Topic 6 Ib Tb Questions And Answers 734p1f

1.

Which organ secretes enzymes that are active at a low pH? A.

Mouth

B.

Pancreas

C.

Stomach

D.

Liver (Total 1 mark)

2.

C [1]

3.

Which vessel carries deoxygenated blood? A.

The pulmonary artery

B.

The coronary artery

C.

The aorta

D.

The pulmonary vein (Total 1 mark)

4.

A [1]

1

5.

Which of the following structures help the absorption of food by the small intestine? I.

Capillary networks

II.

Villi

III.

Microvilli

IV.

Membrane proteins

A.

I and II only

B.

II and III only

C.

II, III and IV only

D.

I, II, III and IV (Total 1 mark)

6.

D [1]

7.

Why do antibiotics kill bacteria but not viruses? A.

Antibiotics stimulate the immune system against bacteria but not viruses

B.

Viruses have a way of blocking antibiotics

C.

Viruses are too small to be affected by antibiotics

D.

Viruses do not have a metabolism (Total 1 mark)

8.

D [1]

2

9.

In thermoregulation, what would happen over a short period of time in each of these areas, if a person was placed in water at 15°C ? Peripheral circulation

Sweat glands

Liver

Skeletal muscle

Increased blood flow

Increased secretio n

Decreased temperature

Decreased shivering

Decreased blood flow

Decreased secretio n

Decreased temperature

Increased shivering

Decreased blood flow

Increased secretio n

No change in temperature

Increased shivering

Decreased blood flow

Decreased secretio n

No change in temperature

Increased shivering (Total 1 mark)

10.

D [1]

11.

What is transported by the blood? I.

Carbon dioxide

II

Antibodies

III

Urea

A.

I only

B.

I and II only

C.

II and III only

D.

I, II and III (Total 1 mark)

12.

D 3

[1]

4

13.

What is the function of the right ventricle? A.

Pumping blood into the pulmonary artery

B.

Pumping blood into the pulmonary vein

C.

Pumping blood into the aorta

D.

Pumping blood into the coronary artery (Total 1 mark)

14.

A [1]

15.

What are the characteristics of the lipase used in digestion? Source

Optimum pH

Substrate

A.

Pancr eas

8

Lipid

B.

Smal l intestine

8

Lipid

C.

Stom ach

2

Sucrose

D.

Liver

8

Lipid (1)

16.

A [1]

5

17.

The diagram below shows a section through the lower part of the heart, with two of the heart’s four chambers visible.

Labels X and Y show the walls of two chambers of the heart. Which two chambers are they? X

Y

A.

Right ventricle

Right atrium

B.

Left atrium

Right atrium

C.

Left ventricle

Right ventricle

D.

Right ventricle

Left ventricle (Total 1 mark)

18.

C [1]

19.

How do skin and mucous membranes act as barriers to infection? Skin

Mucous membranes

A.

Skin is tough and forms an effective physical barrier.

Mucous membranes are thick and elastic so pathogens are repelled.

B.

Phagocytes on the skin surface trap pathogens.

Mucus is moved out of the body by the beating of hair-like cilia.

C.

Skin is tough and forms an effective physical barrier.

Pathogens are trapped by sticky mucus.

D.

Phagocytes on the skin surface trap pathogens.

The acidity of mucus kills harmful bacteria. (Total 1 mark)

6

20.

C [1]

21.

In a human diet, what effect does a high intake of both protein and salt have on urea and salt concentrations of urine? Urea Concentratio n

Salt Concentration

A.

High

Low

B.

Low

High

C.

High

High

D.

Low

Low (Total 1 mark)

 Œ22.

