2015.2 L.37-38 ms -16 ha-final -...

2014 L.37/38_MS 2/64 Page 2 of 64

L.37/38

Pre-Leaving Certificate Examination, 2015

Biology

Marking Scheme

Ordinary Pg. 4 Higher Pg. 33

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Biology

Ordinary & Higher Level

Table of Contents

Ordinary Level Higher Level Section A Section A

Q.1 .................................................. 04 Q.1 .................................................. 33

Q.2 .................................................. 06 Q.2 .................................................. 35

Q.3 .................................................. 07 Q.3 .................................................. 36

Q.4 .................................................. 08 Q.4 .................................................. 37

Q.5 .................................................. 09 Q.5 .................................................. 38

Q.6 .................................................. 10 Q.6 .................................................. 39

Section B Section B Q.7 .................................................. 11 Q.7 .................................................. 40

Q.8 .................................................. 13 Q.8 .................................................. 42

Q.9 .................................................. 14 Q.9 .................................................. 44

Section C Section C Q.10 .................................................. 15 Q.10 .................................................. 46

Q.11 .................................................. 19 Q.11 .................................................. 49

Q.12 .................................................. 21 Q.12 .................................................. 51

Q.13 .................................................. 23 Q.13 .................................................. 54

Q.14 .................................................. 26 Q.14 .................................................. 57

Q.15 .................................................. 29 Q.15 .................................................. 61

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Biology

Ordinary & Higher Level

Explanation

1. A dash – before an answer indicates that the answer is a separate answer, which may be

considered as independent of any other suggested answers to the question. 2. A single forward slash / before an answer indicates that the answer is synonymous with that

which preceded it. Answers separated by a forward slash cannot therefore be taken as different answers.

3. A double forward slash // is used to indicate where multiple answers are given but not all

are required. 4. Round brackets ( ) indicate material which is not considered to be essential in order to gain

full marks. 5. ‘etc.’ is used in this marking scheme to indicate that other answers may be acceptable. In all other cases, only the answer given or ‘words to that effect’ may be awarded marks. 6. Answers which are given in this marking scheme should not be considered as the only possible

answers that may be accepted. Answers which are synonymous with or equivalent to those in this marking scheme are also acceptable.

7. Marks for diagrams are shown as follows (e.g. 0m, 3m, 6m), where 0m indicates the lowest possible

and 6m the highest.

Current Marking Scheme Assumptions about these marking schemes on the basis of past SEC marking schemes should be

avoided. While the underlying assessment principles remain the same, the exact details of the marking of a particular type of question may vary from a similar question asked by the SEC in previous years in accordance with the contribution of that question to the overall examination in the current year. In setting these marking schemes, we have strived to determine how best to ensure the fair and accurate assessment of students’ work and to ensure consistency in the standard of assessment from year to year. Therefore, aspects of the structure, detail and application of the marking schemes for these examinations are subject to change from past SEC marking schemes and from one year to the next without notice.

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Biology

Ordinary Level Marking Scheme (400 marks)

Section A (5 × 20m) (100) 1. Answer any five of the following parts (a) to (f): (5 × 4m) (20) (a) A solution used to test for the presence of protein is – biuret reagent (b) An element required in the diet for strong bones and teeth is – calcium / Ca (c) A food that is a good source of carbohydrate in the diet is Any 1: – bread // – rice // – potatoes // – sugar // – fruits // – cakes // – sweets // etc. ** Accept other appropriate answers. (d) An example of a water-soluble vitamin is Any 1: – vitamin C // – vitamin B ** Accept correct scientific names. (e) What term is used to describe the sum of all the chemical reactions in the human body? – metabolism

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(f) Give one function of fat in the human body. Any 1: – provides insulation // – stores energy // – stores vitamins // – forms membranes // – provides energy // etc. ** Do not accept ‘supplies heat’.

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2. Choose each term from the following list and place it in Column B to match a description in Column A.

The first one has been completed as an example. (5 × 4m) (20) List: Habitat; Producers; Ecosystem; Niche; Biosphere; Predators.

Column A Column B

A place where organisms live. Habitat

(a) Organisms that make their own food. – producers

(b) The role of an organism in an ecosystem. – niche

(c) All places on the Earth and its atmosphere where life exists. – biosphere

(d) Organisms which kill and eat other organisms for food. – predators

(e) The position or feeding level of an organism in a food chain. – trophic level

(a) – producers (b) – niche (c) – biosphere (d) – predators (e) – trophic level

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3. (a) What is an enzyme? (2 × 2m) (20) – a biological / protein / organic that – speeds up a reaction without being used in it / catalyst (b) Where in the cell are enzymes produced? (4m) – ribosomes (c) You came across and used some enzymes during the course of your practical investigations. 1. Name an enzyme you have studied. Any 1: (4m) – amylase // – catalase // – pepsin // – lipase // etc. ** Accept other appropriate answers. 2. Name a substrate it reacts with. Any 1: (4m) ** Substrate should correspond to the enzyme named. amylase – starch // catalase – hydrogen peroxide // pepsin – protein // lipase – lipids ** Accept other appropriate answers. (d) Name one factor which affects the rate of activity of an enzyme. Any 1: (4m) – temperature // – pH // – enzyme concentration // – substrate concentration

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4. Use your knowledge of genetics to complete the following sentences: (5 × 4m) (20) (a) Genetics is the study of inheritance / hereditary characteristics / chromosomes / DNA . (b) In DNA, the bases guanine and cytosine always pair together. ** Accept use of ‘C’, the first letter of base for full marks. (c) The genetic make-up of an individual is called its genotype . (d) Cells having two identical alleles can be described as being homozygous . (e) If an animal cell has a diploid number of 24, its haploid number is 12 .

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5. Indicate whether the following statements are true (T) or false (F) by drawing a circle around T or F in each case. (6 × 3m + 2m) (20)

Example: Photosynthesis is the process by which plants make food. T F

(a) Mitosis takes place in the meristem tissue of plants. T F

(b) Water is absorbed through the leaves of plants. T F

(c) The term transpiration refers to the loss of water from the leaves of plants. T F

(d) Yeast reproduces by budding. T F

(e) Athlete’s foot, ringworm and thrush are all human diseases caused by fungi.

T F

(f) An onion is a modified leaf. T F

(g) Phototropism is the growth response of plants to gravity. T F

(a) – true (b) – false (c) – true (d) – true (e) – true (f) – true (g) – false

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6. The diagram shows a section through a human heart. (20) (a) Give the exact location of the heart in the human body. Any 1: (3m) – behind the ribs // – in the thorax // – in the chest cavity (b) Name the parts labelled A and D. (2 × 3m) A – pulmonary artery D – right atrium (c) What is the function of the septum? Any 1: (3m) – to separate the left and right chambers of the heart // – to separate oxygenated blood from deoxygenated blood ** Accept other appropriate answers. (d) Why is the wall of chamber B thicker than the wall of chamber C? (3m) – it has to pump blood further around the body ** Accept other appropriate answers. (e) State two factors which could increase heart rate. Any 2: (3m + 2m) – exercise // – infection // – anxiety / stress // – drugs // etc. ** Accept other appropriate answers.

