Name: B5 Homeostasis and Response · 2018-03-27 · (e)€€€€€Student A’s mean reaction...

B5 Homeostasis and ResponsePractice questions

Name: ________________________

Class: ________________________

Date: ________________________

Time: 209 minutes

Marks: 201 marks

Comments: HIGHER TIER

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Amylase is an enzyme that digests starch.

A student investigated the effect of pH on the activity of amylase.

This is the method used.

1. Mix amylase solution and starch suspension in a boiling tube.

2. Put the boiling tube into a water bath at 25 °C.

3. Remove a drop of the mixture every 30 seconds and test it for the presence of starch.

4. Repeat the investigation at different pH values.

The table below shows the students’ results.

pHTime when no starch was

detected in minutes

5.0 7.0

5.5 4.5

6.0 3.0

6.5 2.0

7.0 1.5

7.5 1.5

8.0 2.0

(a) The student concluded pH 7.25 was the optimum pH for the amylase enzyme.

This is not a valid conclusion.

Suggest two reasons why.

1. _________________________________________________________________

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2. _________________________________________________________________

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(2)

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(b) The student did another investigation.


1. Put amylase solution and starch suspension into a boiling tube.

2. Make the pH 7.25.

3. Put the boiling tube into a water bath at 25 °C.

4. Measure the amount of sugar produced every 30 seconds.

The results are shown in the figure below.

Calculate the mean rate of sugar produced per minute during the first 5 minutes.

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Mean rate = ________________ units per minute

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(c) Iodine solution is added to a sample taken from the boiling tube after 10 minutes and 60minutes.

Suggest what you would see in these samples.

After 10 minutes _____________________________________________________

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After 60 minutes _____________________________________________________

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(2)

(d) The scientist repeated the investigation at 37 °C.

Draw a line on the figure above to show the results the scientist would get.

(2)

(e) The same investigation was done at 65 °C.

How would this affect the results?

Explain why.

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(3)

(Total 11 marks)

Neurones pass information around the body.

(a) Why are reflex reactions important?

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(b) Caffeine is a drug found in coffee.

After a person drinks coffee information passes through neurones in the nervous systemmore quickly.

Suggest a hypothesis for the effect of caffeine concentration on reaction time.

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(1)

(c) Two students investigated the effect of caffeine concentration on reaction time.


1. Student A drinks a cup of coffee.

2. Student B holds a ruler above Student A’s hand.

3. Student B drops the ruler.

4. Student A catches the ruler as quickly as she can.

5. The distance the ruler falls is recorded.

Suggest how this method could be improved to produce valid results.

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(Total 8 marks)

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The nervous system allows humans to respond to their surroundings.

The figure below shows two nerve pathways.

Nerve pathway A Nerve pathway B

(a) Nerve pathway A is 92 cm long.

A nerve impulse travels along pathway A at 76.2 m / s.

Calculate how long it takes for the nerve impulse to travel the length of the pathway.

Use the equation:

distance = speed × time

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Time = _________________ s

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(b) Nerve pathways A and B are the same length.

The nerve impulse takes longer to travel along pathway A than along pathway B.

Use the figure above to explain why.

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(c) Two students compare their reactions using a ruler.


1. Student A sits with his elbow on a table top.

2. Student B holds the ruler so the bottom of the ruler is level with the top of student A’sthumb.

3. Student B drops the ruler.

4. Student A catches the ruler.

5. Record the drop distance.

6. Repeat steps 1 to 5 four more times.

7. Repeat the whole experiment with student A dropping the ruler and student Bcatching it.

Both students are right-handed.

Student A uses his right hand to catch the ruler.

Student B uses her left hand to catch the ruler.

The table below shows the students’ results.

StudentDrop distance in mm

Test 1 Test 2 Test 3 Test 4 Test 5

Student A – right hand 203 167 140 156 163

Student B – left hand 230 211 279 215 264

What is the range of student A’s results?

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(d) The students are testing the hypothesis:

The drop distance of the ruler is smaller when a right-handed person uses their righthand to catch the ruler.

The students’ results in the table above are not a good test of the hypothesis.

Suggest what the students should have done to test the hypothesis.

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(e) Student A’s mean reaction time was 0.19 s.

Mean reaction time can be calculated using the equation:

Calculate the mean reaction time for Student B.

Give your answer to two significant figures.

Student B’s results are repeated here to help you answer the question.

Drop distance in mm

Test 1 Test 2 Test 3 Test 4 Test 5

Student B – left hand 230 211 279 215 264

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Mean reaction time = ____________ s

(4)

(Total 14 marks)

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The rate of chemical reactions can be changed by changing the conditions.

(a) Methane burns in oxygen to produce carbon dioxide and water.

The activation energy for the reaction is 2648 kJ / mol.

The reaction gives out 818 kJ / mol of energy.

The figure below shows the reaction profile for this reaction.

Complete the reaction profile.

Draw arrows to represent:

• the activation energy

• the energy given out.

(4)

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(b) What percentage of the activation energy is the energy given out?

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(1)

(c) Calcium carbonate decomposes when it is heated:

The decomposition of calcium carbonate is an endothermic reaction.

How would the reaction profile for decomposition of calcium carbonate be different from thereaction profile of methane burning in oxygen?