C [1]

7

The sense of taste is normally caused by the stimulation of chemoreceptors in the taste buds of the tongue. There are four main “tastes”: sweet, salty, bitter and sour. The tongue also has receptors for temperature. It is known that the taste of food can vary according to whether it is cold, warm or hot. Scientists discovered that just warming or cooling parts of the tongue, even when no food was present, also caused a sensation of taste. Scientists experimented with a group of people. They gradually cooled the tips of their tongues and measured the intensity of the taste felt by each member of the group. The experiment was repeated, this time warming the tip of the tongue. The graphs show the average values for the group. C o o lin g th e to n g u e tip

W a rm in g th e to n g u e tip m o d e ra te

T a s te in te n s ity fe lt / a rb itra ry u n its

23.

w eak

ju s t d e te c ta b le 35

25 35

20 35

15 35

10 35

5

D e c re a s e in te m p e ra tu re fro m 3 5 ºC K ey:

S a lty

B itte r

20

25

20

30

20

35

20

40

In c re a s e in te m p e ra tu re fro m 2 0 ºC Sw eet

Sour

[Source: modified from Cruz and Green, Nature (2003) 403, page 889]

(a)

Identify which taste was felt most strongly when the tip of the tongue was (i)

cooled................................................................................................................

(ii)

warmed.............................................................................................................. (1)

(b)

Compare the effects on the taste of sweetness, of warming and cooling the tip of the tongue. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2) 8

(c)

It is important that such experiments use a population sample that is representative. Suggest two biological criteria the scientists would have used to select the people to be tested. ..................................................................................................................................... ..................................................................................................................................... (1)

(d)

Explain whether cooling or warming the tip of the tongue has the greater effect on the sensation of taste. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2)

The scientists discovered that there were two types of chemoreceptor in the tongue tip. They called these A and B. They tested these chemoreceptors using solutions of sucrose to find out the type of taste and the intensity felt. The results are shown in the bar chart. m o d e ra te w eak

T a s te in te n s ity fe lt / a rb itra ry u n its

ju s t d e te c ta b le s w e e t d e te c te d K ey:

s o u r d e te c te d A

B

9

(e)

Compare the effects of sucrose on the A and B chemoreceptors by giving two similarities and two differences. Similarities ................................................................................................................. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... Differences ................................................................................................................. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (4) (Total 10 marks)

24.

(a)

(b)

(c)

(d)

(Both answers are required for [1]) cooled: sour; warmed: sweet;

warming causes a greater sensation of sweetness than cooling; on warming the sensation of sweetness increases (but) on cooling the sensation decreases; on cooling sweetness becomes undetectable (but) on warming it becomes more detectable; sensation of sweetness on warming is always "weak" but cooling it is always "just detectable"; neither cooling nor warming causes moderate taste intensity; (Accept other suitable paired answers based on the data in the graph.)

(Two correct answers are required for [1]) age / gender / ethnic origin / health / sensitivity to taste / smoker (or non-smoker) / genetic (taster / non-taster) / drugs (use) / pregnancy; (not size / weight)

cooling; because two tastes (sour and salty) detectable (weakly) compared with only one (sweet) when warmed; responses to cooling show the greatest changes;

1

2 max

1

2 10

11

(e)

similarities [2 max] both (A and B) result in sweetness being detected; both (A and B) result in sourness being detected; both give a greater sensation of sweetness than sourness; differences [2 max] A (chemoreceptors) give a greater sensation of sweetness than B; B (chemoreceptors) give a greater sensation of sourness than A; the difference between sweet and sour taste intensity for A is greater than the difference between sweet and sour for B;

4 max [10]

25.

In warm humid weather, marathon runners are at risk of hyperthermia. Sometimes during races, their body temperatures exceed 41C. At this level of hyperthermia, fatigue and other physiological problems are common. For example, heat stroke occurs when the body becomes dehydrated. This condition reduces blood volume making it difficult for the body to lose heat through vasodilation and sweating. The graph below shows the relationship between the maximum temperatures recorded in individual patients suffering hyperthermia and heat stroke. All of the patients in this study subsequently recovered without any long-term health effect. 47

K ey:

