Centre Number
Candidate Number
Name
CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education
0610/03
BIOLOGY Paper 3
May/June 2003 1 hour 15 minutes Additional Materials: Answer Paper
READ THESE INSTRUCTIONS FIRST Write your Centre number, Candidate Number and Name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided on the Question Paper. Section B Answer any two questions. Write your answers on the separate Answer Paper provided. At the end of the examination, 1. fasten all your work securely together; 2. enter the numbers of the Section B questions you have answered in the grid below. The number of marks is given in brackets [ ] at the end of each question or part question.
For Examiner’s Use If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page.
Section A Section B
Stick your personal label here, if provided. Total This document consists of 8 printed pages. SP (AT/KN) S41697/2 © CIE 2003
[Turn over
For Examiner’s Use
2 Section A Answer all the questions. Write your answers in the spaces provided.
1
Fig. 1.1 shows an incomplete diagram of the female urinary system. to heart
from heart
Renal artery kidney
Ureter
bladder
Urethra
Fig. 1.1 (a) On Fig. 1.1, draw and label the following parts: renal artery, urethra and ureter.
[4]
(b) Name three components that are present in the urine of a healthy person.
water 1. ...................................................................................................................................... urea 2. ......................................................................................................................................
salts e.g. sodium chloride 3. ..................................................................................................................................[3]
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For Examiner’s Use
3 (c) If the kidneys fail, the patient may be put on a kidney machine. Explain how a kidney machine works.
Blood from the patient passes through a length of partially permeable dialysis .......................................................................................................................................... tubing submerged in a bath of washing fluid. This fluid contains dissolved ..........................................................................................................................................
glucose and some salts but no urea. It has the same osmatic potential as .......................................................................................................................................... blood. Urea and excess salts and toxins diffuse from the blood into the fluid ..........................................................................................................................................
which is continuously being changed. The blood, without excretory materials ......................................................................................................................................[4] (d) The kidneys are part of the body’s homeostatic mechanism. (i)
*rest of answer below
Define homeostasis.
Homeostasis is the maintenance of a constant internal environment. ................................................................................................................................... ................................................................................................................................... ...............................................................................................................................[2] (ii)
Outline the role of the kidneys in homeostasis.
The kidneys maintain a constant level of water and salts in the blood. ...................................................................................................................................
The process is called osmoregulation and involves filtering the blood then ................................................................................................................................... reabsorbing only the required amounts of water or salts back into the ...............................................................................................................................[2] blood to maintain the required concentration. (iii)
Name another organ of the body also involved with homeostasis and outline its role.
the skin name of organ ........................................................................................................... role ............................................................................................................................ It maintains a constant body temperature by regulating the amount
of heat lost from its surface. More heat is lost when vasodilation ...................................................................................................................................
brings more blood to the skin surface and when greater amounts of ...............................................................................................................................[3] **rest of answer below
[Total : 18]
*(c)continued...and at the correct osmotic potential, is then passed through a filter to remove
bubbles and is pumped back into the patient. **I(d)(iii) continued...sweat evaporate. Less heat is lost when arterioles constrict causing less blood to flow at the skin surface and when sweating is reduced.
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4 2
A study was carried out to compare the amount of tooth decay in the children of two different towns. Town A had drinking water containing fluoride at a concentration of 2 parts per million. Town B had no fluoride in its drinking water. Fig. 2.1 shows the results of the study, but the graph is incomplete. 50
town A 40 town B % children
30
20
10
0
0
1
2
3
4
5
6
7
8
9
10
11-19
number of decayed teeth Fig. 2.1 (a) Complete Fig. 2.1, using the following data.
(b) (i)
town
number of decayed teeth
% children
A
2
13
B
2
9
[2]
For town B, state the percentage of children with three decayed teeth.
I2 ...............................................................................................................................[1]
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For Examiner’s Use
5 (ii)
For town A, calculate the total percentage of children with less than five decayed teeth. Show your working.
For Examiner’s Use
50 + I2 + I3 + 6 + 7 = 88
88% total percentage .................................................[2] (c) (i)
What conclusion, relating to the effect of fluoride, can be drawn from this study?
Fluoride in the drinking water reduces tooth decay in children ................................................................................................................................... ...............................................................................................................................[1] (ii)
Based on your conclusion, what recommendation should be given to town B?
Town B should add fluoride to its drinking water ................................................................................................................................... ...............................................................................................................................[1] (iii)
Explain why some people may object to this recommendation.