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(d) Catalysts are used in chemical reactions in industry.

Give two properties of catalysts.

For each property, explain why it makes the catalyst useful in industry.

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(4)

(e) Enzymes are biological catalysts.

What type of molecule is an enzyme?

Tick one box.

Carbohydrate

Hydrocarbon

Lipid

Protein

(1)

(f) If enzymes are denatured they stop working.

Give two ways an enzyme can be denatured.

1. _________________________________________________________________

2. _________________________________________________________________

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(g) An enzyme called lactase catalyses the reaction that breaks down lactose to smallermolecules.

One model used to explain how enzymes affect reactions is called the lock and key model.

Use the lock and key model to explain why lactase cannot be used to speed up allchemical reactions.

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(3)

(Total 16 marks)

Amylase catalyses the breakdown of starch into sugars.

A student investigated the effect of amylase on the reaction at different temperatures.

Figure 1 shows the apparatus the student used.

Figure 1

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1. Put starch suspension into a test tube.

2. Add amylase solution.

3. Put the test tube in a beaker of water at 15 °C.

4. Remove a small sample of the mixture every 30 seconds and put in a spotting tile.

5. Test the sample for starch.

6. Time how long it takes to break down all of the starch in the mixture.

7. Repeat steps 1–5 at 20 °C, 25 °C and 30 °C.

8. Repeat for each temperature twice more.

The table below shows the student’s results.

Time taken until there was no starch in the sample in

minutes

Temperature in°C

Test 1 Test 2 Test 3 Mean

15 6.1 9.4 10.0 8.5

20 4.8 5.0 4.6 4.8

25 3.0 2.5 3.0 3.2

30 1.5 2.0 2.0

(a) One of the results in the table above is anomalous.

Draw a ring around the anomalous result.

(1)

(b) Calculate the mean for 30 °C.

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(c) Figure 2 shows a graph of the student’s results.

Figure 2

Use the graph to predict how long it would take to break down all of the starch at 10 °C.

Time = _________________ minutes

(1)

(d) The student tested samples of the mixture for starch every 30 seconds.

In each test she added one drop of iodine to the sample in the spotting tile.

Predict the colour of the samples from the 20 °C test at 4.0 minutes and 7.0 minutes.

Colour at 4.0 minutes __________________________________________

Colour at 7.0 minutes __________________________________________

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(e) The student did a fourth test at 30 °C.

In this test the starch did not break down, even after 45 minutes.

Why did the amylase not break down the starch in this test?

Tick one box.

The amylase solution and the starch suspension were mixed before thestart of the experiment.

The amylase solution had been prepared with water at 95 °C.

The amylase solution had been prepared with water at 20 °C.

The amylase solution had been stored in the fridge.

(1)

(f) The student made the following conclusion about the optimum temperature for amylase towork at.

‘Amylase works fastest at 40 °C’

Her teacher said that this is not a valid conclusion from her results.

Describe how the student could change her method to give results that would improve thevalidity of her conclusion.

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(6)

(Total 12 marks)

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The human body is organised to carry out many different functions.

(a) Use words from the box to complete Figure 1 by putting the parts of the body in order ofsize from smallest to largest.

The smallest one has been done for you.

(2)

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(b) The stomach is made of different types of tissue.

Draw one line from each type of stomach tissue to the correct description.

(3)

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(c) Animals can react to their surroundings because they have nervous systems.

A student investigated the behaviour of small animals called woodlice.

The student set up the investigation as shown in Figure 2.

• The student covered one half of a Petri dish with black paper to make that side of thePetri dish dark.

• The other side had no cover.

• The student put five woodlice into each side of the dish and then put the clear Petridish lid back on the dish.

Figure 2

After 30 minutes, all the woodlice had moved to the dark side of the Petri dish.

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(i) In this investigation, what is the stimulus that the woodlice responded to?

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(ii) In this investigation, what is the response that the woodlice made?

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(iii) The student concluded that woodlice prefer dark conditions.

Give two ways in which the student could improve the investigation to be sure thathis conclusion was correct.

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2. ____________________________________________________________

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(2)

(Total 9 marks)

This question is about hormones.

(a) (i) Hormones carry messages.

What type of messenger is a hormone?

Draw a ring around the correct answer.

chemical electrical environmental

(1)

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(ii) Which part of the brain secretes hormones?


cerebellum medulla pituitary gland

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(b) Figure 1 shows the level of a pregnancy hormone over a 40-week pregnancy.

This hormone can be detected in a pregnancy test.

Figure 1

A woman takes a pregnancy test.

In which week of pregnancy is the test most likely to give a positive result?

Use information from Figure 1.

Write the correct answer in the box.

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(c) Figure 2 shows the levels of three other hormones during pregnancy.

The baby is usually born at about 40 weeks.

Figure 2

Adaptation by kind permission of Biozone International

(i) Describe the patterns in the levels of oestrogen and progesterone from 0 to 36weeks.

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(4)

(ii) Which hormone is likely to stimulate contractions of the uterus (womb) when thebaby is born?

Use information from Figure 2 to give a reason for your answer.

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(2)

(Total 9 marks)

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(a) Control systems help to keep conditions in the human body relatively constant.

