1.ง่าย
What are stomata?
- ATubes that carry water up the stem
- BHairs on roots that absorb minerals
- CGreen structures in the leaf that store starch
- DSmall pores in leaves that allow gas exchange
2.ง่าย
What is a pedigree in genetics?
- AA chart that shows how a trait is inherited in a family
- BA list of all the genes in an organism
- CA table of codons and amino acids
- DA picture of a person's chromosomes arranged in pairs by size
3.ง่าย
What is the main material in the cell walls of fungi?
- ACollagen
- BCellulose
- CChitin
- DPeptidoglycan
4.ปานกลาง
HIV is a retrovirus. What does its enzyme reverse transcriptase do?
- AIt makes proteins from the virus's DNA
- BIt breaks down the host's ribosomes
- CIt makes RNA from the host's DNA
- DIt makes DNA from the virus's RNA
5.ปานกลาง
Red-green colour blindness is X-linked recessive. A colour-blind woman (XᵇXᵇ) has children with a man with normal colour vision (XᴮY). What fraction of their sons is expected to be colour-blind?
- AOne half
- BOne quarter
- CAll
- DNone
6.ปานกลาง
Why do chromosomes condense into short, thick shapes before mitosis?
- ASo that genes can be transcribed more easily
- BSo that they can leave through the nuclear pores
- CSo that they can be copied more quickly
- DSo they can be moved apart without tangling or breaking
7.ยาก
A person's body temperature starts to fall in a cold room. Which responses help bring it back up?
- ASweating and widening of blood vessels in the skin
- BShivering and narrowing of blood vessels in the skin
- CSlower heart rate and less muscle activity
- DFaster breathing and more urine production
8.ยาก
The rate of an enzyme reaction rises as substrate is added but then levels off, even when more substrate is added. Why?
- AAll the active sites are occupied
- BThe products have turned back into substrate
- CThe substrate has become an inhibitor
- DThe enzyme has been denatured
เฉลย
- 1. D · Small pores in leaves that allow gas exchange
- 2. A · A chart that shows how a trait is inherited in a family
- 3. C · Chitin
- 4. D · It makes DNA from the virus's RNA
- 5. C · All
- 6. D · So they can be moved apart without tangling or breaking
- 7. B · Shivering and narrowing of blood vessels in the skin
- 8. A · All the active sites are occupied
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