Grade 10 biology – Specimen Collection and Preservation Quiz
1. Why is it important to preserve biological specimens collected from the field?
Preservation stops decay and microbial breakdown so scientists can examine the specimen's structure, identify it, and use it for future studies.
2. Which method is best for preserving plant samples for a herbarium collection?
Pressing and drying plant specimens between papers and blotters preserves their shape and details for herbarium mounting and long-term study.
3. Which preservative is best for long-term morphological storage of animal specimens in a school collection?
Seventy percent ethanol preserves animal tissues well for morphology, preventing decomposition while avoiding the brittleness high concentrations cause.
4. What concentration of ethanol is most suitable when preserving tissue specifically for DNA analysis in the field?
High-concentration ethanol (about 95%) dehydrates tissues quickly and helps preserve DNA by reducing enzymatic degradation and microbial growth.
5. Before sending fish specimens to the museum, what is the correct sequence of steps for preserving them?
Large animal specimens are usually fixed in 10% formalin to stabilize tissues and then transferred to 70% ethanol for safe long-term storage and handling.
6. When collecting insects to keep as specimens for display, which method is commonly used to kill and preserve them quickly?
Ethyl acetate in a killing jar quickly and humanely kills insects, after which they can be pinned and dried for display without damage to important features.
7. Which practice should be done for every specimen collected to ensure its scientific value?
Accurate labels (date, location, collector, habitat) are essential for future identification, comparison and study of the specimen.
8. If you collect leaf tissue in a hot field and cannot refrigerate immediately, which method best preserves material for DNA later?
Silica gel rapidly desiccates leaf tissue, preventing DNA-degrading enzymes from acting and preserving material for later molecular work without refrigeration.
9. Which of the following should you avoid doing when collecting specimens from a protected area in Kenya?
Collecting in protected areas requires permits (for example from relevant national authorities); taking specimens without permission is illegal and harms conservation efforts.
10. Why is a sterile container necessary when collecting microbial swabs from soil or surfaces?
Sterile containers prevent introduction of outside microbes that would hide or change the sample’s true microbial community, ensuring accurate laboratory results.
11. Which step helps prevent mold growth when pressing plant specimens for a herbarium?
Regularly changing drying papers removes moisture and prevents mold, ensuring the pressed plant dries properly and remains useful for study.
12. What is the main reason formalin (formaldehyde solution) is used when fixing tissues?
Formalin fixes tissues by creating chemical bonds between proteins, stabilizing structure and preventing decay so microscopic features remain intact for study.
13. How should blood samples usually be handled for short-term transport to the laboratory?
Keeping blood cool and using the right collection tubes (with anticoagulant if needed) slows degradation and preserves sample integrity until analysis.
14. When preserving insects for DNA work, why is 95% ethanol preferred over 70% ethanol?
95% ethanol removes water rapidly and inhibits enzymes and microbes that degrade DNA, making it more suitable than 70% ethanol for molecular studies.
15. What is a suitable way to preserve small fungal fruiting bodies collected in the field for later identification?
Fungi are best preserved by rapid drying to stop enzymatic activity and mould growth, which keeps key features visible for identification.
16. Why must specimen labels include the exact location (preferably GPS coordinates)?
Precise locality data allow scientists to relate specimens to environmental conditions, monitor species distributions, and return to sites for further study.
17. Which of these is a correct safety consideration when using preservatives like formalin or high‑strength ethanol in school collections?
Formalin and high-strength ethanol are hazardous; using protective gear, ventilation and proper disposal protects collectors and the environment.
18. Which method is best for long-term storage of microbial cultures in a research laboratory?
Freezing cultures with a cryoprotectant at very low temperatures stops metabolic activity and preserves viability for years without genetic change.
19. When collecting a surface bacterial swab for culturing, why should you avoid applying antiseptic to the area first?
Using antiseptic before sampling removes or kills microbes and prevents an accurate culture of the natural microbial community.
20. Why is it important to change drying papers regularly when pressing plant specimens?
Changing papers draws out moisture and keeps airflow so specimens dry properly and remain in good condition for herbarium storage.
21. What is a voucher specimen and why is it collected?
Voucher specimens are kept in museums or herbaria to document exactly which organism was studied, allowing verification and future research.
22. Which preservative is known to damage DNA by crosslinking and so is not ideal if genetic analysis is required?
Formalin crosslinks proteins and nucleic acids, which preserves structure but can fragment or modify DNA, making genetic analyses difficult.
23. What immediate action should you take when you discover a rare or possibly new species while collecting?
Detailed records and notifying experts or institutions help confirm the find, protect the population, and ensure proper scientific study while following regulations.
24. Which is the best time of day to collect plant specimens for pressing and why?
In the morning plants are full of water (turgid), so leaves and flowers are fresh and less wilted, giving better quality pressed specimens.
25. When transporting temperature-sensitive specimens by road in Kenya, what is a practical way to keep them stable?
A cool box with ice packs maintains a stable, low temperature (cold chain), slowing degradation of temperature-sensitive specimens during transport.
26. What is the main purpose of fixation in specimen preservation?
Fixation chemically stops enzyme action and decomposition, preserving cellular and tissue structures for microscopy or long-term study.