A-level Biology (7401/7402)



Yüklə 294,43 Kb.
səhifə1/4
tarix05.02.2018
ölçüsü294,43 Kb.
  1   2   3   4

Feversham College



A-level Biology (7401/7402)

Practical Techniques



Name:

Class:





 

Author:




Date:




Time:

2 hours

Marks:

103

Comments:




 



Q1.A student investigated the effect of different wavelengths of light on the rate of photosynthesis. She used the apparatus shown in Figure 1.

Figure 1
(a)     What measurements should the student have taken to determine the rate of photosynthesis?

........................................................................................................................

........................................................................................................................

(1)

(b)     Other than temperature and pH, give two factors which should be kept constant during this investigation.

1 .....................................................................................................................

2 .....................................................................................................................



(2)

(c)     The student did not use a buffer to maintain the pH of the solution.


Explain what would happen to the pH of the solution during this investigation.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................



(2)




(d)     Figure 2 shows the student’s results.



Figure 2
Suggest and explain why the rate of photosynthesis was low between 525 nm and 575 nm wavelengths of light.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................



[Extra space] ................................................................................................

........................................................................................................................



(2)

(Total 7 marks)










Q2.          (a)     Give two ways in which active transport is different from facilitated diffusion.

1 ...................................................................................................................

......................................................................................................................

2 ...................................................................................................................

......................................................................................................................

(2)

Scientists investigated the effect of a drug called a proton pump inhibitor. The drug is given as a tablet to people who produce too much acid in their stomach. It binds to a carrier protein in the surface membrane of cells lining the stomach. This carrier protein usually moves hydrogen ions into the stomach by active transport.

The scientists used two groups of people in their investigation. All the people produced too much acid in their stomach. People in group P were given the drug. Group Q was the control group.

The graph shows the results.

 

(b)     (i)      The scientists used a control group in this trial. Explain why.



.............................................................................................................

.............................................................................................................



(1)
(ii)     Suggest how the control group would have been treated.

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

(2)

(c)     Describe the effect of taking the drug on acid secretion.

......................................................................................................................

......................................................................................................................

......................................................................................................................

(1)

(Total 6 marks)

Q3.          A protease is an enzyme that digests protein. The graph shows how the activity of a protease varies with temperature.

 

(a)     (i)      Describe what the graph shows about the effect of temperature on the rate of reaction.



.............................................................................................................

.............................................................................................................

.............................................................................................................

(1)




(ii)     Explain the shape of the curve between 30 °C and 50 °C.

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................



(Extra space) ......................................................................................

.............................................................................................................



(3)

(b)     Students investigated the effect of pH on the activity of the protease.

•        The students used agar plates containing protein. The protein made the agar cloudy.

•        They made four wells of equal size in the agar of each plate.

•        They added a drop of protease solution to each of the wells. The protease solution in each well was at a different pH.

•        The students incubated the agar plates for 4 hours at a constant temperature.

The diagram shows the agar plates after they were incubated and the pH of the protease solution in each well.

 

(i)      How should the students make sure that the pH of the protease solution did not change?



.............................................................................................................

(1)




(ii)     Use the graph to suggest a suitable temperature for incubating the agar plates.

Explain your answer.

.............................................................................................................

.............................................................................................................

.............................................................................................................



(1)

(iii)     Use the diagram to describe the effect of pH on the activity of this protease.

.............................................................................................................

.............................................................................................................

.............................................................................................................

(1)

(Total 7 marks)

 Q4.Ecologists studied a community of fish in a lake.

(a)     Explain what is meant by a community.

........................................................................................................................

........................................................................................................................

........................................................................................................................



(1)

(b)     (i)      The ecologists could have used the mark-release-recapture method to estimate the number of one species of fish in the lake. Describe how.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................



(Extra space) ........................................................................................

...............................................................................................................

...............................................................................................................

(3)

(ii)     This species of fish breeds at a certain time of the year. During this fish-breeding season, the mark-release-recapture technique might not give a reliable estimate.


Suggest one reason why.

...............................................................................................................

...............................................................................................................

...............................................................................................................



