Scientific+Article+Questions+Answers by Stafford Final

.............................................................................................................................................................................................................. Compiled by Stafford Valentine Redden (Head of Department, VIHS, Maldives), Author and publisher of Advanced Level Biology textbooks. Contact: [email protected] for additional resources or consultation. Phone: +9607765507 Page 10

1. Discuss the advantages and disadvantages of exercise regimes. P1 Advantages of moderate exercise regimes include

Increased BMR;

Decreased blood pressure

Increased HDL

Decreased LDL

Decreased risk of CHD

Maintaining healthy BMI

Decreased risk of diabetes

Increased bone density

Improved well being

Decreased adrenaline levels

Less stress

Moderate exercise increases levels of Natural Killer cells, which secrete apoptosis-inducing chemicals in response to non-specific viral or cancerous threat.

Disadvantages of exercising too much (over-training) include; Chronic fatigue (tiredness) and poor athletic performance Increase in upper respiratory tract infections (URTI) - Sore throats and flu-like

symptoms, due to a suppressed immune system with a decrease in the number and activity of cells in the immune system.

An inflammatory response in muscles due to damage to muscle fibres. Increased wear and tear of joints Increased risk of cardiac failure, specially in older untrained individuals.

2. Explain what is meant by a tissue. P1 A group of specialised cells working together to perform a specific function. Brown Adipose Tissue is made up of specialised adipocytes.

3. Suggest how an unspecialised cell can become specialised into brown adipose tissue (BAT). Specific genes which are needed to form BAT get „switched on‟. The induction of these genes produces active mRNA which can form specific proteins. These proteins will transform the unspecialised cell into a specialised BAT cell. The trigger for gene induction comes from an environmental cue, cold surroundings in this case. This also shows that the environment can influence the phenotype.

4. What criteria might have been used to assess obesity, to arrive at the estimate that almost

two thirds of adults and one third of children are obese? P2 Obesity indicators – BMI or waist to hip ratio – may be used to assess obesity. A person with BMI greater than 30 or a waist to hip ratio above 0.80 for women and above 0.95 for men may be considered obese.

BMI = Weight (in kg) / Height2 (in m)

Waist-to-Hip ratio = waist circumference / hip circumference

A sizeable population should have been sampled and the number of obese individuals would be divided by the total number of people in the sample to get a ratio.


5. Obesity has been linked with heart disease. Suggest a sequence of events that could causally link obesity with an increased risk of heart disease. P3

Obesity (BMI > 30)

Increased adipose tissue

Increased high blood pressure

Increased Endothelial damage in coronary arteries

Increased atheroma or plaque formation

Increased risk of blood clotting

Coronary arteries get blocked leading to lack of oxygen and promotion of anaerobic respiration, lactic acid formation and subsequent necrosis or death of cardiac tissue

(heart attack)

6. Describe the structure of triglycerides. P3

Triglycerides are composed of one glycerol attached to three fatty acid tails by ester linkages. The fatty acid tails may be saturated or unsaturated.

7. Distinguish between correlation and causation. P3

Correlation is when a change in one factor is reflected by a change in another factor, where

as, causation is when a change in one factor is responsible for a change in the other factor.

The cause for the change can be clearly explained by a biological phenomenon.

8. If the average adult woman has a mass of 62kgs, calculate the average mass of the fashion model of ‘today’. P4 Answer: 47.74kgs

Ask your teacher for help or email me for the WORKING

9. Explain what is meant by a risk factor. P6

Any factor which increases the chance or probability of facing an undesirable event.

10. What is meant by the prevalence of a disease or condition? P6 Prevalence is a measurement of all individuals affected by the disease within a particular period of time. It is typically expressed as a percentage or proportion of the population affected by the condition of disease within a particular period of time.

11. Why is mortality for anorexia expressed as a rate,( in %, or deaths per 100,000), rather than in numbers of deaths? P6 Expressing the number as a percentage, gives a clear idea of the prevalence of the disease irrespective or regardless of the population size. It also makes it easier to compare the prevalence of other disorders or to compare the same disorder in other populations.

12. State the features of studies referred to in this paragraph that will render it reliable. P7 The studies should have

a large sample size

a control group

statistical analysis of data

randomised selection of participants to reduce bias


13. Describe the technique of fMRI and explain how it can be used to investigate brain function. P8 fMRI (functional Magnetic Resonance Imaging) shows which parts of the brain are active during a particular task. Deoxygenated haemoglobin is more magnetic than oxygenated haemoglobin, which is virtually nonmagnetic. Oxyhaemoglobin does not absorb radio signals but deoxyhaemoglobin absorbs radio signals. The difference in oxyhaemoglobin content of the brain is used to rapidly produce a three dimensional (3D) image of the active and non active regions of the brain.