Too much fluoride is known to discolour tooth enamel ................................................................................................................................... ...............................................................................................................................[1] [Total : 8]
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6 3
The seaweed, Caulerpa taxifolia, lives in tropical oceans but is now also found in the Mediterranean sea, where it grows at twice the rate of local seaweeds. As a result, the local seaweeds are becoming rare. Although not poisonous, Caulerpa produces a chemical in its cells that makes it inedible to Mediterranean herbivores, such as sea urchins. They do not feed on it and their numbers are decreasing. Carnivorous fish populations have also decreased by up to 50 %. Marine conservationists are very concerned. At first they used chlorine to kill Caulerpa but are now considering the introduction of tropical sea slugs (herbivorous molluscs). Caulerpa is part of their natural diet. (a) The seaweed, Caulerpa taxifolia, is named using the binomial system. Explain the term binomial system.
Binomial means ‘two names’ - one for the genus and one for the species. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (b) (i)
Suggest why the local seaweeds are becoming rare.
Caulerpa grows at twice the rate of other seaweeds, taking the space ................................................................................................................................... they need and both blocking the light and absorbing the carbon dioxide ...............................................................................................................................[2]
they need for photosynthesis
(ii)
Sea urchins are herbivores. Define the term herbivore.
Herbivores are primary consumers that feed on producers (plants). ................................................................................................................................... ...............................................................................................................................[1] (iii)
Suggest why the populations of carnivorous fish have decreased by up to 50%.
The decline in the numbers of sea urchins might lead to a shortage ...................................................................................................................................
of food for, and thus to the death of, carnivorous fish. ................................................................................................................................... ...............................................................................................................................[2] (c) Suggest why using chlorine to kill Caulerpa might not be a good idea.
Chlorine is a poison likely to pollute the water and damage or kill .......................................................................................................................................... other organisms ......................................................................................................................................[1]
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For Examiner’s Use
7 (d) (i)
Suggest why conservationists are concerned about the effects of Caulerpa on other organisms in the Mediterranean.
For Examiner’s Use
A................................................................................................................................... decline in local, edible seaweeds may lead to the decline and possible extinction of other organisms in the food webs of the ecosystem. This ................................................................................................................................... would reduce biodiversity in the area. Organisms which might decline ...............................................................................................................................[2] (ii)
*rest of answer below
Explain how the introduction of herbivorous sea slugs from the tropics could be effective in re-establishing a balanced ecosystem.
The Sea slug feeds specifically on Caulerpa and thus, by reducing the ................................................................................................................................... population of Caulerpa it will reduce the competition between Caulerpa ...................................................................................................................................
and local seaweeds allowing their numbers to recover. ...............................................................................................................................[2] (iii)
Outline the possible dangers of introducing tropical sea slugs.
The sea slug may introduce disease into the ecosystem. They may have ................................................................................................................................... no natural predators drastically changing the nature of the natural food ................................................................................................................................... webs. They may eat other (local) seaweeds leading to their extinction. ...............................................................................................................................[2] [Total : 14]
*d(i) continued...in numbers or become extinct could include fish caught for human consumption and organisms of possible medical value.
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For Examiner’s Use
8 Section B Answer any two questions. Write your answers on the separate answer paper provided.
4
(a) (i)
Describe the main similarities between insects and arachnids.
[3]
(ii) By means of a table, show the differences between insects and arachnids. (b) Suggest and explain how a named insect could evolve over a period of time.
[5] [7]
[Total : 15]
5
(a) Explain why, in some parts of the world, not enough food is available to feed the people living there. [10] (b) Describe the uses of hormones in food production.
[5] [Total : 15]
6
(a) Explain the term codominance.
[3]
(b) Using a suitably labelled genetic diagram, explain how a baby can have blood group O (IoIo) when its mother is group A and its father is group B. [6] (c) (i) (ii)
Describe and explain what could happen when blood of different groups is mixed. [3] Describe and explain the role of the placenta in relation to this problem.
[3] [Total : 15]
7
(a) State the functions of five named parts of the male reproductive system. (b) (i) (ii)
[5]
Explain how sperm, deposited in the vagina during sexual intercourse, reach an egg. [4] Describe the process of fertilisation.
(c) Outline the ways in which HIV can be prevented from spreading.
[3] [3] [Total : 15]
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Model Answers to Section B 4
(a)(i)
Insects and spiders are both members of a group of invertebrates, called arthropods, which have jointed limbs, segmented bodies, and exoskeletons.