What is the general name for the processes that keep body conditions relatively constant?


eutrophication homeostasis hydrotropism

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(b) The concentration of glucose in the blood is controlled by hormones.

Use the correct answer from the box to complete each sentence.

glucagon glycerol glycogen

kidney liver pancreas

When the blood glucose concentration increases, an organ called

the ______________________ releases the hormone insulin.

Insulin causes glucose to move from the blood into the cells of the muscles

and the ______________________ .

Inside these organs, the glucose is changed into a carbohydrate called

______________________ , which can be stored.

When the blood glucose concentration falls, another hormone is released,

which causes the storage carbohydrate to break down into glucose again.

This hormone is called ______________________ .

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(c) A person with Type 1 diabetes does not make enough insulin.

The person needs to test their blood at intervals throughout the day.

If the concentration of glucose in their blood is too high, the diabetic person needs to injectinsulin.

(i) Insulin is a protein.

It must be injected and cannot be taken by mouth.

Explain why.

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(2)

(ii) Apart from injecting insulin, give one other way that a diabetic person couldhelp to control the concentration of glucose in their blood.

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(d) Pet dogs have been trained to detect if the concentration of glucose in the blood of theirdiabetic owners is outside the normal healthy range. These dogs are called ‘medicalresponse dogs’.The dogs respond in different ways. They may bark, jump up, or stare at their owners.Theymay even fetch a blood-testing kit.

(i) Suggest what stimulus the dogs might be responding to when they behave likethis.

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(1)

(ii) Table 1 shows how the concentration of glucose varied in blood samples fromfive diabetic people. Measurements were made both before and after getting amedical response dog.

Table 1

Mean percentage of blood samples withdifferent concentrations of glucose from the

five diabetic people

Number ofblood

samplesmeasured

Low glucoseWithin normal

range ofglucose

High glucose

Before getting a dog 1704 32.6 54.8 12.6

After getting a dog 1724 18.6 61.6 19.8

A survey was made of the effect of a medical response dog on the lives of 16 diabeticpeople.

Table 2 shows how well these diabetic people agreed with each statement in thesurvey.

Table 2

Statement in surveyTotallyagree

Somewhatagree

Neitheragreenor

disagree

Somewhatdisagree

Totallydisagree

I am more independentsince getting my dog.

12 2 2 0 0

There are disadvantagesto having a medical

0 0 4 4 8

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response dog.

I trust my dog to alert mewhen my sugar levels arelow.

11 3 1 0 1

I trust my dog to alert mewhen my sugar levels arehigh.

6 7 0 1 2

Evaluate how useful medical response dogs are for warning diabetic people that theconcentration of glucose in their blood is outside the normal range.

Use information from Tables 1 and 2.

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(e) Table 3 shows the concentrations of some substances in the urine of a non-diabetic personand in the urine of a diabetic person.

Table 3

Concentration of substance in urine in g per dm3

Substance Non-diabetic person Diabetic person

Protein 0 0

Glucose 0 2.0

Urea 20.0 19.5

Sodium ions 6.0 5.8

Compare the results for the non-diabetic person and the diabetic person.Give reasons for any differences.

Use your knowledge of how the kidney works.

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(5)

(Total 19 marks)

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This question is about the nervous system.

(a) Describe the function of receptors in the skin.

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(2)

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(b) A response is caused when information in the nervous system reaches an effector.

(i) There are two different types of effector.

Complete the table to show:

• the two different types of effector

• the response each type of effector makes.

(4)

(ii) Some effectors help to control body temperature.

Give one reason why it is important to control body temperature.

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(1)

(Total 7 marks)

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The diagram shows the position of two glands, A and B, in a woman.

(a) (i) Name glands A and B.

A ___________________________________

B ___________________________________

(2)

10

(ii) Gland A produces the hormone Follicle Stimulating Hormone (FSH).

FSH controls changes in gland B.

How does FSH move from gland A to gland B?

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(b) (i) A woman is not able to become pregnant. The woman does not produce matureeggs. The woman decides to have In Vitro Fertilisation (IVF) treatment.

Which two hormones will help the woman produce and release mature eggs?

Tick ( ) one box.

FSH and Luteinising Hormone (LH)

FSH and oestrogen

Luteinising Hormone (LH) and oestrogen

(1)

(ii) Giving these hormones to the woman helps her to produce several mature eggs.Doctors collect the mature eggs from the woman in an operation.

Describe how the mature eggs are used in IVF treatment so that the woman maybecome pregnant.

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(3)

(iii) IVF clinics have been set a target to reduce multiple births.

At least 76% of IVF treatments should result in single babies anda maximum of 24% of treatments should result in multiple births.

Suggest one reason why the clinics have been set this target to reduce multiplebirths.

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(c) Two clinics, R and S, used IVF treatment on women in 2007. Doctors at each clinic usedthe results of the treatments to predict the success rate of treatments in 2008.

The table shows the information.

Total number of IVFtreatments in 2007

Number of IVFtreatments resulting in

pregnancy in 2007

Predicted percentagesuccess rate in 2008

Clinic R 1004 200 18–23

Clinic S 98 20 3–56

(i) Compare the success rates of the two clinics in 2007.

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(1)

(ii) The range of the predicted success rate in 2008 for clinic R is much smaller than therange of the predicted success rate for clinic S.