46

H e a t s tro k e E x e rc is e h y p e rth e rm ia

45 44 B ody te m p e ra tu re / C 43 42 41 40 1970

1975

1980

1985

1990

1995

2000

2005

Year [Source: Reprinted from M. Kosaka, “Human body temperature regulation in extremely stressful environment: epidemiology and pathophysiology of heat stroke”, Journal of Thermal Biology (October-December 2004), vol. 29, issue 7–8, pp. 495–501, © 2004 with permission from Elsevier]

12

(a)

(i)

Identify the year in which the maximum temperature achieved by a surviving patient was recorded. ......................................................................................................................... (1)

(ii)

Compare the temperatures of those suffering heat stroke with those suffering exercise hyperthermia. ......................................................................................................................... ......................................................................................................................... (1)

(b)

It has been claimed that publication of research on hyperthermia has lead to a reduction in the number of cases of hyperthermia in athletes. Evaluate this claim using the data provided in the graph opposite. ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... (2)

(c)

Suggest how athletes can avoid hyperthermia. ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... (2) (Total 6 marks)

26.

(a)

(i)

1982

1

13

(ii)

(b)

heat stroke temperatures were generally higher than exercise hyperthermia

1

there is no change / a slight increase in the maximum body temperature recorded for exercise hyperthermia; the data is limited so difficult to draw a conclusion; accept numerical data (e.g 1993 is highest recorded body temperature);

(c)

2 max

reducing exposure to high temperature conditions; drinking sufficient water / fluids while exercising; reduce body hair; minimize clothing; spray with water; acclimatisation training;

2 max [6]

27.

The surface area to volume ratio is an important variable in determining biological structure. (a)

Explain the importance of the surface area to volume ratio as a factor limiting cell size. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2)

(b)

Define the term absorption. ..................................................................................................................................... ..................................................................................................................................... (1)

(c)

State one feature of alveoli that adapts them to gas exchange. ..................................................................................................................................... 14

(1)

15

(d)

Figure 1 below shows a cross-section through the small intestine and Figure 2 an enlarged longitudinal section through a single villus.

Figure 1 [Source: adapted from M Roberts et al., Advanced Biology, Nelson, 2000, page 185]

Figure 2 [Source: adapted from Taylor et al., Biological Science 1 Cambridge University Press, 1997, page 244]

Using these diagrams, outline three ways in which the structure of the small intestine is related to its function of absorbing food. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (3) (Total 7 marks)

28.

(a)

as a cell grows, volume increases faster than surface area / surface area : volume ratio decreases; the rate of consumption of resources / nutrients / oxygen is a function of volume; the rate of production of wastes is a function of volume; the rate of exchange of wastes / nutrients is a function of surface area; the rates of diffusion are too low relative to cell needs for larger cells; 2 max

16

(b)

(c)

(d)

absorption is taking up of a substance by the skin / mucous membranes / digestive tract / cell membranes / layers of cells / the bloodstream;

large total surface area / many alveoli; a wall consisting of a single layer of (flattened) cells; moist lining; dense network of capillaries;

1

1 max

villus intestinal wall has many folds to increase surface area ( : volume ratio); surface of villus close to blood vessels so materials can easily diffuse; surface of villus close to lymph vessels so lipids can be easily absorbed; greater surface area related to greater rate of diffusion; villus wall consists of single layer of cells; 3 max Do not accept microvilli – not visible in diagrams. [7]

29.

The diagram below shows the male reproductive system.

[Source: Adapted from J Vellacott and S Side, Understanding Advanced Human Biology, (1998), Hodder and Stoughton, page 281]

(a)

State the names of I and II. I:

...........................................................................................................................

II:

........................................................................................................................... 17

(2)

(b)

Discuss the ethical issues of family planning and contraception. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (4) (Total 6 marks)

30.

