Edexcel A (SNAB) A Level Biology

Topic Questions

8.2 The Brain, Behaviour & Disease

1a
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1 mark

The brain contains many different regions that each carry out different functions.

Which of the following functions correctly matches each region of the brain?

      Cerebrum Cerebellum Hypothalamus Medulla Oblongata
  A Involved with conscious activities such as vision, hearing and thinking Enables dancing, playing musical instruments and keeping our balance This is where functions such as breathing and heart rate is controlled Plays an important role in homeostatic mechanisms such as thermoregulation
  B Enables dancing, playing musical instruments and keeping our balance Involved with conscious activities such as vision, hearing and thinking Plays an important role in homeostatic mechanisms such as thermoregulation This is where functions such as breathing and heart rate is controlled
  C Plays an important role in homeostatic mechanisms such as thermoregulation This is where functions such as breathing and heart rate is controlled Involved with conscious activities such as vision, hearing and thinking Enables dancing, playing musical instruments and keeping our balance
  D Involved with conscious activities such as vision, hearing and thinking Enables dancing, playing musical instruments and keeping our balance Plays an important role in homeostatic mechanisms such as thermoregulation This is where functions such as breathing and heart rate is controlled
1b
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4 marks

Scientists use a variety of different equipment and techniques to study the brain in a non-invasive manner. Magnetic resonance imaging (MRI) and functional MRI (fMRI) are two of these techniques that can be used to study the brain.

Compare and contrast these two techniques.

1c
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2 marks

The visual cortex which is located in the outer layer of the cerebrum, develops during the critical period.

Explain the importance of the critical period in the development of the visual cortex.

1d
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2 marks

Studies regarding the development of the visual cortex was carried out by Hubel and Wiesel during the 1960s and 1970s. They used animals to model the effects of their experiments on the development of the visual cortex. The use of animals in scientific research remains controversial.

State two arguments against animal research.

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2a
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3 marks

The following graph shows the decrease in dopamine producing neurones over time during normal ageing and ageing in patients suffering from Parkinson's disease.

ddsdi-j-picture2

Describe the trends in the graph.

2b
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2 marks

Calculate the percentage decrease in dopamine producing neurones in 80 year old patients suffering from Parkinson's disease compared to those that aged normally. Round your answer to the nearest whole number.

2c
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4 marks

L-dopa forms part of a group of drugs known as dopamine precursors. These chemicals have been successfully used to treat the symptoms of Parkinson's disease.

Explain why L-dopa is an effective treatment for Parkinson's disease with reference to its action on synapses.

2d
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2 marks

Currently, research is being done on other potential treatments for Parkinson's disease that may eliminate the need to take drugs as a form of treatment.

Name two such possible treatments that is under investigation.

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3a
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2 marks

A scientist used a restriction enzyme to cut a section of mouse DNA into multiple pieces. The enzyme produced a staggered cut. A scientist wanted to insert these pieces of DNA into plasmids and used the same restriction enzyme to cut the plasmids. 

Explain why the pieces of mouse DNA would be able to join to the cut DNA of the plasmids.

3b
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2 marks

Name the other enzyme the scientist added to the mixture to form recombinant plasmids and describe its function.

3c
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2 marks

The plasmid formed from this experiment is used as a vector.

State what is meant by the term 'vector' when used in this context.

3d
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2 marks

Using micro-organisms such as bacteria in genetic engineering is often advantageous over using multicellular organisms such as plants or animals.

Give two possible advantages of using micro-organisms in genetic engineering.

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4a
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1 mark

The following graph shows an investigation comparing the reaction time of three species of snails (A, B and C). The snail's heads were gently brushed using a blade of grass and the time taken for the eye stalks to fully extend was measured.


xt8zLy-5_habituation

Which of the following statements is the most accurate regarding the results?

  A Species A had the longest reaction time, meaning that they were the first to become habituated to the stimulus.
  B Species B and C had similar reaction times throughout the entire experiment.
  C All three species of snails had a very similar reaction time near the end of the experiment.
  D Species A had the shortest reaction time, meaning that they were the first to become habituated to the stimulus.
4b
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4 marks

Habituation occurs when organisms become used to a stimulus, such as the blade of grass on the snail's head.

Explain how the transmission of nerve impulses changed in the snail species during the investigation into habituation.

4c
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2 marks

State two ways in which the validity of the experiment at part (a) could be improved.

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5a
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2 marks

HER2-positive breast cancer is a type of breast cancer in which patients test positive for human epidermal growth factor receptor 2 (HER2). Cancer cells with extra copies of the gene that codes for HER2 will produce large amounts of this protein. HER2 is a receptor protein found on the surface of breast cells which under normal circumstances help control the growth, division and repair of healthy cells. However, large amounts of HER2 stimulates the growth and division of cancer cells. This makes HER2-positive breast cancer a very aggressive form of cancer that spreads rapidly throughout the body.

Treatment involves a combination of chemotherapy, as well as trastuzumab, which is an antibody that binds specifically to HER2 proteins. Trastuzumab is an example of personalised medicine.

State what is meant by the term 'personalised medicine'.

5b
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2 marks

Explain how trastuzumab could act as a treatment for HER2-positive breast cancer.

5c
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2 marks

Personalised treatments, such as trastuzumab, have many social, moral and ethical issues.

Give two possible issues with personalised medicine.

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