1. In a dihybrid cross between pure-breeding plants with round yellow seeds and wrinkled green seeds, which are the parental combinations?
A.
Round yellow and wrinkled green
B.
Round green and wrinkled yellow
C.
Round yellow and round green
D.
Wrinkled yellow and wrinkled green
Correct Answer:
Round yellow and wrinkled green
Explanation:
The parental combinations are the original trait combinations present in the two parents: round yellow and wrinkled green.
2. Which cross represents the parental generation in a dihybrid cross for seed shape and seed colour?
A.
RrYy × RrYy
B.
RRYY × rryy
C.
RRYy × rrYy
D.
RrYY × Rryy
Correct Answer:
RRYY × rryy
Explanation:
RRYY and rryy are pure parental genotypes carrying the original combinations of both traits.
3. In the cross YYRR × yyrr, which phenotype represents one parental combination?
A.
Green wrinkled
B.
Yellow wrinkled
C.
Yellow round
D.
Green round
Correct Answer:
Yellow round
Explanation:
The YYRR parent has yellow, round seeds, so yellow round is one of the parental combinations.
4. If the parents in a dihybrid cross are tall red-flowered and dwarf white-flowered plants, which is a parental combination?
A.
Tall white-flowered
B.
Dwarf red-flowered
C.
Tall red-flowered
D.
Intermediate-height red-flowered
Correct Answer:
Tall red-flowered
Explanation:
A parental combination is a trait combination found directly in one of the original parents. Tall red-flowered is one such combination.
5. In a cross between AABB and aabb plants, which gametes carry the parental combinations?
A.
AB and ab
B.
Ab and aB
C.
AA and bb
D.
Aa and Bb
Correct Answer:
AB and ab
Explanation:
The AABB parent produces AB gametes and the aabb parent produces ab gametes. These preserve the parental combinations.
6. A plant with genotype RrYy has parental combinations RY and ry. Which statement correctly identifies them?
A.
They are combinations originally present in the parents
B.
They are combinations formed only by mutation
C.
They are combinations that cannot occur in gametes
D.
They are combinations found only in the F2 generation
Correct Answer:
They are combinations originally present in the parents
Explanation:
Parental combinations are the allele combinations inherited from the original parental chromosomes, such as RY and ry in this example.
7. In the parental cross RRYY × rryy, which genotype is the F1 offspring and contains both parental alleles?
A.
RRYY
B.
rryy
C.
RrYy
D.
RRyy
Correct Answer:
RrYy
Explanation:
The F1 offspring receives R and Y from one parent and r and y from the other, giving the genotype RrYy.
8. Which pair shows the original parental phenotypes in Mendel's dihybrid cross involving seed shape and seed colour?
A.
Round yellow and wrinkled green
B.
Round green and wrinkled yellow
C.
Round yellow and round green
D.
Wrinkled yellow and wrinkled green
Correct Answer:
Round yellow and wrinkled green
Explanation:
Mendel used parents with round yellow seeds and wrinkled green seeds. These are the parental phenotype combinations.
9. If the original parents are AABB and aabb, which genotype represents a parental combination in the offspring?
A.
AABB
B.
AAbb
C.
aaBB
D.
AaBb
Correct Answer:
AABB
Explanation:
AABB is identical to one of the original parental genotypes and therefore represents a parental combination.
10. In a dihybrid cross, a combination that is the same as either original parent is called a:
A.
Parental combination
B.
New mutation
C.
Dominant mutation
D.
Hybrid combination
Correct Answer:
Parental combination
Explanation:
A parental combination is a trait or allele combination that matches one of the original parents in the cross.
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