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All living things can remove toxic materials and other substances that are in excess of requirements. What is this process called?
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560
Two animals have an identical sequence of amino acids in one of the proteins found in their cells. What does this indicate about these animals?
558
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524
The diagram shows some tissues in part of a plant root. The arrows represent the movement of water into and across the plant root tissues.
How many different tissues are shown?
570
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503
The length of a mitochondrion in a photomicrograph is 15 mm.
The actual length of the mitochondrion is 3 \mu m.
What is the magnification of the photomicrograph?
581
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500
The diagram shows some cells.
Where are these cells found?
539
510
570
Which statement about diffusion is correct?
521
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552
The diagram shows the uptake of mineral ions by root hair cells. Which type of molecule is labelled X in the diagram?
505
598
583
The bases on one of the strands of a DNA molecule have the sequence shown.
A-A-T-C-T-G
What is the corresponding sequence of bases on the other strand?
542
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512
In a photosynthesis experiment, a plant is left in bright sunlight for several hours. A leaf is then removed from the plant and tested for starch, using iodine solution.
The diagram shows the leaf from the plant that was used in the experiment.
Which diagram shows the result of the experiment?
561
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536
An experiment was carried out to investigate the effect of pH on enzyme action. The graph shows the results. What are the labels for the x-axis and the y-axis?
582
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554
Four test-tubes were set up as shown in the diagram.
In which test-tube is the starch digested most quickly?
544
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Two similar leaves are set up in test-tubes as shown. One is exposed to light, while the other is kept in the dark.
After a few hours, which colour would the hydrogencarbonate indicator solution be in each test-tube?
571
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568
The diagram shows the surface view of part of the epidermis of a leaf.
How many guard cells are present?
544
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596
The diagram shows part of the alimentary canal and associated organs. Where does most water absorption take place?
600
518
595
The diagram shows a large food molecule changing into smaller molecules.
What is process X?
510
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The diagram shows a newly planted seedling and the same seedling a few hours after being planted.
What is the correct explanation for the change in the appearance of the leaves?
576
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571
Translocation is the movement of sucrose and amino acids in the phloem tissue of a plant from source to sink. Which organ can act as a source?
504
527
526
Which component of blood produces antibodies?
568
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548
Which graph shows how the pressure inside the lungs changes when taking one breath in?
507
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579
Some features that help to defend the body against pathogens are listed.
1 mucus
2 skin
3 stomach acid
4 phagocytosis
Which features can prevent pathogens entering body tissues?
592
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594
The diagram shows the apparatus used to measure the rate of respiration in germinating seeds. As the seeds respire, the bubble of coloured water moves along the glass tube.
The temperature is increased from 20°C to 40°C.
What happens to the movement of the bubble as the temperature increases?
561
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582
The diagram shows a mammalian kidney.
What are areas X, Y and Z?
561
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591
The structures listed are part of the nervous system.
1 brain
2 effector
3 receptor
4 relay neurone
In a reflex arc, which structures are connected to a motor neurone by synapses?
556
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551
Which process is a response of the body that is part of a negative feedback process?
588
572
529
Which row shows the pupil reflex in bright light?
501
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508
A seed is placed and grown on a rotating disc, as shown.
Which diagram shows the appearance of the seedling shoot after seven days?
513
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579
Commercial plant growers use asexual reproduction to grow coffee plants which produce crops of coffee beans. What is a disadvantage of asexual reproduction?
544
534
547
Which statement about the human immunodeficiency virus (HIV) is correct?
578
523
534
Which statement about a diploid human cell is correct?
530
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542
The gene for haemophilia is found on the X chromosome and the allele for haemophilia is recessive.
In the pedigree diagram the dominant allele is shown as $X^H$ and the recessive allele is shown as $X^h$.
What is the probability of child M having haemophilia?
565
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535
What is an adaptive feature of xerophytes?
573
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The graph shows the growth of a bacterial population.
Which section represents the exponential (log) phase?
575
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588
A species of insect usually has pale-coloured wings. This helps to camouflage them on pale-coloured tree trunks. A few of the insects in this species have darker coloured wings.
After a number of years the tree trunks become darker in colour due to environmental changes. The insects with dark-coloured wings become more common than insects with pale-coloured wings in this species.
Which process causes this change in the proportion of insects with dark-coloured wings?
543
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576
The diagram shows part of the nitrogen cycle.
Which processes are carried out by bacteria?
554
573
575
What is a characteristic of bacteria that makes them useful in genetic engineering?
519
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563
What is the useful product of anaerobic respiration in the manufacture of bread?
501
536
579
What are reasons why species become endangered?
596
544
542
If the nitrate concentration in a lake increases, fish may die due to the events listed.
1 increased aerobic respiration by decomposers
2 increased decomposition of dead producers
3 increased growth of producers
4 reduction in dissolved oxygen
Which sequence of events would lead to the death of the fish?
573
570
565