B

C

D

A

Right-handside

SeptumLeft-hand

side

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Section B (2 × 30m) (60) 7. (a) (i) Name the kingdom to which yeast belongs. (3m) (6) – Fungi (ii) Name another organism which belongs to this kingdom. Any 1: (3m) – mushrooms // – Rhizopus // – mould // – mildew // etc. ** Accept other appropriate examples. (b) Answer the following questions in relation to an activity you carried out to investigate the

growth of leaf yeasts. (24) (i) From what plant did you obtain the yeast? Any 1: (3m) – privet // – ash // – sycamore // etc. (ii) What type of container did you use to grow the leaf yeast? (3m) – petri dish (iii) What is the function of the nutrient agar in this investigation? Any 1: (3m) – to provide food // – to provide nutrients // – to provide energy // – to act as a growth medium // etc. (iv) Describe the steps you followed to put the leaf yeast into the container containing the nutrient agar. Any 3: (3 × 3m) – sterilised tweezers / equipment // – how sterilised // – cut leaves // – how cut // – used Blu-Tack / vaseline // – on lid // – underside of leaf faced downwards // – seal dish // – any named safety precaution // etc.

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(v) How long did it take for the leaf yeast to appear? (3m) – 2 - 7 days (vi) Describe the appearance of the leaf yeast which grew in the containers. (3m) – pink / red spots / colonies (circles)

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8. (a) Give two differences between a plant cell and an animal cell. (6) Any 2: (2 × 3m) Plant cells Animal cells – have chloroplasts // – no chloroplasts // – have cell walls // – no cell walls // – have large vacuoles // – no (or small, if any) vacuoles // – contain chlorophyll // – no chlorophyll (b) Answer the following questions in relation to the preparation of a slide of stained animal cells

for viewing under a light microscope. (24) (i) Name the animal cell that you used. Any 1: (3m) – cheek cells // etc. ** Accept other appropriate answers. (ii) Describe how you obtained a sample of the cells and prepared it for examination. Any 3: (3 × 3m) – rub mouth // – with a cotton bud / lollipop stick / other reasonable answer // – spread thinly // – onto a glass slide // – add stain // – leave for a few minutes // – add a coverslip // – at an angle to prevent air bubbles // – any safety precaution named // etc. ** Accept other appropriate answers. (iii) Name the stain that you used on the cells. (3m) – methylene blue ** Accept ‘iodine’ for full marks. (iv) Describe how you applied the stain. Any 1: (3m) – with a dropper // – using a tissue to draw stain under the cover slip // etc. ** Accept other appropriate answers. (v) Which objective lens should you use first when using the microscope? (3m) – 4× / lowest power lens (vi) The objective lenses in the microscope in a school laboratory are usually labelled 40×,

10× and 4×. If the magnification of the eyepiece lens is 10× and the objective lens is 40× what is the total magnification of the microscope? (3m)

– 400×

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9. (a) (i) In ecology, what is meant by the term quantitative survey? (3m) (6) – number / amount / how many organisms / species / communities (ii) What is a quadrat frame? (3m) – a (framed) square (or unit) area / square frame ** Allow a diagram. (b) For what purpose did you use each of the following in the course of your practical work? (24) (i) Iodine. Any 1: (3m) – to test for starch // – to stain cells // etc. (ii) Buffer solution. (3m) – to keep pH constant (iii) Sodium chloride (salt) solution. (3m) – to isolate DNA / cause DNA to clump (iv) Elodea (pond weed). (3m) – to investigate the effect of light intensity of carbon dioxide levels on the rate of photosynthesis (v) Sodium alginate. (3m) – to immobilise enzymes (or yeast cells) / make beads (vi) Limewater. (3m) – to test for carbon dioxide (vii) Visking tubing. Any 1: (3m) – to demonstrate osmosis // – to show the movement of water molecules (viii) Scalpel. Any 1: (3m) – to cut dicot stems // – to dissect a heart // etc. ** Accept other appropriate answers.

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Section C (4 × 60m) (240) 10. (a) (i) Distinguish between biotic and abiotic factors by writing a sentence about each. (9) biotic (3m) – the living factors in an ecosystem abiotic (3m) – the non-living factors in an ecosystem (ii) An edaphic factor is an example of an abiotic factor. What is an edaphic factor? (3m) – a factor relating to soil, e.g. soil pH, moisture level, air content,

mineral content, etc. (b) (i) Name an ecosystem you have studied. (27) Any 1: (3m) – hedgerow // – stream // – rock pool // – rocky seashore // – old wall // etc. – small woodland or grove // – meadow // – freshwater pond // – waste land // – an overgrown garden // – soil // – peatland // – grassland // etc. ** Accept other appropriate answers. (ii) List one plant and one animal that are normally present in this ecosystem. ** Plant and animal should correspond to ecosystem named. Plant Any 1: (3m) - woodland – oak tree // – beech tree // – bluebell // – snowdrop // – foxglove // – honeysuckle // – fern // – moss // etc.

Further answers overleaf

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Animal Any 1: (3m) - woodland – mouse // – fox // – badger // – hedgehog // – weasel // – owl // – squirrel // – deer // etc. ** Accept other appropriate answers. (iii) In the case of a named plant or animal, explain how it has adapted to living in this ecosystem. ** Adaptation should correspond to plant or animal named. Any 1: (3m) - badger – sharp claws for digging roots // - owl – large eyes for better night vision // - deer – camouflage coat to blend into woodland / evade predators // - moss – ability to absorb / store large amounts of water // - oak tree – long roots for stability / finding water // ** Accept other appropriate named examples. (iv) Explain how plants depend on animals for survival in your chosen ecosystem. Any 1: (3m) – transferring pollen // – allows fertilisation // – spreads seeds // – provides nutrients for soil // etc. ** Accept other appropriate named examples. (v) Describe how you would carry out a quantitative study to estimate the population of a particular plant in your chosen ecosystem. Any 3: (3 × 3m) – mark boundaries of the ecosystem // – choose a sample area or transect (line or belt) // – quadrat // – random throw along transect // – 10 - 20 times or at stations // – count or observe // – method of recording data // – calculate percentage cover / frequency / density // – calculation = number of times present divided by the number of quadrats // – presentation of results // etc.

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(vi) Name two pieces of apparatus that could be used to collect animals in an ecosystem. Any 2: (2m + 1m) – pooter // – pitfall trap // – net // – beating tray // – sweep net // – plankton net // – Tullgren funnel // – Baermann funnel // – mammal trap // – cryptozoic trap // etc. (c) The diagram shows a food web. (24)

Hawk

Leaves

Spider

Ladybird

CaterpillarGreenfly

ThrushBlackbird

Snail

(i) Why are the leaves in this food web called autotrophs? (3m) – they make their own food (ii) Name one example of each of the following from the food web: 1. Primary consumer. Any 1: (3m) – greenfly // – snail // – caterpillar 2. Secondary consumer. Any 1: (3m) – ladybird // – blackbird // – thrush


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(iii) Using the food web above, construct a food chain which has at least three feeding levels.