(ii) insects 3 pairs of legs have wings have antennae have compound eyes body has three parts do not spin webs can be social
arachnids , 4 pairs of legs, do not have wings, do not have antennae, do not have compound (or have simple) eyes, body has two parts, spin webs, can be social
(b) An insect such as a butterfly, which reproduces sexually, as a result of mutations,
will produce offspring which will show variation . If for example drought caused a decrease in the number of plants growing in the area, the butterflies might have to fly further to obtain sufficient food to survive. Larger or stronger wings, would then be an advantage since the insect could travel greater distances when collecting nectar. The butterflies with the larger wings would survive by a process of natural selection, and pass on the gene for better wings to the next generation. 5
(a) Insufficient food production to sustain the population of an area might be the result
of a climate which may be too hot too dry or polluted. Plants may be killed or die as a result of natural disasters such as flooding, disease or damage by pests, or as a result of poor irrigation. Poor quality of soil, which may be the result ofthe lack of fertiliser, leads to poor yield. It may also be the result of deforestation which in some cultures can also eliminate useful food plants or remove the habitats for food animals. The population may be forced to eat next year’s seed. Lack of money may make it difficult to buy enough seed or fertiliser or pesticide or the necessary agricultural machinery. War or political activity, may make it too dangerous to tend the crops or it may deprive the population of the necessary labour. Towns spread out occupying farmland, which cannot then sustain the growing population. Cash crops may be grown, and food reserves may be sold to maintain the economy. Lack of education, about modern farm practices, may lead for example to overgrazing. Inadequate transport or distribution may fail to move surplus food to areas of famine. (b) The plant growth hormone auxin, can be sprayed onto flowers to encourage fruit
development, even when pollination has not occurred. Auxins are also used in weedkillers. They kill broad−leaved plants so monocotyledonous crop plants are not affected, and have less competition. Some plant hormones can encourage root and shoot formation, in tissue samples taken from food plants in a process called tissue culture. Plant hormones are also used to produce seedless fruits, to promote seed germination, to delay ripening so that fruit can be transported, to increase yield, and to produce short stems to reduce wind damage. In animals hormones can be used to increase milk production, and growth hormones and testosterone are used to increase meat production.
6
Codominance refers to a pair of alleles, which are equally dominant, so that both have an effect on the phenotype in a heterozygous organism.
(a)
Mother = I A I O , IA I O
(b)
I I
I
A
A
Father = I B I O , I B IO
x
IO
I
B
I
A
I
O
B
I
O
gametes
IO
IB
I
Parents
I
O
I
O
Offspring
baby with Group O Blood (c)(i) The blood cells may stick together to form clumps (' agglutinate' ), as a result of the
interaction between the antigens on the red blood cell surfaces, and the antibodies of the other blood . If the donor blood is Group O this does not happen since there are no relevant antibodies in Group O blood. (ii) The blood groups of the fetus and the mother may be different. The placenta allows
necessary materials to be exchanged between mother and fetus, but does not allow blood to pass. 7
(a)
I. 2. 3. 4 5
(b)(i)
(ii)
The penis is used to place sperms into the vagina. The urethra is the tube running through the penis which carries the sperms. The testes make the sperms and also the sex hormone testosterone. The sperm duct (or vas deferens) carries sperms from a testis to the urethra. The prostate gland produces seminal fluid.
Sperms use their tails, for swimming, through the cervix, and then up into the uterus. From here, they pass through the oviduct, towards the egg attracted by chemicals. A sperm penetrates the membrane surrounding the egg, using enzymes. The tail is left outside the egg while the head enters the egg and moves towards the egg nucleus. The sperm nucleus and the egg nucleus fuse, to form a zygote.
(c) Since HIV is transmitted in body fluids during sexual intercourse using a condom or femidom reduces the chances of contact with the body fluids of the male and female. Avoiding intercourse, or staying with one uninfected partner would also be effective. Blood is a body fluid in which the virus is transmitted thus the use of rubber gloves when handling blood is strongly advised. All blood should be checked (or ‘screened’) for the virus and used for transfusions only if shown to be clear. Only sterile needles
should be used for injections or for taking blood, and the population in general must be educated on the risks and how best to avoid them.
Summary of Examiner’s Notes on IGCSE Biology Paper 3 June 2003 Page: 2 Q1 (a)
The label ‘from heart’ identifies the blood vessel of which the renal artery is a branch. Always be careful to spell accurately the words ‘urethra’ and ‘ureter’. Note that the question asks you both to draw and label the structures. Credit will be given for the quality of your drawing – neat lines, accurately and carefully drawn.
Q1 (b)
Some other substances such as broken down hormones and uric acid would also qualify for a mark, but avoid vague terms such as ‘waste products’.
