plant of water.

(a) Assuming this protein belongs to a class of signalling molecules, identify protein X.

______

1 mark

(b) Describe the process that would have initiated the production of Protein X under these

conditions.

______

2 marks

In order to accurately identify this protein was isolated from the plant and subjected to

proteomic analysis. This involved trypsin digestion followed by mass-spectrometry of the

resulting peptides. The results are presented in Table 1 below. Each amino acid has a

unique molecular mass and isoelectric point which is affected by pH. The Molecular Weight

(daltons) and the isoelectric point (pI) shown in Table 2 is calculated from the primary

structure.

for the protein X peptide.

______

(ii) Briefly justify your answer.

______

1+1=2 marks

(d) What is the rationale for the identification of unknown proteins using MolWt and pI of

amino acids in a peptide?

______

1 mark

Total 6 marks

answers

(a) Phtyohormone-most likely Abscisic Acid.

(b) The plant cells responded to environmental stimulus of water stress (1). This involves a

series of molecular steps called a signal transduction pathway where the information is

relayed through secondary messenger molecules. Finally, a specific effector molecule-

Protein X brings about the cellular response (1).

(ii) The first 7 amino acids have molecular masses corresponding to the known masses from Table 2. The last amino acid, Valine, was determined using simple arithmetic (842-743) following the pattern used on the grap and matching the calculated mass of 99 daltons to Table 2.