Cambridge IGCSE™

BIOLOGY 0610/42

Paper 4 Theory (Extended) February/March 2020

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use a calculator. ● You should show all your working and use appropriate units.

INFORMATION ● The total mark for this paper is 80. ● The number of marks for each question or part question is shown in brackets [ ].

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This document has 20 pages. Blank pages are indicated.

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1 (a) Fig. 1.1 is a diagram of the human gas exchange system.

A

B

C

Fig. 1.1

(i) Identify the structures labelled A, B and C in Fig. 1.1.

A ........................................................................................................................................

B ........................................................................................................................................

C ........................................................................................................................................ [3]

(ii) Explain how the structures in the gas exchange system cause inspiration.

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When a person inhales, the air pressure in lungs is lesser as compared to

the atmospheric air pressure.This causes entry of air through the trachea into the

lungs to equalise this pressure difference. Entry of air in lungs leads to increase

in volume in respiratory cavity.The lungs inflate causing the ribs to move upwards.

This brings contraction of diaphragm and external intercostal muscles.This is

how the different parts of respiratory system cause inspiration.

Bronchus (airway branching from trachea responsible for conducting air into lungs)Trachea (also known as 'windpipe' that connects voice box to bronchi oflungs)

Trachea

Bronchus

Diaphragm

Diaphragm ( muscular sheet which separates the respiratory cavity from the abdominl cavity)

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(b) A person who does not smoke can be exposed to tobacco smoke from other people smoking.

Researchers studied the effect of exposure to tobacco smoke on the development of lung cancer in three groups of women who did not smoke:

• group 1 – no exposure to tobacco smoke• group 2 – low level exposure to tobacco smoke• group 3 – high level exposure to tobacco smoke.

Their results are shown in Table 1.1.

Table 1.1

group number of womenstudied

number of women who died from lung cancer

percentage of women who died from lung cancer

1 21 895 32 0.15

2 44 184 86

3 25 461 56 0.22

(i) Calculate the percentage of women in group 2 who died from lung cancer.

Write your answer, to two significant figures, in Table 1.1.

[2]

(ii) Many countries have laws that ban smoking in public buildings.

Discuss the evidence from Table 1.1 that supports these laws.

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Data obtained from group 2 and group 3 explains that by exposure to

tobacco smoke,occurrence of lung cancer increases. This proves that even

non-smokers are prone to lung cancer.The greater the exposure to tobacco smoke

the greater the risk of dying from lung cancer.

?

No. of women who died from lung cancer in group 2 = 86No. of women studied in group 2 = 44184Percentage of women in group 2 who died from lung cancer = No of women who died from lung cancer x 100 No of women studied in group 2 Therefore, 86 / 44184 × 100 = 0.19%

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(iii) Smoking has been found to increase the risk of developing diseases other than cancer.

State two other diseases that can be caused by smoking.

1 ........................................................................................................................................

2 ........................................................................................................................................ [2]

[Total: 14]

CHD- Coronary Heart Disease (heart failure caused by reduction of blood flow to heart muscle)COPD- Chronic Obstructive Pulmonary Disease(poor airflow to lungs caused bytobacco smoking)

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2 (a) Fig. 2.1 shows the transfer of materials between blood and tissues.

arteriole

lymphaticvessel

venule

Key:flow of bloodtransfer of materials

fluid Afluid B

Fig. 2.1

(i) Complete Table 2.1 by:

• stating the names of the fluids• writing yes if the fluid contains red blood cells or no if the fluid does not contain

red blood cells.

Table 2.1

letter on Fig. 2.1 name of the fluid

contains red blood cells

A

B

[2]

(ii) State the name of the process by which oxygen is transferred from fluid B to the cells.

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(iii) Explain why cells need oxygen.

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Cells use oxygen for aerobic respiration. They produce energy from glucose with the

help of oxygen.Oxygen is also utilised for performing various metabolic processes

such as cellular respiration.

lymph

tissue fluid

Diffusion( movement of molecules from an area of high concentration to an area oflow concentration)

lymphtissue fluid

no

no

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(b) Describe the functions of arterioles in the skin.

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(c) Describe the functions of lymph nodes in the lymphatic system.

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(d) Lacteals are part of the lymphatic system.

(i) State where in the body lacteals are found.

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(ii) Describe the role of lacteals.

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[Total: 12]

Arterioles perform microcirculation by supplying oxygen and nutrients from arteries

to capillaries of the skin.They control blood flow to the surface of the skin. During extreme

heat and cold,they help in maintaining body temperature by undergoing vasodilation

and vasoconstriction respectively.

