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.
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.
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.
Both alleles are expressed, resulting in an intermediate phenotype.
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.
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
Genotypic ratio: 1 RR : 1 Rr : 1 rr, Phenotypic ratio: 1 red : 2 pink : 1 white
What is the primary function of chromosomes in eukaryotic cells?
Energy production
Cellular respiration
Genetic information storage and transmission
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
A double-stranded DNA molecule wrapped around histone proteins
How many pairs of chromosomes are present in a typical human somatic cell?
20
23
46
How is the determination of sex in humans primarily influenced?
Environmental factors
Genetic factors
Nutritional factors
Which of the following sex chromosomes is typically found in females?
XY
XX
YX