Suggest why.

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(2)

(Total 11 marks)

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People with Type 1 diabetes cannot control the concentration of glucose in their blood.

This is because they do not produce the hormone insulin.

The same concentration and volume of glucose solution is given to two people.

• Person with Type 1 diabetes.

• Person without Type 1 diabetes.

Figure 1 shows how the blood glucose concentration of these people changes after they eachdrink a glucose solution.

Figure 1

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(a) The blood glucose concentration increases at a faster rate in the person with diabetescompared to the person without diabetes.

Calculate how much faster the rate of increase in blood glucose concentration is in theperson with diabetes.

Give the rate of increase for the first 30 minutes after drinking the glucose solution.

Give your answer in units / h.

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___________________ Units / h

(2)

(b) The blood glucose concentration of the person without diabetes starts to change 30minutes after drinking the glucose solution.

Explain why the blood glucose concentration changes.

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(c) People with diabetes should try to keep their blood glucose concentration within the samerange as a person without diabetes.

Most people with Type 1 diabetes regularly check their blood glucose concentration using ameter, as shown in Figure 2.

The meter reading is used to estimate how much insulin they need to inject.

Figure 2

© Vincente Barcel/Hemera/Thinkstock

Figure 3 shows a new system.

It is connected to the person all the time.

Figure 3

The new system:

• gives better control of blood glucose concentration

• reduces the number of times the glucose concentration falls too low.

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Evaluate the two systems as methods for controlling blood glucose concentrations forpeople with Type 1 diabetes.

Give a justified conclusion to your evaluation.

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(4)

(d) How does the body respond if slightly too much insulin is injected into the body.

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(5)

(Total 13 marks)

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Hormones are released from glands.

(a) Which gland produces hormones to control other glands in the endocrine system?

Tick one box.

Adrenal

Ovary

Pituitary

Thyroid

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(b) The figure below shows the level of adrenaline in a man’s bloodstream while he waswatching a 12-minute film.

Calculate the percentage increase in adrenaline after point B.

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Percentage increase in adrenaline = _________________

(2)

(c) Suggest why the percentage increase in adrenaline after point B is different from thepercentage increase after point A.

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(d) Adrenaline causes changes in the body to prepare for a ‘fight or flight’ response.

What changes in the man’s body are caused by adrenaline?

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(2)

(Total 7 marks)

The figure below shows how the concentrations of the reproductive hormones in the blood of awoman change over 28 days.

(a) Name hormones A and B.

A _________________________________________________________________

B _________________________________________________________________

(2)

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(b) Use information from the figure above to explain what happens on Day 14.

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(c) In Vitro Fertilisation (IVF) treatment can be used to help women become pregnant.

IVF uses some of the hormones shown in the figure above.

Explain why IVF increases the chance of some women becoming pregnant.

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(6)

(Total 10 marks)

In this question you will be assessed on using good English, organising information clearly andusing specialist terms where appropriate.

Homeostasis keeps conditions in the body relatively constant.

The amount of water in the body is controlled by homeostasis.

Kidney function is controlled by a gland in the brain.

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Describe how the water content of the blood is controlled.

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(Total 6 marks)

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The diagram below shows how a nerve impulse passing along a relay neurone causes animpulse to be sent along another type of neurone, neurone X.

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(a) What type of neurone is neurone X?

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(1)

(b) Describe how information passes from the relay neurone to neurone X.Use the diagram to help you.

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(3)

(c) Scientists investigated the effect of two toxins on the way in which information passesacross synapses. The table below shows the results.

Toxin Effect at the synapse

CurareDecreases the effect of the chemicalon neurone X

StrychnineIncreases the amount of the chemicalmade in the relay neurone

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Describe the effect of each of the toxins on the response by muscles.

Curare _____________________________________________________________

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Strychnine __________________________________________________________

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(2)

(Total 6 marks)

Phenylketonuria (PKU) is an inherited condition. PKU makes people ill.

(a) PKU is caused by a recessive allele.

(i) What is an allele?

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(1)

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(ii) What is meant by recessive?

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(b) The diagram below shows the inheritance of PKU in one family.

(i) Give one piece of evidence from the diagram that PKU is caused by a recessiveallele.

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(ii) Persons 6 and 7 are planning to have another child.Use a genetic diagram to find the probability that the new child will have PKU.

Use the following symbols in your answer:

N = the dominant allele for not having PKU

n = the recessive allele for PKU.

Probability = _________________________

(4)

(c) Persons 6 and 7 wish to avoid having another child with PKU.

A genetic counsellor advises that they could produce several embryos by IVF treatment.

(i) During IVF treatment, each fertilised egg cell forms an embryo by cell division.

Name this type of cell division.

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(1)

(ii) An embryo screening technique could be used to find the genotype of each embryo.

An unaffected embryo could then be placed in person 7’s uterus.

The screening technique is carried out on a cell from an embryo after just three celldivisions of the fertilised egg.

How many cells will there be in an embryo after the fertilised egg has

divided three times?

(1)

(iii) During embryo screening, a technician tests the genetic material of the embryo tofind out which alleles are present.

The genetic material is made up of large molecules of a chemical substance.

Name this chemical substance.

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(1)

(d) Some people have ethical objections to embryo screening.

