USABO /
Open
/ /
Exam
/ /
2025 Exam Questions With Correct Answers
/ // // // // //
The /
/production //of //the //genetically //engineered //"golden //rice" //could //be //important //to //people //of
//developing //nations, //especially //in //South-East //Asia, //because:
A. //people //are //more //likely //to //consume //yellow //grains //than //white.
B. //golden //rice //is //less //expensive //to //grow //and //harvest //than //white //rice.
C. /
/golden /
/rice //has //been //engineered //to //be //resistant //to //most //commercially //available //herbicides.
D. //golden //rice //has //been //engineered //to //contain //higher //concentrations //of //β-carotene //than
//white //rice.
E. /
/golden /
/rice //has //been //engineered //to //produce //biodegradable //plastics. //- //verified //answer(s)-
✔✔D. //golden //rice //has //been //engineered //to //contain //higher //concentrations //of //β-
carotene //than //white //rice.
A/
/large /
/population /
/of /
/laboratory /
/rats /
/was /
,/allowed /
/to /
/breed /
/randomly /
/for //
a/
/number /
/of /
/generations. /
/In /
/this //population, //agouti //fur //is //encoded //by //the //A //allele //and //is //dominant //to //the //black //fur
//trait //encoded //by //the //a //allele. //At //the //beginning //of //the //breeding //cycles, //49% //of //the //rats
//had /
/black /
/fur. /
/At /
/the /
/end /
/of /
/the /
/breeding /
/cycles, /
/this /
/percentage /
/was /
/the /
/same. /
/The /
/rest /
/of /
/the /
/animals /
/had /
/agouti /
/fur. /
/The //heterozygotes //with //agouti //fur //were //indistinguishable //from //homozygotes //with //agouti
//fur. /
/What /
,/percentage /
/of /
/this /
/population /
/is //probably //heterozygous //for //the //fur //color //trait //assuming //the //rats //are //following //Hardy-
Weinberg //population //genetics?
A. //7%
B. //30%
C. //42%
D. //49%
E. //70% //- //verified //answer(s)-✔✔C. //42%
An /
/individual /
/suffers /
/brain /
/damage /
/that //results //in //respiratory //failure. //Which //region //of //the //brain //was //most //likely //damaged?
A. //Substantia //nigra
B. //Pons
C. //Red //nucleus
D. //Superior //colliculus
E. //Reticular //formation //- //verified //answer(s)-✔✔B. //Pons
To /
/keep /
/their /
/dog /
/breeds //"pure," /
, /breeders /
/will /
/keep /
/dogs /
/of //different //breeds //in //physically //separate //areas //when //the //female //is //in //heat. //This //aspect
//of /
/artificial /
/selection /
/is //most //closely //analogous //to //which //of //the //following //reproductive //isolating //mechanisms?
A. //Mechanical //isolation
B. //Gametic //isolation
C. //Cooperative //breeding
D. //Ecological //isolation
E. //Hybrid //breakdown //- //verified //answer(s)-✔✔D. //Ecological //isolation
A/
/man /
/and //
a/
/woman /
/get /
/married /
/and //soon //learn //that //they //both //have //a //rare, //genetically //inherited //recessive //disorder //that
//makes /
/them /
/prone /
/to /
/dizziness. /
/Worried /
/about /
/the /
/fate /
/of /
Open
/ /
Exam
/ /
2025 Exam Questions With Correct Answers
/ // // // // //
The /
/production //of //the //genetically //engineered //"golden //rice" //could //be //important //to //people //of
//developing //nations, //especially //in //South-East //Asia, //because:
A. //people //are //more //likely //to //consume //yellow //grains //than //white.
B. //golden //rice //is //less //expensive //to //grow //and //harvest //than //white //rice.
C. /
/golden /
/rice //has //been //engineered //to //be //resistant //to //most //commercially //available //herbicides.
D. //golden //rice //has //been //engineered //to //contain //higher //concentrations //of //β-carotene //than
//white //rice.
E. /
/golden /
/rice //has //been //engineered //to //produce //biodegradable //plastics. //- //verified //answer(s)-
✔✔D. //golden //rice //has //been //engineered //to //contain //higher //concentrations //of //β-
carotene //than //white //rice.
A/
/large /
/population /
/of /
/laboratory /
/rats /
/was /
,/allowed /
/to /
/breed /
/randomly /
/for //
a/
/number /
/of /
/generations. /
/In /
/this //population, //agouti //fur //is //encoded //by //the //A //allele //and //is //dominant //to //the //black //fur
//trait //encoded //by //the //a //allele. //At //the //beginning //of //the //breeding //cycles, //49% //of //the //rats
//had /
/black /
/fur. /
/At /
/the /
/end /
/of /
/the /
/breeding /
/cycles, /
/this /
/percentage /
/was /
/the /
/same. /
/The /
/rest /
/of /
/the /
/animals /
/had /
/agouti /
/fur. /
/The //heterozygotes //with //agouti //fur //were //indistinguishable //from //homozygotes //with //agouti
//fur. /
/What /
,/percentage /
/of /
/this /
/population /
/is //probably //heterozygous //for //the //fur //color //trait //assuming //the //rats //are //following //Hardy-
Weinberg //population //genetics?
A. //7%
B. //30%
C. //42%
D. //49%
E. //70% //- //verified //answer(s)-✔✔C. //42%
An /
/individual /
/suffers /
/brain /
/damage /
/that //results //in //respiratory //failure. //Which //region //of //the //brain //was //most //likely //damaged?
A. //Substantia //nigra
B. //Pons
C. //Red //nucleus
D. //Superior //colliculus
E. //Reticular //formation //- //verified //answer(s)-✔✔B. //Pons
To /
/keep /
/their /
/dog /
/breeds //"pure," /
, /breeders /
/will /
/keep /
/dogs /
/of //different //breeds //in //physically //separate //areas //when //the //female //is //in //heat. //This //aspect
//of /
/artificial /
/selection /
/is //most //closely //analogous //to //which //of //the //following //reproductive //isolating //mechanisms?
A. //Mechanical //isolation
B. //Gametic //isolation
C. //Cooperative //breeding
D. //Ecological //isolation
E. //Hybrid //breakdown //- //verified //answer(s)-✔✔D. //Ecological //isolation
A/
/man /
/and //
a/
/woman /
/get /
/married /
/and //soon //learn //that //they //both //have //a //rare, //genetically //inherited //recessive //disorder //that
//makes /
/them /
/prone /
/to /
/dizziness. /
/Worried /
/about /
/the /
/fate /
/of /