(1)

(c)     The ecologists found that each species of fish had adaptations to its niche. One of these adaptations was the shape of its mouth.

Suggest how the shape of mouth is an adaptation to its niche.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................



(2)

Q5.Scientists investigated the effect of drinking tea and coffee on reducing the risk of developing one type of brain cancer. The investigation involved 410 000 volunteers and was conducted in 10 European countries over a period of 8.5 years.

(a)     (i)      Apart from age, suggest two factors that the scientists should have considered when selecting volunteers for this trial.

1 ............................................................................................................

2 ............................................................................................................



(2)

(ii)     Give two features of the design of this investigation that would ensure the reliability ofthe results obtained.

1 ............................................................................................................

...............................................................................................................

2 ............................................................................................................

...............................................................................................................



(2)




(b)     The incidence for this type of brain cancer is 6 cases per 100 000 per year.


Use this information to calculate the expected number of volunteers developing this cancer during the 8.5 year period of this investigation. Show your working.

 

 



 

 

 



 

                Answer..................................................................................



(2)

(c)     In analysing the results of this investigation, the scientists took into account the age of the volunteers. Suggest why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

(1)




(d)     During the investigation, the volunteers were asked to estimate the volume of tea and/or coffee that they drank each day. The types of tea and coffee consumed in different countries varied. When the data from all the countries were collected there was a correlation between drinking more than 100 cm3of tea or coffee each day and a reduced risk of developing this type of brain cancer.

Tea and coffee contain caffeine. A newspaper reported the results of this investigation under the headline ‘Caffeine helps cut cancer risk’. Explain why scientists could not support this view solely on the basis of this investigation.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

(Extra space) .................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................



(4)

(e)     Another group of scientists investigated the effect of caffeine on blood flow to certain parts of the brain. Volunteers were given different concentrations of caffeine solution to drink. A control group was also set up.

(i)      Describe how the control group should have been treated.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................



(2)

(ii)     Volunteers who drank the same concentration of caffeine solution often had different concentrations of caffeine in their blood. Suggest one reason for the difference in concentration of caffeine in the blood of volunteers.

...............................................................................................................

...............................................................................................................

...............................................................................................................

(1)

(iii)    The investigation showed that caffeine reduces the blood flow to certain parts of the brain. Suggest one way in which this could lead to a reduced risk of brain cancers.

...............................................................................................................

...............................................................................................................

...............................................................................................................

(1)

(Total 15 marks)










Q6.Catalase is used in a number of industrial processes. It is normally obtained from a fungus called Aspergillus niger. Scientists produced a mutant strain of A. niger called K30. They wanted to know if this mutant strain produced more catalase than the normal strain of A. niger.

•        The scientists grew samples of the normal strain of the fungus and of the K30 strain on jelly in separate Petri dishes. The jelly contained a blue substance which is turned colourless by catalase.

•        They incubated the dishes for 3 days then measured the diameter of the colourless zone around the fungus.

•        They calculated the ratio of the diameter of the colourless zone to the diameter of the fungus.

The diagram shows the dishes after incubation.

Normal
strain

 


K30 strain

 
(a)     The scientists grew both strains of fungi on dishes kept at 30 °C. Keeping the dishes at a temperature of 15 °C would affect the results. Use your knowledge of kinetic energy to explain why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

(2)

(b)     (i)      The scientists gave their results as ratios. Explain the advantage of giving the results of this investigation as a ratio.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

(2)

(ii)      For the normal strain the ratio of the diameter of the colourless zone to the diameter of the fungus was 1.1 : 1.

Calculate the ratio of the diameter of the colourless zone to the diameter of the fungus for the K30 strain. Show your working.

 

 



 

 

Ratio = ...................................................



(2)

(c)     The catalase produced by the K30 strain of the fungus is mainly an extracellular enzyme. This means that the fungus secretes catalase from its cells into the jelly in the Petri dish.

Describe and explain the evidence from the investigation which shows that the catalase is an extracellular enzyme.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................





Dostları ilə paylaş:
  1   2   3   4


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©genderi.org 2017
rəhbərliyinə müraciət

    Ana səhifə