doneasbio(unit1)

8/6/2019 doneASBio(unit1)

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1 Read through the following account and then write in the spaces provided the most appropriate

word or words to complete each statement.

(8)

The water molecule is composed of one atom of oxygen and two atoms of hydrogen, combined

by __shared__ electrons (__hydrogen__ bonding). However, the water molecule is _v-shaped__

rather than linear, and the nucleus of the oxygen atom draws _electrons _ (negatively charged)

away from the hydrogen nuclei (positively charged) with an interesting consequence. Although

overall the water molecule is electrically neutral, there is a net __negative __ charge on the

oxygen atom and a net __positive __ charge on the hydrogen atoms. In other words, the water

molecule carries an __uneven __ distribution of electrical charge within it. This arrangement is

known as a __dipole__ molecule.

2 The diagram below shows the structure of two monosaccharide sugars, glucose and fructose.

a Draw a diagram to show the structure of the disaccharide formed when these two molecules

bond.

(2)

b What type of reaction has occurred, and what type of bond has been formed?

Condensation reaction. Glycosidic bond has been formed.

(2)

3 The table below refers to three polymers. In each box, place a tick to show if the statement is

correct for that polymer. Place a cross to indicate if the statement is incorrect.

(6)

Statement Glycogen Amylose Amylopectin

polymer of glucose monomers

found in cells of plants

built from unbranched chains only

formed by condensation reaction

energy store found in muscles

glycosidic bonds present

4 Explain in your own words the difference between a saturated and an unsaturated lipid.


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blanks.

(6)

The molecules that make up a substance are constantly on the move in a __passive__ way. It is

these movements that cause molecules to be dispersed from areas of _higher __ concentration

to areas of __lower __ concentration, a process called diffusion. We say that molecules diffuse

along a concentration gradient. Diffusion occurs freely across thin, _ permeable_ membranes, too.

Each type of molecule diffuses along its concentration gradient; diffusion in one direction is

_same_ of diffusion of other molecules in an opposite direction. An example of this proces s is

the inward diffusion of __oxygen_ into a respiring cell and outward diffusion of _CO2_. Another

molecule constantly on the move across cell membranes is water. Movement of water is by

_osmosis__, a special case of diffusion, due to the presence of a _ semi_-permeable membrane.

Free water molecules diffuse across such a membrane unhindered. Dissolved substances attract

a group of the __water__ molecules around them, held by _hydrogen __ bonds, and their free

movements are __________.

7 In an experiment to investigate whether a particular concentration of caffeine will increase the

heart rate of a water flea such as Daphnia, describe what control you would require as part of

your procedure, and why.

Measure the heart rate ofDaphnia in dilute water. It is used as a control to show the increase in

heart rate is due to the presence of caffeine.

(6)

8 The blood-clotting mechanism may be represented by a simple flow diagram.

a From the list below, select substances that are the essential components of the blood-clotting

process identified in the flow diagram by the letters A-F.

cholesterol prothrombin glucose fibrin fibres amino acids prothrobin

adrenalin calcium ions + vitamin K blood cells thromboplastin insulin

fibrinogen vitamin C

A __thromboplastin _____ B _calcium ions + vitamin K

C ___prothrombin _______ D _fibrinogen ____________

E ____fibrin fibres _______ F __blood cells ___________


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b Suggest an advantage to the body of the complexity shown by the clotting mechanism.

A relatively small event is amplified through a series of steps.

(8)

9 For an adult male, the estimated average daily energy requirement is about 10 600 kJ. The table

shows the composition of a typical meal eaten by an adult male with a sedentary lifestyle, found

to have a Body Mass Index of over 30.

Carbohydrate/g Protein/g Fat/g Saturated fatty acids/g Energy/kJ

roast chicken 0.0 24.8 5.4 1.6 621

chips 49.2 5.3 6.9 3.0 1134

Peas 6.8 4.2 0.6 0.1 204

canned pineapple in juice 9.8 0.2 0.0 0.0 160

ice cream 7.7 1.1 2.9 1.5 249

coffee 0.2 0.3 0.0 0.0 8

semi-skimmed milk 1.5 1.0 0.5 0.0 59

jam tart 19.5 1.1 4.3 1.6 517

a What was the total energy content of this meal, and what percentage of the estimated total daily

requirement does it represent?

