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Which process provides an organism with the raw materials needed for tissue repair?
597
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547
Which name is given to a group of individuals that can reproduce to produce fertile offspring?
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518
596
Root hair cells are found on plant roots.
Which feature is present in a root hair cell but not in a sperm cell?
514
556
573
Some examples of substances moving across membranes are listed.
1. glucose molecules into the epithelium that lines the small intestine
2. nitrate ions from a dilute solution in soil into a more concentrated solution in root hair cells
3. water molecules from mesophyll cells into the air spaces of a leaf
For which examples must oxygen be present?
540
576
514
Plant tissue is placed in a solution.
What would cause plasmolysis of the plant cells?
1 the external solution having a higher water potential than the plant cells
2 the external solution having a lower water potential than the plant cells
3 water moving out of the plant cells
4 water moving into the plant cells
525
599
564
DNA is a molecule consisting of two linked strands.
Part of a single strand of DNA has the sequence of bases shown.
ACCGTTGAA
What is the sequence of bases in the second strand?
580
600
501
The graph shows the concentration of a substance during the course of an enzyme-controlled reaction.
564
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592
The graph shows the effect of temperature on the activity of an enzyme. [Image_1: Graph of enzyme activity against temperature]
At which temperature do effective collisions happen most frequently?
592
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519
Two test-tubes were filled with hydrogencarbonate indicator. An aquatic plant was placed into each test-tube and the test-tubes were sealed with bungs, as shown:
Test-tube X was illuminated and test-tube Y was kept in the dark. The results are shown:
What causes the colour changes in the hydrogencarbonate indicator in X and Y?
528
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539
The substances listed are found in the leaf of a plant.
Which substance is obtained from the soil?
568
541
565
The cholera bacterium produces toxins that cause chloride ions to be secreted into the small intestine. What is the immediate effect of this on the water potential of blood in the intestinal capillaries, and on the water potential of the contents of the small intestine? [Table_1]
578
540
509
The graph shows the concentration of maltose in different parts of the alimentary canal.
What causes the change in concentration at X?
582
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538
The diagram shows a bean seedling soon after it has germinated.
Where is most water absorbed?
516
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Scientists investigate the movement of substances in a plant.
They cut a ring of tissue from the stem. Removing the tissue removes some of the transport vessels found around the edge of the stem.
A few days later they notice swelling above the area where the tissue has been removed.
!(image_reference)
What causes the swelling?
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The diagram shows the outside of a human heart. Which structure is a coronary artery?
589
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574
The photomicrograph shows some different types of blood cell. What is the function of the cell labelled X?
588
548
528
Campylobacter is a bacterium that can cause food poisoning.
Which word describes Campylobacter?
546
561
579
What is the approximate percentage of oxygen in expired air?
570
594
523
Which process could continue without energy from respiration?
552
587
510
Which row shows the products of anaerobic respiration in humans and yeast?
[Table_1]
533
572
582
A person eats foods containing proteins. Some of the amino acids in the proteins are converted to urea and excreted from the body.
!(Diagram showing the conversion process: proteins -> 1: amino acids -> 2: urea -> 3: urine)
Which row identifies the sites of processes 1, 2 and 3?
557
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560
What is a response to a low concentration of glucose in the blood?
572
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600
Which hormone causes an increase in breathing rate, an increase in heart rate and the widening of pupils?
576
556
539
Which row about tropic responses is correct?
[Table_1]
532
564
582
What is the sequence of events in sexual reproduction in plants?
512
568
586
What happens to the number of chromosomes when a cell divides by meiosis?
534
572
553
A sex-linked condition is caused by a recessive allele. A healthy male and female are both unaffected by the condition but the female has one copy of the recessive allele.
What is the chance of their offspring being affected by the sex-linked condition?
545
525
523
The diagram shows the unspecialised cells of a mammalian embryo soon after fertilisation.
What is the correct description of these cells?
596
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584
Which feature is a leaf adaptation for a xerophyte?
519
523
563
The diagram shows the flow of energy through living organisms.
Which term should be placed in both boxes to complete the diagram?
530
551
567
The diagram shows the nitrogen cycle in the ocean. Which stage represents nitrification?
542
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561
The graph shows how much penicillin is produced by the fungus *Penicillium* in a fermenter. It also shows the concentrations of sugars, ammonium ions and *Penicillium*. *Penicillium* uses sugars as a food source and needs ammonium ions.
What does the graph show about the conditions needed for penicillin production?
543
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599
The list shows some of the steps in the production of human insulin by genetic engineering.
1. The human insulin gene is inserted into a bacterial plasmid using DNA ligase.
2. A recombinant plasmid is inserted into a bacterium.
3. The bacterium containing the recombinant plasmid replicates.
4. The insulin gene is removed from human DNA using a restriction enzyme.
What is the correct sequence of these steps?
512
578
519
Deforestation results in an increase in the concentration of carbon dioxide in the atmosphere. What is the correct explanation?
503
573
503
Which definition of sustainable development is correct?
506
535
501
