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SEC Preventive Classes Secondary Education Certificate

Examination Papers – 2017

Biology

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The University of Malta, including the Matriculation and Secondary Education Certificate

Examination Board, shall not be held responsible for any mistakes in the questions as printed or the answers, workings or comments as contained in this publication.

Index Number:___________ SEC04/1.17m

© The MATSEC Examinations Board reserves all rights on the examination questions in all examination papers set by the said Board.

MATRICULATION AND SECONDARY EDUCATION CERTIFICATE EXAMINATIONS BOARD UNIVERSITY OF MALTA, MSIDA

SECONDARY EDUCATION CERTIFICATE LEVEL

MAY 2017 SESSION

SUBJECT: Biology PAPER NUMBER: I DATE: 8th May 2017 TIME: 4:00 p.m. to 6:05 p.m. ANSWER ALL QUESTIONS IN THIS PAPER IN THE SPACES PROVIDED. 1. The table below contains incomplete biological statements. Complete each statement by writing

the correct number in the box. The first statement has been completed for you.

Statement Number

a. The number of bronchi in the human respiratory system is 2

b. The number of ventricles in the human heart is

c. The number of different elements in a fat molecule is

d. The number of hydrogen atoms in glucose is

e. The number of waste products of human anaerobic respiration is

f. The number of chromosomes in red blood cells is

g. The number of trophic levels in a food chain that ends with a tertiary consumer is

h. The number of cells produced after a zygote divides four times by mitosis is

i. The number of ova released by the ovary which results in identical twins is

j. The number of the different types of blood groups is

k. The number of cotyledons in the seed of a monocotyledon is

(1 each) (Total: 10 marks)

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2. a. In the table below write the name of the part of the cell that corresponds to each of the

following descriptions:

Description Part of cell

Regulates entry and exit of materials into and out of the cell

Controls all the cell’s activities

Contains cell sap

The site where most of the cell’s chemical reactions take place

(4)

b. Water is taken in by the roots of flowering plants. The water then travels up the stem andpasses out through the leaves.

i) In the space provided, draw and label a root hair cell. Its function is to take up water fromthe surrounding soil.

(3)

ii) Give the feature that root hair cells have so that they take up water more efficiently.

(1)

iii) Name ONE organelle that is present in a palisade cell but absent in a root hair cell.

(1)

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c. Figure 2 shows cells that line the inside surface of the nose and trachea.

Figure 2: Cells of ciliated epithelium lining the nose and the trachea

Describe how each type of cell helps to keep the lungs clean:

i) mucus-secreting cell;

(1)

ii) ciliated epithelial cell.

(1)

(Total: 11 marks)

Please turn the page.

Mucus-secreting cell

Ciliated epithelial cell

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3. Figure 3.1 below shows part of the human digestive system.

stomach

X

Figure 3.1: Part of the human digestive system

a. Fat molecules form an important part of the human diet. They are digested in the alimentarycanal by the enzyme lipase.Name and label the organ shown in Figure 3.1, which produces the enzyme lipase.

(2)

b. Digestion of fat is very slow without lipase. It would be even slower in the absence of an additional substance produced by another organ also shown in Figure 3.1.

i) The substance released:

ii) The organ that secretes it:

iii) The organ where it is stored before it is released: (3)

c. Figure 3.2 shows the action played by the secretion mentioned in part b i) in the digestion of fats.

Fat globule Fat droplets

Figure 3.2: Action on fat globule during digestion of fat

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i) Name the process shown in Figure 3.2 and explain how it helps to increase the rate atwhich lipase breaks down fats.

Process:

Explanation:

(2)

ii) Describe the action of the enzyme lipase on fat molecules.

(2)

d. Describe how the partially digested food moves along structure X, shown in Figure 3.1.

(2)(Total: 11 marks)


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4. The photomicrograph below shows a vascular bundle from a dicotyledonous root.

Figure 4.1: Photomicrograph showing a vascular bundle in a root http://iws.collin.edu/jbeck/PlantstructureHtml/Dicotroot40x.jpg

a. i) On the photomicrograph in Figure 4.1, label the xylem tissue. (1)

iii) Water travels up the stem of a plant in the xylem. State ONE other function of xylemtissue in plants.

(1)

b. List ONE feature of the cells making up xylem which help water travel up the stem.

(1)

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c. Bark ringing is the process when a ring of bark is removed from a tree. In the process, thetissue that transports sugar in the plant is removed as shown in Figure 4.2.

Figure 4.2: Investigation of bark ringing http://images.slideplayer.com/39/10931322/slides/slide_9.jpg

i) Name the tissue that has been removed with the bark.

(1)

ii) Name the organ where sugars are formed in the plant and name the process of synthesisof sugars.

Organ:

Process: (2)

ii) Explain why the majority of trees will die when a ring of bark is removed.

(3)

(Total: 9 marks)


To Leaves

To Roots

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5. Three broad bean seeds were tied at different places on a transparent glass slide as shown inFigure 5.1 below. The glass slide was placed in a beaker of water such that the middle broadbean just touched the water. The setup was left for 7 days.

Figure 5.1: Apparatus to investigate germination in three broad bean seeds

a. Give ONE reason why seeds A and C did not germinate.

Seed A:

b. Seed C: (2)

c. The graph below shows the change in dry mass of the germinating seed and the cotyledons.

Figure 5.2: Change in dry mass of the germinating seed and the cotyledons

X

Y

Z

glass slide

beaker

water

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Explain, giving biological reasons, what happens to the dry mass of the germinating seed in the following regions shown on the graph:

i) between points X and Y;

(2)

ii) between points Y and Z.

(2)

c. The mass of the cotyledons decreased drastically after a few days.

i) Name the carbohydrate stored in the cotyledons.

(1)

ii) Describe a test to show the presence of the carbohydrate stored in cotyledons.

(2)

(Total: 9 marks)


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6. Figure 6.1 shows four arthropods.

Figure 6.1: Four arthropods

a. State ONE characteristic that is common to all arthropods.

(1)

b. Use the dichotomous key below to name arthropod W and Z.

Key Name of Arthropod 1. Body has no stripes

Body has stripesGo to 2 Go to 3

2. Antennae are longer than width of headAntennae are shorter than width of head

Lilioceris cheni Coccinella septempunctata

3. Head is wide and roundedHead is long and narrow

Leptinotarsa decemlineata Otiorhynchus sulcatus

W: Z: (2)

c. Give the species name of arthropod Y.

(1)

d. Name the class to which organisms W, X, Y and Z belong to and state TWO characteristics,visible in the diagram that are common to this class.

Class:

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Characteristic 1:

Characteristic 2: (3)

e. Figure 6.2 shows a whitefly. Whiteflies live on the underside of plant leaves. They inject theirmouth parts in the plant leaves and suck sugars. They suck more sugars than they can digestand they excrete the excess as a sweet, sticky substance called honeydew. Black fungusgrows and feeds on the honeydew, thus covering the leaf.

Figure 6.2: A whitefly

i) Give the biological term that describes the movement of sugars from the leaves to otherparts of the plant.

(1)

ii) Explain how black fungus growing on leaves can harm the plant.

(2)

iii) Organism Y is often introduced in fields to eat whitefly. Name this mechanism and stateONE advantage of it.

Name:

Advantage: (2)

iv) Whiteflies lay tiny oblong eggs which hatch into young whiteflies which increase in sizethrough four nymphal stages called instars. Name this type of metamorphosis.

(1)

(Total: 13 marks)

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7. a. The table below lists some features of the five groups of living organisms.

Use the terms YES, NO or SOME to complete the table. Some answers have been included.

Group Can

photosynthesise Have cell

walls Produce

seeds Are decomposers

Plants no

Animals some

Fungi no

Bacteria some

Viruses no

(5)

b. The following two statements are incorrect. Write the correct statement and give ONE reasonfor your answer.

i) Although biologists believe that deforestation is harmful to planet Earth, it can improvethe fertility of the soil in the deforested area.