** Food chain must start with a producer. ** Award (3m) if food chain constructed starting with a producer without reference to the food web. Any 1: (3 × 3m) – leaves → caterpillar → thrush → hawk // – leaves → snail → blackbird → hawk // – leaves → caterpillar → blackbird → hawk // – leaves → greenfly → ladybird → spider → blackbird → hawk // etc. (iv) Identify the top consumer from the food web. (3m) – hawk (v) Energy passes along the food chain from one organism to another. What happens to

this energy between each trophic level? (3m) – it is lost (as heat)

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11. (a) Natural selection is an important part of evolution. (9) (i) What is natural selection? Any 1: (3m) – survival of the fittest // – those best adapted will survive // – the mechanism by which evolution occurs (ii) Name a scientist who is associated with the Theory of Natural Selection. Any 1: (3m) – (Charles) Darwin // – (Alfred) Wallace (iii) Mutations are changes in the structure or amount of DNA. Give one cause of mutations. Any 1: (3m) – radiation // – chemicals // etc. ** Accept any relevant example. (b) (i) What is meant by DNA profiling? (2 × 3m) (27) – making / preparing / revealing a unique pattern of bands from the DNA

of a person – which can then be used to compare / distinguish that DNA from other DNA, etc. (ii) In DNA profiling what is used to cut the DNA strands into fragments? (3m) – enzymes (iii) On what basis are the fragments separated? Any 1: (3m) – by size // – by weight // – by mass // – by gel electrophoresis (iv) Give two applications (uses) of DNA profiling. Any 2: (2 × 3m) – forensic / crime scene// – medicine // – paternity / maternity // – archaeology // – taxonomy // – evolutionary biology // etc.


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(v) As part of your practical activities you isolated DNA from a plant tissue. Answer the following questions in relation to this activity: 1. What plant did you use to obtain the tissue? Any 1: (3m) – onion // – kiwi // etc. ** Accept any appropriate answers. 2. What is the function of washing up liquid? (3m) – to break down / disrupt cell membranes 3. What is the function of ice cold ethanol? (3m) – to separate the DNA (c) In humans, the allele for brown eyes (B) is dominant to the allele for blue eyes (b). Two

parents, one heterozygous for eye colour and the other with blue eyes, start a family. (24) (i) What are the genotypes of the parents? Parents’ genotypes: Bb × bb (2 × 3m) (ii) Using a Punnett square or otherwise, work out the possible genotypes and phenotypes

of their children.

b b

Offspring: B Bb Bb

b bb bb

Offspring phenotypes and genotypes: – Bb = – brown eyes (2 × 3m) – bb = – blue eyes (2 × 3m) (iii) If the brown-eyed parent was homozygous for brown eyes, what percentage of the

offspring would have: 1. Brown eyes? (3m) – 100% 2. Blue eyes? (3m) – 0%

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12. (a) (i) Write a balanced equation for photosynthesis. (2 × 3m) (9) – 6CO2 + 6H2O → C6H12O6 + 6O2

** Left hand side correct (3m). ** Right hand side correct (3m). (ii) From where does the energy for photosynthesis come? (3m) – the sun (b) (i) If photosynthesis did not take place, life on Earth would eventually cease to exist. List three ways in which photosynthesis is of importance to life on Earth. (27) Any 3: (3 × 3m) – plants are producers / make food for themselves and animals // – animal eat plants / animals eat other animals which ate the plants // – produces oxygen // – uses carbon dioxide // – reduces the greenhouse effect // – forms fossil fuels // etc.

** Accept other appropriate answers. (ii) As part of your practical activities you investigated the effect of light intensity or carbon

dioxide concentration on the rate of photosynthesis. Answer the following questions in relation to this activity:

1. Draw and label the apparatus you used. Diagram (0m, 3m, 6m) Labels Any 3: (3 × 1m) – plant // – variable // – container // etc. 2. How did you know that the plant was undergoing photosynthesis? (3m) – bubbles were visible


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3. The graph below was drawn using your results, but it has not been completed. Copy this graph into your answer book and complete it.

Axes labelled (3m) Graph completed (3m) (c) (i) Plants contain a green pigment called chlorophyll. What is the function of chlorophyll

in photosynthesis? (24) Any 1: (3m) – to absorb light // – to convert light energy into chemical energy (ii) Name the part of a plant cell where chlorophyll is found. (3m) – chloroplast (iii) During photosynthesis, water is split into three products. Name each of these products. (3 × 3m) – oxygen / O2

– proton / H+ – electron / e– (iv) Describe what happens to each of the products you have named in (iii). - oxygen / O2 Any 1: (3m) – forms water / H2O // – releases electrons // – released from the leaf - proton / H+ Any 1: (3m) – used in dark stage // – goes to the proton pool // – used in pathway 2 - electron / e– Any 1: (3m) – goes to chlorophyll // – makes energy / ATP // – to reduce CO2

CO2 concentrationLight intensity or

Rat

e of

pho

tosy

nthe

sis

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13. (a) (i) Explain the term secondary sexual characteristics. (3m) (9) – features developing at puberty which are not directly involved in reproduction (ii) Give one example of a secondary sexual characteristic in a human male and one

example of a secondary sexual characteristic in a human female. Secondary sexual characteristics in human male Any 1: (3m) – facial hair // – deeper voice // – enlargement of larynx // – broader shoulders // – pubic hair // – enlargement of genitals // – increase muscle // etc. Secondary sexual characteristics in human female Any 1: (3m) – enlargement of breasts // – growth of pubic hair // – increased body fat // – widening of pelvis // etc.

** Accept other appropriate answers. (b) (i) Draw a large labelled diagram of the human female reproductive system. (27) Diagram (0m, 3m, 6m) Labels Any 3: (3 × 2m) – vagina // – cervix // – fallopian tube // – uterus // – ovary // etc. (ii) Indicate clearly on your diagram where each of the following events takes place: 1. Ovulation. (3m) – shown on ovary 2. Fertilisation. (3m) – shown on fallopian tube 3. Implantation. (3m) – shown on lining of uterus


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(iii) What is the menstrual cycle? Any 1: (3m) – monthly cycle in female // – lining of uterus is shed // – blood is discharged ** Accept other appropriate explanations. (iv) How long does it take to complete one menstrual cycle? (3m) – 28 days (c) The diagram shows a human sperm. (24)

A

B

CMidpiece (i) Name the parts labelled A, B and C. (3 × 2m) A – tail B – head C – nucleus (ii) In what organ of the body is sperm produced? (3m) – testis / testes (iii) What is meant by the term infertility? Any 1: (3m) – the inability to produce / release gametes // – the inability to fertilise gametes // – the inability to conceive or have offspring (iv) State one cause of male infertility and give a possible treatment for it. Cause of male infertility Any 1: (3m) – low sperm count // – low sperm motility // – hormonal // – exposure to harmful chemicals // – suffering from mumps in adult life // – drug abuse // – smoking // – erectile dysfunction // etc. ** Accept other appropriate answers.