(a)

(b)

I: the prostate gland; II: the urethra;

2

ethical arguments against: [3 max] not natural; against religious teaching; allows casual sex / multiple partners / promotes promiscuity; zygotes / embryos killed (by IUDs) / (some) contraceptive pills; contraceptive pill / methods other than condoms encourage spread of STDs; IUD / contraceptive pills have side effects / named side effect;

ethical arguments for: [3 max] helps to control the human population; prevents birth of unwanted children / reduces abortion / reduces number of single parent families; freedom of choice / women can pursue careers; condoms prevent spread of STDs / HIV / AIDS; economic reasons / cannot afford children / cost to society;

4 max [6]

18

19

31.

(a)

Define homeostasis. ..................................................................................................................................... ..................................................................................................................................... (1)

(b)

Blood glucose levels are controlled by several hormones. (i)

State the name of one of these hormones and the specific site of its production. hormone: ........................................................................................................... site: ................................................................................................................... (2)

(ii)

Outline how the hormone chosen in (b) (i) controls blood glucose. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2)

(c)

Explain the roles of estrogen in regulating change at puberty in young women. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (3) (Total 8 marks)

20

32.

(a)

maintains the internal environment at constant levels / between narrow limits; maintains as steady state / balance in the internal environment (of organisms); NB: examples are not a definition 1 max

(b)

(i)

insulin; produced in beta cells of pancreas; or glucagon; produced in alpha cells of pancreas;

(ii)

2 max

high blood glucose levels stimulates the production of insulin; (insulin) is transported in blood; insulin increases uptake of glucose by cells / storage of glucose; converts glucose to glycogen; lowers blood glucose levels; or low blood glucose levels stimulates the production of glucagon; glucagon increases breakdown of glycogen / release of glucose from liver; raises blood glucose levels; (glucagon is) transported in blood;

(c)

at puberty estrogen production is increased; (increased estrogen) stimulates female secondary sex characteristics; example of secondary sex characteristics eg: initiates menstrual cycle / growth of vagina and uterus / growth of breasts / growth of pubic and armpit hair / fat deposit; another example from same list;

2 max

3 max [8]

33.

Explain the relationship between the structure and function of arteries, veins and capillaries. (Total 8 marks)

34.

([3 max] for information on arteries) thick wall / elastic fibres to help withstand the high(er) pressure; outer fibrous coat prevents artery from rupturing under the high pressures; lumen small compared to wall thickness to maintain high pressure; 21

except lumen large near the heart to conduct a large volume of blood; valves in aorta and pulmonary artery to prevent back flow into ventricles in diastole; layers of (smooth) muscle to allow arteries to contract / elastic recoil; allows the pressure to be altered (vasoconstriction and vasodilation);

([3 max] for information on veins) lumen always large in relation to diameter; thin wall / more collagen and fewer elastic fibres (than arteries) since pressure low(er); very little muscle since not needed for constriction; valves to prevent back flow between pulses;

([3 max] for information on capillaries) no muscle / elastic tissue since pressure very low; endothelial layer one cell thick to allow permeability / diffusion of chemicals / tissue fluid; small diameter leads to exchange; some fenestration / pores to allow rapid diffusion; no valves since pressure very low; [8]

35.

Draw a diagram of the human gas exchange system. (Total 5 marks)

36.

Award [1] for each of the following structures clearly drawn and labelled. mouth / nose; trachea; bronchi; bronchioles; lungs; alveoli; diaphragm; ribs / rib eye / intercostal muscles; [5]

37.

Describe the role of enzymes in the process of digestion of proteins, carbohydrates and lipids in humans. (Total 6 marks) 22

38.

Award [1] per role. Examples of specific enzymes: protease / trypsin / pepsin / chymotrypsin / other named protease digest proteins into polypeptides / dipeptides / amino acids / peptides; lipase digest lipids into glycerol / fatty acids; amylase digest polysaccharides into disaccharides / monosaccharides;

Enzymes must match products. speed up / catalyze reactions / increased efficiency; lower the (activation) energy required for digestive reactions to occur; occurs at body temperature; require optimum pH; enzymes are specific; digestive enzymes carry out hydrolytic processes; [6]

39.