Total energy content: 2952KJ

Percentage: 27.85%

b Bearing in mind this persons BMI and lifestyle, identify three changes that a dietician might

recommend concerning his choice of food items, and explain what the chief advantages of such

changes would be.

1. Less carbohydrate: starch / sugar2. No more fired food or No desert or snacks: jam tart / ice cream

3. More vegetables and fruits

These can reduce the persons energy take in from food. From the person s BMI, he is obesity.

(8)

10 Studies of the incidence of conditions such as cardiovascular disease include investigations of the

risks of contracting the condition in different populations.

a In the design of statistically significant studies, explain why the following are given special

attention.

i Size of samples:Large sample size increase the reliability of the research.

ii Composition of samples:

b Given the establishment of a statistically significant association between a particular factor and

the incidence of a disease, outline two types of study that are necessary to confirm the existence

of a causal relationship.

1.

2.


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(8)

11 The incomplete equation below contains the structure of a molecule of a monoglyceride.

a Draw a line around that part of the molecule described as an ester linkage.

b Complete the equation to show the structure of the products of hydrolysis.

c Write in the names of the products of the hydrolysis reaction.

Fatty acid and glycerol

d Explain how a molecule of triglyceride differs in structure from the monoglyceride molecule

shown above.

Triglyceride have 3 ester bond which is formed from 3 OH and 3 fatty acid.

(6)

12 The diagrams A and B show the left side of the heart in two stag es of the cardiac cycle.

a Identify the stages in the cardiac cycle represented by diagrams A and B.

A atrial systole, ventricular diastole

B atrial diastole, ventricular systole

b Name the labelled structures X, Y and Z.

X ____pulmonary vein ___

Y ____bicuspid valve_____

Z ____aorta____________

c Describe the events of the stage of the cardiac cycle shown in B, referring to the conditions

generated in all parts of the structures shown, and explaining how these are brought about.

The blood is pushed into ventricle. The atrium relaxes. The pressure in ventricle is now higher

than atrium. The pressure forces the bicuspid valves to shut. The ventricle has a higher pressure

than aorta, when ventricle contract, the blood pressure force the semi-lunar valves open. Blood

fill in the aorta.


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(10)

13 Atherosclerosis is an unhealthy condition of blood vessels, particularly of arteries.

a In describing this disease, explain what is meant by the following terms:

i plaque

Build up by cholesterol

ii thrombus

An enzyme catalysts the conversion of fibrinogen to fibrin.

iii embolus

A blood clot or a piece of fatty deposit that block a blood vessels which cause embolism.

b The following are factors that are statistically correlated with a raised incidence of coronary

heart disease. For each, suggest how they may directly contribute to a diseased heart condition.

i A condition of severe hypertension:

High blood pressure damages tiny blood vessels and weaken the arterial wall. Also more strain is

put on the endothelium lining the vessels, cause small areas of damage. Atherosclerosis formed.

Heart needs to pump harder since the blood vessels are clogged by plaque or blood clot. If the

blood clot blocks the coronary blood vessels, angina and myocardial infarction formed.

ii The practice of smoking cigarettes:

Nicotine narrow the blood vessels and puts an added strain in the heart. Tar and carbon

monoxide decrease the oxygen content in the blood. So heart needs to work harder to pump

sufficient oxygen around the body. Other chemicals in cigarettes damage blood vessels and

hence greatly increase the chance of atherosclerosis. The chemicals also increase the level of

fibrinogen. Formation of blood clot is increased. As a result, heart may suffer from heart failure,

angina or myocardial infarction.

(7)


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c Blood cholesterol levels are measured in blood samples collected from patients who have not

eaten for at least 12 hours. Suggest why this condition is necessary.

d Explain what you understand by the heart conditi on known as angina, and how a diet with a high

cholesterol content may cause this condition.

e Persistent serum levels of cholesterol above 5 mmols l-1

are considered to be potentially

dangerous. What treatment is typically prescribed for this condition ?

(9)

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