Correct statement:

Reason:

(2)

ii) In fish farming, persistent pesticides, not harmful to the farmed fish, are added to thecages to kill disease-causing organisms. Live shellfish, such as mussels, found livingclose to the fish farm are not found to contain any pesticide.

Correct statement:

Reason:

(2)

(Total: 9 marks)

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8. a. Students in a Biology class wanted to investigate if huddling, i.e. when a group of animals

stay close to each other reduces temperature loss. They prepared two sets of apparatus: agroup of seven test-tubes with one thermometer in the middle test-tube and anotherthermometer in an outer test tube and a single test tube with a thermometer. They added hotwater to all the test tubes and took temperature readings for 10 minutes every minute. Theset-up is shown below.

Figure 8.1: Apparatus to investigate the effect of huddling on heat loss

i) The students found the total surface area of each apparatus set up. The following are theresults obtained.

Test tube/s Total surface area (cm2)

7 test tube group 367.5

Single test tube 103.5

In the space below, work out the average surface area per test-tube for the setup containing 7 test tubes.

Answer: (2)

This question continues on the next page.

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ii) In the table below, compare the expected change in temperature in each of the test tubesby using the following terms: large decrease in temperature; medium decrease intemperature and small decrease in temperature.Each term may be used once, more than once or not at all.

Thermometer Temperature change

Thermometer placed in the outer test tube in the setup with a group of 7 test tubes Thermometer placed in the inner test tube in the setup with a group of 7 test tubes Thermometer in setup with a single test tube

(3)

iii) Give ONE reason for each answer given in part a ii).

Thermometer Reason

Thermometer placed in the outer test tube in the setup with a group of 7 test tubes.

Thermometer placed in the inner test tube in the setup with a group of 7 test tubes.

Thermometer in setup with a single test tube.

(3)

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b. The photograph below shows Ankole-Watusi cattle native to Africa. These cattle haveelongated horns that can reach up to 2.4 m wide. The interior of the horns have a network ofbone that carries blood vessels to the outer surface of the horn. The Ankole-Watusi cattletypically live in warm climates.

Figure 8.2: https://c2.staticflickr.com/6/5151/7111672751_9f139be708_b.jpg

Explain, with reference to thermoregulation, the biological importance of blood vessels within the large horns.

(2)

(Total: 10 marks)


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9. Give TWO reasons to suggest why each of the following initiatives have been promoted as‘beneficial to the environment.’

a. People who buy a new electric car get more money for their old car than those who buy a newcar that runs on fuel.

(2)

b. A company in USA is packing water in carton boxes instead of plastic bottles.

(2)

c. The LifeMedGreenRoof project promotes the setting up of roof gardens in Malta.

(2)

d. WasteServ Malta has introduced the separation and collection of organic waste in a numberof localities.

(2)

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e. In the past years, different areas in Malta such as Il-Majjistral National Park and InwadarNational Park were designated as conservation areas.

(2)

(Total: 10 marks)


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10. The nephron is a functional unit of the kidney. One of its functions is to regulate theconcentration of water and salts in blood.

a. The figures in the tables show parts of the nephron.Table 10.1: Parts of a nephron

1 2 3 4 5

Fill in the missing numbers to show the correct order of each part shown above in a nephron.

4 1

(1)

b. The following table shows the change in the concentration of components in the bloodplasma, filtrate and urine.

Table 10.2: Blood components in plasma, filtrate and urine

Blood component

Plasma (g/100 cm3) Filtrate (g/100 cm3) Urine (g/100 cm3)

Water 90.00 98.00 98.00 Mineral salts 0.72 0.72 1.10

Albumin 8.00 0.00 0.00 Glucose 0.10 0.10 0.00

Urea 0.05 0.05 1.80

Using your biological knowledge and the information in the table above, explain why:

i) Mineral salts and glucose are present in the filtrate, but albumin is not.

(2)

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ii) Glucose is present in the filtrate but not in urine.

(2)

iii) The concentration of mineral salts and urea is higher in urine than in blood plasma.

(2)

c. Name the region of the nephron where ADH causes the reabsorption of water.

(1)

(Total: 8 marks)

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MAY 2017 SESSION

SUBJECT: Biology PAPER NUMBER: IIA DATE: 9th May 2017 TIME: 4:00 p.m. to 6:05 p.m.

Write your answers on the booklet provided. Write down the number of the questions you answer on the front page of your answer booklet. Please note that for question 2 of this paper you need the graph paper in the booklet.

SECTION A: Answer ALL questions in this section. This section carries 25 marks.

1. Read the following passage and then answer the questions that follow.

Researching Vibriosis – a disease in farmed fish One of the main problems in fish farming of marine fish is the disease called Vibriosis. It is called so as it is caused by a genus of bacteria called Vibrio. The processes in fish farms lead to stressful conditions for the fish. These include changes in salinity, changes in temperature, handling and transportation, accumulation of waste and overcrowding. All these factors have an effect on the physiology of fish and make them more prone to infection by Vibrio. This disease is very common in Sparus aurata (gilthead sea bream in English, awrata in Maltese). Although this species is the most commonly farmed marine finfish species in the Mediterranean, it is easily infected by Vibrio harveyi when compared to other more commonly farmed marine finfish. Athough Vibriosis is generally treated by antibiotics; Vibrio harveyi is becoming antibiotic resistant. Thus further research is going on to look into alternative methods of preventing and controlling the bacterium. This research involves the product TEX-OE® which is extracted from the outer skin of the prickly pear, Opuntia ficus-indica (bajtar tax-xewk). TEX-OE® accelerates the production of heat shock proteins (HSPs) inside cells. These proteins are normally produced when cells are under stressful conditions. HSP’s help the cell to repair vital proteins and ensures that it continues to produce new

proteins. So if HSP’s are present in the fish before it is infected by Vibrio harveyi, the fish will kill the bacterium faster and suffer less damage. In this study, the scientist tried to establish the pattern of growth of Vibrio harveyi at 20 oC, 30 oCand 37 oC using a turbidimetry method. This method involves passing light through the flask wherebacteria are grown. The greater the number of bacteria, the less light will pass through. The experiment was performed twice. First the bacteria were grown in the absence of TEX-OE® and then in the presence of TEX-OE®. The results showed that TEX-OE® had no effect on the growth of the bacterium. These results confirmed that TEX-OE® does not directly decrease the rate of growth of the bacterium Vibrio harveyi.

(Adapted from Walker L., Studies on the effects of Tex-OE® on microbial physiology and pathogenicity; in Biology Symposium Abstracts 2015, UOM)

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a. Give TWO differences between a cell extracted from Sparus aurata, and a cell of thebacterium Vibrio. (2)

b. List TWO differences between a cell extracted from Sparus aurata and a cell extracted fromOpuntia ficus-indica. (2)

c. Name ONE cellular structure that is present in all of the following: the bacterium Vibrio, in acell extracted from Sparus aurata and a cell extracted from Opuntia ficus-indica. (1)

d. Name the phylum that Sparus aurata is classified in. Give ONE characteristic structuralfeature of all organisms belonging to this phylum. (2)

e. List TWO characteristics that may be used to distinguish Sparus aurata from other fish. (2) f. Explain how an increase in salinity would have a stressful effect on fish. (2) g. At which of the three temperatures used in the experiment is the greater number of bacteria

observed? Give ONE reason for your answer. (2)

(Total: 13 marks)

2. Green plants contain different pigments that absorb light at different wavelengths. The resultsbelow indicate the light absorbed by chlorophyll and the rate of photosynthesis over this range ofwavelengths.

