Specimen Collection and Preservation

20 Grade 10 Biology questions on Specimen Collection and Preservation, with worked marking schemes. 20 questions are available on this topic in full.

1. Question 1

   1 mark

   During a field study in a woodlot near Kakamega, a learner wants to collect very small beetles hiding in cracks on tree bark without crushing them. Which apparatus is most suitable?

   A. A pitfall trap

   B. A sweep net

   C. A pooter

   D. A plant press

   (1 mark)

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2. Question 2

   1 mark

   A learner mounts a pressed leaf on a herbarium sheet and writes only "maize leaf" on the label. The most important information still missing is

   A. the number of learners in the collecting group

   B. the colour of the leaf when it was fresh

   C. the mass of the pressed specimen

   D. the place and the date of collection

   (1 mark)

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3. Question 3

   1 mark

   A hairy caterpillar found on a mango tree in Makueni should be picked up using forceps or gloved hands because

   A. bare fingers transfer body heat that kills the caterpillar at once

   B. its hairs can break off and irritate the skin

   C. the caterpillar changes colour immediately it touches human skin

   D. forceps make the caterpillar crawl faster into the specimen bottle

   (1 mark)

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4. Question 4

   4 marks

   Describe how a learner would use a sweep net to collect grasshoppers in a maize field, and state one precaution to be observed.

   (4 marks)

   Marking scheme

   Award 1 mark each, maximum 4: 1. Hold the handle and sweep the net from side to side (figure-of-eight) through the tops of the vegetation while walking slowly forward. 2. Sweep in the cooler part of the morning, when the grasshoppers are less active and fewer escape. 3. At the end of the sweep, twist or flick the handle so that the net bag folds over the mouth, trapping the catch inside. 4. Transfer the catch quickly into a specimen bottle or killing jar, for example by inverting the mouth of the net into the bottle or drawing the insects out with a pooter. 5. Precaution (any one): avoid sweeping over thorny or wet plants that tear or soak the net; do not drag the net hard over the ground, as the insects would be crushed; keep the mouth of the net closed after sweeping so that the catch does not escape.

5. Question 5

   2 marks

   Distinguish between a pooter and a sweep net as apparatus used for collecting insects.

   (2 marks)

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6. Question 6

   6 marks

   Explain six factors a learner should consider when choosing a suitable method of preserving a collected specimen.

   (6 marks)

   Marking scheme

   Award 1 mark for each factor correctly explained, maximum 6: 1. The body structure of the specimen: soft-bodied animals need a preserving fluid, while hard-bodied insects are dried and pinned. 2. Whether the natural colour must be retained: fluids such as alcohol leach out colour, so coloured specimens are better dried. 3. How long the specimen is to be kept: refrigeration suits short-term storage, while fluid preservation or drying suits a permanent collection. 4. The intended use: a specimen meant for dissection must remain soft and pliable, while one meant for display must keep its shape and appearance. 5. Availability and cost of the preservative and equipment in the school. 6. Safety: the chemical chosen must be one the learner can handle safely with the protective equipment available. 7. The size of the specimen: a large specimen needs preservative injected into it, or it may have to be cut into portions.

7. Question 7

   4 marks

   Explain four ways in which a collection of dried specimens can be protected from damage while in storage.

   (4 marks)

   Marking scheme

   Award 1 mark for each way with its reason, maximum 4: 1. Keep the specimens in tightly closed insect boxes or cabinets so that pests such as ants and cockroaches cannot reach them. 2. Place naphthalene balls or an insecticide in the box to repel or kill pests that feed on the dried material. 3. Store in a dry place with low humidity, because damp conditions allow moulds to grow on the specimens. 4. Keep the boxes away from direct sunlight, which fades the natural colours of the specimens. 5. Handle the specimens with forceps rather than fingers, since dried material is brittle and breaks easily. 6. Pin the specimens firmly to the base of the box so that they do not shake loose and break during handling.

8. Question 8

   1 mark

   A learner in Machakos wants to collect flying insects that are active only at night around the homestead. The most suitable method is

   A. setting a pitfall trap along a footpath

   B. setting a light trap after dark

   C. using a pooter on flowers at midday

   D. sweeping the grass with a net in the morning

   (1 mark)

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9. Question 9

   1 mark

   State one reason why a learner should wash the hands with soap and water after handling preserved specimens.

   (1 mark)

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10. Question 10

    3 marks

    Explain why an insect is first killed in a killing jar containing ethyl acetate before it is pinned and mounted.

