Candidate Name Centre Number Candidate Number 0

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Candidate Name Centre Number Candidate Number 0

GCSE

ADDITIONAL SCIENCE

**HIGHER TIER (Grades D-A*)**

BIOLOGY 2 − Cells and metabolism, digestion and respiration, biodiversity

SPECIMEN PAPER (1 hour)

INSTRUCTIONS TO CANDIDATES

Write your name, centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided in this booklet.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets at the end of each question or part-question.

You are reminded that assessment will take into account the quality of written

communication used in your answers to questions 2(b) and 7.

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1. The diagram below shows the human digestive system.

(a) Label parts A and B on the diagram. [1]

(b) What is meant by the term digestion? [3]

...

(c) Describe the digestion in the small intestine of a meal containing

carbohydrate, protein and fat. [4]

...

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2. The activity of the enzyme carbohydrase on starch can be investigated using the following apparatus which measures the amount of light passing through the solution.

The solution in the boiling tube consisted of starch, carbohydrase and iodine.

The following graph appeared on the computer screen at the end of the investigation.

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(a) Iodine is used to test for starch. In the presence of starch, iodine changes colour from

... to ... [1]

(b) Describe and explain the results seen in the graph by referring to the expected colour changes and reactions taking place in the boiling tube.

[6 QWC]

...

(c) On the graph, draw a line to show what result you would expect if boiled, cooled carbohydrase was used with a solution of starch and iodine. [1]

(d) Describe a test that you would carry out to show the end product of the

reaction taking place in the boiling tube. [2]

...

…...

...

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3. (a) Define the term biodiversity. [2]

...

(b) Floating pennywort is an alien plant species in Britain. It grows in slow flowing waterways such as canals and lakes where it forms dense mats which grow at the rate of 20cm a day. Floating pennywort out-competes native plants, reduces the oxygen content of water and has a damaging effect on flood control.

(i) What is meant by an alien species? [1]

...

(ii) State one harmful effect that floating pennywort could have on native

wildlife. [1]

...

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(c) In Florida, the southern army worm is known to eat floating pennywort and in Argentina there is a weevil (an insect) that only eats floating pennywort.

What advice would you give the Environment Agency about the dangers of introducing these organisms into Britain as methods of biological control

against floating pennywort? [2]

...

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4. Tendons are tissues that attach muscles to bones.

Recent treatment of sports horses with leg tendon injuries involves the injection of stem cells into the tendon. Stem cells from bone marrow behave like embryonic stem cells.

Bone marrow is obtained from the breastbone of the horse and sent to a laboratory where the stem cells are cultured (grown).

After 48-72 hours the stem cells are injected into the injured tendon.

This process is shown below.

(a) What are stem cells? [1]

...

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(b) The photograph below shows ultrasound scans of an injured leg tendon of a horse before and after stem cell treatment.

Explain how the stem cells have helped to repair the tendon. [1]

...

(c) The use of human embryonic stem cells is regulated because this kind of stem cell comes from human embryos. Why are many people concerned about using stem cells from human embryos whilst others are in favour.

Give one reason for using embryos and one reason against. [2]

...

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5. Maple leaves were analysed for their sugar and starch content over a 24 hour period.

The data, together with the light intensity readings, are shown in the chart below.

Time

(a) State the relationship between light intensity and starch production. [1]

...

(b) Sugar and starch are products of photosynthesis. Suggest why the level of

sugar in the leaf is highest at night. [1]

...

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(c) (i) Choose the time you would expect to find the highest concentration of oxygen in the air at the surface of the leaf.

Tick ( ) one box only. [1]

Time Tick Midnight

4 am 8 am 12 Noon

4 pm 8 pm

(ii) Explain your answer. [3]

...

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6. The following experiment was carried out to show the effect of ethanol (alcohol) on yeast when it fermented glucose anaerobically.

The sterile syringes were prepared as shown in the diagram and left for 1 hour. At the end of the hour, the distance the liquid in the glass tube moved in each syringe was measured.

(a) Explain

(i) why the liquid moved in the glass tube; [2]

...

(ii) why the temperature in syringe 1 was higher than that in syringe 2 at

the end of one hour; [2]

...

(iii) why it is important to use sterile syringes. [1]

...

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(b) The results of the experiment were as follows:

Time (min) Distance moved by liquid in the glass tube (mm) Syringe 1 Syringe 2

0 0 0 40 30 10 50 100 16 60 220 20

Suggest an explanation of the results. [1]

...

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7. The following advert for Joy's cigarettes appeared in a newspaper more than 100 years ago.

This advert would not appear in modern newspapers. Describe how and why

attitudes to smoking have changed. [6 QWC]

...

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8. The first contact lenses to be developed were made of glass. The diagram shows what happened when a glass contact lens was put on the eye.

These lenses proved to be unsuitable because they caused pain.

(a) The diagram shows water entering the cornea of the eye by osmosis.

Define osmosis. [2]

...

(b) Modern contact lenses are gas permeable.

Use the information in the diagram to explain why these modern contact lenses are more suitable than glass contact lenses. [4]

...

………...

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9. There are several methods of sampling animals or plants in their natural habitats.

(a) State two limitations of random sampling methods. [2]

...

(b) During an investigation into numbers of trout in a lake, a method of capturing the trout, marking them with a harmless dye, and then recapturing them was used.

(i) In this investigation, what data would you need to record and how could it be used to estimate the size of the trout population? [4]

...

(ii) When using such a capture-recapture technique to estimate population size, what assumptions are being made about