Table 2: % of light absorbed by chlorophyll a and the rate of photosynthesis at different wavelengths of light.

a. On the graph paper provided (use the 2 mm grid scale), draw a graph to show the relationshipbetween the wavelength of light, the light absorbed and the rate of photosynthesis. Join thepoints of the graph with straight lines. Plot the wavelength of light on the x-axis. Using the samescale plot the light absorbed by chlorophyll a and the rate of photosynthesis on the y-axis. (6)

b. Use the graph to explain why the highest rate of photosynthesis occurs at a wavelength of 400nanometres. (2)

c. Besides the wavelength of light, name TWO other abiotic factors that affect the rate ofphotosynthesis. (2)

d. State how the surface area of the leaf affects the rate of photosynthesis and give a reason foryour answer. (2)

(Total: 12 marks)

Wavelength of light (nanometres)

Light absorbed by chlorophyll a (%)

Rate of photosynthesis (arbitrary units)

400 54 70 450 5 60 500 7 35 550 9 18 600 10 35 650 50 58 700 4 10

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SECTION B: Answer any THREE questions from this section.

3. A newspaper reported the case of an Australian teenage girl, whose menstrual bleeding could notstop. Finally doctors diagnosed the Von Willebrand’s disease; a genetic bleeding disorder where a

clotting protein in the blood is missing or defective.a. This girl reported frequent fainting and breathlessness. Explain why her doctor prescribed iron

supplements to help her overcome these problems. (3)b. Von Willebrand’s disease is an autosomal recessive disease. It occurs equally in men and

women, however, the phenotype is more pronounced in females.i) Define the term autosomal. (2) ii) Explain why the phenotype is more pronounced in females. (1)

c. Neither the girl’s mother nor father had the disease. Using R to represent normal and r torepresent the disease, draw a genetic diagram to explain how this girl inherited the disease. (4)

d. Blood clotting is a very important process taking place in the human body.i) Give TWO reasons why blood clotting is important. (2) ii) Name the blood components essential for blood clotting. (1)

e. Blood cells in human blood include red blood cells and lymphocytes, a type of white bloodcells.i) State the function of red blood cells and lymphocytes. (2) ii) List TWO structural differences between red blood cells and lymphocytes. (2)

f. The heart pumps blood around the body in blood vessels.i) Explain why humans are said to have a double circulation. (3) ii) List THREE differences in structure between arteries and veins. (3)

g. During a medical test, an old man was diagnosed with a heart murmur resulting from a leakingbicuspid valve. Explain how this can affect the old man’s life. (2)

(Total: 25 marks)

Please turn the page

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4. The Citrus Tristeza virus attacks citrus trees. It may be introduced into the citrus trees eitherthrough grafting or by aphids that are infected by the virus. There are several species of aphidsthat can infect citrus trees with the virus including the aphid Taxoptera citricida.

a. i) Describe TWO ways how the scientific name of other species of aphid may vary from that of Taxoptera citricida. (2)

ii) Aphids can exist in two forms winged or wingless. Winged forms develop when aphidnumbers are high in their habitat. Explain how this adaptation is a benefit to theseorganisms. (2)

iii) A farmer finds aphids on the leaves of orange trees. The farmer sprays a mixture of avegetable oil and detergent on the leaves instead of using a broad–range insecticide.Explain the choice made by the farmer. (2)

b. Both aphids and the Citrus Tristeza virus are considered to be parasites on citrus trees. TheCitrus Tristeza virus brings about stem pitting (open pores in stem), yellowing of leaves,smaller fruit yield, stunted growth and occasionally the death of the citrus trees. The virusreproduces in the phloem.i) Define the term parasite. (1) ii) Although the Citrus Tristeza virus infects both the aphids and the citrus trees, it is

considered to be parasitic on the citrus tree only. Give ONE reason for this observation.(2)

iii) Define the term tissue. (1) iv) Draw a well-labelled diagram of a virus. (4) v) Describe, using diagrams if required, the replication cycle of a virus. (4) vi) Indicate ONE reason why the infection of the virus causes a smaller fruit yield and

stunted growth. (2)c. Aphids, garden snails, earwig, grasshoppers and ants feed on leaves of citrus trees. Earwigs

feed also on aphids and snails. Birds and mice feed on grasshoppers and spiders. Spiders feedon ants. Rats feed on orange fruit as well as insects such as grasshoppers. Draw a food web ofthe above feeding relationships. (5)

(Total: 25 marks)

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5. a. The diagram below shows a setup used in determining the rate of diffusion at differenttemperatures. Students used cores of the vegetable beetroot in water at different temperatures. An increase in temperature also increases the rupturing of membranes.

Figure 5: Beetroot core placed in a beaker of water

The students observed the diffusion of the beetroot pigment in water and compared the different intensities of colour obtained under the naked eye and using a colorimeter. A colorimeter reads the intensity of a colour. Clear water gives a reading of 100 while full colour gives a reading of 0. The following results were obtained.

Table 5: Experimental results showing colour of solutions and colorimeter readings at different temperatures

Temperature (°C) 0 20 40 60 80 Colour in solution Clear Very pale

pink Pale pink Pink Dark pink

Colorimeter reading (% transmission)

99.5 95.0 78.0 36.7 4.2

i) Describe and explain the relationship between the rate of diffusion and temperature. (5)ii) List TWO factors that need to be kept constant in this investigation. (2) iii) The pigment is stored in the vacuole of plant cells. It is only when the cell membrane or

vacuolar membrane ruptures that the pigment seeps out. Explain why. (1) iv) Give ONE other function of permanent vacuoles. (1)

b. The vegetable beetroot is a storage tap-root.i) Explain how this statement indicates that the vegetable beetroot is a dicot. (2) ii) State how the leaves and the flowers of the beetroot plant will also indicate that the

beetroot plant is a dicot. (2) iii) Explain why the beetroot plant is expected to be larger than a moss plant. (2) iv) Explain why the sexual reproduction in a beetroot plant can occur in drier environments

than in ferns. (2) v) State how the formation of seeds in the beetroot plant is different from the formation of

seeds in a gymnosperm. (2)

This question continues on next page.

Beetroot core

Water

Beaker

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c. In an investigation on transpiration, a student used one stalk and leaf of the beet plant tomeasure the rate of water loss. The student measured the total surface area of the leaf anddetermined the rate of water loss per unit area. The student then took readings as the conditionssurrounding the leaf were changed.State the change in the potometer readings in the following conditions and give ONE reasonfor your answer:i) lower surface of the leaf covered with VaselineTM (petroleum jelly); (3) ii) leaf closed in bag. (3)

(Total: 25 marks)

6. a. Ten years ago, a man was diagnosed with a brain tumour in the cerebral hemisphere thatcontrolled speech and movement. A tumour is an abnormal growth of cells which due to a mutation, start dividing uncontrollably. i) Name the type of cell division occurring in a tumour and state TWO characteristics of

cells produced by this cell division (1, 2) ii) In multicellular organisms, cell division is a continuous process. State TWO reasons why

cell division is important. (2) iii) During the surgery, the man was given local anaesthetic and was wide awake, talking

throughout the operation. Local anaesthetic stopped pain sensations in the area of thebody undergoing surgery. Explain how the anaesthetic affected the nervous system. (2)

iv) List TWO ways how the brain is protected from injury. (2) v) A person who is unconscious is still able to breath and the pulse can still be felt. Explain.

(2) vi) The brain is an organ. Define the term organ. (2) vii) The cerebrum is part of the brain. It includes sensory, motor and association areas within

in. Distinguish the different role of each area within the cerebrum. (3)

b. When touching a hot kettle, a person immediately withdraws his hand. Receptors in the skindetect the stimulus and send a nerve impulse to the spinal cord. A nerve impulse then passesback to the effectors which bring about an immediate response.i) Name this immediate response. (1) ii) Draw a well labelled diagram of a cross section of the spinal cord. Label the neurones

involved in the response. Draw arrows to show the direction of the nerve impulse.(2, 3, 3)

(Total: 25 marks)

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7. A group of students studied the effects of sewage run-off into a local stream. The studentsobserved the changes in the levels of oxygen concentration, bacterial population and algae (algal)growth in the stream. Figure 7 below shows a graph showing the changes in these three factors.