(i) Give one ethical objection to embryo screening.

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(ii) Give one reason in favour of embryo screening.

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(1)

(Total 12 marks)

The diagram shows the structures involved in the knee-jerk reflex. When the person is hit at pointP, the lower leg is suddenly raised.

(a) Name the structures labelled A, B and C.

A __________________________________________________________

B __________________________________________________________

C __________________________________________________________

(3)

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(b) How is information passed across a synapse?

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(1)

(c) What is the effector in this response?

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(1)

(Total 5 marks)

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The number of cases of Type 2 diabetes in the UK is increasing rapidly.

(a) Describe how insulin and glucagon help control the blood sugar concentration in a healthyperson.

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(b) What is Type 2 diabetes?

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(c) Body mass index (BMI) is a person’s body weight divided by the square of his or her height.

(i) Graph 1 shows the relationship between BMI and the percentage probability ofdeveloping Type 2 diabetes.

Graph 1

Percentage probability of developing Type 2 diabetes

Suggest an explanation for the relationship between BMI and the risk of developingType 2 diabetes.

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(ii) Graph 2 shows changes in the number of new cases of Type 2 diabetes in the UK.

Graph 2

Year

Suggest explanations for the trend shown by the data in Graph 2.

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(3)

(Total 12 marks)

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The pancreas and the liver are both involved in the control of the concentration ofglucose in the blood.

The liver has two veins:

• the hepatic portal vein taking blood from the small intestine to the liver

• the hepatic vein taking blood from the liver back towards the heart.

Scientists measured the concentration of glucose in samples of blood taken from thehepatic portal vein and the hepatic vein. The samples were taken 1 hour and 6 hoursafter a meal.

Graph 1 shows the concentration of glucose in the two blood vessels 1 hour after the meal.

Graph 1

Blood vessel

(a) The concentration of glucose in the blood of the two vessels is different.Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(3)

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(b) Graph 2 shows the concentration of glucose in the two blood vessels 6 hours after themeal.

Graph 2

Blood vessel

(i) The concentration of glucose in the blood in the hepatic portal vein 1 hour after themeal is different from the concentration after 6 hours.

Why?

______________________________________________________________

______________________________________________________________

(1)

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(ii) The person does not eat any more food during the next 6 hours after the meal.

However, 6 hours after the meal, the concentration of glucose in the blood in thehepatic vein is higher than the concentration of glucose in the blood in the hepaticportal vein.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(3)

(Total 7 marks)

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The diagram shows the nervous pathway used to coordinate the knee-jerk reflex.When the person is hit at point P, the lower leg is suddenly raised.

20

(a) Name neurones A, B and C.

A __________________________________________________________

B __________________________________________________________

C __________________________________________________________

(3)

(b) The receptor in the muscle in the leg is sensitive to a stimulus.

Suggest the stimulus.

___________________________________________________________________

(1)

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(c) Describe what happens at the synapse during this reflex.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(3)

(Total 7 marks)

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Mark schemes

(a) any two from:

• same result at pH 7 and 7.5orcould be any pH between 7 and 7.5ornot tested at pH 7.25orneed to test at smaller pH intervals (between 7 and 7.5)

• accuracy of result only to nearest 0.5 minutes• no repeats• difficult to determine end point (colour)

2

1

(b) 2.7 / 51

0.54 (units per minute)

allow 0.52 with no working shown for 2 marks1

allow 1 mark for 0.52 or 0.56

(c) (after 10 minutes) solution goes black1

(after 60 minutes) solution stays the sameordoes not go blackorgoes slightly orange

1

(d) steeper curve1

levels off at 11.8 units and before 45 minutes1

(e) no / little sugar produced

allow a correct description of what the graph would look like1

(because at 65 °C) the enzyme will be denatured

allow (because) the enzyme’s shape will be changed

or

(because) the active site is damaged1

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(so) will no longer fit the starchor(so) will not be able to catalyse the reaction

1

[11]

(a) fast reaction to reduce / protect from harm

allow named examples1

2

(b) higher caffeine concentration causes shorter reaction time.

allow converse

ignore ‘faster / slower reaction time’1

(c) Level 3 (5–6 marks):A coherent method is described with relevant detail, which demonstrates a broadunderstanding of the relevant scientific techniques and procedures. The steps in themethod are logically ordered. The method would lead to the collection of valid results.

Level 2 (3–4 marks):The bulk of a method is described with mostly relevant detail, which demonstrates areasonable understanding of the relevant techniques and procedures. The method maynot be in a completely logical sequence and may be missing some detail.

Level 1 (1–2 marks):Discrete relevant points are made which demonstrate some understanding of the relevantscientific techniques and procedures. They may lack a logical structure and would notlead to the production of valid results.

0 marks:No relevant content.