Page: 3 Q1 (c)
Although there are only four marks available for this section, there are many more than four separate points made in the answer given above. Be as thorough as you can in your explanation, but allow the number of lines on the paper to be your guide on how much to write.
Q1 (d) i
This is a simple definition which just has to be learnt.
Q1 (d) ii
Be clear when mentioning ‘reabsorption’ in the kidneys that it is the useful substances, after first having been filtered from the blood, that are then reabsorbed back into it.
Q1 (d) iii
Avoid mention of blood capillaries moving towards or away from the skin surface – they don’t! Also, since capillaries have no muscles, unlike the arterioles in the skin, they do NOT constrict. Many other examples of organs with homeostatic functions could be given. E.g, the pancreas helps to keep blood glucose levels constant by producing the hormone insulin which converts excess glucose in the blood into glycogen to be stored in the liver. Also, the liver helps to control the blood glucose level by releasing some of the stored glycogen after it has been re-converted into glucose (under the effect of the hormone glucagon from the pancreas and adrenaline from the adrenal glands).
Page: 4 Q2 (a)
Remember to use a ruler and take care to draw the blocks accurately.
Page: 5 Q2 (b) ii
Make sure you are looking at the results for Town A (the shaded blocks). There are 50 children who have no decayed teeth, 12 with 1 decayed tooth, 13 with 2, 6 with 3 and 7 with 4, making a total of 88.
Q2 (c) i
The study involved only children so that must be made clear in the conclusion. There are more children with less than three decayed teeth in Town A and more children with more than three decayed teeth in town B.
Q2 (c) ii
Other advice involving the use of fluoride would also be acceptable such as the use of fluoride toothpastes.
Q2 (c) iii
There are other valid objections including the cost, possible allergies and the removal of personal choice.
Page: 6 Q3 (b) i
There would always be likely to be enough oxygen in the sea water to meet requirements.
Q3 (b) iii
Other answers could be given which might be reasonable explanations of the decline in numbers of carnivorous fish such as disease, migration or increased predation
Page: 7 Q3 (d) i
This is a section on the more general topic of Conservation and thus wider issues than those so far considered need to be addressed.
Q3 (d) iv
In all parts of (d), there are more points that can be made than there are marks available. Make sure you put what you consider to be the most important points first, then fill as much of the space provided as possible. It is a guide to how much you are expected to write.
Page: 8 Section B
Note that in this Section, more extended answers are expected. There are often more relevant things to say than there are marks available. The answers given below indicate the main relevant points, any combination of which when used in a context of Biological accuracy, may be used to obtain maximum marks for a question subsection. Individual marking points have been separated either by commas or full stops.
Q4 (a) i
Limbs of arthropods are not segmented, though they are divided, by their joints, into distinct sections.
Q4 (a) ii
The body sections, like the sections of the legs mentioned in (i) are not segments. The question asks for a table and one of the available marks is awarded for drawing a table with suitable headings.
Q4 (b)
Any named insect would be acceptable, but the variation mentioned would have to be at least a likely advantage to the insect in question. Be very careful not to suggest that the insect makes any effort to change as a result in a change in the environment. Variations are random and most of those occurring in a population will be of no evolutionary advantage at all to the organisms in their particular environment and will not be retained in the population.
Q5 (a)
Not all points in this extensive list of possibilities will be familiar to all those answering the question but they allow you to give examples relevant to your own experience. Remember that the question asks for an explanation and thus each stated cause must be supported by an explanation of why that particular cause may lead to a shortage of food.
Q5 (b)
This time, only a description rather than an explanation of each use is required.
Q6 (a)
The correct term here is allele, not gene.
Q6 (b)
You may use a Punnett Square with the gametes arranged across the top and down one side, but if you use the method shown above and include lines to show how the gametes my link at fertilisation, then they must be drawn correctly. If you are not sure that you can do this, then it is better to leave them out. Gametes may be shown in circles, but if no circles are used, then make sure that the gap between the alleles is clearly larger than the gap between the alleles in the parental genotypes.
Q6 (c) ii
Red blood cells and large protein molecules do not pass through capillary walls.
Q7 (a)
The question asks for five named parts. If you give more than five, make sure that the first five you mention are the ones of which you are most certain. The epididymis for collecting sperms from the testis and temporarily storing them and the scrotum for holding the testes and keeping them at a temperature slightly below body temperature are also accurate answers. Ensure that you spell urethra correctly.
Q7 (b) ii
Fertilisation occurs in the oviduct and is defined as the moment when the male and female nuclei fuse.
Q7 (c)
The dangers of injecting drugs with shared needles is covered in the last sentence of this answer.
