Human Bio

Model Answer to Semester 1 HBS3AB 2010 EXAM

PART II (100 marks)

QUESTION 31 (Total 18 marks)

The diagram below shows the cerebral hemispheres of the brain, functional areas of the brain, connecting nerves and the eyes.

(a) A small electric shock was used to stimulate part of the brain. This caused a muscle in the left leg to contract. Label the diagram with the X to show the area of the brain that would cause the muscle to contract.

(2 marks)

(b) The vision centre is located in the occipital lobe. Circle this area on the diagram above.

(1 mark)

(c) Recent research has suggested that adults who play video games regularly improved their eyesight. The researchers found that playing action games, like Counter-Strike, improved the player’s contrast sensitivity. This means that their night driving, where light is minimal, was better. The experiment consisted of 22 University students divided into 2 groups. One group played an action game and the other group, a game that required a lot less hand-eye coordination. The two groups played 50 hours of their assigned game. At the end of training, the action game players showed an average of 43 per cent improvement in their ability to discern ‘shades of gray’ while the other group showed no improvement.

(i) State the hypothesis in this experiment.

That watching action video games improves a person’s night driving ability. (1)

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The market for board games has seen annual increases of 10-20 per cent over the last decade, leading some to suggest we are in a “board game renaissance” (Carlson, 2013). 401 Games is a Toronto-based retailer of board games, card games, and collectibles which also provides on-site gaming space. A recognized early mover in the board game revolution, owner John Park was among the first to tap into ...

(1 mark)

(ii) What is the independent variable being tested in this experiment?

Action Video Games (1)

(1 mark)

(iii) List TWO variables that were controlled during the experiment.

Even size groups (11 students), (1) 50 hours each (1) (2 marks)

(iv) Describe ONE improvement that could be made to this experiment.

Increase number of people in group, use different games (1) (1 mark)

(d) The sympathetic and parasympathetic divisions are described as ‘antagonistic.’

What does this term mean?

Antagonistic means having the opposite effect (1)

(1 mark)

(e) Complete the following table to show the effect of sympathetic stimulation on the listed body organs.

Body Organ

Sympathetic Effect

Heart

Increase heart rate (1)

Sweat Glands

Increase sweating (1)

Small Intestine

decrease blood flow or digestive rate (1)

(3 marks)

(f) Motor Neurones are found in the autonomic nervous system. The autonomic nervous system consists of the sympathetic and parasympathetic nervous systems.

(i) What effect would the sympathetic stimulation of these neurons have on the diameter of arterioles leading to the skeletal muscles?

Dilates vessels (1) (1 mark)

(ii) Explain the effect of the parasympathetic division of the autonomic nervous system on cardiac output.

Decreases rate (1) and strength of the contraction (1)

(2 marks)

(g) Describe how the synapses ensure that a nerve impulse is transmitted in only one

direction only.

Neurotransmitters diffuse across the synaptic gap and attach to receptors on the membranes of the next neuron (1)

Nerve impulses crossing a synapse will only go from axon to dendrite or from axon to cell body (1)

After the neurotransmitter produces its effect, the receptor releases it and the neurotransmitter goes back into the synapse. In the synapse, the cell “recycles” the degraded neurotransmitter (1)

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(3 marks)

QUESTION 32 (Total 11 marks)

Researchers wanted to observe and record changes in urine volumes in response to drinking different solutions. One person volunteered to drink one litre (1 L) of distilled water that contained no salts. Another person volunteered to drink a saline solution that had the same salt concentration as the body fluids (0.96% salt).

Urine volumes were collected every 30 minutes for both the volunteers, starting 30 minutes before they drank the solutions.

Time (minutes) Urine Volumes

(mL)

Person 1

0% salt solution Person 2

0.96% salt solution

-30 55 50

0 40 35

30 345 55

60 410 90

90 205 45

120 60 95

150 85 105

180 60 95

210 45 55

240 55 45

(a) Graph these results on the grid provided below. (5 marks)

title – includes both axes labels

labels for axes

units for axes

proper number line spaces on axes

key to graph lines

points plotted correctly

Deduct 1 mark for each incorrect point up to a maximum of 5.