The lymph nodes of the lymphatic system store abundant amount of lymphocytes

which produce antibodies for the development of immunity. Lymphocytes build

resistance to various infectious diseases by eliminating pathogenic bacteria and viruses.

Lacteals present in small intestine are involved in absorption and transport of

fat.

Small intestine(villi of small intestine)

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3 (a) One of the characteristics of living organisms is sensitivity.

Define the term sensitivity.

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(b) State the names of two sense organs.

1 ................................................................................................................................................

2 ................................................................................................................................................ [1]

Sensitivity is the ability of an organism to sense stimuli in the internal

or external environment. It enables the organism to make appropriate responses

to the stimuli.

3 Tongue4 Ear5 Skin

Eyes

Nose

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(c) Scientists investigated the effect of adrenaline on blood glucose concentration in rats.

The rats were put into two groups:

• group A was given an injection of adrenaline• group B was given an injection that did not contain adrenaline.

The blood glucose concentrations of the rats in both groups were monitored for three hours after the injections.

The rats did not eat for 12 hours before the investigation or while they were being monitored.

The results are shown in Fig. 3.1.

3.50.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

4.0

4.5

5.0

blood glucoseconcentration

/ mmol per dm3

monitoring time / hours

Key:group A (adrenaline)group B (no adrenaline)

time ofinjection

Fig. 3.1

decrease

peak

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(i) Suggest why group B was given an injection that did not contain adrenaline.

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(ii) Describe and explain the results shown in Fig. 3.1 for group A.

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(d) Another group of rats was given an injection that did not contain adrenaline.

These rats were given food after 2 hours of monitoring.

Predict the changes to blood glucose concentration in this group of rats.

Sketch a line to show your prediction on the graph in Fig. 3.1. [2]

(e) Describe two effects of adrenaline on the body, other than a change in blood glucose concentration.

1 ................................................................................................................................................

2 ................................................................................................................................................ [2]

[Total: 14]

The objective of investigation is to detect the effect of adrenaline on blood glucose

concentration,hence group B injection did not contain adrenaline.This would also

help in comparing the effects of both the injections, as the group B injection will

have no effect on water potential.

The results can be separated into two categories; observations in blood glucose

concentrations before and after the injection.Before the injection, the blood glucose is

observed decreasing. Decrease in blood glucose concentration can result due to

insulin hormone as its main function is to decrease bood glucose levels.

After the injection,a peak in blood glucose level is observed at 4.75 mmol per dm3.

This increase is caused by breakdown of glycogen into glucose in liver.

The peak gradually decreases as the glucose produced by breakdown gets

utilised for respiration.The peak decreases below 4.5 mmol per dm3.

Increased blood pressure.

Increased breathing rate.

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4 (a) Describe the similarities and differences between marasmus and kwashiorkor.

similarities .................................................................................................................................

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differences ................................................................................................................................

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(b) Researchers at a hospital recorded the total number of children admitted to the hospital between 1984 and 2002.

A common reason for children being admitted to this hospital was severe diarrhoea.

Table 4.1 shows this information.

Table 4.1

yeartotal number of

children admitted to the hospital

1984 1386

1986 1604

1988 1955

1990 2054

1992 1726

1994 1143

1996 1422

1998 1419

2000 1580

2002 1161

Water retention is observed in kwashiorkor but absent in marasmus.

Children with kwashiorkor are deficient in protein only whereas children suffering from

marasmus are deficient in carbohydrates and fats along with protein.

symptoms are common to both which include tiredness, wastage of muscles,dry skin,

anaemia,brittle hair,diarrhoea.

is caused by an unbalanced diet.Both the diseases primarily affects children. Most of the

Both the diseases are caused by protein energy malnutrition. Protein deficiency

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(i) Calculate the percentage decrease in the total number of children admitted to the hospital between 1998 and 2002.

Give your answer to the nearest whole number.

Space for working.

............................................................ % [3]

(ii) Health workers in the communities near the hospital were trained in the prevention and treatment of diarrhoea. This affected the total number of children being admitted to the hospital.

Suggest the year in which the training took place.

Give a reason for your answer.

year ...................................................................................................................................

reason ...............................................................................................................................

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(iii) The health workers provided advice to the community on ways of preventing the spread of the pathogens that cause diarrhoea.

Suggest the advice that was given to the community.

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[Total: 12]

1992

The healthcare workers emphasized on inculcation of basic hygeinic practices in daily

life for preventing spread of pathogens. These practices include washing hands with

soap or sanitizing when water is unavailable. Using clean utensils for cooking and eating.

Identification of infected individuals and isolating them.Using boiled water only for

drinking.