Figure 7: Variation of oxygen concentration, algae population and bacterial population with distance down the stream http://www.hourlybook.com/wp-content/uploads/2015/02/403x286x162.png.pagespeed.ic.5-f4VPotvK.png

a. i) Use the graph to describe the changes in the bacterial population in relation with the oxygen concentration from the point of sewage entry up to 12 km downstream. (4)

ii) Explain the reason behind the relationship. (2) b. Explain how the change in oxygen concentration from 3 km to 6 km downstream may affect:

i) aquatic animals; (2) ii) aquatic plants living in that area. (3)

c. Explain how the death of bacteria affects the increase in the algal population from 8 km to10 km. (3)

d. Ta’ Barkat sewage treatment plant uses biological treatments to clean sewage waste water fromdissolved waste particles. Denitrification is a useful process in sewage treatment but consideredwasteful in the nitrogen cycle. Explain. (3)

e. The sewage treatment plant also breaks down solid waste filtered from sewage using bacteriato produce methane gas (biogas). The gas is then used to generate electricity to work part of theplant.i) The production of methane is a fermentation process. Explain. (2) ii) Methane fermentation is described as a Pollution Reduction Process. Explain. (3)

f. Methane is a greenhouse gas.i) Name ONE other greenhouse gas. (1) ii) Describe TWO effects of greenhouse gases on the environment. (2)

(Total: 25 marks)

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MAY 2017 SESSION

SUBJECT: Biology PAPER NUMBER: IIB DATE: 9th May 2017 TIME: 4:00 p.m. to 6:05 p.m.

Write your answers on the booklet provided. Write down the number of the questions you answer, on the front page of your answer booklet. Please note that for question 3 of this paper you need the graph paper in the booklet.

Answer any FOUR questions.

1. The disease Vibriosis affects marine fish growing in fish farms. It is called Vibriosis as it iscaused by a genus of bacteria called Vibrio.Vibriosis is very common in Sparus aurata (gilthead sea bream in English, awrata in Maltese).Although this species is the most commonly farmed marine finfish species in theMediterranean, it is easily infected by Vibrio harveyi when compared to other farmed marinefinfish.

a. Name the kingdoms in which Vibrio harveyi and Sparus aurata are classified in. (2) b. Give TWO structural differences between a cell extracted from a fish, and a cell of the

bacterium Vibrio. (2) c. i) Name the phylum and class that Sparus aurata is classified in. Give TWO characteristic

structural features of all organisms belonging to this phylum. (4) ii) List TWO characteristic structural features that Sparus aurata shares with other fish. (2)iii) List ONE characteristic that may be used to distinguish Sparus aurata from other fish. (2)

Athough Vibriosis is generally treated by antibiotics, Vibrio harveyi is becoming antibiotic resistant. Due to this fact, more research is going on to try to find other methods to prevent and control the bacterium. This research involves the product TEX-OE®; a substance that is extracted from the outer skin of the flowering plant, Opuntia ficus-indica (prickly pear in English, bajtar tax-xewk in Maltese).

d. Name the kingdom and phylum in which Opuntia ficus-indica is classified in. (2) e. List TWO similarities and TWO differences between a cell extracted from Sparus aurata and

a cell extracted from Opuntia ficus-indica. (4) f. Name ONE cellular structure that is present in all of the following: the bacterium Vibrio

harveyi, in a cell extracted from Sparus aurata and a cell extracted from Opuntia ficus-indica. (2)

Question continues on next page.

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TEX-OE® makes the production of heat shock proteins inside cells go faster. These proteins are normally produced when cells are under stressful conditions e.g. very high temperature. Heat shock proteins help cells to repair vital proteins and to continue producing new proteins. So if HSP’s are present in the fish before it is infected by Vibrio harveyi, the fish will kill the bacterium faster and suffer less damage.

g. Explain how a high temperature can have a negative effect on fish. (2)

In this study, the scientist tried to establish the pattern of growth of Vibrio harveyi at 20 oC, 30oC and 37 oC. The method involves passing light through the flask where bacteria are grown.The greater the number of bacteria, the less light will pass through.

h. At which of the three temperatures used in the experiment is the greater number of bacteriaobserved? Give ONE reason for your answer. (3)

(Adapted from Walker L., Studies on the effects of Tex-OE® on microbial physiology and pathogenicity; in BiologySymposium Abstracts 2015, UOM)

(Total: 25 marks)

2. A foreign newspaper reported the case of an Australian teenage girl, whose menstrual bleedingcould not stop. Doctors diagnosed the Von Willebrand’s disease; a genetic bleeding disorderwhere a clotting protein in the blood is missing or defective.

a. This girl reported frequent fainting and breathlessness due to excess bleeding. Name a:i) deficiency disease she had developed;ii) mineral that was missing in her body. (2)

b. Von Willebrand’s disease is an autosomal recessive disease, occurring on chromosome number12. It occurs equally in men and women, however, the phenotype is more pronounced infemales.i) Define the term autosomal. (2) ii) Explain why the phenotype is more pronounced in females. (1)

c. Both the girl’s parents were heterozygous for Von Willebrand’s disease. Using R to representnormal and r to represent the disease, draw a genetic diagram to show the probability of thiscouple having a child with Von Willebrand’s disease. (5)

d. Blood clotting is a very important process taking place in the human body.i) Give TWO reasons why blood clotting is important. (2) ii) Name the blood components essential for blood clotting. (1)

e. Blood cells in human blood include red blood cells and lymphocytes, a type of white bloodcells.i) State the function of red blood cells and lymphocytes. (2) ii) List TWO structural differences between red blood cells and lymphocytes. (2) iii) Phagocytes are other cells found in human blood. State the function of phagocytes. (2)

f. The heart pumps blood around the body in blood vessels. In the form of a table, list THREEdifferences in structure between arteries and veins. (6)

(Total: 25 marks)

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3. Green plants contain different pigments that absorb light at different wavelengths. The resultsbelow indicate the rate of photosynthesis at different wavelengths of light.

Table 3: The rate of photosynthesis at different wavelengths of light

a. On the graph paper provided (use the 2 mm grid scale), draw a graph to show the relationshipbetween the wavelength of light (nm) and the rate of photosynthesis. Join the points of thegraph with straight lines. (6)

b. Name a plant pigment that absorbs light. (1) c. From the graph, list TWO wavelengths of light when the rate of photosynthesis is 40 (arbitrary

units). (2) d. Besides the wavelength of light, name TWO other abiotic factors that affect the rate of

photosynthesis. (2) e. Name TWO plant cells which carry out photosynthesis. (2) f. One of the products of photosynthesis is glucose.

i) Name the other product produced in photosynthesis. (1) ii) Plants store glucose as starch. Describe how starch is built up from glucose. (1)

g. When humans eat starch they digest it back to glucose.i) Describe the process how starch is digested to glucose in the human alimentary canal. In

your answer, include the regions of the alimentary canal where starch is digested, theenzyme involved, the structure that releases the enzyme and the product formed. (Youmay present your answer in table format.) (6)

ii) Explain why humans need to digest starch back to glucose. (2)iii) Explain why glucose is an important chemical in living organisms. (2)

(Total: 25 marks)


Wavelength of light (nanometres)

Rate of photosynthesis (arbitrary units)

400 70 450 60 500 35 550 18 600 35 650 58 700 10

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4.a. Ten years ago, a man was diagnosed with a brain tumour in a part of the cerebral hemispherethat controls speech and movement. A tumour is an abnormal growth of cells which due to a mutation, start dividing uncontrollably. i) Name the type of cell division occurring in a tumour and state TWO characteristics of

cells produced by this cell division. (2, 2)ii) In multicellular organisms, cell division is a continuous process. State ONE reason why

cell division is important. (2) iii) Name ONE way how the brain is protected from injury. (2) iv) State ONE function of each of the following parts of the brain:

Cerebellum;

Pituitary gland. (2) v) A person who is unconscious is still able to breath and the pulse can still be felt. Explain.