Question 32 (continued)

(b) Why were recordings made prior to Person 1 and Person 2 drinking the solutions?

(2 marks)

To provide the control value of normal urine production (1)

For comparison of volumes after drinking (1)

(c) State one factor that is changed in the internal environment as a result of drinking 1 L of 0% salt solution.

(1 mark)

blood volume (1)

Osmolarity (concentration) of the blood fluids (1)

(d) At what time would the blood concentration of ADH be the lowest for Person 1? Explain your answer.

(2 marks)

Between 30-60 minutes because urine volume is greatest at 60 minutes (1) ADH causes urine retention. Low or no ADH = high urine production (1)

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1. Review the data flow diagrams you developed for questions in the BEC case at the end of Chapter 5 (or diagrams given to you by your instructor.) Study the data flows and data stores on these diagrams and decide if you agree with the team’s conclusion that there are only the six entity types listed in this case and in BEC Figure 6-1. If you disagree, define additional entity types, explain why ...

(e) What do the letters HRT stand for? (1 mark)

Hormone Replacement Therapy (1)

Question 33 (Total 8 marks)

Refer to the following diagrams showing the parts of a neurone and some components of a reflex arc.

(a) Identify the structures labelled A and B in the diagram of the neurone above.

(2 marks)

A: axon (1)

B: dendrite (1)

(b) Which neurone in the reflex arc in the diagram below is of the type shown above?

(1 mark)

Neurone X (1)

Question 33 (continued)

(c) (i) The blue-ringed octopus, which is common on shallow inshore reefs along the coastal beaches and offshore islands of south-west Western Australia, produces a toxin that blocks nerve transmission at some synapses. A person who was revived after being stung by a blue-ringed octopus said he was consciously aware of all efforts of the rescuers when they were doing CPR, but that he could not respond to any of their questions.

Which synapse, A or B, shown in the diagram of a reflex arc would be blocked by the

toxin?

Synapse A: (1)

(1 mark)

(ii) Give two reasons to explain your choice of synapse.

• talking requires muscle movement (1) and

• impulses to muscles are blocked at A (1)

• The sensory pathway through B is okay as he is aware of what the rescuer were doing (1) must have this point

(2 marks)

(d) In Hansen’s disease (leprosy) nerve endings in the skin degenerate. Sufferers of Hansen’s disease often do not realise they have been cut or burned. Explain why.

• Receptor needs to be stimulated to produce a nerve impulse. (1)

• The nerve impulse is either not formed or not transmitted. (1)

(2 marks)

Question 34 (Total 9 marks)

Refer to the following diagram showing the location of major endocrine organs of the body for this question.

(a) Identify the endocrine glands labeled B and F in the diagram above.

(2 marks)

B: thyroid gland (1)

F: pancreas/islets of Langerhans (1)

(b) Adrenal glands (C) have two distinct parts, the medulla and the cortex. State one hormone produced by each part.

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(2 marks)

Adrenal medulla Adrenal cortex

Hormone produced

Epinephrine (mostly)/adrenaline

Norepinephrine /noradrenaline (1) Cortisol

Aldosterone

(1)

(c) Name one hormone produced by the anterior pituitary that influences the fertility of males and females.

(1 mark)

Gonadotrophins or LH or FSH (1)

(d) State two ways in which hormones affect target cells.

(2 marks)

• changes cell membrane permeability

• activates specific genes (changing the rate of transcription)

• changes the rate of enzymatic activity (hence metabolic activity in the cell)

• promotes protein synthesis

1 mark per correct point

(c) Some athletes take anabolic steroids, such as testosterone, to improve their performance. This practice has been banned by the International Olympic Committee.