No of children admitted in 1998= 1419No of children admitted in 2002= 1161Percentage decrease in the total number of children = No of children admitted in 1998-No of children admitted in 2002 x 100 No of children admitted in 19981419-1161 x 100 = 18.18 = 18 1419

the number of children admitted to hospital decreases after 1992.

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5 (a) Mitosis is a type of nuclear division.

Fig. 5.1 is a series of photomicrographs showing a cell dividing by mitosis.

before mitosis 0 minutes 34 minutes

40 minutes 45 minutes 55 minutes

Fig. 5.1

(i) State the change that has occurred to the mass of DNA immediately before mitosis in Fig. 5.1.

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(ii) Estimate the time when the chromosomes shown in Fig. 5.1 begin to separate.

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Mass of DNA doubles before mitosis

34–39 minutes

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(b) Meiosis is another type of nuclear division.

Describe how the nuclei in cells produced by meiosis differ from the nuclei in cells produced by mitosis.

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(c) Stem cells divide by mitosis during the growth of an embryo.

Describe the role of stem cells in the growth of an embryo.

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The daughter cells are genetically different from each other.Nuclei formed by

meiotic division is haploid whereas nuclei formed by mitotic division is diploid.

Daughter cells produced by meiosis have half the number of chromosomes from

that of the parent cell.

Stem cells are unspecialised cells which possess the ability to differentiate into specialised

cells of any organ system after division.They can undergo continous cell division

which leads to formation of anatomy and physiology of the organism.

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(d) An embryo develops into a fetus.

Outline the processes of labour and birth.

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[Total: 13]

Pregnancy ends at childbirth.Childbirth is the result of labour.Fetus is surrounded and cushioned

by fluid filled membranous sac called as amniotic sac.At the beginning of labour,this

membranous sac will rupture release the amniotic fluid through vagina.Typically after this

event labour begins if it hasn't.The most prominent characteristics of labour is uterine

contractions which cause the cervix to dilate.After the cervix is fully dilated,fetus is

expelled out of the vaginal tract.Once the baby is delivered,the umbilical cord is clamped.

Just after the delivery of the fetus,placenta gets physiologically separated from the wall of

the uterus and is expelled via the same route of fetal expulsion.

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6 (a) Atlantic cod, Gadhus morhua, is a type of fish that is an important resource for commercial fishing.

Fig. 6.1 shows the estimated mass of Atlantic cod over 40 years.

19700

1

2

3

4

5

6

7

8

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1975 1980 1985year1990 1995 2000 2005 2010

mass ofAtlantic

cod/ milliontonnes

Fig. 6.1

(i) In 1970, the mass of Atlantic cod was 8 000 000 tonnes.

State one year when the mass of Atlantic cod was half this value.

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(ii) State the years when there was a continuous increase in the mass of Atlantic cod for at least five years.

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(iii) Suggest reasons for the trend shown between 1990 and 1995.

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1996

Period between 1990 and 1995 showed significant decrease in the mass of Atlantic cord.

Such sharp decline can be result of increased predation,overfishing,rapid spread of parasites,

water pollution due to leaching or release of detergents and chemicals ultimately leading to death

of the fish.

increase

Period between 1975 and 1983 observed continous increase

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(iv) Explain how fish stocks can be conserved by restocking.

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(b) Fish have adaptive features that enable them to live successfully in their environment.

Fig. 6.2 is a photograph of a great white shark, Carcharodon carcharias.

Great white sharks are efficient predators and have very good eyesight to see in poor light conditions underwater.

Fig. 6.2

Excessive manmade intervention can lead to decrease in fish stocks,however they can be

conserved by various practices.Captive breeding programmes ensure restoration of wild

population of fish.During breeding,their numbers can be monitored as predation and overfishing

is under control.Encouraging utilisation of farmed fish so that wild stocks can recover.

- streamlined body

- sharp teeth/jaw

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(i) Describe two features, other than eyesight, visible in Fig. 6.2 that suggest that great white sharks are efficient predators.

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(ii) Describe how the ancestors of the great white shark developed adaptive features such as good eyesight.

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[Total: 15]

According to 'Theory of Natural selection' by Charles Drawin organisms which are more

'fit' have better chances of survival.Variations are observed in almost all the organisms

produced by sexual reproduction.These variations are the result of random mutations

which arise in genes due to interaction of genes with environment.These mutations

get inherited by the offsprings. Sharks with good eyesight make them better predators

ultimately increasing their chances of survival and reproduction.Good eyesight makes

sharks fit for survival.This adaptive feature of good eyesight gets inherited by the

offsprings of these sharks.Eventually through continous reproduction all the great white

sharks will have the feature of good eyesight.

They have sharp teeth

They have streamlined body