Biol121 The Harmful Uv Radiation Assessment Answer

Answer:

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 

Cell name	Where would you usually expect to find this cell type?	What is its job (or primary role)?
Melanocyte	In the deep layer of the stratified squamous epithelium of the skin.	Production of melanin to protect underlying tissue from harmful UV radiation.
Pacemaker	In the sinoatrial node which is situated at the upper part of the right atrium wall.	Spontaneously depolarise to trigger contraction of cardiac muscle. Establishes the heart rate.
Schwann cell	In the peripheral nervous system	They myelinate the axons of the peripheral nervous system.
		Maintain the protein and mineral content of the surrounding bone matrix.
	1%">	Non-specific immune surveillance of peripheral tissues (recognising and destroying abnormal cells).
		Contains large quantities of haemoglobin, enabling it to bind and transport respiratory gases.
Parathyroid chief cells

Name the personal protective equipment that should be worn when handling someone else’s urine, and explain why those items are needed.Protective equipment like gloves, gown and mask. This is to protect one from the spill overs and therefore reducing risk of exposure of the skin to infections.

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.

	B-lymphocytes	Cytotoxic T-lymphocytes
Overall role	Produce antibodies	Attack and destroy any cell infected with a cytosolic pathogen
Target	Antigen to initiate an antibody response	Antigen-bearing host cells recognised as ‘foreign’; e.g., cancer cells, virus-infected cells, or cells with intracellular bacteria
Facilitated by which helper cell?	Helper T cells	Helper T cells
Is this specific immunity? (yes or no)	Yes	yes
What cells provide long-term immunity?	B- cells	T-cells

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 mark 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           Ca²⁺        from the             sarcoplasmic reticulum                     . This exposes binding sites on     actin     .               Myosin  heads bind to the exposed sites on         actin      to form cross-bridges.

·         Na+	·         Sarcoplasm	·         mitochondria
·         K+	·         Sarcolemma	·         Golgi apparatus
·         Ca2+ ·         Mg2+	·         sarcoplasmic reticulum ·         sarcomere	·         myofibril ·         myosin
·         actin	·         nucleus	·         myofilament

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 action of osteoclasts is stimulated by Parathyroid hormone when the level of calcium in blood falls. This leads to calcium being transferred from bone to blood. Calcitonin on the other hand lowers the osteoclasts activity and thereby reducing the breakdown of bone.

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

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

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

The anterior lobe will produce hormones upon getting the inhibiting or releasing hormones from the hypothalamus. For example, the release of Growth Hormone Releasing Hormone and Growth Hormone Inhibiting Hormone from hypothalamus controls the levels of Growth hormone release by anterior lobe.

The posterior lobe has nerve endings cells from the hypothalamus whereby the hypothalamus sends hormones straight to this lobe through this nerves and then they are released by pituitary gland. For example, during suckling by a baby, sensory receptors found in the nipple sends signals to hypothalamus and in turn oxytocin is secreted and released to bloodstream.

Duchenne muscular dystrophy (DMD) is 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.

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

XdX. this is because the dominant allele will be seen but the individual will still be having recessive trait gene.

1. What is the father’s genotype? Explain your reasoning. Because he has no history of DMD in the family.

1. What is the likelihood of the male foetus having DMD? Use a Punnett square to explain your answer.

Mother’s genotype

X^d                                              X

XdX Female carrier	XX Normal female
XdY Male having DMD	XY Normal male

e 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.

The volume decreases and thus increasing the pressure in thoracic cavity. This is because the diaphragm relaxes and external inter coastal muscles contract and lungs and thoracic wall moves inward. Upon airflow the air moves out of the lungs until equal pressure inside and out is achieved.

Regarding quiet ventilation, which process is active — inhalation or exhalation? Briefly explain your answer.Inspiration is an active process. This is because it needs muscular contractions.

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. 

When the temperature is increased, the affinity of haemoglobin for oxygen decreases hence reduce supply into the skeletal muscle blood supply. Lower temperature on the other hand will increase the affinity of haemoglobin for oxygen hence more supply. Higher pH and lower co2 increases the haemoglobin affinity for oxygen and this will increase the release of oxygen into the skeletal blood supply whereas lower pH and higher co2 leads to decrease oxygen release into the skeletal muscle since it lowers the affinity of haemoglobin for oxygen.

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
2. Could a person with your chosen blood type safely receive type AB blood via transfusion?  Explain your answer below. 

Blood group A cannot receive type AB blood since donor with blood type AB can only donate to recipients with blood type AB only.

Blood Group	A	B	AB	O
Red blood cell type
Antigens on red blood cells	A antigen
Antibodies in plasma	Anti-B

Why is injury to the medulla oblongata usually fatal

Medulla oblongata functions to regulate heart rate, breathing and reflex actions. Therefore, injury may lead to abnormal regulation of the heart rate and breathing hence being fatal.