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Possible treatment ** Treatment should match the cause given. Any 1: (3m) – changes to diet // – changes to lifestyle, e.g. no smoking // – administering hormones // – reducing stress // – IVF treatment // etc. ** Accept other appropriate answers. (v) Explain how any two of the following methods of contraception work: natural,

chemical, mechanical, surgical. Any 2: (2 × 3m) - mechanical or example – prevents contact between sperm and egg // - surgical or example – prevents contact between sperm and egg // - chemical or example – prevents ovulation / hormone levels changed // - natural - (safe period) – intercourse takes place avoiding ovulation

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14. Answer any two of (a), (b), (c). (30, 30) (a) (i) Name the type of gland which secretes hormones. (3m) – endocrine (gland) (ii) What is a hormone? – a chemical messenger (3m) Any 1: (3m) – secreted by ductless gland // – transported in the blood // – to a target area // – causing a response (iii) Copy the table below into your answerbook and use your knowledge of hormones to

complete the table. Some boxes have been filled as examples.

Name of Gland Hormone Function of Hormone

Pituitary

Any 1: (3m) – growth hormone // – LH // – FSH // etc.

Any 1: (3m) ** Function must match hormone named.e.g. GH – causes bone elongation / growth, etc.

– thyroid (3m) Thyroxine – controls rate of metabolism (3m)

– adrenal (3m) – adrenaline (3m) To prepare for ‘fight or flight’ (iv) State one way in which hormone action differs from nerve action. Any 1: (3m) Hormone action Nerve action – slow acting // – fast / immediate acting // – carried by chemicals // – carried mostly by electrical impulses // – slow transmission (in blood) // – fast transmission // – effects may be widespread // – effect is localised // etc.

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(b) The diagram shows a section through human skin. (30) (i) Name the parts labelled A and B. (2 × 3m) A – hair B – erector muscle (ii) The skin plays an important role in temperature control. 1. What happens to the small arteries (arterioles) in the skin when the external temperature drops? (3m) – they contract 2. What happens to part A when the external temperature drops? (3m) – stands up (iii) The skin plays an important role in our immune system. 1. Explain the term immunity. (3m) – the ability to resist / defend against disease / infection 2. Outline two ways in which the skin provides immunity. Any 2: (2 × 3m) – acts as a physical barrier // – forms scabs to prevent blood loss // – sweat (contains the enzyme lysozyme which attacks bacteria) // – sebum (oil produced by the sebaceous glands) // etc. ** Accept other appropriate answers. (iv) The skin also plays an excretory role in the human body. 1. What is meant by the term excretion? (3m) – the removal of the waste products of metabolism from the body ** Accept other appropriate material. 2. Name a substance excreted by the skin. Any 1: (3m) – sweat // – salts and water // ** Accept other appropriate answers. 3. Name one other excretory organ in the body. Any 1: (3m) – kidney // – lung

A B

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(c) The diagram shows the human ear. (30) (i) Name the parts labelled A, B, C and D. (4 × 3m) A – semi-circular canals B – cochlea C – eardrum D – hammer / ossicles (ii) Which labelled part is responsible for: 1. Balance. (3m) – semi circular canals / A 2. Hearing. (3m) – cochlea / B (iii) What would happen if part C became damaged? (3m) – damage to hearing / deafness (iv) Name the nerve which carries impulses from the ear to the brain. (3m) – auditory / cochlear nerve (v) Name one disorder of the ear or the eye and give one possible treatment for it. ** Disorder named (3m), Possible treatment (3m). ** Treatment must be appropriate to the disorder named. Any 1: (2 × 3m) Disorder Possible treatment – glue ear // Any 1: – insert grommets // – use decongestants // – short sight // Any 1: – use a concave lens // – laser eye surgery – long sight // Any 1: – use a convex lens // – laser eye surgery

A

B

D

C

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15. Answer any two of (a), (b), (c). (30, 30) (a) (i) To which kingdom does Amoeba belong? (3m) (30) – Protista (ii) Draw a diagram of Amoeba and on it label a contractile vacuole, a food vacuole

and a pseudopod. Diagram (0m, 3m, 6m) Labels (3 × 1m) – food vacuole – contractile vacuole – pseudopod (iii) Give the function of the following parts of Amoeba: 1. contractile vacuole. Any 1: (3m) – regulates water in Amoeba // – prevents Amoeba from bursting 2. food vacuole. Any 1: (3m) – kill prey (by secreting acid) // – digest prey (by secreting enzymes) 3. pseudopod. Any 1: (3m) – used for movement // – used to engulf prey (iv) Amoeba is heterotrophic. Explain the underlined term. (3m) Heterotrophic – (an organism) that takes in food made by other organisms (v) List two differences between an Amoeba cell and a plant cell. Any 2: (2 × 3m) Amoeba cell Plant cell – no cell wall // – cell wall // – no chlorophyll // – contains chlorophyll // – has a contractile vacuole // – no contractile vacuole

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(b) (i) Draw a diagram of the urinary system and label a kidney, a ureter, the urethra and the bladder. (30)

Diagram (0m, 2m, 4m) Labels: (4 × 2m) – kidney – ureter – urethra – bladder (ii) The diagram shows the kidney. 1. Name the parts labelled A and B. (2 × 3m) A – cortex B – medulla 2. In which of the labelled parts does filtration of the blood take place? (3m) – cortex / A 3. In which of the labelled parts does reabsorption of salt take place? (3m) – medulla / B (allow cortex / A) (iii) Urine is made from urea salts and water. Where is the urea formed? (3m) – (the) liver (iv) The renal artery in the kidney is connected

to which main blood vessel in the body? (3m) – (the) aorta

A

B

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(c) (i) Plants can be monocotyledonous or dicotyledonous. Give any one difference between a monocotyledonous plant and a dicotyledonous plant. (30)

Any 1: (3m) Monocotyledons Dicoytledons – single cotyledon // – two cotyledons // – long narrow leaf // – broad leaf // – parallel veins in leaf // – network of veins in leaf // – scattered vascular bundles // – ring of vascular bundles // – flower parts in multiples of three // – flower parts in multiples of four or five // – fibrous roots – tap roots (ii) Give one example of a monocotyledonous plant and one example of a dicotyledonous

plant. Monocotyledonous plant Any 1: (3m) – grasses // – daffodils // – irises // – orchids // – rice // – wheat // – maize // – lilies // etc. Dicotyledonous plant Any 1: (3m) – beans // – oak trees // – tomatoes // – roses // – honeysuckle // – peppers // – maple trees // – beech trees // etc.

