Biotechnology: PCR, gel electrophoresis and genetic engineering

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Model PCR card (model data)

   item	value
   start	5 pieces
   each cycle	doubles the pieces
   goal	more than 1000 pieces

2. 1.

   Ari starts a model PCR with 5 pieces. Each cycle doubles the pieces. After how many cycles does the count first pass 1,000?

   • 200 cycles
   • 7 cycles
   • 498 cycles
   • 8 cycles
3. 2.

   Bo finds 192 pieces in a model PCR tube after 6 cycles. Each cycle doubled the pieces. How many pieces were in the tube at the start?

   • 3 pieces
   • 96 pieces
   • 180 pieces
   • 32 pieces
4. 3.

   Each cycle doubles the pieces. Esme runs two model PCR tubes. Which tube has more pieces at the end, and by how many?

   • Tube P, by 320 pieces
   • Tube P, by 87 pieces
   • Tube Q, by 320 pieces
   • Tube P, by 1,500 pieces
5. 4.

   not to scale; model data. Lane 3, one band: 300 bp. Lane 4, one band: 1200 bp. Jun runs PCR on a long piece of model plant DNA and loads the main product in one lane. Which lane is it, and why?

   • Lane 1, because PCR copies the whole 5000 bp piece
   • Lane 3, because each cycle halves the length of the product
   • Lane 4, because each cycle doubles the length of the product
   • Lane 2, because PCR copies the region between the primers

6. Use this

   Model gel (not to scale; model data). Lane 1 is model corn plant DNA and lane 2 is model soil bacterium DNA, both cut by the same enzyme.

7. 5.

   Luz compares the two lanes of this model gel. Which statement matches the gel?

   • The 700 bp bands match, and the 200 bp band moved farthest of all
   • The 700 bp bands match, and the pieces moved toward the negative (−) end
   • No bands match, because the samples come from different kinds of organisms
   • The 700 bp bands match, and the 1200 bp band moved farthest of all

8. Notebook on gene cloning (model data)

   line	what it says
   1	A restriction enzyme cuts DNA at a specific sequence
   2	Cutting the plasmid and the gene with the same enzyme leaves matching sticky ends
   3	DNA ligase cuts the plasmid so the gene can fit
   4	Bacteria copy the plasmid as they divide

9. 6.

   Milo checks a classmate's notebook on putting a gene into a plasmid. Exactly one line is wrong. Which line, and why?

   • Line 1, because a restriction enzyme joins DNA pieces
   • Line 3, because DNA ligase joins DNA and does not cut it
   • Line 2, because sticky ends form with different enzymes, not the same one
   • Line 4, because a plasmid cannot be copied inside bacteria

10. Use this

    Notebook on genetic engineering (model data), 4 rows. Columns: line, what it says. 1, Bt corn carries a gene from Bacillus thuringiensis. 2, Golden rice carries added genes that let the endosperm make provitamin A. 3, Adding the gene replaces the corn plant's whole genome with the genome of the bacterium. 4, An organism that gets recombinant DNA is a genetically modified organism.

11. 7.

    Noah checks a classmate's notebook on genetic engineering. Exactly one line is wrong. Which line, and why?

    • Line 1, because the gene comes from a plant and not from a bacterium
    • Line 3, because the plant keeps its own genes and gains the added gene
    • Line 4, because a GMO must have a completely new genome from another species
    • Line 2, because added genes cannot work in the edible part of a grain

12. Use this

    Notebook on PCR and gels (model data), 4 rows. Columns: line, what it says. 1, PCR copies the region between the two primers. 2, Each cycle doubles the target pieces, so 3 cycles turn 1 piece into 8. 3, In a gel, smaller pieces travel farther from the wells. 4, DNA pieces move toward the negative end of the gel.

13. 8.

    Pia checks a classmate's notebook on PCR and gels. Exactly one line is wrong. Which line, and why?

    • Line 3, because larger pieces travel farther from the wells in a gel
    • Line 4, because negatively charged DNA moves toward the positive end
    • Line 2, because each cycle adds two pieces, so 3 cycles give 7 pieces
    • Line 1, because PCR makes copies of the whole genome in the cell

14. Model PCR card (model data)

    item	value
    start	1 piece
    each cycle	doubles the pieces
    cycles	10

15. 9.

    Tala predicts the pieces in a model PCR tube after 10 cycles. Which claim and reason are correct?

    • 1,024 pieces, because each cycle doubles the number
    • 100 pieces, because each cycle multiplies the number by 10
    • 10 pieces, because each cycle adds one piece
    • 21 pieces, because each cycle adds two pieces

16. Two crops card (model data)

    crop	what was added	what it makes
    Bt corn	a gene from Bacillus thuringiensis	a protein that protects it from some insect pests
    golden rice	a combination of added genes	provitamin A in the endosperm

17. 10.

    Zee compares Bt corn and golden rice. Which claim and reason are correct?

    • Each crop carries added genes, because engineering puts recombinant DNA into the organism
    • Bt corn carries added genes but golden rice does not, because rice cannot take up recombinant DNA
    • Each crop has a replaced genome, because engineering swaps out the plant's genes
    • Each crop carries added genes, because restriction enzymes join them to the plant's DNA