Similar to MRI, but the doctor not only knows what the tissues look like, but whether they are active. This is the only technique, that shows brain activity. It is therefore very useful in the study of brain function.

14. Explain how fMRI was able to show that activity increases in the prefrontal cortex in subjects engaged in self-reflection. P9

Control setup Experimental setup

No neural activity in pre frontal cortex when person is not engaged

in self reflection.

15. Describe the method used to classify people as ‘healthy’, ‘obese’ or ‘overweight’. P10

BMI Category

Less than 20 Underweight

20 to 24.9 Healthy

25 to 29.9 Overweight

Above 30 Obese

16. The paragraphs 11 to 14 refer to gender differences in responding to media images. Justify the statement that the difference in responses of males and females to media images is influenced more by genes (nature) rather than by nurture (environment). P11 to 14

Both men and women live in the same environment and are exposed to the same stimuli, so the differences may be attributed to genetic differences.

17. The pre-frontal cortex is part of the frontal lobe of the brain. Describe some of the

functions of this part of the brain, and compare it with the function of the medulla.

Frontal lobe Medulla oblongata

Involved in decision making, reasoning, planning and emotions. Involved in learned movements (Associated learning).

Controls rate of heartbeat, breathing rate, reflexes like coughing, sneezing and vomiting.


18. What evidence is given in the text that what is perceived as the ideal body shape for a woman is a cultural construct, rather than from a genetically determined way of identifying a healthy potential mate? Paragraph 23 describes the features of a genetically healthy female. Heterosexual human females maintain/adapt physical appearance in accordance with sexual dimorphism – the systematic difference in form between individuals of different sex. In females, more subcutaneous fat and fat deposits mainly around the buttocks, thighs and hips are central to sexual selection. Paragraph 24 describes how female attractiveness is influenced by cultural and media influences. The waist-hip ratio of any physique is very strongly correlated to male perception of female attractiveness across all cultures and throughout history. This is a key health and fertility indicator and core feature of feminine beauty. Exposure to visual images depicting attractive females is found to alter women‟s perception of their own sexual attractiveness and mating viability through a cognitive comparison process referred to as the „contrast effect‟.

19. Describe the inflammatory process P18

Whenever there is a cut in the skin or tissue damage, damaged white blood cells

(Basophils and mast cells) release histamine at the site of infection. Histamine causes local

arterioles to vasodilate, increasing the blood supply to the infected area. It also causes

capillary walls to become more permeable. This increases the rate of formation of tissue

fluid and leads to local oedema (the swelling associated with inflammation). Oedema

allows monocytes and neutrophils into the infected area to engulf and destroy foreign

bodies and pathogens. Neutrophils consume fewer bacteria than macrophages. The

phagocytes (macrophages and neutrophils) complete the job by engulfing cell debris and

dead cells. Dead monocytes and pathogens may form pus.


20. Suggest what cells may be reduced in number when cortisol produces ‘impaired immunity’ T Cells will be „muted‟ by cortisol, so that the immune response will not be triggered. Remember that T helper cells activate the B cells to produce antibodies. T and B lymphocytes are produced in the bone marrow, but the T cells mature in the thymus gland (hence T lymphocytes). The B cells mature in the bone marrow (hence B lymphocytes).

21. Explain how the ‘contrast effect’ might occur in the retina of the eye, with the stimulus of ‘luminescence’ p25 Rhodopsin: this is the photosensitive pigment found in the rod cells of the retina. It is sensitive to light of low intensity / dim light (luminescence).

The detection of light is carried out on the membrane discs (vesicles) in the outer segment. These

discs contain thousands of molecules of rhodopsin, the photoreceptor molecule. Rhodopsin

consists of a membrane-bound protein called opsin and a covalently-bound prosthetic group

called retinal. Retinal is derived from vitamin A, and a dietary deficiency in this vitamin causes

night-blindness (poor vision in dim light). Retinal is the light-sensitive part, and it can exists in 2

forms: a cis form and a trans form. Light causes cis-retinal to be converted into trans-retinal,

which splits away from opsin. Trans-retinal is reconverted into cis-retinal by an enzyme

retinal isomerase. The cis-retinal recombines with opsin to form Rhodopsin. ATP is used

for this process. The process is illustrated in the fig. below.