** Accept other appropriate answers. (iii) Draw a labelled diagram to show a transverse (T.S.) section of a dicotyledonous stem.

Include the following labels in your diagram: ground tissue, dermal tissue and vascular tissue.

Diagram (0m, 3m, 6m) Labels (3 × 1m) – ground tissue – dermal tissue – vascular tissue (iv) Name the two types of tissue found in vascular tissue and state a function of each type. Vascular tissues named (2 × 3m) Function of each (2 × 3m) Vascular tissue Function – xylem Any 1: – transports water and mineral salts // – provides support – phloem – transports food

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Notes:

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Biology

Higher Level Marking Scheme (400 marks)

Section A (5 × 20m) (100) 1. Give an example of any five of the following: (5 × 4m) (20) (a) An anabolic reaction in a plant. (4m) – photosynthesis ** Accept other appropriate answers. (b) A monosaccharide. Any 1: (4m) – glucose // – fructose // – galactose (c) An autotrophic organism. Any 1: (4m) – plant // – algae // – bacteria // etc. ** Accept other appropriate examples. ** Accept any named examples of the above. (d) A prokaryotic cell. (4m) – bacteria ** Accept other appropriate examples. ** Accept any named examples of the above.

examsDEB

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(e) A protein that has a structural role. Any 1: (4m) – keratin // – myosin // – haemoglobin // – collagen // – elastin // etc. ** Accept other appropriate examples. (f) A trace element. Any 1: (4m) – iron / Fe // – copper / Cu // – zinc / Zn

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2. Explain each of the following terms from your study of ecology. (20) (a) Contest competition. (4m) – the active physical struggle / contest between two organisms (with one winner) (b) Symbiosis. (4m) – (close) relationship between two species involving benefit (c) Abiotic factor. (4m) – any non-living environmental factor, e.g. steepness, altitude, aspect, exposure,

currents, etc. (d) Population. (4m) – the number of organisms of the same species living in an area (e) Niche. (4m) – the functional role of an organism in a community

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3. Enzymes play an important role in controlling the rate of many metabolic reactions. (20) (a) What is meant by the optimum pH of an enzyme? (3m) – the pH at which an enzyme works best (b) What is a denatured enzyme? (3m) – a enzyme that has lost its shape and so cannot carry out its function (c) Name the theory used to explain the specificity of an enzyme. (3m) – the active site theory / induced fit model / lock and key theory Answer the following questions in relation to immobilised enzymes. (d) Name a compound used to immobilise an enzyme. (3m) – (sodium) alginate (e) Name the chemical used to harden the prepared immobilised beads. (3m) – calcium chloride (f) Give two advantages of using immobilised enzymes. Any 2: (3m + 2m) – enzymes can be reused // – enzymes can be recovered easily // – enzymes are more stable so less need to be used // – allows for a cheaper production process // – no effect on enzyme efficiency // – a pure product

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4. The diagram shows a longitudinal section of a vascular plant tissue. (20) (a) Name this vascular tissue. (3m) – phloem (b) Name the cells labelled A and B. (2 × 3m) A – sieve tube cell B – companion cell (c) State the precise location of this vascular tissue in the stem

of a typical dicotyledonous plant. (3m) – vascular bundle (d) Name the openings found on the leaves of plants which allow gas exchange. (3m) – stomata (e) What factor influences the opening and closing of the openings referred to in (d)? (3m) – (level of) carbon dioxide (f) Name the openings on the stems of plants which allow gas exchange. (2m) – lenticels

A

B

Nucleus

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5. The diagram shows a mammalian heart. (20) (a) Name the parts labelled A, B and C. (3 × 1m) A – bicuspid valve B – left ventricle C – pacemaker / SA node (b) What is the function of C? (3m) – to control heartbeat (c) Name the two circuits which make up the human

circulatory system. (2 × 3m) – pulmonary – systemic (d) Which of the circuits referred to in (c) involves blood being pumped by B? (2m) – systemic (e) Name the main gas transported by the blood in blood vessel D. (3m) – carbon dioxide (f) How is the gas referred to in (e) transported in the blood? Any 1: (3m) – in plasma // – in red blood corpuscles

B

C D

A

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6. (a) In the space below draw a labelled diagram of a cell during anaphase of mitosis where 2n = 4. (20)

Diagram (0m, 3m) Any 2 labels: (2 × 1m)

spindle fibre

centromerechromatid / chromosome

2n = 4 (b) What is the function of mitosis in single-celled organisms? (3m) – reproduction (c) Give one function of mitosis in multi-cellular organisms. Any 1: (3m) – growth // – cell repair // – cell replacement / renewal // – in reproduction, during development of macrospore after meiosis has occurred // – in reproduction, during development of microspore after meiosis has occurred (d) Meiosis is another form of cell division. Identify one precise location in the human body

where meiosis occurs. Any 1: (3m) – ovary // – testes (e) Variations occur within a group of organisms of the same species as a result of meiosis.

Explain the following terms: (i) Variation. Any 1: (3m) – differences within a population // – differences within a species // – differences between individuals (ii) Species. (3m) – organisms which can interbreed to produce fertile offspring

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Section B (2 × 30m) (60) 7. (a) Name a part of a cell which is: (6) (i) Fully permeable. (3m) – cell wall (ii) Selectively permeable. Any 1: (3m) – cell membrane // – nucleus // – mitochondrion // – vacuole // – chloroplast (b) Answer the following questions in relation to an activity that you carried out to demonstrate

osmosis. (24) (i) What did you use as a selectively permeable membrane? Any 1: (3m) – visking tubing // – cellophane // – potato cell membranes (ii) Draw a labelled diagram of the apparatus and solutions you used. Possible experiments – inverted thistle funnel // – potato with hollow and salt // – visking tubing // etc. Diagram (3m) Any 3: labels: (3 × 1m) ** Diagram must show apparatus and solutions used. (iii) Describe briefly how you carried out the investigation. (3 × 3m) ** Any three correct points of procedure relating to the experiment shown in (ii). (iv) What did you use as a control? Any 1: (3m) – a bag with water solution // – boiled potato // etc. ** Accept any appropriate control relating to the experiment

described in (ii) and (iii).

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(v) How were you able to tell that osmosis had taken place? Any 1: (3m) – extra mass // – more turgid // – increased height / level of liquid in tube // – salt dissolves in ‘well’ of potato / water fills up in ‘well’ of potato // etc. ** Accept any appropriate answer relating to the experiment

described in (ii) and (iii).