(2) vi) The brain is an organ. Name TWO organs located in the abdomen. (2)

b. i) When touching a hot kettle, a person immediately withdraws his hand. Receptors in the skin detect the stimulus and send a nerve impulse to the spinal cord. A nerve impulse then passes back to the effectors which bring about an immediate response. Name this immediate response. (1)

ii) Draw a well labelled diagram of a cross section of the spinal cord. In your diagram,clearly show the following labels:

Effectors, Stimulus, Sensory neurone, Motor neurone, Relay neurone Draw arrows to show the direction of the nerve impulse. (2, 5, 3)

(Total: 25 marks)

5. a. The diagram below shows a section through a flower at two stages in its development.

Figure 5.1: A cross section through an insect-pollinated flower at two different stages

a. i) List TWO features shown in the diagram which suggest that the flower is insect pollinated. (2)

ii) Cell division by meiosis takes place in the flower. Identify the TWO structures labelledin the diagram where meiosis takes place. (2)

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iii) What information shown in the diagrams would suggest that cross pollination takes placein this flower? (2)

iv) A sequence of events occurs during sexual reproduction in a self-pollinated floweringplant. Write a short paragraph to describe what happens from the time of cell division bymeiosis until the process of fertilization. (4)

b. i) Tomato seeds will germinate after passing through the digestive system of an animal.Give ONE advantage that tomato plants gain when their seeds are eaten and passedthrough the digestive system of an animal. (2)

ii) A student investigated germination in tomato seeds and wrote this conclusion:“Stems show negative geotropism whilst roots show positive geotropism.”

Explain this statement. (3) c. The diagram below shows a fruit.

Figure 5.2: A closed and an open fruit

i) From which parts of the flower have the fruit wall (pericarp), the seed and the partlabelled X developed? (3)

ii) Explain how the seeds of this fruit are dispersed. (2) d. The diagram below shows the human male reproductive organs.

A

B

Figure 5.3: The human male reproductive system

i) Name parts A and B. (2) ii) Name the organ through which semen is ejaculated out of the male body. (1) iii) During puberty, testosterone secretion leads to the growth of hair on the body. Describe

TWO other secondary characteristics, other than hair growth, that also develop duringpuberty in a male. (2)

(Total: 25 marks)

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6. The Citrus Tristeza virus attacks citrus trees. It may introduced into the citrus trees eitherthrough grafting or by aphids that are infected by the virus. There are several species of aphidsthat can infect citrus trees with the virus including the aphids Taxoptera citricida (Brown citrusaphid), Aphis spiraecola (Spirae aphid) and Taxoptera aurantii (Black citrus aphid).

a. i) Identify the TWO aphids that are closely related to each other. Give a reason for your answer. (3)

ii) Give ONE advantage of using the scientific name of an organism instead of its commonEnglish name. (2)

iii) Aphids can exist in two forms; winged or wingless. Winged forms develop when aphidnumbers are high in their habitat. Explain how this adaptation is of a benefit to theseorganisms. (2)

iv) A farmer finds aphids on the leaves of orange trees. The farmer sprays a specific mixtureof vegetable oil and detergent on the leaves instead of using a broad–range insecticide.Explain the choice made by the farmer. (2)

b. Both aphids and the Citrus Tristeza virus are considered to be parasites on citrus trees. TheCitrus Tristeza virus brings about stem pitting (open pores in stem), yellowing of leaves,smaller fruit yield, stunted growth and occasionally the death of the citrus trees. The virusreproduces in the phloem.i) Define the term parasite. (2)ii) Define the term tissue. (2) iii) Draw a well-labelled diagram of a virus. (4) iv) Indicate ONE reason why the infection of the virus causes a smaller fruit yield and

stunted growth. (3) c. Aphids, earwig, grasshoppers and snails feed on leaves of citrus trees. Earwigs feed also on

aphids and snails. Birds and mice feed on grasshoppers. Draw a food web of the above feedingrelationships. (5)

(Total: 25 marks)

7. A group of students studied the effects of sewage run-off into a local stream. The studentsobserved the changes in the levels of oxygen concentration, bacterial population and algae (algal)growth in the stream. Figure 7 below shows a graph showing the changes in these three factors.

Figure 7: Variation of oxygen concentration, algae population and bacterial population with distance down the stream http://www.hourlybook.com/wp-content/uploads/2015/02/403x286x162.png.pagespeed.ic.5-f4VPotvK.png

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a. Use the graph to describe the changes in:i) bacterial population; (3) ii) oxygen concentration from the point of sewage entry up to 12 km downstream. (2)

b. Explain how the change in oxygen concentration from 3 km to 6 km downstream may affectaquatic animals living in the area. (3)

c. i) Describe the relationship between the algae population and the oxygen concentrationbetween 2 km and 9 km of the stream. (2)

ii) Explain what might cause the algae population to decrease at 11 km downstream. (3) d. Ta’ Barkat sewage treatment plant uses biological treatments to clean sewage wastewater from

dissolved waste particles. Below is a flow chart showing how the plant works.

i) The sewage treatment plant uses both aerobic and anaerobic processes. Distinguishbetween an anaerobic process and an aerobic process. (2)

ii) In one chamber denitrifying bacteria are used for denitrification. Describe the role ofthese bacteria and name the gas produced by these bacteria. (2, 1)

iii) The sewage plant also breaks down solid waste filtered from sewage using bacteria toproduce methane gas (biogas). The gas is then used to generate electricity to work part ofthe plant. Use the statement to show why the production of methane is a means to reduceair pollution. (3)

e. Methane is a greenhouse gas.i) Name ONE other greenhouse gas. (1) ii) List THREE effects of greenhouse gases on the environment. (3)

(Total: 25 marks)


Mechanical filtration of waste. Large solid parts removed.

Flocculation.

Removal of particles by solidification.

Mechanical filtration of waste. Large solid parts removed.

Biogas produced.

Anaerobic digestion of solid particles.

Denitrification of solutes

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8. a. In an investigation on transpiration, a student used one stalk and leaf of the beet plant tomeasure the rate of water loss. The student determined the total surface area of the leaf and then calculated the rate of water loss per unit area. The student took readings as the conditions surrounding the leaf were changed. The following are the results taken by the students.

Table 8: Water loss from leaves of a beet plant placed in different environmental conditions

Treatment Water loss from leaves in arbitrary units1st reading 2nd reading 3rd reading 4th reading 5th reading

Room 5 5 5 5 5 Warm air 5 5 5 7 8 Fan 5 6 7 8 9

i) Describe the change in readings when the plant was first put in warm air and then near afan. Give ONE reason for each change. (2, 4)

ii) Explain the change in reading you would expect if the shoot and leaf were enclosed in abag. (3)

iii) Explain how gaseous exchange occurs in a leaf. (3) b. In a second investigation, the student set up the following apparatus to investigate the rate of

diffusion of a pigment from the vegetable beetroot. The student used cores of the beetroot andput each core in a beaker.

