Answer :

QUESTION 1

Fill in the blank boxes to complete TWO rows of your choice in the following table, which summarises the name, location, and function of a variety of cells throughout the body. The first line is completed as an example of the level of detail required. Only the first TWO rows completed will be marked (1 mark/row; 2 marks total)

QUESTION 2

Name the personal protective equipment that should be worn when handling someone else’s urine, and explain why those items are needed. (2 marks) 

 The personal protective equipment that must be worn while handling someone else’s urine are gloves, gowns as well as masks. These items are needed and must be worn in order to protect ourselves from the harmful germs and also from the disease-causing organisms. By wearing such equipment the individual can protect themselves from the transmission of the infectious diseases.

QUESTION 3

Complete the table to compare how the following cells carry out the third line of defence:

• B-lymphocytes 
• Cytotoxic T-lymphocytes 

Some sections are completed for you to help guide your answers. (0.5 marks/box; 4 marks total)

QUESTION 4

The following paragraph refers to muscle contraction. Fill in each of the blanks to complete the paragraph using terms from the list provided.  More terms than necessary are provided, and terms may be used more than once. (0.5 marks each; total 3 marks)

The action potential spreads along the Sarcolemma until it reaches a T-tubule. The action potential continues down the T-tubule, where it triggers the release of Ca++ ions from the sarcoplasmic reticulum. This exposes binding sites on Actin. Myosin Heads bind to the exposed sites on Actin to form cross-bridges.

QUESTION 5 

Describe the role of osteoblasts and osteoclasts in the regulation of blood calcium ion concentration.  You must include the role of the relevant hormones for full marks. (3 marks)

The calcium homeostasis is described as the regulation of the concentration of the calcium ions in the extracellular fluid. The PTH hormone which is secreted from the parathyroid glands helps in the regulation of the blood calcium levels. Moreover, the PTH hormone helps in increases the blood calcium levels by stimulating the osteoclasts that break down bones in order to release calcium into the bloodstream. Furthermore, Calcitonin is a hormone that is produced by thyroid which acts in the opposition of PTH by inhibiting osteoclasts and stimulating osteoblasts which assist in increasing the excretion of calcium into the urine through the help of kidneys. In addition, the role of osteoblast is that it helps in the formation of bones. 

QUESTION 6

Describe how the hypothalamus controls the release of hormones from the:

1. anterior lobe of the pituitary gland 
2. posterior lobe of the pituitary gland

In your answer, give specific examples and clearly name any hormones involved. (2 marks/lobe)

1. The hormones of the pituitary gland used to send signals to the other endocrine glands in order to stimulate or inhibit their own hormone production. The anterior lobe of the pituitary gland releases hormones through receiving releasing or the inhibiting hormones from the hypothalamus. Hence, these hypothalamic hormones send signals to the anterior lobe of the pituitary gland whether to release hormones or to stop the production of it. 
2. The posterior lobe of the pituitary glands consists of the end of the nerve cells which is coming from the hypothalamus. Therefore, the hypothalamus used to sends hormones directly to the posterior lobe of the pituitary gland through these nerves and then the pituitary gland release those hormones. 

QUESTION 7

Duchenne muscular dystrophy (DMD) is a recessive sex-linked disorder, which causes muscle degeneration and premature death. A couple is pregnant with a boy and neither has DMD. The father’s family has no history of DMD, but the mother is unsure of her genetic family history as she was adopted. The mother decides to take advantage of some of the new genomic screening tests and learns information about a large number of her genes. She finds that she is a carrier of the DMD-affected allele. (3 marks total)

1. What is the mother’s genotype? Explain your reasoning. (1 mark)

The mother’s genotype is XX as the mother consists of the two sex-linked genes. 

2. What is the father’s genotype? Explain your reasoning. (1 mark)

The father’s genotype is XY as the father consists of only one sex-linked gene. 

3. What is the likelihood of the male fetus having DMD? Use a Punnett square to explain your answer.  (1 mark)

Let the healthy copy of the gene is represented as X^B and the damaged one is represented as X^b. 

QUESTION 8 

Describe the changes in volume and pressure inside the chest cavity during a normal, quiet exhalation. Explain why these changes are occurring, and the effect upon airflow. (4 marks)

The mechanism of the breathing follows the Boyle’s law that states that the pressure, as well as volume, possesses an inverse relationship. The process of the inhalation occurs due to the rise in the lung volume that results in the decrease in the pressure in the lungs as compared to the atmosphere and hence the air rushes in the air passage. Similarly, the process of exhalation occurs because of the elastic recoil of the tissues of lungs that causes a reduction in the volume results in a rise in pressure as compared to the atmosphere and therefore air rushes out from the lungs. '

QUESTION 9

Regarding quiet ventilation, which process is active — inhalation or exhalation? Briefly explain your answer. (1 mark)

During quiet ventilation, inhalation occurs as the air moves from the atmosphere into the lungs which are also known as the tidal volume and is referred to as V_T  that is of 500 millilitres. 