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8. (a) Yeast produces ethanol in a process called fermentation. (6) (i) To which kingdom do yeasts belong? (3m) – Fungi (ii) Explain the term fermentation. (3m) – anaerobic respiration (b) Answer the following questions in relation to an activity that you carried out to prepare and

show the production of alcohol by yeast. (24) (i) Why is it very important to sterilise all glassware before use? (3m) – to prevent contamination (ii) Name a substrate that you used. Any 1: (3m) – sugar // – glucose // etc. (iii) What control did you use? (3m) – same substrate / set up but no yeast present (iv) What other product is produced during the alcohol fermentation process? (3m) – carbon dioxide / CO2 (v) How did you test for the presence of the product referred to in (iv)? (3m) – limewater turns milky (vi) Name the chemical test or the chemicals used to show the presence of alcohol. Any 1: (3m) – iodoform test / potassium iodide and sodium hypochlorite // – potassium dichromate and sulfuric acid // In your answer describe any colour change which may occur. ** Colour change must match the test given. Any 1: (3m) iodoform test – brown-orange to pale yellow crystals (in presence of alcohol) // alcohol test – orange to green colour (in presence of alcohol)

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(vii) How did you achieve anaerobic conditions? Any 1: (3m) – boil the solution for 5 minutes // – cover the liquid with a layer of oil // – fermentation lock // – anaerobic jar

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9. (a) (i) Write the general formula carbohydrates. (3m) (6) – Cx(H2O)y (ii) In relation to food tests, name the reagents used when testing for reducing sugars. Any 1: (3m) – Benedict’s solution // – Fehling’s I and II (b) Answer the following in relation to investigations that you carried out in the course of your practical studies. (24) (i) When carrying out a quantitative study of plants: 1. Name one possible source of error that could have arisen in your survey. Any 1: (3m) – human error // – accidental discovery // – changing environmental conditions // – sample size // – misidentification of plant // – non-random (quadrat distribution) // – not ‘thrown’ enough times // – unsuitable quadrat size // – miscount // – miscalculation 2. How were you able to identify the plants that you found in your survey? (3m) – use a key // etc. (ii) When investigating the effect of pH on the rate of enzyme activity: 1. How did you measure the rate of activity of the enzyme? Any 1: (3m) – measured the height of foam / froth produced per unit of time // – record time taken for blue-black colour of iodine to disappear

and calculate 1/time 2. What factor did you keep constant? (3m) – temperature (iii) When investigating the factors necessary for the germination of seeds: 1. Why did you use at least 10 seeds in each experimental set up and the control? Any 1: (3m) – to obtain a reliable result // – allow for failure of some seeds to germinate

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2. How did you demonstrate the requirement for oxygen? Any 1: (3m) – anaerobic jar (or described) // – boiled water and a layer of oil // – alkaline pyrogallol (iv) When dissecting, displaying and identifying parts of the heart: 1. How did you identify the front of the heart in preparation for dissection? Any 1: (3m) – presence of coronary blood vessels // – walls of the left ventricle feel firmer than those of the right ventricle // – the front is more rounded // – thick-walled arteries are found to the front of the heart 2. Which part of the heart prevents the mixing of oxygenated and deoxygenated

blood? (3m) – septum

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Section C (4 × 60m) (240) 10. (a) (i) List the three shapes by which bacteria are classified. (3 × 1m) (9) – rods – spirals – round (ii) What is an antibiotic? (2 × 3m) – substances made by micro-organisms / bacteria / fungi – to kill other microorganisms / bacteria or fungi (b) The diagram shows Amoeba. (27)

B

A

(i) Name the kingdom to which Amoeba belongs. (3m) – Protozoa (ii) Name the parts labelled A and B. (2 × 3m) A – contractile vacuole B – pseudopod (iii) 1. What is the function of A? Any 1: (3m) – osmoregulation // – homeostasis // – excretion 2. Explain why A is more active in freshwater amoebae than in marine amoebae. Any 1: (3m) – freshwater is more hypotonic than salt water // – more water intake in freshwater ** Any reasonable reference to concentration difference.

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(iv) 1. What is the function of B? Any 1: (3m) – movement // – feeding / engulfing prey // 2. Briefly outline how B works. (3m) – the pseudopodia extend in the direction Amoeba wishes to go , cytoplasm

(endoplasm) flows into the pseudopodia causing them to move (v) Give two differences between Amoeba and bacteria, other than the kingdom they

belong to. Any 2: (2 × 3m) Amoeba Bacteria – no cell wall // – cell wall // – moves using pseudopodia // – moves using flagellum // – carnivore / scavenger // – parasitic / saphrophytic or photo- / chemosynthetic – can form endospores // – found in freshwater / – found everywhere marine habitats ** Accept other appropriate answers. (c) (i) Fungi can be saprophytic or parasitic. Explain each of the underlined terms. (24) Saprophytic (3m) – feeds on / obtains nutrition from dead material Parasitic (3m) – feeds on / obtains nutrition from a live host causing harm (ii) State one role of each of these types of fungus in the overall scheme of nature. Saprophyte (3m) – recycling / decay Parasite (3m) – population control (iii) Using your knowledge of bacteria and fungi, suggest a reason for each of the following: 1. Some fungi inhibit the growth of bacteria. (3m) – (fungi) act as / produce an antibiotic


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2. Leaf yeasts are more common on leaves in the countryside than on leaves in the city. (3m)

– leaf yeast (fungi) less likely to survive in polluted areas 3. Antibiotics should not be prescribed if a patient is suffering from influenza. (3m) – antibiotics are not effective against viruses 4. Fungi are more likely than bacteria to grow on bread. (3m) – not enough moisture on bread for bacteria

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11. (a) (i) State the precise location in the body where urea is made. (3m) (9) – the liver (ii) Where does urea enter the blood? (3m) – the hepatic artery (iii) Name a food source from which urea is derived. (3m) – protein (b) (i) Draw a diagram of the urinary system and its associated blood supply. (27) Diagram (0m, 2m, 4m) Any 5 labels: (5 × 1m) – kidneys // – ureters // – bladder // – urethra // – renal artery // – renal vein (ii) Excretion in the kidneys takes place in three stages: filtration, reabsorption and

secretion. Explain each of the underlined terms. Filtration (3m) – small substances are pushed out Reabsorption (3m) – nutrients are returned to the blood (iii) The nephron is the functional unit of the kidney. State the precise location in the nephron where: 1. Filtration occurs; (3m) – Bowman’s capsule / glomerulus 2. Reabsorption of valuable nutrients occurs. (3m) Any 1: – loop of Henle // – proximal convoluted tubule // distal convoluted tubule (iv) List two differences between blood and glomerular filtrate. (2 × 3m) – no protein in glomerular filtrate – no blood cells in glomerular filtrate

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(c) Using your knowledge of excretion and homeostasis, suggest a reason for each of the following: (24)

1. Glucose is not usually found in urine. (2 × 3m) – should be reabsorbed – in the nephron / proximal convoluted tubule 2. Frogs hibernate in Ireland in winter. (2 × 3m) – frogs are exotherms / unable to maintain metabolism – hibernation reduces metabolic rate 3. A very low salt diet causes a high volume of dilute urine to be produced. (2 × 3m) – no ADH produced – impermeable collecting duct 4. Birds puff up their feathers in winter. (2 × 3m) – traps air – aids insulation

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12. (a) (i) DNA is made up of two strands held together by the matching of paired bases. (9) 1. Which base can link only with adenine? (3m) – thymine 2. Which base can link only with guanine? (3m) – cytosine (ii) Name the two purine bases found in DNA. (3m) – adenine and guanine ** Expect both answers for full marks. (b) (i) Distinguish between Mendel’s Law of Segregation and Mendel’s Law of Independent

Assortment by writing a sentence about each. (27) Law of Segregation (3m) – traits are governed by pairs of factors (or alleles or genes) that separate at gamete

formation (each gamete receiving one factor), etc. Law of Independent Assortment (3m) – either member of a pair of alleles (or factors or genes or chromosomes) can

combine with either member of another pair (in gamete formation), etc. (ii) In snapdragon plants there is incomplete dominance between the allele governing

red flowers and the allele governing white flowers. Snapdragon plants that show incomplete dominance have pink flowers.

