Genetics - SS3 Biology Past Questions and Answers - page 2
In a test cross, why is it necessary for one parent to have a homozygous recessive genotype?
To ensure a higher number of offspring in the cross.
To improve the chances of producing hybrid offspring.
To improve the chances of producing hybrid offspring.
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In a backcross, what is the expected ratio of phenotypes in the offspring when crossing a hybrid (Hh) with one of its parents (HH)?
All offspring will have the same phenotype as the hybrid.
1:1 ratio of dominant to recessive phenotype.
1:1 ratio of dominant to recessive phenotype.
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In incomplete dominance, what is the phenotypic outcome when a heterozygous individual inherits two different alleles for a specific trait?
The dominant allele completely masks the recessive allele.
The recessive allele completely masks the dominant allele.
Both alleles are expressed, resulting in an intermediate phenotype.
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If a flower with red petals (RR) is incompletely dominant to a flower with white petals (rr), what will be the phenotype of a heterozygous individual (Rr)?
The flowers will have red petals.
The flowers will have white petals.
The flowers will have pink petals.
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In a cross between a red-flowered plant (RR) and a white-flowered plant (rr) with incomplete dominance, what will be the genotypic and phenotypic ratios of their offspring?
Genotypic ratio: 1 RR : 2 Rr : 1 rr, Phenotypic ratio: 1 red : 1 white
Genotypic ratio: 1 RR : 1 Rr : 1 rr, Phenotypic ratio: 1 red : 2 pink : 1 white
Genotypic ratio: 1 RR : 2 Rr : 1 rr, Phenotypic ratio: 2 pink : 1 white
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What is the primary function of chromosomes in eukaryotic cells?
Energy production
Cellular respiration
Genetic information storage and transmission
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Which of the following describes the structure of a chromosome?
A single-stranded RNA molecule encased in a lipid membrane
A circular DNA molecule found only in prokaryotic cells
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How many pairs of chromosomes are present in a typical human somatic cell?
20
23
46
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How is the determination of sex in humans primarily influenced?
Environmental factors
Genetic factors
Nutritional factors
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Which of the following sex chromosomes is typically found in females?
XY
XX
YX
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