AS & A Level Biology - 9700 Paper 2 2015 Summer Zone 2

Each of statements A to E describe a structure associated with the mammalian heart.
For each statement, identify the structure that is being described.

A The chamber that pumps blood into the pulmonary artery. ...........................................................................................................................

B A blood vessel that transports deoxygenated blood into the right atrium. ...........................................................................................................................

C The specialised tissue responsible for delaying the conduction of impulses from the atria to the ventricles. ...........................................................................................................................

D The blood vessels that supply cardiac muscle with oxygenated blood. ...........................................................................................................................

E The valve that prevents the backflow of blood from the ventricle that contains oxygenated blood. ...........................................................................................................................

(a) Describe the damage caused by B. pertussis that is shown in the area labelled X on Fig. 2.1 and explain how this will affect the functioning of the epithelial tissue of the trachea.

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(b) Goblet cells produce mucus. Name one other structure in the gas exchange system that also produces mucus.
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(c) Suggest how whooping cough is transmitted.
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(d) The presence of B. pertussis stimulates the production of mucin, a gel-like glycoprotein that is the main component of mucus.

The mucin produced by the cell is packaged into vesicles ready for exocytosis.

(i) The first stage in the production of mucin involves transcription of the gene MUC5AC.
Outline the stages occurring in transcription.
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(ii) Following translation, the polypeptide formed is modified by the addition of many short chains of monosaccharides in a process called glycosylation.

Suggest where glycosylation occurs in the cell and explain why mucin is packaged into vesicles.
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(e) Overproduction of mucus is one of the symptoms of chronic obstructive pulmonary disease (COPD).

Describe the signs and symptoms that enable diagnosis of COPD.
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(a) Explain why red blood cells can be maintained in an intact state by keeping them in a normal saline solution.

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(b) In the blood, red blood cells are suspended in plasma. The main component of blood plasma is water.

Suggest \textbf{one} other component of blood plasma that could enter red blood cells \textbf{and} describe how it would cross the cell surface membrane.

\textit{component} ............................................................................................................

\textit{description} ............................................................................................................
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(c) The actual diameter of the lumen of the capillary at the point X–Y in Fig. 3.2 is 9.5 \textmu m.

Calculate the magnification of the image shown in Fig. 3.2. Show your working.

magnification \times .................................................................................................
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(d) With reference to Fig. 3.2, explain \textbf{one} feature that enables the surrounding body cells to receive an adequate supply of oxygen from the blood supplied by the capillary.

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(e) Some areas of the brain, known as blood-brain barriers, have a type of capillary that is relatively impermeable to substances.

Suggest \textbf{one} way in which the structure of a capillary in the blood-brain barrier differs from the structure of the capillary shown in Fig. 3.2.

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Many microorganisms can digest cellulose by using a group of enzymes collectively known as cellulases. Cellobiose is the disaccharide produced during cellulose digestion. The cellulase known as β-glucosidase completes the digestion of cellulose by hydrolysing the cellobiose molecule to produce two β-glucose molecules.

(a) Draw the ring structure of one β-glucose molecule in the space provided. [2]

(b) β-glucosidase was extracted from two different bacteria, Agrobacterium tumefaciens and Thermotoga maritima. Fig. 4.1 shows the results of an investigation into the effect of temperature between 0 °C and 100 °C, on the activity of each enzyme.

• L represents the lowest temperature at which activity of each enzyme was detected.
• H represents the highest temperature at which activity of each enzyme was detected.



(i) With reference to Fig. 4.1, describe the differences in the results for the two enzymes, A and T. [4]

(ii) Both enzyme A and enzyme T act on cellobiose. They have a similar, but not identical, primary structure. Suggest how similarities and differences in the primary structure of the two enzymes could help to explain the results obtained in the investigation. [4]

(a) Natural immunity and artificial immunity can both be acquired in a passive or in an active manner.

Table 5.1 shows information about immunity acquired by two individuals, P and Q.

Complete Table 5.1.

[Table_1]

Table 5.1
| description of event | outcome for the individual | production of memory cells / yes or no | type of immunity acquired by individual | |----------------------|-----------------------------|----------------------------------------|----------------------------------------| | individual P is injected with a live, weakened disease-causing organism | individual P does not become ill from the disease and has long-lasting protection from the disease | .................. | ...................................... ..................................... | | individual Q is injected with antibody against a specific disease-causing organism | individual Q does not become ill from the disease but is ill with the disease a year later | .................. | ..................................... ..................................... |

(b) Fig. 5.1 is a light micrograph of a sample of blood. Cell X is a phagocyte.



Fig. 5.1

State the origin of the blood cell labelled X.
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(c) Phagocytes play an important role when an immune response is initiated against cancerous tumour cells.

(i) Suggest how phagocytes can recognise the difference between healthy body cells and cancerous tumour cells.
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(ii) Outline briefly how a tumour forms.
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(a) Sentences (i) and (ii) are extracted from longer definitions of ecological terms. Each has one or more missing words.
Complete (i) and (ii) using the correct terms chosen from the list below.

a population a community an ecosystem
a niche a habitat trophic level
producers organisms consumers

(i) ............................................. is the particular location and type of local environment occupied by ..........................................................
or organism, characterised by its physical features or by its dominant .................................................. . [3]

(ii) ............................................... is the functional role or place of a species of organism within ....................................................... . [2]

(b) Only a small proportion of the light energy striking the leaves of producers becomes converted to chemical energy. The proportion that is converted is known as the photosynthetic efficiency (PE).

(i) Outline the possible reasons why a large proportion of light energy striking the leaves of plants is not converted into chemical energy.
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(ii) Most crops have a PE of 1% to 4%. Sugar cane, an important crop plant for food production and for the production of biofuel, has a PE of 7% to 8%.
Suggest the advantages of growing crops with high PE for food production or for biofuel.
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(iii) Fertilisers containing nitrate are added to improve or maintain yield of crops such as sugar cane.
Name two organic compounds containing nitrogen that are made by plants and state one function of each in plant growth.

organic compound 1 ................................................................................
function ......................................................................................................
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organic compound 2 ................................................................................
function ......................................................................................................
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