What are two changes to the body that occur as a result of taking steroids?

• liver damage

• shrinking of the testes

• eventual sterility

• increased protein synthesis and muscle growth

• increases libido (sexual drive)

1 mark per correct point

(2 marks)

Question 35 (Total 19 marks)

(a) Give the corresponding letter from the above diagram and give the name of the canals that run between lacunae. (1 mark)

D – Canalicula (1)

(b) Which letter from the above diagram is pointing to the lacunae? (1 mark)

C (1)

(c) What is the purpose of these canals? (1 mark)

So that materials can pass from cell to cell (1)

(d) Where in a long bone would you expect to find osteons arranged this way?

(1 mark)

Compact bone of diaphysis (1)

(e) Give two ways cancellous bone is different to compact bone: (2 marks)

Not organised into osteons

Consists of Trabeculae ( an irregular arrangement of thin bony plates)

Bone cells occupy a space in the trabeculae

Lamellae are not arranged in concentric circles

Any 2

(f) How does a sarcomere of a contracted muscle fibre differ from a saromere of a relaxed muscle fibre? [Your answer must include all the structures of a sarcomere] (6 marks)

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Simple cuboidal epithelium m. Simple columnar epithelium n. Pseudostratified columnar epithelium o. Stratified squamous epithelium p. Stratified cuboidal epithelium q. Stratified columnar epithelium r. Transitional epithelium s. Glandular epithelium i. Lining of intestines ii. Lining of ducts of mammary glands iii. Lining of urinary bladder iv. Salivary glands v. Air sacs of lungs vi. Respiratory ...

Actin and myosin filaments have slid over each other (1) causing the Z lines (1) to draw closer together (1) and the sacromere has shortened (1) in a contracted muscle. (1) Further apart in a relaxed muscle (1)

(g) In the space provided draw a contracted and a relaxed sarcomere, both fully labelled: (4 marks)

(h) Cartilage is a different type of connective tissue, name the three different types of cartilage and give one example where each would be found in the body in the following table: (3 marks)

Type of cartilage Where found in the body

Hyaline

Ring of trachea and bronchi

Ends of bones of movable joints

Elastic

Ear; nose

Fibrocartilage

Intervertebral discs

Articular cartilage of knee

Pubic symphisis

Question 36 (6 marks)

(a) Structure Z is involved in the process of facilitated diffusion. Name Z and explain what it does?

(2 marks)

Carrier protein in cell membrane (1)

Molecule to be transported attaches itself to a binding site on carrier and when carrier changes shape, molecule is released on the other side (1)

(b) Describe TWO functions of the structure labeled X.

(2 marks)

Physical barrier

Regulation of passage of materials – any 2 with explanation

Sensitivity

Support

(c) Describe what happens to the cell membrane during the process of exocytosis and give

ONE example of exocytosis.

(2 marks)

Vesicle migrates to cell membrane and fuses with membrane

Contents of vesicle then pushed out into extracellular fluid

E.g. mucus / digestive juices

Question 37 (Total 13 marks)

Figure 1 shows an inferior view of the Human brain

(a) Fill in t the following table with reference to the labels.

(4 marks)

Label Name of part Function of part

A

cerebellum

(1 mark) controls skeletal muscle contractions for co-ordination of skilled movements, posture and balance (1 mark for any one of the above)

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B

medulla oblongata

(1 mark) regulation of vital body functions through the (1 mark for any of the following)

• cardiovascular centre – regulates rate and force of heart beat and diameter of blood vessels

• respiratory centre – adjusts breathing rhythm

• other centres co-ordinate swallowing, vomiting coughing, sneezing and hiccupping

The section of the brain, outlined in the box labelled C, is shown below in sagittal section in Figure 2.

Figure 2

(b) Identify the structures in Figure 2 labelled. (2 marks)

A. hypothalamus (1)

C. anterior pituitary (1)

(c) Where are the hormones secreted from B produced? (1 mark)

hypothalamus

(d) Complete the following table for any two hormones produced at C.