Beaker A Beaker B Figure 8: Beetroot placed in two beakers of water at different temperatures

The student observed the diffusion of the beetroot pigment in water and compared the different intensities of colour obtained under the naked eye. i) Define diffusion. (2) ii) Give the letter of the beaker where you would expect the most pigment to diffuse out of

the core. (1) iii) The pink pigment is stored in the vacuole of plant cells. Give ONE other function of

permanent vacuoles. (2) iv) The main storage carbohydrate in vegetable beetroot is sucrose. Describe the molecule of

sucrose. (2) c. The vegetable beetroot is a storage tap-root. This type of root system indicates that the plant is

a dicot.i) State how the leaves and the flowers of the beetroot plant will also indicate that the

beetroot plant is a dicot. (2) ii) Explain why the beetroot plant is expected to be larger than a moss plant. (2) iii) Explain why the sexual reproduction in a beetroot plant can occur in drier environments

than in ferns. (2)(Total: 25 marks)

Beetroot core

Water temperature at 20°C

Water temperature at 50°C

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Index Number:___________ SEC04/1.17s




SEPTEMBER 2017 SESSION

SUBJECT: Biology PAPER NUMBER: I DATE: 30th August 2017 TIME: 9:00 a.m. to 11:05 a.m.

Answer ALL questions in this paper in the spaces provided.

1. Name the part of the circulatory system described by each of the statements below.

a. Blood vessel that receives deoxygenated blood from the

whole body

b. Controls backflow of blood between the left atrium and the

left ventricle of the heart

c. Controls backflow of blood flowing into the aorta

d. Heart chamber that pumps blood with high pressure to the

whole body

e. Heart chamber that receives oxygenated blood from the lungs

f. Blood vessel that pumps oxygenated blood to the whole body

g. Carries blood rich in nutrients from the ileum to the liver

h. Light-coloured liquid carrying salts, hormones, nutrients and

metabolic waste

i. Blood components responsible for forming a scab to prevent

further loss of blood

j. Substance in red blood cells that carries oxygen

(Total: 10 marks)

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SEC04/1.17s DO NOT WRITE ABOVE THIS LINE

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2. a. Figure 2.1 and Figure 2.2 below show two local wild ferns.

Figure 2.1 Figure 2.2

i) List ONE common structural characteristic feature of these two plants.

(2)

ii) List TWO characteristic conditions of the habitat of these ferns.

2)

b. Explain the following statement:

Mosses are plants that typically have a very small size. Their structure limits their growth.

(2)

Maltese Polypody Polypodium vulgare

Maltese Maidenhair fern Adiantum capillus-veneris

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c. Figure 2.3 shows three fruits labelled A, B and C.

A B C

Figure 2.3 showing three fruits labelled A, B and C

List the fruit/s that use/s animal dispersal to spread the seeds they carry.

(1)

d. Name the structure of a seed that:

i) develops into a shoot; (1)

ii) is the main food source of the seed; (1)

iii) allows the entry of water in the seed. (1)(Total: 10 marks)


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3. Figures 3.1 and 3.2 below show two new insect species that have been discovered in 2016 and2017 respectively:

Ilomantis ginsburgae Neopalpa donaldtrumpi (Whole organism) (Head of organism)

Figure 3.1 Figure 3.2 (Photograph A: http://media3.s-nbcnews.com) (Photograph B: http://expatmedia.net)

a. Refer to Figure 3.1 and list TWO visible characteristics that show that Ilomantis ginsburgaeis an insect.

(2)

b. Name the phylum to which Ilomantis ginsburgae and Neopalpa donaldtrumpi belong.

(1)

c. Another moth belongs to the same genus as Neopalpa donaldtrumpi. The species name ofthis moth is neonata. Write the full scientific name of this moth.

(3)

d. Explain why, no fertile offspring will form, if a male Neopalpa donaldtrumpi moth is crossedwith a female moth of the neonata.

(2)

e. Neopalpa donaldtrumpi shows complete metamorphosis. List in the correct order the FOURstages in its life cycle.

(2) (Total: 10 marks)

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4. Distinguish between each of the following:

a. a Platyhelminth (flatworm) and an Annelid;

(2)

b. a community and a population of organisms;

(2)

c. the function of the duodenum and the ileum in the human body;

(2)

d. a herbivore and a carnivore in a food chain;

(2)

e. emulsification of fats and digestion of fats.

(2)(Total: 10 marks)


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5. Figure 5.1 below is a graph showing the relationship between the populations of a predator and aprey over a number of years.

Figure 5.1: Graph showing the relationship between the populations of a predator and a prey

a. Describe the population of the predator and the prey in the graph at point A and point B.

Prey population at A:

(1)

Predator population at B:

(1)

b. Give an example of a vertebrate predator and its invertebrate prey.

Vertebrate predator:

Invertebrate prey: (1)

c. Predators are important for the prey species. Give ONE reason for this statement.

(2)

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d. Give TWO reasons why the prey population tends to be higher than the predator populationin the given graph.

(2)

e. Name ONE adaptation for a successful prey.

(1)

f. A farmer sprayed fungicide on the area where these predators and prey live. After a month,she realised that the bodies of both dead predators and prey were taking longer to decompose.Give ONE reason for this observation.

(2)

(Total: 10 marks)


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6. Figure 6.1 below shows the apparatus setup to investigate the rate of enzyme-catalysed activityat different pH levels.

Figure 6.1: The apparatus used to investigate the effect of pH on enzyme-catalysed activity

The investigation was repeated 5 times with the potato catalase at different pH levels. The number of bubbles produced in 5 minutes was counted for each experiment. The results obtained are given in the table below.

pH level 2 4 7 9 11 No. of oxygen bubbles 8 15 34 21 12

Table 6.1: The number of oxygen bubbles produced in five minutes at different pH values

a. From the table of results, state the optimum pH for potato catalase. Give ONE reason foryour answer.

Optimum pH: (1)

Reason: (1)

b. Name ONE variable kept constant during this investigation.

(1)

c. The students who carried out the experiment presented the results as a graph. On the axis onpage 9:

i) label the y-axis and the x-axis; (2)

ii) sketch the expected shape of the graph for this experiment. (1)

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d. In this investigation, name:

i) the substrate; (1)

ii) the product. (1)

di. A student repeated the experiment and changed the substrate with another substance. No reaction occurred. Give ONE reason for this.

(1)

f. The student also boiled the enzyme before adding the substrate. Again no reaction occurred.Explain.

(2) (Total 11 marks)


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7. When Maria and Alex decided to conceive, the doctor told Maria to chart her basal bodytemperature at the same time every day, first thing before getting out of bed in the morning. Thiswill help her detect any small change in temperature. The day after ovulation, hormonal changescause the basal body temperature to rise by 0.4 to 1.0oC and this rise lasts till the nextmenstruation. Maria started menstruation on the 10th of March and recorded her temperatures asshown on Figure 7.1 below.

Figure 7.1: Maria’s basal body temperature between the 10th March and the 5th April

a. What was Maria’s body temperature on the:

i) 15th of March: (1)

ii) 22nd of March: (1)

b. The doctor told Maria to measure her basal body temperature at the same time every day, first thing before getting out of bed in the morning. Explain why this was important.

(1)

c. Use the graph to give the date when Maria is most likely to have her next menstruation.

(1)

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d. Ovulation is caused by the release of a hormone. Name this hormone and name the endocrine

gland that produces it.

Name of hormone: (1)

e. Name of endocrine gland: (1)

f. Physical changes that take place in a boy’s and girl’s body at puberty are controlled by

hormones.

State how hormones travel along the body.

(1)

f. After 21 weeks of pregnancy the couple was informed that they are expecting a boy. Maria isa carrier for colour-blindness. Alex has normal vision. Colour blindness is a sex-linked trait.

Using the letter B for normal and b for colour blindness, complete the genetic diagram toindicate the percentage probability that the child will be a boy with normal vision.

Parents’ phenotype Carrier mother Normal father

Parents’ genotype ________ ________

Gamete’s genotype

Offspring genotype _______ _______ _______ _______

Probability of child having normal vision: (4) (Total: 11 marks)


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8. a. Figure 8.1 below shows 5 different pyramids of numbers A – E.

Figure 8.1: Five different pyramids of numbers

In the table below, write the letter of the pyramid that best matches the description of feeding relationships of different organisms. Each letter is to be used only once.

Description Letter of pyramid

Fruit eating birds feed on fruit of a berry tree. Many lice suck up blood

from the fruit eating birds. Several fungi live on lice.

