Question
A researcher used a light microscope to observe epithelial cells from a human cheek.
Fig. 1.1 is a photograph that the researcher made of these cells.
(a) (i) Name the parts labelled A and B.
A ……………………………………………………………………………………………………………………….
B ……………………………………………………………………………………………………………………….[2]
(ii) The cells in Fig. 1.1 each have a cell membrane.
State one of the functions of a cell membrane. [1]
(iii) State how the shape of the cells shown in Fig. 1.1 differs from the shape of a palisade
mesophyll cell in a leaf. [1]
(b) Fig. 1.2 shows an electron micrograph of a mitochondrion.
Mitochondria have two membranes, an inner membrane and an outer membrane. The inner
membrane is folded and used in respiration.
Suggest why the inner membrane of mitochondria is folded.
(c) Table 1.1 shows different specialized cells and the average number of mitochondria each cell
contains.
Explain the differences between the average numbers of mitochondria in the cells shown in
Table 1.1 [4]
[Total: 9]
Answer/Explanation
Ans
1 (a) (i) A cytoplasm ;
B nucleus ;
(ii) forms a barrier between the cell and its surroundings ;
keeps contents of cell inside ;
allows / controls /(movement of) substances, into/ out, of the cell/ across
membrane ;
(iii) irregular shape/rounded shape/not columnar/ not cylindrical/ not rectangular/ no
specific shape ;
(b) large surface area ;
more surface for respiration ;
allows, increased/ faster/ efficient, respiration ;
(c) 1 mitochondria are site of aerobic respiration/production of (most of the) ATP ;
2 liver cell/ heart cell, is very active/ use lots of energy /respire more ;
3 e.g. function of liver cell or heart cell ;
4 sperm cells, are active/ swim/ beating flagella ;
5 sperm cells have few mitochondria, as they are small ;
6 red blood cells, full of haemoglobin/ more space for oxygen/AW ;
7 red blood cells, use less energy / do not actively move ;
Question
(a) Fig. 4.1 is a diagram of Vibrio cholerae, the bacterium that causes cholera.
(i) Describe two similarities and two differences between a palisade mesophyll cell and the
bacterial cell shown in Fig. 4.1.
similarity 1 ………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
similarity 2 ………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
difference 1 …………………………………………………………………………………………………………
………………………………………………………………………………………………………………………….
difference 2 …………………………………………………………………………………………………………
………………………………………………………………………………………………………………………….
(ii) Explain how the cholera bacterium causes diarrhoea.
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
(b) A scientist tested the resistance of one strain of bacteria to different antibiotics.
The scientist tested solutions of five different antibiotics, A to E.
She soaked a paper disc in each antibiotic solution.
The paper discs with antibiotics were placed in a Petri dish containing bacteria on agar jelly.
Fig. 4.2 is a diagram of the appearance of the Petri dish after 48 hours. The shaded areas
show where bacteria grew. The clear areas show where bacteria did not grow.
(i) The strain of bacteria used in this investigation causes a disease.
Using the information in Fig. 4.2, explain why antibiotic E would be the most effective at
treating this disease.
………………………………………………………………………………………………………………………….
(ii) The results in Fig. 4.2 show that this strain of bacteria is resistant to antibiotic A.
Five years ago, a similar investigation found that the clear area for antibiotic A was the
same size as antibiotic B is in Fig. 4.2.
Explain how bacteria become resistant to antibiotics.
………………………………………………………………………………………………………………………….
(iii) Describe how to minimise the risk of antibiotic B developing the same results as
antibiotic A.
………………………………………………………………………………………………………………………….
Answer/Explanation
Ans
Question
Fig. 8.1 shows a cell from the palisade layer of a leaf.
(a) In Table 8.1 tick (✔) the numbers that label the three features of the palisade cell
which are also found in animal cells.
(b) State and describe the function of two features of the palisade cell that are only found
in plant cells.
(c) Fig. 8.2 shows some red blood cells, which are animal cells.
(i) Which feature normally present in an animal cell is absent from a red blood cell?
(ii) State the function of a red blood cell and describe one way in which the red blood
cell is adapted to carry out its function.
Answer/Explanation
Ans:
QUESTIONS:
(a) Table 1.1 shows a key which can be used to identify these cells.
Use this key to identify cells A, B, C, D and E. Cell F has been done for you.
(b) (i) State the main function of a palisade cell.
……………………………………………………………………………………………………………………..
(ii) Suggest and explain two ways in which the structure of a palisade cell is adapted to this function.
adaptation 1 ……………………………………………………………………………………………………….
explanation …………………………………………………………………………………………………………
………………………………………………………………………………………………………………………….
adaptation 2 ……………………………………………………………………………………………………….
explanation …………………………………………………………………………………………………………
…………………………………………………………………………………………………………………….
Answer/Explanation
Ans:
1 (a) 
(b) (i) photosynthesis / make carbohydrate/ glucose/ sugar;
(ii) contains (many) chloroplasts;
to absorb energy / light;
long and thin/ elongated;
so many can fit into a small area (of the leaf);
chloroplasts close to edge of cell/ thin cytoplasmic layer;
so that more light/ energy can be absorbed;