No questions found
Fig. 1.1 shows the change in the biomass of the fungus *Penicillium* when grown in a fermenter to produce the antibiotic penicillin.
Fig. 1.1
(a) Name the stages in the growth of *Penicillium* indicated by V, W and X.
V .............................................................................................................................................
W ............................................................................................................................................
X .............................................................................................................................................. [3]
(b) State two factors that are kept constant when *Penicillium* is grown in a fermenter.
1 ............................................................................................................................................
2 ............................................................................................................................................ [2]
(c) Suggest why the growth of *Penicillium* is measured in biomass rather than numbers of cells.
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554
568
517
Fig. 2.1 shows the changes in a human ovary during the first part of the menstrual cycle and after the fertilisation of an egg.
(a) (i) Name:
organ A ..................................................................................................................... [2]
process B ..................................................................................................................
cell C. ......................................................................................................................... [3]
(ii) Name the hormone that promotes:
the growth of the follicle .........................................................................................
process B. ................................................................................................................ [2]
(iii) Explain how a sperm cell is adapted for its functions. ..............................................
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(b) Explain the advantages of sexual reproduction to an animal species. ..................
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510
541
573
Fig. 3.1 is a diagram of the water cycle.
(a) Water is a large component of the cells in the leaves of trees, as labelled D on Fig. 3.1.
Explain how water passes from a leaf cell to the atmosphere.
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(b) Explain how the loss of water from the leaves helps to move water from the roots to the leaves.
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(c) Explain how water enters the roots of the trees from the soil.
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(d) Fig. 3.1 shows a sewage treatment works, labelled E.
Describe three processes used in the treatment of sewage.
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(e) Herbicides are used by farmers to control weeds.
Explain the environmental damage that may be caused by herbicides.
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589
506
550
Table 4.1 shows the composition of blood plasma.
[Table_4.1]
(a) From Table 4.1, name:
(i) an excretory product
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(ii) a plasma protein.
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(b) (i) State what could cause the lactic acid concentration in the blood to increase to 200 mg dm$^{-3}$.
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(ii) State the function of fibrinogen.
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(iii) State two effects that a concentration of adrenaline of 100 ng dm$^{-3}$ might have on the body.
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(c) Table 4.1 shows that the glucose concentration varies between 700 and 1000 mg dm$^{-3}$. Describe the role of the liver in regulating the concentration of glucose in the body.
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(d) Lymphocytes and phagocytes are white blood cells.
A woman had some blood tests taken before and during a bacterial infection.
Table 4.2 shows the number of white blood cells in the two blood samples.
[Table_4.2]
(i) Calculate the percentage increase in lymphocytes that occurred during the bacterial infection. Show your working and give your answer to the nearest whole number.
answer .........................................% [2]
(ii) Describe the role of phagocytes in defence against disease.
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(iii) Describe the roles of white blood cells in tissue rejection.
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547
511
584
(a) Describe how food is moved along the small intestine.
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(b) The small intestine is lined by many villi.
Fig. 5.1 shows a longitudinal section of a villus.
Fig. 5.2 shows a cross-section of the same villus at V–W.
The diagrams are not drawn to the same scale.
(i) Name structures P, Q, and R.
P .........................................................................................................................
Q .........................................................................................................................
R ......................................................................................................................... [3]
(ii) The blood that flows from S enters a vein.
Name the vein that transports blood away from the small intestine.
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(iii) Cell T is an example of the cells that form the surface of the villi.
Explain why there are many microvilli on cell T.
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(iv) Some of the cells on the surface of the villi secrete mucus for protection.
Suggest what the villi need to be protected against.
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509
554
590
Myriapods are a group of arthropods that are commonly found in soil habitats in many parts of the world. Many myriapods are very small and not easy to identify.
Fig. 6.1 shows four species of myriapod, not drawn to the same scale.
(a) State three features of all myriapods that are visible in Fig. 6.1.
1 ..........................................................................................................................
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3 ..........................................................................................................................
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(b) Describe three features of myriapods that could be used to make a dichotomous key to distinguish between the four species in Fig. 6.1.
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2 ..........................................................................................................................
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3 ..........................................................................................................................
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(c) Mitochondria are cell structures that contain a small quantity of DNA.
Scientists are sequencing the DNA of one particular gene in mitochondria to help identify different species of many animals including myriapods. The sequences that they find are called 'barcodes'.
(i) State the part of the cell that contains most of the DNA.
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(ii) Suggest how DNA barcoding might be useful in the conservation of animals, such as myriapods.
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(iii) State the function of DNA in cells.
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(d) A student found the following information about the feeding relationships between some organisms in a soil habitat.
Dead organic matter, such as leaves, provides food for bacteria and soil fungi.
Earthworms eat dead leaves.
Many millipedes feed on dead plant matter and also on soil fungi.
Nematodes feed on bacteria and are eaten by springtails.
Centipedes are predators that feed on earthworms, millipedes and springtails.
(i) Draw a food web to show the feeding relationships described above. [4]
(ii) Describe the roles of the soil organisms in the carbon cycle.
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583
562
507