(4 marks)

Hormones produced by C Target organ

human growth hormone (hGH) stimulates general body growth and regulates aspects of metabolism

adrenocorticotropic hormone (ACTH) adrenal cortex

prolactin mammary glands

thyroid stimulating hormone (TSH) thyroid

follicle stimulating hormone (FSH) ovaries

testes

luteinising hormone (LH) ovarian follicle (ovulation)

formation of corpus luteum

testes (secretion of testosterone)

(any 2 – 2 marks for hormone and target organ)

(e) Hormones from B and C in Figure 2 travel to all parts of the body via the blood.

How does a hormone affect specific target cells and not other types of cells?

(2 marks)

hormones bind to and activate their specific receptors in cells to (1 mark) and any of the following for 1 mark

• change the permeability of the cell membrane

• alter gene expression (promoting synthesis of enzymes/other hormones)

• act as enzymes to alter the rate of specific cellular reactions

Question 38 (16 marks)

The figure below shows some cellulose tubing, containing a sugar solution (sucrose), immersed in distilled water. Cellulose tubing behaves as a differentially permeable membrane.

(a) If examined several hours later, explain what you would expect to have happened to the components of liquid in the beaker and that of the liquid inside the cellulose tubing. (2 marks)

Level of liquid would have dropped (1)

Liquid in cellulose tubing would have increased – larger in mass (1)

(b) If, after several hours you tasted the water in the test tube, what would you expect and why? (4 marks)

Sweet (1) – sugar molecules are small enough to diffuse (1) once osmosis has taken place.(1)

Monoscaccharides (1)

(c) Briefly describe the events that occur when a muscle contracts. (10 marks)

Sliding Filament Model to explain muscle contraction (1)

Thin actin filaments (1) slide over thick myosin filaments (1)

Z lines are drawn closer together (1) and the sacromere is shortened (1)

Results in shortening of the muscle fibres and hence a shortening of the whole muscle (1)

Myofilaments are the same length in the contraction position as they were before contracting (1)

Fibril has shortened because the myofilaments overlap more (1)

Energy is required for the shortening of the muscle fibres (1)

Energy comes from the breakdown of ATP in the muscle cells (1)

END OF PART II

PART III (40 marks)

Answer ONE question from SECTION A and ONE question from SECTION B. Illustrate your answers with diagrams where appropriate. Up to TWO MARKS may be deducted for poorly structured answers: that is, answers in point form or diagrams not explained in the text of your answers. DO NOT WRITE ANSWERS IN PENCIL. Write your answers on the lined pages in your Question / Answer Booklet following the end of questions.

SECTION A

ANSWER EITHER QUESTION 39 OR QUESTION 40 – NOT BOTH

QUESTION 39 (Total 20 Marks)

On a hot day you spend several hours working or playing sport and you notice that your skin becomes red and your clothes become wet with sweat. You feel thirsty and have several large drinks of water. When you get home you notice that your urine is darker than usual and you recall with some surprise that you hadn’t felt the need to empty your bladder since you left home in the morning.

Outline the way in which these observations can be related to the physiological process of homeostasis.

(a) the sweating

(b) the thirst

(c) the low volume of strong urine produced

(20 marks)

(a) Temperature regulation:

a. Body temperature increase due to

i. Hot day.

ii. Metabolic heat production.

b. Detected by:

i. Thermoreceptors

ii. Hypothalamus

iii. Autonomic nervous system

c. Body cooled by:

i. Vasodilation – brings blood near the surface; increased heat loss by convection

ii. Sweating – cools the skin by evaporation

(b) The thirst – regulation of body fluids

d. Osmotic pressure of the blood is reduced by:

i. Water loss from the extracellular fluid / plasma

1. Sweating

2. Evaporation

e. Detected by:

i. Osmoreceptors in hypothalamus

f. Thirst is stimulated by:

i. Nerve impulses to the thirst centre in the hypothalamus

ii. Drinking behaviour activated.