Draw a labelled diagram of the digestive system. (Total 5 marks)

40.

Award [1] for each two of the following structures clearly drawn and correctly labelled. Connections between organs must be correct for full marks. mouth / teeth / tongue; esophagus; stomach; small intestine; large intestine / colon; anus; pancreas; liver; gall bladder; rectum; salivary glands; sphincters; [5]

23

41.

Draw a labelled diagram of the reproductive system of a human female. (Total 6 marks)

24

42.

Award [1] for each of the following structures, clearly labelled and drawn in the correct position relative to the other organs, up to [6 max]. ovary; oviduct / fallopian tube; uterus; cervix; vagina; vulva / labia; clitoris; endometrium; [6]

43.

Draw a labelled diagram to show the internal structure of the heart. (Total 6 marks)

44.

Award [1] for each of the following structures clearly drawn and labelled correctly in a diagram of the heart. left and right ventricle; left and right atria; atrioventricular valves / bicuspid / mitral and tricuspid valves; semilunar valves; aorta and vena cava; pulmonary artery and pulmonary vein; ventricle wall thicker than atria; left ventricle wall thicker than right ventricle wall; Do not award marks for a diagram with only the ventricles or atria. However, it is not necessary to show the cordae tendinae. [6]

45.

Outline the events that occur within the heart, which cause blood to move around the body. (Total 6 marks)

25

46.

blood is collected in the atria; blood is pumped from the atria to the ventricles; opened atrio-ventricular valves allow flow from the atria to the ventricles; closed semi-lunar valves prevent backflow from the arteries to the ventricles; blood is pumped out from the ventricles to the arteries; open semi-lunar valves allow flow from ventricles to arteries; closed atrio-ventricular valves prevent backflow to the atria; pressure generated by the heart causes blood to move around the body; pacemaker (SAN) initiates each heartbeat; [6]

47.

Up to two additional marks are available for the construction of your answers. (2)

(a)

Draw and label a diagram of the carbon cycle. (5)

(b)

Outline the mechanism of inhalation in human lungs. (5)

(c)

Discuss the causes and effects of the greenhouse effect and ways to control it. (8) (Total 20 marks)

48.

(a)

Award [1] for any of the following clearly drawn and correctly labelled. plants taking in CO2 (making carbohydrates) in photosynthesis; animals eating plants; animals / plants giving off CO2 by (cell) respiration; decomposers / micro-organisms giving off CO2 by (cell) respiration; fossilization of plant / animal parts / store carbon as fossil fuels; factories / cars giving off CO2 through combustion of fossil fuels; (dead) plants / animals to decomposers / saprotrophs;

(b)

5 max

inhalation means air entering; 26

external intercostal muscles contract; diaphragm contracts / flattens / moves downwards; thorax volume increases; creates pressure difference / lower pressure in thorax / lungs / correct reference to Boyles Law; air enters lungs / inhales air by nose and mouth;

5 max

Accept any of the above points if clearly explained in a labelled diagram.

27

(c)

causes: [2 max] increased CO2 levels (from combustion of fossil fuels by cars / transport); increased methane levels (from intensified animal farming / rice (paddy / padi) fields); increased CFCs levels (from sprays / industrial processes); increased burning of forests / urbanization;  reduced use of N-fertilizers ( NO 3 etc);

effects: [3 max] higher levels of greenhouse gases increase the retention of heat reflected from earth; cause increased temperatures of atmosphere / global warming; increase water evaporation / droughts / crop losses; increase melting of polar ice / glaciers / release of trapped methane; increased levels of sea / possible flooding of coastal areas; changing weather patterns / climatic extremes; controls: [3 max] international measures to reduce combustion of fossil fuels (eg Kyoto convention); reduce use of cars / combustion motors / smaller cars / drive less / lower speed limits / mass transit; reduce energy consumption / use low energy light bulbs / use better insulation in houses / increase use of electric cars; increased protection / restoration of ecosystems / reforestation; alternative energy sources (eg wind, solar, waves, nuclear); eat local food; feasible suggestion to increase photosynthesis / reduce CO 2 (eg spreading of nutrients in ocean to induce algae growth);

8 max

(Plus up to [2] for quality) [20]

28

49.