In the dark retinal is in the cis form, but when it absorbs a photon of light it quickly switches to the trans form. This causes the trans-retinal to split from the opsin. This process is called bleaching. The reverse reaction (trans to cis retinal) requires an enzyme reaction and is very slow, taking a few minutes. This explains why you are initially blind when you walk from sunlight to a dark room. Some time is needed to resynthesise rhodopsin. This is called as the dark adaptation.


Rod cell membranes contain a special sodium channel that is controlled by rhodopsin. Rhodopsin with cis retinal opens it and rhodopsin with trans retinal closes it. The synapse with the bipolar cell is an inhibitory synapse, so the neurotransmitter (glutamate) stops the bipolar cell making a nerve impulse.

Generating an impulse

1. Photon hits rhodopsin

2. Bleaching occurs by

converting cis-retinal to trans

retinal

3. Trans-retinal blocks Na+

channels in outer segment

4. Inner segment pumps sodium

ions out by active transport

5. The rod is hyperpolarised and

stops releasing inhibitory

neurotransmitter (glutamate)

6. The bipolar neurone is

depolarised

7. Action potential is generated

in the Ganglion cell, which

passes to the brain as a nerve

impulse by formation of local

circuits.

No impulse formed

1. Absence of light 2. Trans-retinal converted to

cis-retinal 3. Cis-retinal opens Na+

channels in outer segment 4. Inner segment pumps

sodium ions out by active transport

5. The rod is not hyperpolarised and releases inhibitory neurotransmitter (glutamate)

6. The bipolar cell cannot depolarise

7. Action potential is Not generated in the Ganglion cell


22. Describe the processes taking place in mitochondria, when ATP production is not

uncoupled from the respiration process p28

Oxidative phosphorylation: Phosphorylation of ADP to ATP in the presence of oxygen. The diagram below summarises the events that occur during oxidative phosphorylation in the inner mitochondrial membrane.

NADH2 from glycolysis, link reaction and Kreb‟s cycle get oxidised by LOSING

hydrogen to the electron transport chain.

The components of the electron transport chain split hydrogen into electrons and

hydrogen ions. The electrons pass down the chain through a series of redox reactions, controlled by oxidoreductase or dehydrogenase enzymes.

As the electrons are passed from one component to another, hydrogen ions are pumped from the matrix, into the inter-membranal space.

This causes a high concentration of hydrogen ions in the inter-membranal space.

ATP is generated from free energy released when H+ ions move back into mitochondrial matrix, through stalked particles, which contain the enzyme ATP synthase or ATPase. These stalked particles are called chemiosmotic channels and the movement of hydrogen ions into the matrix is called chemiosmosis.

Oxygen is used to absorb electrons from the electron transport chain and combines these electrons with H+ ions to form water. This ensures that the Electron Transport Chain (ETC) continues to function and NAD+ (oxidized Hydrogen carriers) can be regenerated for aerobic respiration to continue.

4H+ + 4e- + O2 2H2O

Note: During oxidative phosphorylation, one NADH2 produces 3ATP and one FADH2 produces 2ATP, as it joins the chain later and pumps in less hydrogen ions to the inter membranal space.


23. Using your knowledge of chemiosmosis suggest a mechanism by which an uncoupling protein might work.

24. BAT is activated by both the SNS and thyroid hormones. Compare and contrast the way in which these two methods of communication operate.

Feature Hormonal control Nervous control

Nature of signal

All hormones are chemical signal (Chemical)

Nerve impulses are electrical signals. Chemical signalling takes place at synapses (Electrochemical)

Speed of signal

Slow Rapid. Between 0.7 metres per second and 120 metres per second

Effect in the body General effect. The hormones can influence cells in many different parts of the body.

Localized effect – affects only the particular muscle or the gland

Effect on growth Can affect growth Cannot affect growth

Capacity for modification

Cannot be modified by learning from previous experience

Can be modified by learning from previous experiences

Duration of effect Short term or long lasting. Only short – lived


25. Strictly speaking it is absurd to suggest that a baby has a large body surface, as compared with an adult (p30). Express this relationship in an appropriate way to explain why a baby would have a higher rate of heat loss than an adult. The cubes show the relationship between size and surface area to volume ratio.

Babies behave like the smaller cube and have a lower diffusion distance and larger surface area to volume ratio than an adult. Hence babies lose heat more rapidly than a larger adult human.