(c) The low volume of strong urine

g. Osmotic pressure of the blood reduced (as above)

h. Detected by osmoreceptors (as above)

i. Further water loss is restricted by

i. Nerve impulses from the hypothalamus

ii. To the posterior pituitary

1. ADH produced and released into the bloodstream.

iii. ADH acts on the kidney

1. Distal convoluted tubules permeability increases.

2. More water is returned to the bloodstream

3. Less water enters the urine – causing a low volume of strong urine.

OR

QUESTION 40 (Total 20 Marks)

The following diagram below shows an overview of the process of protein synthesis. Each of the major steps in the process is numbered, while structures are labelled with letters.

(i) Identify each of the structures marked with a letter. (5)

A DNA strand

B nucleotide

C RNA polymerase (enzyme)

D mRNA

E nuclear membrane

F nuclear pore

G tRNA ½ mark each

H amino acid

I ribosome

J polypeptide chain

(ii) Describe the process of protein synthesis. (Use numbered steps from the diagram) (15)

Protein synthesis is the assembly of amino acids to form polypeptides/proteins 2 processes – Transcription and Translation

1 DNA contains the code

2 RNA polymerase unzips DNA and copies code onto mRNA (transcription) – 1 gene is transcribed at a time

3 The 2 strands of DNA coil up into a helix

4 mRNA travels through a nuclear pore into the cytoplasm to ribosome. A single strand of mRNA can be translated by more than one ribosome

5 tRNA moves into the ribosome bringing in amino acids to add to the chain of polypeptides

6 Anticodons on tRNA must match the codon on mRNA

7 tRNA unloaded can reload with amino acids

8 Specific amino acid loads up on tRNA

SECTION B

ANSWER EITHER QUESTION 41 OR QUESTION 42 – NOT BOTH

QUESTION 41 (Total 20 Marks)

(a) Snake and spider bites inject toxins into the body. These toxins inhibit or replace the neurotransmitters doing their normal function. What is a neurotransmitter, where are they found and what is their function in the body? All nerve types can be affected by animal bites. What are the THREE types of nerves found in the body and describe their respective structure in the body?

• A chemical substance

• Found at the end of the axon.

• Released, diffuse across the synapse and attach to the dendrite of the next neuron or effector.

• Stimulates a nervous impulse in the next dendrite (4)

Neuron Type Description/Characteristics

Sensory or Afferent

• receptors on dendrites.

• cell body central to structure

• cell body found in ganglion

• long dendrite and short axon

Motor or Efferent

• motor end plate at end of axon

• cell body close to dendrite.

• short dendrite and long axon.

Association or Connector

• dendrites and axon same length

• central cell body.

(any two points for each neuron type) (6)

(b) Fiona, a very excitable young girl, was walking along a busy street talking intensely on her mobile phone to her best friend. She was so focused on her conversation that, without thinking, she stepped onto the road and was immediately startled by the screeching of tyres and the blaring sound of a very loud horn. When she realised that she had stepped in front of a car but had not been run over, she felt greatly relieved but noticed that her body had responded in several different ways.

(i) Identify the responses that Fiona’s body would automatically demonstrate in her reaction to danger and explain how each is useful in this situation.

(6 marks)

(ii) Compare and contrast the actions of nerves and hormones in the control of body responses.