Indicative content• use decaffeinated coffee as control• control volume of coffee• blind trial or do not tell students which coffee they are drinking• left for standard time between drink and test• at least 10 minutes• control start position of ruler• control other factors such as light in the room• same person for different concentrations• repeat for each caffeine concentration• use a range of caffeine concentrations• start with lowest concentration of caffeine• use caffeine solution instead of coffee to control for other ingredients• repeat investigation with more people and calculate means

6

[8]

(a) 0.92 = 76.2 × time13

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time = 0.92 ÷ 76.21

= 0.012

allow 0.012 with no working shown for 3 marks1

(b) pathway B has two synapses

allow converse for pathway A1

chemicals diffuse across each synapse1

which slows down the impulse1

(c) 140−2031

(d) use the same person for each test1

use left hand and right hand1

use a bigger sample size or more people

allow take more readings with each person1

(e) mean drop distance = (230 + 211 + 279 + 215 + 264) ÷ 5 = 239.81

239.8 mm = 0.2398 m1

mean reaction time =

1

= 0.221

incorrect sig. figs max. 3 marks1

allow 0.221 with no working shown for 4 marks

[14]

(a) products below reactants14

correct energy profile1

activation energy correctly labelled1

energy given out correctly labelled1

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(b) 31 (%)1

(c) the products would be above the reactants1

(d) catalysts increase rate of reaction

1 mark for each property

1 mark for each explanation

so products formed in less time

or

catalysts lower activation energy

explanation must be linked correctly to the property to gain the mark

so lowers energy requirements

or

catalysts not used up in the reaction

so only an initial outlay needed

or

only a small amount of catalyst needed

so small initial costmax. 4

(e) Protein1

(f) high temperatures1

extremes of pH1

(g) lactase acts as the lock, lactose is the key (substrate)1

lactase has an active site which will only fit lactose molecules1

so lactase will not work with other molecules1

[16]

(a) 6.1 circled on table (15 °C, test 1)15

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(b) 1.8

do not allow 1.831

(c) 16 (minutes)

correct number extrapolated from curve1

(d) 4.0 min – blue / black / purple1

7.0 min – yellow / orange / brown1

(e) The amylase solution had been prepared with water at 95 °C1

(f) Level 3 (5–6 marks):A clear and coherent method is described using logical steps and demonstrating a goodunderstanding of how to improve the validity of the method. The method would lead tothe production of valid results that would give rise to a more valid conclusion.

Level 2 (3–4 marks):The substantive content of a method is present and demonstrates reasonableunderstanding of how to improve the validity but may be missing some detail. The planmay not be in a completely logical sequence but leads towards the measurement ofrate of the reaction.

Level 1 (1–2 marks):Simple relevant statements made, which demonstrate limited understanding of how toimprove the experimental method. The response lacks logical structure and would notlead to the production of valid results or a more precise optimum temperature.

0 marks:No relevant content

Indicative content• conduct at a greater range of temperatures• use temperatures both above and below 40 °C• use smaller temperature intervals to get a more accurate optimum (eg go

up in 2 °C increments)• take samples at smaller time intervals to get a more accurate result for

‘time taken’• control the volume of starch used (eg 5 cm 3)• control the volume of the amylase solution (eg 1 cm 3)• control the temperature (eg using a water bath)• heat the two solutions separately before mixing• control the concentration of the starch solution• control the concentration of the amylase solution

6

[13]

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(a) tissue → organ → organ systemone right for 1 mark

three right for 2 marks2

6

(b) Epithelial tissue → covers the outside and the inside of the stomachmore than one line from a tissue = no mark

1

Glandular tissue → produces digestive juices1

Muscular tissue → allows food to be churned around the stomach1

(c) (i) light

ignore dark1

(ii) moving (to the dark)1

(iii) any two from:

• use more woodlice• repeat the experiment• run for a longer time

2

[9]

(a) (i) chemical1

(ii) pituitary gland1

7

(b) 8

allow 9 or 101

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(c) (i) any four from:• progesterone starts being produced at 4 weeks / no progesterone before

4 weeks• and then / from 4 weeks increases• oestrogen at constant / low level (from 0) to 20 weeks• and then / from 20 weeks increases• from 20 − 36 weeks level of O rises more steeply than that of Por• P is always higher than 0 from 6 to 36 weeks

if no other marks awarded, allow progesterone and oestrogen bothincrease / rise for 1 mark.

4

(ii) oxytocin1

level of oxytocin increases just before birth1

[9]

(a) homeostasis1

(b) in sequence:

pancreas1

liver1

glycogen

correct spelling only1

glucagon


8

(c) (i) broken down / digested1

further detail eg into amino acids / by enzymes / by proteases1

(ii) diet / eating less sugar / less fat

ignore balanced dietor

ignore ‘dieting’ / slimming diet

exercise

accept pancreas transplant1

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(d) (i) sensible suggestioneg (owner’s) smell / sweating / change in owner’s behaviour / dizziness /tiredness

1

(ii) any five from:

allow 1 mark for justified conclusion

do not allow full marks unless at least 1 pro and 1 con.

Pro:• % below normal decreases• % in normal increases• reliable / repeatable / valid data as large number of samples

do not allow accurate / precise• patients express satisfaction.

Con:• may not be reliable as blood glucose measurements for only 5 patients /

survey of only 16 (dog owners)• % above normal increases / dogs are less good at detecting high glucose.