Many caterpillars feed on a single ash tree. The caterpillars are eaten by

robins. Owls eat robins.

Water fleas feed on algae. Stickleback (fish) feed on water fleas. Pike

(fish) eat sticklebacks.

Cattle feed on grass. Ticks suck up blood from the cattle. Egrets (birds)

snatch ticks from the cattle backs.

Rabbits eat grass. The fox hunts the rabbit. Ear mites infect the fox.

(5)

b. Explain why a pyramid of biomass is a more accurate representation of the transfer of energyin an ecosystem rather than a pyramid of numbers.

(2)

A B C

E D

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c. Give THREE reasons why only about 10% of the energy is transferred from one trophiclevel to another in an ecosystem.

Reason 1:

Reason 2:

Reason 3:

(3)

(Total: 10 marks) 9. Soil erosion is a natural phenomenon. Misuse of resources of land, water and soil lead to a faster

rate of soil erosion. Today, this is one of the most difficult and pressing problems for humans.

a. Describe the process of soil erosion.

(2)

b. List TWO natural causes of soil erosion.

(2)

Contour farming is an important agricultural practice which reduces soil erosion in cultivated lands.

c. i) Describe the agricultural practice known as contour farming.

(2)

ii) State ONE other benefit of contour farming besides the reduction of soil erosion.

(1)

This question continues on the next page.

Page 13 of 16

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d. Crop rotation is another important agricultural practice. It involves varying the crops planted in the same field. State THREE purposes of crop rotation.

Purpose 1:

Purpose 2:

Purpose 3:


10. The pancreas and the liver help to keep the concentration of glucose in the blood within anarrow, normal range.

a. Table 10.1 shows how blood glucose concentration varies in a healthy young adult between7.00 and 15.00.

Table 10.1: The changes in blood glucose level in mg/100ml between 07.00 and 15.00

Time Blood glucose level in mg/100ml 07.00 80 08.00 120 09.00 90 10.00 78 11.00 100 12.00 80 13.00 125 14.00 100 15.00 90

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Plot a graph to show the changes in blood glucose levels during a period of eight hours. Plot time on the x-axis and blood glucose level on the y-axis. Use a ruler to join the points. (6)

b. Give ONE reason why the blood glucose level increased between 12.00 and 13.00.

(1)

c. Name the hormone that causes a decrease in blood glucose level.


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SEC04/2B.17s




SEPTEMBER 2017 SESSION

SUBJECT: Biology PAPER NUMBER: IIB DATE: 30th August 2017 TIME: 4:00 p.m. to 6:05 p.m.

Write your answers on the booklet provided. Write down the number of the questions you answer, on the front page of your answer booklet.

Answer any FOUR questions.

1. Karl maintains his body healthy by following a balanced diet. He decided to eat some salmon,accompanied by potatoes and carrots covered with a cheesy sauce.

a. Define the term balanced diet. (1)

b. i) Humans use teeth to breakdown food into smaller pieces. Give TWO reasons why this processis important during digestion. (2)

ii) Salivary glands in the mouth secrete the digestive juice saliva. Name the enzyme found insaliva, the substance it acts upon and the product formed. (3)

iii) Give ONE reason why the pancreas releases the same enzyme released from the salivaryglands when the partially digested food reaches the duodenum. (2)

c. As food is swallowed, it slides down the larynx into the oesophagus. At the same time, the bolus(food) is prevented from entering the trachea.i) Describe how the food is prevented from entering the trachea. (2) ii) Give TWO differences between the trachea and the oesophagus. (2) iii) Describe how the bolus moves down the oesophagus. (2)

d. Pepsinogen is released in the stomach. Pepsinogen is the inactive form of pepsin.i) Explain why the cells lining the stomach release the inactive form of pepsin. (2) ii) Pepsinogen has some extra amino acids that block the active site of pepsin. Explain how this

makes pepsinogen inactive. (2)

e. Karl believes that salmon has a high amount of proteins. Describe a test he could do to confirmwhether protein was present in salmon. (2)

f. Digestion of all large molecules ends in the small intestine. Describe how fats are broken down.In your account, include the following terms: bile, fatty acids, large globules, lipase, glycerol,small globules, liver and gall bladder. (5)

(Total: 25 marks)

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2. Students carried out an experiment to investigate whether carbon dioxide is necessary for a plantto carry out photosynthesis. Figure 2.1 below shows how they set up the apparatus. They poureda small quantity of soda lime in a glass bottle fitted with a split cork. After de-starching the plant,one of its leaves was placed inside the bottle such that half of the leaf remained inside the bottleand the other half was outside. After checking that all connections were air-tight with Vaseline,the setup was placed in direct sunlight for about four hours.

Figure 2.1: Apparatus set-up to investigate whether carbon dioxide is necessary for photosynthesis

a. Explain why:i) the plant was de-starched before starting the experiment; (2) ii) all connections were air-tight with Vaseline; (2) iii) soda lime was placed in the glass bottle. (2)

b. After four hours, students tested the leaf under investigation for the presence of starch. List thesteps involved in this test. (4)

c. Describe the observations made when testing the leaf under investigation for starch. (4)

d. A plant was kept in light for the first 16 hours of the experiment and in dark for the last eighthours. The graph in Figure 2.2 shows how the concentration of starch varied in a plant over aperiod of 24 hours.

Figure 2.2: Graph showing variation of starch concentration in a plant over a period of 24 hours

soda lime

S

bottle

leaf under investigation

split cork

potted plant

Sta

rch

conc

entr

atio

n / a

.u.

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i) Explain why the concentration of starch increased during the first 16 hours of the experiment.(3)

ii) Explain why the concentration of starch decreased during the last eight hours of theexperiment. (1)

e. An experiment was carried out to investigate the effect of translocation of the products ofphotosynthesis towards fruits growing on a tree. A ring of phloem tissue was removed from partof the stem bearing 3 fruits, labelled A, B and C as shown in Figure 2.3.

Figure 2.3: A stem bearing three fruits and showing the position where phloem was removed.

The diameter of the three fruits was measured every week for three weeks. i) Name the carbohydrate that is translocated in phloem. (1) ii) Write the letter/s of the fruit/s that will show a decrease in diameter after three weeks.

Explain your answer. (3)

f. The plants used in both experiments were dicots. List THREE characteristics that these plantsshare. (3)

(Total: 25 marks)

3. The production of wine depends on the process of anaerobic respiration in yeast.

a. i) State the kingdom in which yeast is classified and name ONE other organism that belongs tothis kingdom. (2)

ii) State if yeast cells are eukaryotic or prokaryotic. Give a reason for your answer. (2) iii) Yeast cells are surrounded by a cell wall. State how this cell wall is different from that in

plant cells. (2)

b. Write TWO word equations to distinguish between aerobic and anaerobic respiration in yeast cells. (4)

c. Anaerobic respiration occurs in humans during vigorous exercise.i) Name the compound formed when humans perform anaerobic respiration. (1) ii) Give TWO reasons why vigorous exercise leads to lack of oxygen and therefore anaerobic

respiration in humans. (4)

Position where phloem was removed

A B

C

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d. Give ONE reason in each case for the following observations:i) during the fermentation of wine, temperature is kept at about 30oC; (2) ii) at the end of the fermentation process, all yeast cells are dead; (2) iii) fermentation is not allowed to be completed in the production of sweeter wines. (2)

e. A student was asked to perform Benedict’s test to determine if there was reducing sugar in sweetwhite wine.i) Describe the expected result if reducing sugar is present and the expected result if reducing

sugar is absent in the sweet white wine. (2)ii) Explain why it is difficult to interpret results if Benedict’s test is performed on red wine. (2)

(Total: 25 marks)

4. Water is possibly the most important molecule on planet Earth as life started in it. Water isessential for the survival of all living organisms.