(4 marks)

(i)

Fiona’s response to the loud noises was mediated by the “Fight or Flight” reaction through the sympathetic nervous system. (1 mark)

The release of the neurotransmitter noradrenaline by sympathetic nerve endings at the heart caused her accelerated heartbeat. (1 mark)

Any of the following: (4 marks)

– increased blood pressure and

– increased cardiac output – increase supply of blood to muscles in case movement is necessary

– increased blood volume to brain – supply increased nutrients to improve perception and response by brain

– increased blood distribution to skeletal muscles – increase supply of nutrients to allow for quick movements

– decreased blood distribution to the digestive system, kidneys, reproductive organs and skin – reduction of blood flow to areas that are not used in flight or fight

– dilated pupils – improved peripheral vision to see what is coming/happening

– dilation of airways in the lungs – improved flow of air into and out of lungs to improve supply and removal of gases

– activation of sweat glands in the skin –

– increased metabolisation of lipids from fat cells and glucose from the liver – to increase availability of energy

– release of endorphins (natural pain killers) in the brain – fight or flee even when injured

(ii)

Compare action of nerves and hormones (1 mark)

– both in response to stimulus

– each has specific target organ(s)

Contrast (3 marks)

Nerves Hormones

electro-chemical impulse chemical messenger

discreet pathways (nerves) to target organ general pathway to target organ (via blood stream)

rapid response time usually slower response time

short duration of effect long duration of effect

localised effect – each neurone links with only one or a few cells more general effect – can influence cells in may different parts of the body

size of signal determined by number of nerve fibres stimulated or frequency of nerve impulses size of response determined by concentration of hormone

some can be modified by learning from previous experience cannot be modified by learning

OR

QUESTION 42 (Total 20 Marks)

(a) For several years, Darren has avoided all physical exercise, preferring to spend all his spare time in front of his computer and TV. One day, quite impulsively, Darren decided to take the family dog for a leisurely walk. The large, muscular dog had other ideas and turned a slow walk into a race for over thirty minutes, leaving Darren exhausted, breathing deeply and rapidly and with a very high heart rate.

With reference to the homeostatic mechanisms involved, explain why Darren’s breathing rate and cardiac output would change during this strenuous exercise and why these changes would continue for quite a few minutes after he finished exercising.

(10 marks)

The strenuous exercise involves repeated forceful contractions of many muscles. The energy consumption required for each muscle contraction involves the production of CO2 as a waste product that is collected by the capillaries surrounding each muscle fibre. The CO2 dissolved in water in the blood plasma releases hydrogen ions, resulting in increased acidity of the blood. The increased blood acidity stimulates increased activity of chemoreceptors in the carotid bodies, aortic arch and blood vessels of the medulla oblongata. These in turn stimulate and increase the activity of respiratory centres that increase the rate and depth of respiratory muscle contractions. This will occur until the blood CO2 concentration decreases to normal (resting) levels. Essentially, the more muscle contractions, the more waste CO2 to be expired, and the longer the period of deep and rapid breathing (recovery to normal respiratory rate).

Possible Answers:

– the degree of stretching at the end of ventricular diastole.

– the contractility of the ventricle (strength of contraction).

– the amount of pressure required to eject blood (vascular resistance).

– length of ventricular diastole (amount of time available for ventricle to fill).

– the volume of blood returning to the heart (venous return).

– activity of the sympathetic division of the autonomic nervous system (noradrenalin increases the force of contraction of cardiac muscle).

(b) Haemorrhage, either internal or external, often causes a number of symptoms: the patient’s skin becomes cold and pale; they complain of thirst, they have a rapid yet weak pulse and, if left untreated, can lose consciousness. Indicate which of these symptoms are due to homeostatic processes, and explain why each of these symptoms would occur in someone losing blood from their circulatory system. (10 marks)

Homeostatic processes –

-Complaining of thirst – the kidney would increase active reabsorption of water -and increase the osmotic pressure of the blood, stimulating centre in hypothalamus so person feels thirsty. 3 or 4 marks

-Rapid, weak pulse – homeostatic – cardiovascular regulating centre stimulated (Increased heart rate. Weak due to the lack of pressure (pressure receptors involved) 3 or 4 marks

-Cold pale skin would not be a homeostatic response – just due to lack of blood flow. 1 or 2 marks

-Lost consciousness – not a homeostatic response 1 or 2 marks