AS & A Level Biology - 9700 Paper 2 2011 Winter Zone 3

(a) Calculate the magnification of the electron micrograph in Fig. 1.1.
Show your working and give your answer to the nearest 10000.
magnification × ............................................................ [2]

(b) Name three structures, present in animal cells, which are not present in the cells shown
in Fig. 1.1.
1. ..................................................................................................
2. ..................................................................................................
3. ..................................................................................................
[3]

(c) E. carotovora is a rod-shaped bacterium.
Explain why two of the bacterial cells in Fig. 1.1 do not appear rod-shaped.
..............................................................................................................
..............................................................................................................
..............................................................................................................
.............................................................................................................. [1]

(d) E. carotovora causes a disease in carrot and potato plants.
The bacteria release an enzyme called pectinase which hydrolyses the polysaccharide
pectin. Pectin helps plant cells to attach to each other.

(i) Name the type of chemical bond which will be hydrolysed by pectinase.
.............................................................................................................. [1]

(ii) Suggest what effect this disease will have on vegetables, such as carrots and
potatoes.
..............................................................................................................
..............................................................................................................
..............................................................................................................
.............................................................................................................. [2]

(a) Describe the function of each of the following structures in the human heart:

(i) sinoatrial node (SAN)
..............................................................................................................................
..............................................................................................................................
................................................................................................................. [2]

(ii) atrioventricular node (AVN)
..............................................................................................................................
..............................................................................................................................
................................................................................................................. [2]

(iii) left atrioventricular (bicuspid) valve.
..............................................................................................................................
..............................................................................................................................
................................................................................................................. [2]

(b) Fig. 2.1 shows the changes in blood pressure in the left atrium, left ventricle and aorta during one complete cardiac cycle.

[Image_1: Graph with key]

Complete the table below using the appropriate letter, A to H, to match the points from the graph to the correct statement.

You must only put one letter in each box. You may use each letter once, more than once or not at all.

| statement | letter |
|-------------------------------------|--------|
| left atrioventricular (bicuspid) valve starting to open | |
| left atrioventricular (bicuspid) valve starting to close | |
| left ventricle starting to contract | |
| minimum blood remaining in left ventricle | |

[4]

Fig. 3.1 is a photomicrograph of a transverse section through a leaf from a tea plant, Camellia sinensis.

(a) Use label lines and the letters X, Y and Z to label the following features on Fig. 3.1.
X a cell of the upper epidermis
Y a palisade mesophyll cell
Z a guard cell [3]
(b) Describe and explain how water moves from inside the leaf at point Q on Fig. 3.1 to the atmosphere outside the leaf during transpiration.

.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
.....................................................................................................................
..................................................................................................................... [4]
(c) The leaf of C. sinensis, shown in Fig. 3.1, has developed in a sunny position.
State three features of the leaf, visible in Fig. 3.1, which show that it has developed in a sunny position.
1. .....................................................................................................................
.....................................................................................................................
2. .....................................................................................................................
.....................................................................................................................
3. .....................................................................................................................
..................................................................................................................... [3]

(a) (i) Use the information in Fig. 4.1 to describe the changes in the number of people newly infected with HIV.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
.............................................................................................................................................................. [3]
(ii) Suggest possible explanations for the decrease in the number of people newly infected with HIV.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
.............................................................................................................................................................. [3]

(b) Explain why it was necessary to include the upper and lower estimates on the graph in Fig. 4.1.
..............................................................................................................................................................
..............................................................................................................................................................
.............................................................................................................................................................. [1]

(c) Use the information given in Fig. 4.1 and Fig. 4.2 to explain the relationship between new HIV infections and deaths due to HIV/AIDS.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
.............................................................................................................................................................. [4]

Fig. 5.1 represents part of a DNA molecule.
[Image_1: DNA molecule]
(a) On Fig. 5.1
(i) draw a box around a nucleotide [1]
(ii) label, with the letter P, a phosphate group. [1]

(a) State the term for each of the following:
(i) all organisms of the same species living in a defined area at a particular time.
.......................................................................................................... [1]

(ii) the interaction of all living organisms with each other and their non-living environment in a self-contained location
................................................................................................................................ [1]

(iii) the process of converting nitrate ions in soil to nitrogen gas in the atmosphere.
.......................................................................................................... [1]

Mangroves are trees which grow on tropical coastlines in salt water.
Fig. 6.1 shows part of a food chain from a mangrove area.



(b) (i) Name the trophic level of the Pied Oystercatchers.
........................................................................................................... [1]

(ii) Explain why the energy taken in by the crabs is not all available to the Pied Oystercatchers.
...........................................................................................................
...........................................................................................................
...........................................................................................................
...........................................................................................................
........................................................................................................... [2]

(c) The crabs in Fig. 6.1 also feed on mangrove leaves that have fallen to the ground. The leaves which are not eaten supply a source of nitrogen for the mangrove trees.

Explain how nitrogen from compounds in the dead leaves is made available to the growing plants.
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................ [4]