26. What is meant by a metabolically active tissue p31, and give examples of tissue that might be described as such. Tissues in which ATP is produced and used rapidly is considered to be metabolically very active. Examples of such tissues will be muscle tissue and liver tissue. They have plenty of mitochondria to provide ATP at the required rate.

27. Describe the mechanisms by which glucose may be taken up by cells. Since glucose is a large molecule with polar groups, it cannot cross the phospholipid bilayer of the cell. Glucose can enter the cell by active transport through a specific glucose transporter protein in the cell surface membrane. The protein will use ATP to transport glucose across the membrane.


28. Describe the responses by the body that might help to prevent death by uncontrollable heat production as described in para 37 Uncontrollable heat production can lead to failure of the thermoregulatory mechanism and lead to hyperthermia. The enzymes and proteins can denature and cause death. In normal circumstances, the thermoregulatory mechanism operates through negative feedback mechanisms to keep the temperature within a narrow range. The mechanism is shown in the flowchart below.

Normal body temperature

370C

Increase in temperature - Exercise / high metabolism - Warm clothes - Heat gain from surrounding / warm surrounding

Decrease in temperature - Physical inactivity / low metabolism - Lack of clothing - Heat loss to surrounding / cold surrounding

Increase in temperature is detected by temperature sensitive receptors in

the hypothalamus and skin

Decrease in temperature is detected by temperature sensitive receptors in

the hypothalamus and skin

Impulses sent to temperature control centre in the hypothalamus (Thermo-regulatory centre)

Impulses sent to temperature control centre in the hypothalamus (Thermo-

regulatory centre)

Thermoregulatory centre brings about following changes Vasodilation – smooth muscles of

arterioles relax and more blood

flows into capillaries below skin.

This increases heat loss by

radiation.

Hair erector muscles relax – this

results in the hair falling towards

the skin and less air is trapped

around the body. Heat loss by

conduction increases.

Increased sweat production –

Evaporation of sweat from skin

cools the body by removing heat.

Decreased metabolism – the

metabolic activity in liver and

muscles is reduced. This helps to

produce less heat.

Behavioral changes – pouring

water on the skin or turning on the

fan helps to cool the body down.

Thermoregulatory centre brings

about following changes

Vasoconstriction – smooth

muscles of arterioles constrict and

less blood flows into capillaries

below skin. This decreases heat

loss by radiation.

Hair erector muscles contract –

this results in the hair becoming

erect. Air is trapped around the

body. Heat loss by conduction

decreases (as air is an insulator).

Decreased sweat production –

Less evaporation of sweat from

skin reduces heat loss.

Increased metabolism – the

metabolic activity in liver and

muscles is increased. This helps to

produce more heat.

Behavioral changes – putting on

warm clothes or turning on the

heater helps to reduce heat loss.

Normal body temperature

370C


29. It is reported no studies for fucoxanthin have been carried out on humans (p38). Outline

the protocols that would be carried out before it can be said that the treatment is effective.

Three-phased testing New drugs are now tested extensively before marketing – it can take over 10 years for some drugs. The following table summarises the process of drug testing in the UK. This process is different in other countries.

Stage Purpose of stage

Pre-clinical testing

1. Proposed drug is tested in a lab with cultured cells to see the general effects of the drug

2. Proposed drug is given to animals to see the effects on a whole animal. Any side effects away from target cells are noted.

Clinical Trials Phase 1

1. A small group of healthy volunteers are given different doses of the drug. They are told what the drug does

2. The distribution, absorbance rate, metabolism & excretion profile of the drug are assessed.

3. The effects of the different doses are assessed to try and determine the optimum dose

4. An independent organisation (UK Medicines Control Agency) assesses whether it is appropriate to move to Phase 2


1. A small group of people with the disease are given the drug. 2. Studies are very similar to Phase 1 3. The optimum dose is worked out


1. A large group of people with the disease are given optimum doses of the drug

2. The patients are either given the drug or a placebo in a double-blind test 3. The results are analysed 4. If the drug has had a significant positive effect in the treatment of the

disease it is put forward to licensing authority

30. Outline the role of transcription factors which lead to a higher expression of PRDM16 in

BAT, compared to WAT. p40

„Switching on a gene‟ – Gene induction or activation

Transcription of a gene is initiated by RNA polymerase and transcription factors binding to a promoter

region (section of DNA upstream to a gene).