Up to two additional marks are available for the construction of your answers. (2)

(a)

Draw a labelled diagram showing the fluid-mosaic model of a biological membrane. (5)

(b)

Explain the processes of active and ive transport that move materials across a membrane. (8)

(c)

Describe the features of the alveoli that make them well adapted for gaseous exchange. (5) (Total 20 marks)

50.

(a)

(b)

Award [1] for each feature clearly drawn and correctly labelled. (phospho)lipid bilayer; hydrophobic tails and hydrophilic heads; integral protein; peripheral protein; cholesterol; (any shape different from lipid bilayer representation) glycoprotein; indication of size;

active transport: lower to higher (solute) concentration / against concentration gradient; uses energy / ATP; protein pumps / channels; gives a cell control; protein pumps transport specific substances; phagocytosis / pinocytosis; example of active transport; ive transport: diffusion; from high to low concentration; low to high; (but must be in context of random movement of particles) partial / selective permeability of membrane; example of simple diffusion; facilitated diffusion; protein channels; example of facilitated diffusion; Award [4 max] for an that deals with only one of active or ive transport.

(c)

5 max

8 max

large surface area (to lung); single cell wall / layer; 29

moist lining; dense network of capillaries; single cell wall to capillary; short distance (for gases to travel);

5 max

(Plus up to [2] for quality) [20]

30

51.

Up to two additional marks are available for the construction of your answers. (2)

(a)

Draw and label a diagram of the digestive system. (4)

(b)

Discuss factors that affect enzyme activity. (9)

(c)

Outline one industrial use of lactose. (5) (Total 20 marks)

52.

(a)

Award [1] for each structure correctly drawn and labelled. esophagus - attached to both mouth and stomach; stomach - j-shaped sac attached to esophagus and u-shaped portion of small intestine; large intestine - wider diameter than small intestine, attached to small intestine; pancreas - leaf-shaped, in u-shaped region of small intestine with small duct connected to small intestine; liver - large, triangular, to left of stomach; gall bladder - small sac drawn on top of liver with tube connected to small intestine at same region as duct from pancreas; anus - at end of large intestine but narrower in diameter;

(b)

4 max

at low temperatures, rate of reaction increases as temperature increases (or vice versa); more kinetic energy / faster movement of molecules means more collisions between enzyme / active site and substrate; optimum temperature is temperature at which rate of enzyme-catalyzed reaction is fastest; at high temperatures enzymes are denatured and stop working; denatured means change of structure in enzyme / protein resulting in loss of its 31

biological properties / no longer can carry out its function; too much kinetic energy / vibrations breaks bonds that give enzyme specific shape; optimum pH is one at which rate of enzyme-catalyzed reaction is fastest; rate of reaction reduced as increase or decrease pH (from optimum); strong acids and alkalis can denature enzymes; affect (weak, ionic, hydrogen) bonds that hold enzyme in specific shape; at low substrate concentrations, as increase concentration get increase in rate of reaction; more chance of collision between substrate and enzyme / active site; at high substrate concentration, have no change in rate as increase concentration; all active sites occupied;

9 max

32

(c)

lactose intolerance high in some human populations / Asian / African / native American and Australian aboriginal populations; lactase used to produce lactose-free / low-lactose milk; lactase breaks down lactose to glucose and galactose; source of lactase is usually yeast / many sources such as bacteria, moulds; milk ed over immobilized lactase / lactase bound to inert substance; increase sweetness of milk; no need to add extra sugar in manufacture of flavoured milk drinks / frozen desserts; can add (harmless) bacterium such as L.acidophilus which has same effect on lactose as in yoghurt;

5 max (Plus up to [2] for quality) [20]

33