5

(e) glucose in urine of diabetic (and not in the non-diabetic)1

urea and Na+ ions are similar in each / slightly lower in diabetic1

+ any three from:• no protein in either urine sample because protein too large / does not pass

through filter• glucose passes through filter in kidney

ignore glucose is reabsorbed• non-diabetic: the / all glucose is reabsorbed / taken back into blood• diabetic: (too much glucose so) cannot all be reabsorbed• because diabetic has high concentration of glucose in blood• urea and Na+ lower in diabetic because less water is reabsorbed (due to extra

glucose in filtrate).3

[19]

(a) detect changes in surroundings or detect stimuli

allow any named stimulus for skin1

9

convert information to impulse

allow send impulse to sensory neurones / brain1

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(b) (i)

muscle contract(ion)

gland release / secrete /produce chemical /hormone / enzyme

1 mark for each effector

1 mark for each response

response must match type of effector (if given)

ignore examples

ignore relax(ation) / movement for contraction

do not allow expansion for muscles4

(ii) any one from:

• (maintain temperature at which) enzymes work best• so chemical reactions are fast(est)• prevent damage to cells / enzymes

allow prevent enzymes being denatured (by temperature being toohigh)

1

[7]

(a) (i) A – pituitary

allow hypothalamus1

10

B – ovary / ovaries1

(ii) in blood (stream)

accept in plasma

ignore dissolved1

(b) (i) FSH and Luteinising Hormone (LH)1

(ii) fertilisedORreference to sperm

1

form embryos / ball of cells or cell division1

(embryo) inserted into mother’s womb / uterus

allow (fertilised egg) is inserted into mother’s womb / uterus1

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(iii) any one from:

• multiple births lead to low birth weight

• multiple births cause possible harm to mother / fetus / embryo / baby /miscarriages

allow premature

ignore reference to cost / ethics / population1

(c) (i) any one from:

• almost identical

allow S (slightly) more successful

• both approximately 20%1

(ii) larger numbers (in clinic R) (in 2007)

allow only 98 (in S) (compared to 1004 (in R))1

results likely to be more repeatable (in 2008)

allow more reliable

do not accept more reproducible / accurate / precise1

[11]

(a) (76 − 28) × 2111

96 (units / h)

allow 96 (units / h) with no working shown for 2 marks1

allow 1.6 units / min for 1 mark

allow answer in range of 94–104

(units / h) for 1 mark

(b) increased blood glucose concentration causes insulin release from pancreas1

which stimulates cells to absorb glucose / sugar from the blood, so blood glucoseconcentration decreases

1

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(c) any three from:

at least one advantage and one disadvantage of the system(s)must be given for full marks

allow responses phrased in terms of the meter and injectionsystems

advantages of the new system:

• better control so reduces risk of future health problems

allow fewer low / high blood glucose periods so safer• no need to estimate dose of insulin• less chance of giving too much / little insulin• system works automatically / continuously so no need to test / inject

disadvantages of the new system:

• system is always attached so may restrict activities

allow pump is difficult to hide• pump has to be carried somewhere

allow risk of discomfort• pump will need re-filling• risk of infection

orrisk of tissue damage (at injection site)

• line might come out

accept new system more expensive3

qualified conclusion: a statement as to which system is better with reference to at leastone advantage and one disadvantage

for example, the new system is better because although it is moreexpensive, it works automatically

1

(d) blood glucose concentration goes too low1

blood glucose concentration detected by pancreas1

pancreas releases glucagon1

(glucagon causes) cells to convert to glycogen into glucose1

glucose released into blood1

[13]

(a) Pituitary112

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(b)

1

= 150 (%)1

(c) the level in the blood is already higher than it was before point A1

levels hadn’t returned to normal yet (before the next scare)

allow he had already been scared so he was expecting the secondscare

1

(d) increased oxygen to brain / muscles1

increased glucose to brain / muscles1

[7]

(a) A FSH

allow follicle stimulating hormone1

13

B Progesterone1

(b) LH peaks

allow luteinising hormone1

which causes an egg to be released.1

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(c) Level 3 (5–6 marks):A detailed and coherent explanation is given, which logically links the role of differenthormones to their use in IVF and a clear explanation of how IVF increases the chance ofa successful pregnancy.

Level 2 (3–4 marks):An attempt is made to link the role of hormones to their use in IVF. The logic used inexplaining how IVF increases the chance of a successful pregnancy may not be clear orlinked to the hormones.

Level 1 (1–2 marks):Discrete relevant points made. The logic may be unclear and links may not be made.

0 marks:No relevant content

Indicative content

Identification of hormones used in IVF:• FSH• LH.

Role of hormones in IVF:• FSH causes eggs to mature• LH causes the eggs to be released.

Effect on chance of successful pregnancy:• high levels of hormones cause many eggs to be matured and released• sperm and eggs are collected and eggs are fertilised (so increased probability

of fertilisation)• fertilised eggs are given time to develop into a small ball of cells• some are transferred into the mother (uterus), to increase the probability of

one successfully implanting.6

[10]

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Marks awarded for this answer will be determined by the Quality of Communication (QC) as wellas the standard of the scientific response. Examiners should also refer to the information onpage 5, and apply a ‘best-fit’ approach to the marking.

0 marksNo relevant content.

Level 1 (1 – 2 marks)There is a brief description of kidney function including a mention of pituitary gland orhormones but roles may be confused.

Level 2 (3 – 4 marks)There is a clear description of kidney function in relation to fluctuations in blood waterlevels and the roles of the pituitary gland or hormone is mentioned with correct role.