RNA Polymerase + Transcription factors = Transcription Initiation Complex

Some transcription factors are always present in all cells (example the transcription factors needed to switch on the genes for respiration or protein synthesis). Other transcription factors are only synthesised in certain cells at a particular stage of development, often in an inactive form, which is later activated by signal proteins or regulator proteins. Signal proteins may act directly by entering the cell (like steroid hormones) or indirectly through a second messenger (cAMP).

The gene is „switched on‟ when all the transcription factors, in their active form, are present.

„Switching off a gene‟ – deactivation

Genes are switched off (not able to be transcribed) by the cell

protein repressor molecules may attach to the promoter region, hence blocking the attachment sites for transcription factors.

protein repressor molecules can attach to the transcription factors preventing them forming the transcription initiation complex.

signal proteins (Hormones) acting as transcription factors may not be present. When the DNA is coiled around histones (Supercoiling), certain genes may be inactivated because its

promoter may not be accessible to the transcription factors or RNA polymerase.


The mode of action for peptide hormones is shown below.

1. Hormone binds to specific receptor on the cell membrane. 2. Adenyl cyclase enzyme is released from the receptor and diffuses into the cytoplasm. 3. Adenyl cyclase converts ATP into cyclic AMP (Second messenger) 4. The second messenger initiates a series of reactions in the cell and activates Transcription Factor 7,in this case. 5. The activated transcription factor (TF7) now binds to the existing Transcription factors (TF1 to TF6, in this case) and completes the Transcription Initiation Complex. This activates RNA polymerase to become active and begin the process of transcription of the gene. The gene is now ‘SWITCHED ON’.

31. Describe the procedures that might be used to genetically modify the mice to produce high levels of PRDM16. Create a mouse embryo by in vitro fertilization. Introduce the gene for PRDM16 and its transcription factors into the fertilised egg. Implant the embryo into a surrogate mother. Transgenic mouse will be born, with high levels of expression of PRDM16.

32. Using your knowledge of brain development, explain why babies are unable to shiver while adults can. P30 At birth, the human brain is still preparing for full operation. The brain‟s neurons exist mostly apart from one another. The brain‟s task for the first 3 years is to establish and reinforce connections with other neurons. These connections are formed when impulses are sent and received between neurons. These connections form synapses. As a child develops, the synapses become more complex, like a tree with more branches. During the first 3 years of life, the number of neurons stays the same and the number of synapses increases. After age 3, the creation of synapses slows until about age 10. Between birth and age 3, the brain creates more synapses than it needs. The synapses that are used very frequently, become a permanent part of the brain. The synapses that are not used frequently are eliminated. “Neurones that fire together, wire together”. “use it or lose it”. This is where experience plays an important role in wiring a young child‟s brain.


33. Give the characteristics of stem cells that can differentiate into BAT and muscle tissue.

These stem cells have the ability of differentiating into different cell types, namely BAT and muscle tissue. They also have the ability of self renewal, which means that when a stem cell divides by mitosis it can give rise to new stem cells. This ensures that there is a sustained supply of stem cells in the body. A cascade of different transcription factors can turn specific genes on and cause cell differentiation.

34. Describe the structure of muscle tissue. P33

35. Compare the structure and function of BAT and WAT.

Brown Adipose Tissue (BAT) White Adipose Tissue (WAT)

Found in specific regions near the neck and shoulder blades

Distributed throughout the body

Brown in colour due to abundant supply of capillaries and mitochondrial cytochromes

Yellow in colour

Smaller in size (25 to 40µm) Larger cells (60 µm)

Many small lipid droplets when exposed to cold conditions

One large lipid globule in all conditions

Lots of mitochondria Fewer mitochondria

Mitochondria have uncoupling protein No uncoupling protien

Produce less ATP and generate more heat Produce lots of ATP and generate less heat


36. Describe the structure of the cell surface membrane and label the glycoprotein. State the

role of glycoproteins. P44

Branched chains of carbohydrates maybe attached to some phospholipid molecules, forming glycolipids or to proteins, forming glycoproteins. This is collectively called the glycocalyx. The glycocalyx is always found only on the outer surface of the cell membrane. The glycocalyx provides chemical protection to the cell membrane and also plays an important role in cell recognition (antigens and binding of hormones to target cells) and adhesion.