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.

Target tissue	Effect of sympathetic stimulation	Effect of parasympathetic stimulation
Contractile force of the heart	Contractile force increases; more blood pumped from heart	No parasympathetic innervation of ventricular myocardium; therefore, no result
Airways in the lungs	Bronchodilation	Bronchoconstriction, mucus secretion and bronchial vasodilation
Pupil	Contraction of radial muscle; dilation of the pupil to let in more light into the eye	Circular muscles contracts; constriction of the pupil lowering the amount of light entering the eye

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.
2. during                   hyperpolarisation            , the ­      resting membrane potential       of the cell is 70 mV more negative than the               outside                 of the cell.  When a stimulus is applied, the membrane potential must reach        peak action potential                in order for an Action Potential to be fired.  At the start of an Action Potential, Na⁺ channels open and Na⁺ ions                            enters   the cell.  This phase is called       depolarisation                   . 

The        repolarisation                                    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.

·         Na+	·         Negatively	·         peak action potential
·         K+	·         Positively	·         absolute refractory period
·         Ca+	·         Repolarisation	·         relative refractory period
·         inside	·         depolarisation	·         +35 mV
·         outside ·         enter ·         exit	·         hyperpolarisation ·         resting membrane potential	·         -70 mV ·         -55 mV

Referring to the graph above, at which numbered point do potassium gates begin to open

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.

	Antidiuretic hormone	Aldosterone
Where is this hormone synthesized?	synthesized by neurons in nucleus of  the hypothalamus	Synthesized by zona glomerulosa of adrenal cortex
Which gland secretes this hormone?	Pituitary gland	Adrenal glands
Primary effect?	allow reabsorption of water  by it collecting ducts	To regulate salt and water in the body thus having an effect on blood pressure
Mechanism of action (How does it work?)	It bind to receptors of its target cell in the kidney tubules and vascular smooth muscle, binding stimulate vasoconstriction, ADH receptors bind to g-protein coupled cAMP messenger system which increases concentration of cAMP in collecting duct creating aquaporin by exocytosis  allowing water for reabsorption	Aldosterone stimulate reabsorption of sodium as well as secretion of potassium ion and hydrogen ions.it binds to intracellular receptors of this ions and stimulate the expression of several genes which in turn leads to transcription and translation resulting in production of new proteins responsible for modulation of ionic transport system

The following table describes the three elementary steps of urine formation. Complete the missing parts of the table.  

Step in urine formation	Where does this step take place?	What happens?
Filtration	Renal corpuscle  specifically glomerulus	Water and solutes is allowed to pass while but blocks blood cells and large proteins
Reabsorption	Renal tubules especially proximal convoluted tubule	Water and/or solutes are transported from the tubular lumen to peritubular capillaries (blood)
Secretion	Along the length of the tubular network; the exact location depends on the substance being transported	Transfer of certain molecules such as toxin out of the blood into urine

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)

Internal urethral function to prevent t prevent reflux of seminal fluid during ejaculation sphincter is under involuntary control, consist of smooth muscle which is continuous with detrusor and parasympathetic impulse induce contractions and relaxation. While external urethral sphincter function to inhibit the release of urine, it consists of striated muscle, its innervated by pudental nerve, it’s under voluntary control

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

When there is increase in blood pressure in the aorta or the carotid sinuses, the walls of these arteries stretch and stimulate increased activity within the baroreceptor which in turn decrease total peripheral resistance and decreases blood pressure.

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

Major vessel	Receives blood from	Carries blood to
Aorta	Left ventricle	Distributes oxygenated blood to all parts of body through systemic circulation To the right atrium
Superior venacava	Carries blood from lower body	To the atrium
Pulmonary vein	Carries blood from the lungs	To the heart
pulmonary artery	from right ventricle	To the lungs for oxygenation

Explain the term ‘normal sinus rhythm’.Sinus rhythm refers to a normal heartbeat both with respect to the heart rate and rhythm.it is a cardiac rhythm where depolarization of the cardiac muscles begins at the sinus node.it has a characteristic of correctly oriented p waves on electrocardiogram.

Type of heart valve	What is their function?	When are the valves closed?
Semilunar valves	Allows blood to flow into arteries and prevent back flow	At the end of ventricular diastole
Atrioventricular (AV) valves	allow blood to flow from the atra to the ventricles and prevent blood from flowing in opposite direction	When ventricles relaxes

References

Spencer, H. (2018). The Principles of Biology, Volume 1 (of 2). Litres.

Abercrombie, M., Hickman, C. J., & Johnson, M. L. (2017). A dictionary of biology. Routledge.