1. Give the genotype of a snapdragon plant that is homozygous for red flowers.

(3m) – RR 2. Give the genotype of a snapdragon plant that is homozygous for white flowers.

(3m) – rr 3. Give the genotype of a snapdragon plant that has pink flowers. (3m) – Rr


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(iii) Determine the possible genotypes and phenotypes of the offspring of a cross between two snapdragon plants with pink flowers. Show clearly how you obtained your answer.

Parents Rr × Rr Gametes: R r × R r (4 × 1m)

– R r

R RR Rr

r Rr rr

Genotypes: RR Rr rr (3 × 1m) Phenotypes: (3 × 1m) – red flower – pink flower – white flower What percentage of the offspring will have pink flowers? (2m) – 50% (c) Protein synthesis takes place in two main stages called transcription and translation. (24) (i) Explain each of the underlined terms. Transcription (3m) – producing mRNA using DNA as a template Translation (3m) – the process of making a protein using the mRNA template (ii) In which structure of the cell does transcription occur? (3m) – the nucleus (iii) Name an enzyme involved in transcription. (3m) – RNA polymerase (iv) The tRNA molecules in the cytoplasm play a vital role in protein synthesis. What do

tRNA molecules carry to aid this process? (3m) – anticodon / code triplet and amino acid ** Expect both answers for full marks. ** Do not accept ‘triplet’ or codon’ on its own. (v) Why is it necessary for folding to occur once the protein has been formed? (3m) – correct shape needed to carry out function

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(vi) Give two structural differences between DNA and RNA. (2 × 3m) DNA RNA – double stranded – single stranded – contains thymine – contains uracil

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13. (a) Name three factors which influence the size of the human population. (9) Any 3: (3 × 3m) – famine / availability of food // – birth control // – war // – disease // – natural disasters // – birth rate // – death rate / longevity // – medical care //

** Accept named examples. (b) Read the article below and answer the questions that follow: (27) Arctic foxes living on a small island in the Bering Sea may be suffering a dramatic population

crash because their diet is limited to marine animals containing high levels of mercury, according to a report in PLOS ONE*. The foxes on Mednyi Island, which have been isolated for thousands of years, were once abundant enough to support resident fur hunters, reported Nature. But since the 1970s, when humans left the island, the number of foxes has fallen off dramatically. Researchers thought this might be due to diseases introduced by humans and their dogs, but when they screened Mednyi’s foxes for canine pathogens, they found no evidence to support the hypothesis.

Next, the team decided to look at mercury levels in the foxes, as the pollutant is known to

accumulate at high levels in the seabirds and scavenged seals that make up the foxes’ diet. They found that the Mednyi foxes had higher levels of mercury than other Arctic fox populations on the larger, neighbouring Bering Island and on the coast of Iceland, neither of which has suffered a similar decline. The researchers suspect that the difference arises because foxes on larger islands can move inland to feast on a more varied diet, including lemmings, voles and human-discarded food waste. The Mednyi foxes, on the other hand, can only eat marine animals, making them more susceptible to increasing environmental mercury levels.

*[PLOS ONE: N. Bocharova, G. Treu, G. Árpád Czirják, O. Krone, V. Stefanski, G. Wibbelt, E. Rut Unnsteinsdóttir, P. Hersteinsson, G. Schares, L. Doronina, M. Goltsman, A.D. Greenwood ‘Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus).’]

Adapted from The Scientist, by Dan Cossins, 09/05/2013. (i) Explain the terms pollutant, hypothesis and pathogen. Pollutant (3m) – any harmful addition to the environment Hypothesis (3m) – an (educated) guess based on observation Pathogen (3m) – a disease-causing micro-organism (ii) Why do the Arctic fox on Mednyi island have high levels of mercury? (3m) – (they have) a diet consisting only of marine life which contain high levels

of mercury

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(iii) Why did scientists initially believe it was a disease which was causing the population drop?

Any 1: (3m) – because they were isolated // – different immunity // – not exposed to as many microbes // etc. ** Accept other appropriate answers. (iv) When humans left the island, what effect did this have on the foxes’ diet? Any 1: (3m) – the foxes’ diet became less varied // – the foxes could no longer feed on human-discarded food waste (v) In your opinion, what are the possible side effects on the Arctic Fox population from

having a diet mainly of seals and seabirds? Any 1: (3m) – may lack specific nutrients // – may have too much vitamins (A and D) // – may suffer from deficiency illness // etc.

** Accept other appropriate answers. (vi) If the population of foxes remain low, suggest two possible consequences for the

organisms they prey on. Any 2: (2 × 3m) – prey numbers increase // – migration of prey // – increase competition between prey for food // – no natural culling // ** Accept other appropriate answers. (c) (i) What is the function of the nitrogen cycle? (3m) (24) – to make nitrogen available for use by organisms (ii) Explain what is meant by nitrogen fixation. (3m) – nitrogen gas (N2) converted to a nitrogen compound e.g. nitrates, nitrites, etc. (iii) What is nitrification? Any 1: (3m) – ammonia is converted to nitrates or nitrates // – nitrites are converted to nitrates


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(iv) Describe, using your own words and/or labelled diagrams, how the nitrogen cycle works.

** Accept a well-labelled diagram explaining how the nitrogen cycle works. Any 5: (5 × 3m) – fixation // – lightning // – plant protein // – animal protein // – death // – excretion // – decomposition // – ammonia produced // – ammonia to nitrites // – denitrification // – any bacteria function explained // etc.

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14. Answer any two of (a), (b), (c). (30, 30) (a) Infertility is an increasing problem in modern society. (30) (i) Name one cause of male infertility and suggest a corrective measure. Cause of male infertility Any 1: (3m) – low sperm count // – low sperm motility // – hormonal // – smoking // – drug abuse // – erectile dysfunction // – unsuitable temperature of testes // – any named pathological condition or cause described // etc. Corrective measure Any 1: (3m) – improve diet // – stop smoking // – reduce alcohol intake // – take regular exercise // – reduce stress // etc. ** Corrective measure must match cause. (ii) What is meant by the term contraception? Any 1: (3m) – prevention of fertilisation // – prevention of implantation // – prevention of pregnancy (iii) List three types of contraception other than chemical contraception. (3 × 3m) – natural – barrier – surgical ** Accept named examples of each type. (iv) The availability of contraception is on the increase. What effect may this have on the

human world population? Any 1: (3m) – decrease / no increase in population // – demographic imbalance // – improved social conditions // – improvement in sexual health, e.g. lack of STIs // etc.