37. Dopaminergic genes are the genes responsible for synthesis of dopamine. Describe and

explain the implications of low levels of dopamine. P48

Dopamine is crucial to human movement and is the neurotransmitter that helps transmit messages that both initiate and control movement and balance. These dopamine molecules ensure that muscles work smoothly, under precise control and without unwanted movement. In Parkinson‟s disease neurons in the frontal cortex, brain stem and spinal cord become inactive. These neurons secrete dopamine neurotransmitter. This results in lack of the neurotransmitter substance dopamine in the brain. The symptoms are more intense in older people. Symptoms

Slowness of movement and poor balance

Shaking of hands (tremors)

Stiffness of skeletal muscles

Difficulty in speaking and breathing

Depression

Treatment of symptoms – Increase the levels of dopamine in the brain. L-dopa: L-dopa (levodopa) is a precursor of dopamine. Dopamine is too large to cross

the blood-brain barrier in the brain. However L-dopa is small enough to cross the barrier and enter the neurones. It is then converted to dopamine and secreted. This relieves the symptoms.

Dopamine agonists: these drugs bind with dopamine receptors and mimic the action of dopamine.

Monoamine oxidase B (MAOB) Inhibitors: Monoamine oxidase B is an enzyme in the brain, which breaks down dopamine in the brain. MAO B Inhibitors are drugs which inhibit the action of MAO B. The level of dopamine remains high and the symptoms are relieved.


38. Describe how HIV/AIDS can eventually lead to death. P52

HIV is the Human immunodeficiency Virus, which eventually leads to Acquired Immunodeficiency Syndrome (AIDS). HIV is spread by direct contact i.e. through unprotected sexual intercourse with an infected person, blood-to blood transfer involving an infected person (tattoos, needle sharing, piercing & cut-to-cut transfer), from an infected mother to baby (through placenta or breast feeding). The fig shows the events that occur inside an infected T helper cell.

Once inside the bloodstream an HIV infection occurs in 3 distinct phases;

1. The acute phase. HIV virus has a ligand (GP120), which attaches to a receptor (CD4) on the membrane of a type of white blood cell called a Helper T cell (T4 lymphocyte), as shown in THE fig. HIV rapidly infects Helper T cells and the virus population increases quickly. The increased number of viruses in the blood will destroy many T Helper cells and their numbers will also begin to fall. The acute phase ends when the Killer T cells begin to recognise infected Helper T cells and kill them, which slows the replication of the virus. The infected person may experience symptoms such as fever, sweats, headache, sore throat and swollen lymph nodes, or they may have no symptoms. Regardless of symptoms, 3 to 12 weeks after infection HIV antibodies appear in the blood, making them HIV positive. 2. The chronic phase or asymptomatic phase. This can last for many years. The virus continues to replicate, but the Killer T cells keep the numbers in check. However, because the immune system is weakened other bacteria and viruses are more likely to infect the person (TB and shingles may reactivate at this point). The chronic phase is represented by the time period between 2 to 6 years on fig 12.7. 3. The disease phase or AIDS. As the numbers of virus increase (viral load increases) and the numbers of Helper T cells fall to less than 200 per mm3 of blood, the immune system becomes weaker and weaker. Eventually a second pathogen will infect the person (an opportunistic infection), which cannot be overcome by the weakened immune system. Severe symptoms begin to appear such as major weight loss, dementia as brain cells become infected, cancers (e.g. Kaposi's sarcoma) and serious infections such as TB and cryptococcal meningitis. The person will die quickly from the secondary infection.


39. Analyse the effects of energy balance on health

Energy balance

When the diet provides more energy than is

needed, the excess is stored as fat and the

person 'puts on weight'. The excess energy

is stored in the body as fat in adipose tissue,

as depicted in fig9.8. When the diet provides

less energy than is needed, the person

'puts loses weight', as depicted in fig.9.7.

When the diet provides the same amount of

energy that is being used, the person's

weight remains constant, as depicted in

fig.9.9.

Fig.9.7

Fig.9.8

Fig.9.9

The table below shows the energy in a meal and the physical activities that could use up the

energy consumed (Energy in versus energy out)

Energy consumed = 400

KJ

Physical activity to burn 400 kJ of energy

White rice boiled (68g)

Milk (205ml)

Margarine (13g)

Milk Chocolate (18g)

Wholemeal bread (44g)

Tomatoes (548g)

Oranges (peeled) (253g)

Boys Girls

Running (16.5 minutes)

Walking (30.5 minutes)

Cycling (16.5 minutes)

Swimming ( 23.5 minutes)

Running (17.5 minutes)

Walking (32.5 minutes)

Cycling (17.5 minutes)

Swimming ( 25.0

minutes)

Energy EAR = BMR x Physical Activity Level (PAL).

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Scientific+Article+Questions+Answers by Stafford Final