QUESTION 10

The graph below displays the oxygen dissociation curve and factors that affect the release of oxygen from haemoglobin (Hb). Explain how these factors will affect the release of oxygen into the blood supply of a hard-working skeletal muscle. (3 marks)

The hard-working skeletal muscle or the exercise causes a rise in temperature, acidity as well as metabolic intermediates and the decrease in the oxygen in the muscle tissues. Hence this leads to a rise in the dissociation of oxygen from the blood flowing through the muscles by supplying them with much-required oxygen. Furthermore, the body increases blood flow to the muscles in order to supply them with more oxygen. In addition the warming up before the exercise aid in prime the muscles to gather ample oxygen by kick-starting metabolism as well as in the increase in temperature. 

Image from http://www.gpnotebook.co.uk/simplepage.cfm?ID=20250669

QUESTION 11 

Choose ONE of the blood types below and answer the following questions. Only the FIRST completed column will be marked

1. State the type of antigens found on the surface of those red blood cells, and the type of antibodies found in the plasma of a person with the blood type shown. Type your answer in the table below  (1 mark total)
2. Could a person with your chosen blood type safely receive type AB blood via transfusion?  Explain your answer below. (2 marks)

The group O blood types do not possess any type of antigens like antigen-A and antigen-B so they can safely receive plasma from any blood group types. However, O positive can receive blood from O positive and negative and O negative will only receive from O negative blood group.

Blood Group	A	B	AB	O
Red blood cell type
Antigens on red blood cells				It does not contain any A or B antigens of the ABO blood system
Antibodies in plasma				Anti-A and Anti-B antibodies are found in the plasma.

QUESTION 12 

Why is an injury to the medulla oblongata usually fatal? (2 marks)

The injury to the medulla oblongata is basically fatal because it is the portion of the hindbrain which generally controls the autonomic functions like digestion, breathing, heart, and functioning of the blood vessels, sneezing as well as swallowing. Apart from this, the medulla oblongata helps in transferring messages to various parts of the body from the brain to the spinal cord. Therefore, the injury of medulla oblongata will lead to severe damage in the body of the individuals.

QUESTION 13 

Complete the following table summarising the effects of autonomic innervation on target tissues. You must include both the effect upon the target tissue and a consequence of this stimulation in your answer. 

The first row has been completed as an example. (1 mark/box; 4 marks total)

QUESTION 14

The paragraph below relates to this graph, which describes changes in membrane potential over time.

1. Fill in each of the blanks to complete the paragraph using terms from the list provided. More words than necessary are provided, and terms may be used more than once. (0.5 marks each; 3.5 marks total) 

During repolarization, the resting membrane potentialof the cell is 70 mV more negative than the outside of the cell.  When a stimulus is applied, the membrane potential must reach +35 mV in order for an Action Potential to be fired.  At the start of an Action Potential, Na⁺ channels open and Na⁺ ionsenter the cell.  This phase is called depolarization.  

The relative refractory period is the period of time in which the nerve membrane can start another action potential only if a much greater stimulus than usual is applied.

2. Referring to the graph above, at which numbered point do potassium gates begin to open? (0.5 marks)

The potassium gates begin to open at +30mV that is at the point numbered as 5.

QUESTION 15

Antidiuretic hormone and aldosterone influence water and electrolyte balance of the body. The following table summarises the main characteristics of these hormones; your task is to fill in the empty cells in the table. (0.5 marks/box; 4 marks total)

QUESTION 16

The following table describes the three elementary steps of urine formation. Complete the missing parts of the table. (0.5 marks/cell; 3 marks total)

QUESTION 17

List two (2) differences between the external and internal urethral sphincters. The differences must relate to structure, function or innervation of these sphincters. (0.5 marks/difference; 1 mark total)

The differences between the internal as well as external urethral sphincter are that the internal sphincter is the thickened area of the bladder urethra junction. It is basically formed by smooth muscles and is involuntary in nature whereas the external sphincter is made up of skeletal muscles and is voluntary in nature.

QUESTION 18 

Explain how baroreceptors contribute to control blood pressure during a short period of widespread vasodilation. (3 marks)

The baroreceptors are referred to as the pressure sensing bodies and it is also known as stretch receptors. However, these receptors are sensitive to the rapid offsets in the blood pressures and it is located in the arch of the aorta as well as in the carotid sinus. During the rapid offsets of the blood pressure a large volume of the blood is shifted from the peripheral to the central region of the body and hence a large volume of blood enters into the heart which leads to the increase in preload causes the heart to rise in the cardiac output. Therefore, this rise in blood pressure is registered by the baroreceptors. Consequently, a drop in blood pressure is also registered by baroreceptors when the individual stands up suddenly from sitting position. The high blood pressure in the blood vessels causes the stretch of these baroreceptors that result in the movement of the Na+ ions into the nerve endings which leads to an initiating of the action potential. Moreover, these baroreceptors possess baseline firing pattern it means they possess the intrinsic potential for generating the action potentials at the particular frequency at all times. 

QUESTION 19 

Name four (4) major vessels attached to the heart, and explain where they receive blood from, and where they carry blood to (4 marks)

QUESTION 20

Explain the term ‘normal sinus rhythm’. (1 mark)

The normal sinus rhythm is referred to as the normal heartbeat with respect to the rhythm and heartbeat. In this condition, the heart rate falls between 60 to 100 beats per minute. QUESTION 21

Complete the table on the heart valves below by briefly explaining the function of each and stating when each set of valves is closed. (0.5 per box; 2 marks total)