Most candidates gave the definition of a gene as the basic unit of inheritance located on the
chromosome, which can be transferred from parents to offspring. Most candidates also could
properly state the difference between genotypes and phenotypes.
The candidates could not properly define the meaning of pure breeding and nucleotide. Candidates gave wrong definition of pure breeding as a process of producing a particular genotype. Nucleotide was given as a component of DNA.
Most candidates forgot to represent the gene for smooth coat as ‘S’, and gene for rough coat
as ‘s’, and so lost few marks.
They also performed poorly in the genetic crossing, expected answers include:
Pure- Breeding
A process of producing a particular genotype; over many generations.
Nucleotide
The basic building block of a nucleic acid; consisting of a ribose/deoxyribose/pentose, a
phosphate group and a nitrogen base.
Crossing for garden peas
S = Gene for smooth coat
s = Gene for rough coat
Parents:
Phenotype: Homozygous rough x smooth whose parent was rough
Phenotype: ½ Rough, ½ smooth