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(v) Pregnancy in humans is maintained by the production of hormones throughout gestation.

1. Which hormone in particular plays a significant role in maintaining pregnancy?

(3m) – progesterone 2. Where is the hormone referred to in 1. produced for the first 12 weeks of

pregnancy? (3m) – corpus luteum (in ovary) 3. From where is the hormone referred to in 1. produced for the remainder of the pregnancy? (3m) – placenta (b) There are two types of reproduction in plants: sexual and asexual. (30) (i) Name one method of asexual reproduction in plants. Any 1: (3m) – runners // – tubers // – bulbs // – corms // – rhizomes // – cuttings // – grafting // – layering // – tissue culture // etc. ** Accept other appropriate answers. (ii) Distinguish between pollination and fertilisation by writing a brief sentence about each. Pollination (3m) – the transfer of pollen from the anther (of the stamen) to the stigma (of the carpel)

of a flower of the same species Fertilisation (3m) – the fusion of gametes (sex cells) to form a zygote (iii) Briefly describe the development of pollen grains in the anther. Any 3: (3 × 3m) – meiosis (in anther) // – four (or tetrad) haploid // – microspores // – divides by mitosis // – tube and generative nucleus // – pollen grain matures // – wall forms

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(iv) Is the pollen grain the male gamete? (3m) – no Explain your answer. (3m) – the generative nucleus divides by mitosis to produce the two male gametes (v) Many changes occur to the flower during fertilisation. State what each of the following

parts of the flower become after fertilisation: 1. Ovule. (3m) – seed 2. Polar nuclei. (3m) – endosperm (c) (i) Give three functions of the skeleton. (30) Any 3: (3 × 3m) – support // – protection // – movement // – anchorage / leverage for muscle // – blood production // – shape // etc. (ii) Give a function of each of the following in relation to the growth of bone. 1. Osteoblasts (3m) – forms bone cells which produce protein or collagen 2. Osteoclasts (3m) – digests bone in (medullary) cavity and deposits calcium into blood (for

bone renewal) 3. Growth plate. Any 1: (3m) – forms cartilage which turns into bone // – forms cartilage which elongates bone (iii) State the role of each of the following in a joint: 1. Cartilage (3m) – protects the ends of bones 2. Ligament. (3m) – connects bone to bone


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3. Tendon. (3m) – connects muscle to bone (iv) What mineral salt is required in adolescence, in particular, to help prevent the

degeneration of bones in later life? (3m) – calcium

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15. Answer any two of (a), (b), (c). (30, 30) (a) (i) For what is ATP an abbreviation? (3m) (30) – adenosine triphosphate (ii) What is the function of ATP in cells? (3m) – to store or provide energy (iii) For what is NADP an abbreviation? (3m) – nicotinamide adenine dinucleotide phosphate (iv) Is NADP+ a high-energy or a low-energy carrier? (3m) – (a) low (energy carrier) (v) Name a metabolic process where NADP+ is used. (3m) – photosynthesis (vi) One laboratory activity that you carried out investigated the effect of heat denaturation

on the activity of an enzyme. Answer the following in relation to this activity: 1. Name the substrate that you used. (3m) – hydrogen peroxide / H2O2 ** Accept other appropriate substrates. 2. Name the enzyme that acted on the substrate. (3m) ** Enzyme named should correspond to the substrate named in 1. – catalase ** Accept other appropriate corresponding enzymes. 3. What control did you use? (3m) – unboiled catalase solution ** Accept other appropriate corresponding control. 4. Describe the results you obtained. (2 × 3m) – foam formed in unboiled catalase / control – no foam formed in boiled catalase ** Accept other appropriate results.

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(b) (i) The first stage of photosynthesis is called the light stage. During this stage electrons gain energy and travel along one of two different pathways. (30)

Give a short account of each of these pathways. Pathway 1 Any 3: (3 × 3m) – light energy is trapped by chlorophyll / light energises electrons // – energised electrons release energy // – to form ATP // – electrons return to chlorophyll Pathway 2 Any 3: (3 × 3m) – electrons are picked up by NADP // – water splits / photolysis // – NADPH forms // – electrons from splitting of water return to chlorophyll // – ATP is formed (ii) At the end of the light stage, the dark stage commences. 1. Where in the cell does the dark stage take place? (3m) – chloroplast 2. Why is this stage called the dark stage? (3m) – it is light independent 3. Give two possible fates of oxygen following its production in photosynthesis.

(2 × 3m) – used in respiration – released (diffused) into the atmosphere

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(c) The pancreas is both an endocrine and an exocrine gland. (30) (i) Distinguish clearly between an endocrine gland and an exocrine gland by writing a

sentence about each. Endocrine (3m) – ductless or secretes into the bloodstream Exocrine (3m) – has ducts (ii) Using your knowledge of the endocrine role of the pancreas state: 1. A substance produced. (3m) – insulin 2. The site of action of the substance referred to in 1. (3m) insulin – all cells 3. The function of the substance referred to in 1. (3m) insulin – to regulate blood sugar levels (iii) Using your knowledge of the exocrine role of the pancreas state: 1. A substance produced. Any 1: (3m) – pancreatic enzymes // – amylase // – lipase // etc. 2. The site of action of the substance referred to in 1. Any 1: (3m) pancreatic enzymes – duodenum // – small intestine amylase – duodenum // lipase – duodenum 3. The function of the substance referred to in 1. Any 1: (3m) pancreatic enzymes – digests food // amylase – breaks down starch to maltose // lipase – breaks down lipids into fatty acids

and glycerol

2015.2 L.37/38_MS 64/68 of 64 examsDEB

(iv) Name a disorder of the nervous system and give a possible treatment for it. Disorder of the nervous system Any 1: (3m) – paralysis // – Parkinson’s disease // – MS // – Motor Neurone disease // etc.

** Accept other appropriate answers. Possible treatment ** Treatment named must correspond to disorder given. Any 1: (3m) paralysis Any 1: – no treatment // – use of mobility aids, e.g. wheelchairs, etc. // Parkinson’s disease Any 1: – physiotherapy // – electrical stimulation // – drugs (that mimic dopamine) therapy // etc. MS – steroid therapy // Motor Neurone disease Any 1: – exercises // – physiotherapy // etc. ** Accept other appropriate answers.

2015.2 L.37/38_MS 65/68 of 64 examsDEB

Notes:

2015.2 L.37/38_MS 66/68 of 64 examsDEB

Notes:

2015.2 L.37/38_MS 67/68 of 64 examsDEB

Notes:

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