    (3 marks)

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11. Question 11

    1 mark

    Small soil animals such as mites are extracted from a soil sample using a Tullgren funnel. The animals end up in the collecting jar below because they

    A. are killed by the heat of the lamp and drop through the sieve

    B. are washed downwards by water poured onto the soil

    C. move away from the heat and dryness at the top of the soil

    D. are attracted upwards by the lamp and then fall back down

    (1 mark)

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12. Question 12

    1 mark

    Formalin is used to preserve soft-bodied animals such as earthworms because it

    A. removes all the water from the specimen by evaporation

    B. bleaches the specimen so that the internal organs become visible

    C. hardens the tissues and stops the activity of decay organisms

    D. dissolves the soft tissues so that only the skeleton remains

    (1 mark)

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13. Question 13

    4 marks

    Explain four precautions a learner should observe when preserving a specimen in formalin.

    (4 marks)

    Marking scheme

    Award 1 mark for each precaution correctly stated with its reason, maximum 4: 1. Wear gloves and work in the open air or a well-ventilated room/fume chamber, because formalin fumes irritate the eyes, skin and breathing passages. 2. Use the recommended dilution (about 4-10%), because a stronger solution over-hardens and distorts the specimen. 3. Immerse the specimen completely, and inject preservative into the body cavity of a large specimen, so that no part is left untreated and begins to decay. 4. Use a container with a tight-fitting stopper so that the fluid does not evaporate or spill. 5. Label the container clearly as formalin and store it out of reach; never taste it or deliberately inhale the fumes.

14. Question 14

    2 marks

    State two reasons why only a few individuals of a species should be collected from a habitat during a field study.

    (2 marks)

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15. Question 15

    1 mark

    A butterfly collected near Watamu is to be kept for the school museum with its wing colours and patterns intact. The best way to preserve it is to

    A. soak it in 70% alcohol in a specimen bottle

    B. immerse it in 10% formalin in a stoppered jar

    C. keep it in a polythene bag in a refrigerator

    D. kill it in a killing jar, then pin it and dry it in an insect box

    (1 mark)

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16. Question 16

    5 marks

    Describe how a plant specimen collected from the field is pressed, dried and mounted for a school herbarium.

    (5 marks)

    Marking scheme

    Award 1 mark each, maximum 5: 1. Spread the specimen between sheets of newspaper or blotting paper, arranging the leaves flat and without overlapping, with at least one leaf turned to show the lower surface. 2. Place the papers between the boards of a plant press and tighten the straps, or put a heavy weight on top, so that the specimen dries flat. 3. Change the papers daily until the specimen is completely dry, because damp papers encourage mould and rotting. 4. Dry in a warm, airy place or with gentle heat; avoid strong direct sunlight, which bleaches the colour. 5. Fix the dried specimen onto a stiff herbarium sheet using glue or gummed strips. 6. Attach a label (usually at the bottom right corner) showing the name of the plant, the locality, the date of collection and the collector's name. 7. Dust with an insecticide or fungicide, or store the sheets with naphthalene in a closed, dry cabinet.

17. Question 17

    1 mark

    When collecting a bean plant from a school garden for a herbarium, the learner digs up the whole plant together with its roots and takes it while it is in flower. This is done because

    A. the roots continue to supply the plant with water after collection

    B. the flowers make the mounted specimen attractive to look at

    C. roots, leaves and flowers are all needed to identify and classify the plant

    D. soil carried on the roots supplies nutrients during drying

    (1 mark)

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18. Question 18

    3 marks

    Suggest three observations that would show a learner that a specimen kept in a jar of preservative is no longer properly preserved.

    (3 marks)

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19. Question 19

    1 mark

    Live tadpoles collected from a dam in Kitui are to be carried to the school laboratory, a journey of about thirty minutes. They should be carried in

    A. a dry polythene bag tied at the top

    B. a tightly sealed bottle filled to the brim with tap water

    C. a wide jar containing water from the dam, covered with a perforated lid

    D. a jar containing 10% formalin

    (1 mark)

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20. Question 20

    1 mark

    A learner sets a pitfall trap in the school compound. Why is the rim of the sunken container placed level with the soil surface?

    A. To prevent the container from being blown away by wind

    B. So that crawling animals walk in without meeting a barrier

    C. To allow sunlight into the container so that insects are attracted

    D. To allow rainwater to drain out of the container

    (1 mark)

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