Level 3 (5 – 6 marks)There is a clear and detailed scientific description of kidney function in relation tofluctuations in blood water levels and of the roles of the pituitary gland and ADH.

examples of biology points made in the response:

• if water content too low, ADH released• from pituitary gland• into the blood• (causing) kidney reabsorbs more water• more concentrated / small volume urine produced• if water content too high, ADH lowered / not produced• less water reabsorbed by kidney• more dilute / larger volume urine produced

full marks may be awarded for detailed description of either waterloss or gain

[6]

14

(a) motor

allow efferent / postsynaptic

allow another relay (neurone)1

15

(b) release of chemical (from relay neurone)

allow ecf for ‘motor’ neurone from (a)

allow release of neurotransmitter / named example1

chemical crosses gap / junction / synapse

allow diffuses across

allow chemical moves to X1

chemical attaches to X / motor / next neurone (causing impulse)1

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(c) (curare) decrease / no contraction

accept (muscle) relaxes1

(strychnine) increase / more contraction

if no other mark awarded allow 1 mark for (curare) decrease / noresponse and (strychnine) increase / more response

1

[6]

(a) (i) one form of a / one gene

do not allow ‘a type of gene’

allow a mutation of a gene1

16

(ii) not expressed if dominant / other allele is present / if heterozygous

or

only expressed if dominant allele not present / or no other allele present

allow need two copies to be expressed / not expressed if only onecopy / only expressed if homozygous

1

(b) (i) two parents without PKU produce a child with PKU / 6 and 7 → 10

allow ‘it skips a generation’1

(ii) genetic diagram including:

accept alternative symbols if defined

Parental gametes:

6: N and nand 7: N and n

1

derivation of offspring genotypes:

NN Nn Nn nn

allow genotypes correctly derived from student’s parental gametes1

identification: NN and Nn as non-PKU

OR nn as PKU

allow correct identification of student’s offspring genotypes1

correct probability only: 0.25 / ¼ / 1 in 4 / 25% / 1 : 3

do not allow 3 : 1 / 1 : 4

do not allow if extra incorrect probabilities given1

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(c) (i) mitosis


(ii) 81

(iii) DNA

allow deoxyribonucleic acid

do not allow RNA / ribonucleic acid1

(d) (i) may lead to damage to embryo / may destroy embryos / embryo cannot giveconsent

allow avoid abortion

allow emotive terms – eg murder religious argument must bequalified

allow ref to miscarriage

allow idea of avoiding prejudice against disabled people

allow idea of not producing designer babies1

(ii) any one from:

• prevent having child with the disorder / prevent future suffering / reduceincidence of the disease

ignore ref to having a healthy child

ignore ref to selection of gender• embryo cells could be used in stem cell treatment

allow ref to long term cost of treating a child (with a disorder)

allow ref to time for parents to become prepared1

[12]

(a) A sensory (neurone)

ignore nerve1

17

B motor (neurone)

ignore nerve1

C spinal cord / central nervous system / white matter

accept grey matter1

(b) by chemical / substance

allow transmitter1

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(c) muscle

allow extensor

ignore muscle names1

[5]

(a) any six from:

• hormone(s) / named produced by pancreas• if blood glucose levels are too high, insulin is produced / released• allowing glucose to move from the blood into the cells / named eg liver• glucose is converted to glycogen• if blood glucose levels fall, glucagon is produced / released• glycogen is converted to glucose• causing glucose to be released into the blood

6

18

(b) diabetes that occurs when the body (cells) do not respond / are less responsive toinsulin

1

(c) (i) higher BMIs due to increase in mass / weight (relative to height) / obesity1

obesity / being overweight / being fat is a (significant) risk factor for Type 2diabetes

allow causes Type 2 diabetes1

(ii) any three from:

• related to described change in diet eg fast foods• and less exercise• which increases the chance of obesity / increases BMI• increased awareness has helped to slow the increase

3

[12]

(a) (concentration high) in the hepatic portal vein is blood with glucose absorbed from theintestine

1

19

concentration is lower in the hepatic vein because insulin1

(has caused) glucose to be converted into glycogen1

or

allows glucose into liver cells

(b) (i) (after 6 hours) most of the glucose has been absorbed from the intestine orfrom food into the blood

1

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(ii) because glucagon (made in the pancreas) causes

if biological terms incorrectly spelt they must be phoneticallyaccurate

do not accept glucagon made / produced by the liver1

glycogen to be converted into glucose1

glucose released into blood

allow the liver maintains the correct / constant level of glucose inthe blood

1

[7]

(a) ignore nerve / neuron(e) throughout

A sensory

accept afferent1

20

B motor

accept efferent1

C relay

accept intermediate1

(b) stretch

allow pressure / pull / tension (in muscle)

allow a hit at (point) P

ignore pain1

(c) any three from:

• chemical (release)

accept neurotransmitter / acetylcholine

• diffuses (across the gap / synapse)

• transmits impulse / information (across synapse)

allow transmits signal / message

• between neurones / nerve cells / named

if named, must be either sensory / A to relay / C or relay / C tomotor / B

allow ‘to the next neurone‘3

[7]

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Name: B5 Homeostasis and Response · 2018-03-27 · (e)€€€€€Student A’s mean reaction...

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