a. Name the elements present in water. (2)

b. Draw a diagram to draw the water cycle. In your diagram, include the following labels:evaporation, condensation, precipitation and collection (or accumulation). (4)

c. State how the following properties of water are important for living organisms:i) water is a transparent liquid; (2)ii) water is a liquid at room temperature; (2) iii) several substances dissolve in water; (2) iv) water flows easily through narrow tubes. (2)

d. Terrestrial organisms have developed different methods to reduce water loss.i) List THREE ways how plants are adapted to reduce water loss. (3) ii) List TWO ways how insects are adapted to reduce water loss. (2)

e. Humans control the amount of water in their blood by changing the concentration of urine. Thenephrons in the kidney play an important role in this. Describe how the nephron re-absorbs waterfrom the filtrate before urine is removed from the body. (2)

f. State how the amount of water re-absorbed from the nephron to the blood varies in the followingsituations and give a reason for your answer:i) when a person drinks one litre of water; (2) ii) when a person has not drank any water for four hours. (2)

(Total: 25 marks)

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5. In January 2017, Malta introduced a law against smoking in cars carrying passengers under theage of 18.

a. Give TWO ways how this law is safeguarding the health of passengers in the car. (3)

b. Nicotine is a harmful chemical in cigarette smoke. Explain how this chemical may affect thesmoker’s health. (2)

c. Carbon monoxide is a poisonous gas also found in cigarette smoke.i) Describe the effect of carbon monoxide on haemoglobin. (2) ii) Explain how this leads the smoker to become breathless. (2)

d. List in the correct order the pathway of air from when it enters the nose till the time it reaches thealveoli. (3)

e. Figure 5.1 below shows an alveolus from a human lung.

Figure 5.1: An alveolus

i) Name gas X and blood vessel Y. (2) ii) List THREE adaptations that enable alveoli to perform their function efficiently. (3)

f. Gaseous exchange occurs by diffusion.i) Define the term diffusion. (2) ii) Explain why diffusion is a passive process. (1) iii) State TWO ways how active transport is different from diffusion. (2)

g. Apple snails have a gas exchange system that includes both a gill and a lung. Apple snails live intropical waters which dry up in certain periods of the year.i) Name the phylum that apple snails belong to. (1) ii) Give ONE advantage that the presence of both a gill and a lung give to apple snails. (2)

(Total: 25 marks)

Deoxygenated blood from blood vessel Y

Oxygenated blood going back to the heart

Alveolus

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6. Vertebrate groups have several distinguishing characteristics. The type of body covering can beused to distinguish amongst the different groups.

a. List the FIVE different vertebrate groups and describe the body covering of each group. Presentyour answer in table format. (10)

b. Explain why the frogs and toads need to keep their body covering constantly wet. (2)

c. Figure 6.1 shows a section through the human skin.

Figure 6.1: A section through the human skin

i) Refer to structures shown in Figure 6.1, and describe THREE ways how a person mayreduce his/her body temperature from 37.9 °C to 37.5 °C. (6)

ii) State how the fatty tissue beneath the dermis helps humans to maintain a constant bodytemperature. (2)

d. Special neurons in the skin detect temperature changes in the external environment and send thisinformation to the central nervous system. State whether the neurons in the skin are sensory ormotor neurons. Give ONE reason for your choice. (3)

e. Polar bears live mainly in Alaska, spending most of their time on the ice or hunting in water.Explain how a polar bear’s body covering helps keep it warm whilst standing on the ice but it isless effective when it is swimming. (2)

(Total: 25 marks)

7. Amoeba and Euglena are two unicellular Protists. Amoeba is an animal-like Protist whilst Euglenais a plant-like Protist.

a. Distinguish between unicellular and multicellular organisms. (2)

b. Plant-like Protists show autotrophic nutrition whilst animal-like Protists show heterotrophicnutrition. Distinguish between autotrophic and heterotrophic nutrition. (2)

c. Euglena have flagella and an eye spot. The eye spot is sensitive to light.i) Explain how the flagellum in Euglena is linked with autotrophic nutrition. (2) ii) Explain how the eyespot in the Euglena is linked with autotrophic nutrition. (2)

Dermis

Epidermis

Fatty tissue

Follicle

Sweat gland

Blood vessel

Nerve

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d. Unlike Euglena, Amoeba shows heterotrophic nutrition. Using diagrams, describe how theAmoeba feeds. (3)

e. Figure 7.1 shows an Amoeba placed in a beaker of fresh water.

Diagram not in correct proportion Figure 7.1: An Amoeba in a beaker of fresh water

i) Copy the diagram above and on it show the direction of the flow of water as a result ofosmosis. Give a reason for your answer. (3)

ii) Define the term osmosis. (3) iii) The Amoeba has a contractile vacuole. Explain why the contractile vacuole allows the

Amoeba to survive when placed in fresh water. (3) iv) Give ONE reason why the Amoeba died when it was placed in salty water. (2)

f. Mixotricha paradoxa is a Protist that lives in the intestines of the termite (ant) speciesMastotermes darwiniensis. This Protist breaks down cellulose in wood eaten by the termite.Without the presence of Mixotricha, the termite dies.i) Name the association between the termite and the Protist. (1) ii) Give ONE reason why the termite dies if Mixotricha is not present in its intestines. (2)

(Total: 25 marks)

8. a. Man-made Chlorofluorocarbons (CFCs) are the main cause of depletion of ozone in the

stratosphere which has several effects. Give ONE positive effect and TWO negative effects ofozone depletion. (3)

b. In a fish farm, a large number of fish are grown in cages in the sea. Suggest TWO reasons whyfish in the cages grow faster than fish of the same species that are free in the sea. (4)

c. 90% of fish stocks (populations) in the Mediterranean Sea are ‘overfished’. Countries in the

Mediterranean are asked to ensure sustainable fishing, that is, they make sure that fishing allowsthe recovery of the fish stocks. The UN Food and Agriculture Organisation says that fish stockscontinue to decrease around the world despite increasing efforts to control catches. State TWOways how sustainable fishing may be ensured. (4)

d. The red spider mite is a pest on fruit trees. It increases in numbers quickly causing damage to thefruit crop.Different predatory mite species exist which feed on red spider mites. When the number of redspider mites was about 1000 per fruit tree, the farmer researched the use of predatory mites on thefruit trees.

Fresh water

Amoeba

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In his research the farmer read the following: Phytoseiulus persimilis is the most commonly used predatory mite to control the red spider mite. It is now widely used in preference to pesticides. Phytoseiulus feed on all life stages of glasshouse red spider mite.

Amblyseius californicus is another predatory mite used to control the red spider mite. Unlike Phytoseiulus, Amblyseius is a predator of various species of spider mite, and can also feed and reproduce on pollen.

i) Name the type of pest control that the farmer is researching and give ONE reason why thistype of pest control ‘is now widely used in preference to pesticides.’ (3)

ii) Describe how the introduction of the predatory mites affects the number of red spider mites.(1)

iii) After nine weeks of introducing the predatory mite Amblyseius, the farmer noticed thatalthough there were no more red spider mites there were still predatory mites present on thefruit trees. Explain how this could lead to other problems for the farmer. (3)

iv) The farmer still preferred to use Amblyseius instead of Phytoseiulus as a predatory mite. Usethe information from the paragraphs above, to give ONE reason why the farmer preferredAmblyseius. (2)

e. Figure 8.1 shows four different Arachnid species labelled A - D. Use the key to identify each oneof them.

A B C D Figure 8.1: Four different Arachnid species

Pincers present Go to 2 Pincers absent Tick

No tail attached to abdomen Pseudoscorpion Tail attached to abdomen Go to 3

Sting visible at tip of tail Scorpion Sting not visible at tip of tail Whip scorpion (4)

f. Red spider mites are also arachnids. Give ONE feature that would show it is an Arachnid. (1) (Total: 25 marks)

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