(a) Define the term hybridization (b) State five aims of crop improvement. (c) Describe a monohybrid cross as explained by Mendel's Law of segregation. Illu...

(a) Define the term hybridization (b) State five aims of crop improvement. (c) Describe a monohybrid cross as explained by Mendel's Law of segregation. Illustrate your answers with clearly labelled diagrams.

(a) Hybridization is a process of cross-breeding two different varieties or species of plants or animals to create a hybrid offspring that possesses desirable traits from both parents.

(b) The five aims of crop improvement are:

1. To increase yield and productivity of crops.
2. To improve the quality of crops for better nutrition and taste.
3. To develop resistance to diseases, pests, and environmental stresses.
4. To reduce input costs, such as fertilizers and pesticides.
5. To develop new varieties with desirable traits, such as drought tolerance, early maturity, or high oil content.

(c) A monohybrid cross is a type of genetic cross that involves the study of one trait in which the parents differ by one pair of contrasting traits. According to Mendel's law of segregation, during gamete formation, the alleles for a trait segregate and each gamete receives only one allele from each parent. This means that when two individuals with different alleles for a trait are crossed, their offspring will receive one allele from each parent, and the two alleles will segregate during gamete formation.

For example, if we cross a pea plant with yellow seeds (YY) with a pea plant with green seeds (yy), the resulting F1 generation will all have yellow seeds because the Y allele is dominant over the y allele. However, the F1 generation will be heterozygous (Yy) because they received one Y allele from the yellow-seeded parent and one y allele from the green-seeded parent. When the F1 plants self-pollinate, their offspring (F2 generation) will exhibit a 3:1 ratio of yellow-seeded to green-seeded plants, with the green-seeded plants being homozygous recessive (yy).

The following Punnett square shows the possible genotypes and phenotypes of the F1 and F2 generations in a monohybrid cross:

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Answer Details

(a) Hybridization is a process of cross-breeding two different varieties or species of plants or animals to create a hybrid offspring that possesses desirable traits from both parents.

(b) The five aims of crop improvement are:

1. To increase yield and productivity of crops.
2. To improve the quality of crops for better nutrition and taste.
3. To develop resistance to diseases, pests, and environmental stresses.
4. To reduce input costs, such as fertilizers and pesticides.
5. To develop new varieties with desirable traits, such as drought tolerance, early maturity, or high oil content.

(c) A monohybrid cross is a type of genetic cross that involves the study of one trait in which the parents differ by one pair of contrasting traits. According to Mendel's law of segregation, during gamete formation, the alleles for a trait segregate and each gamete receives only one allele from each parent. This means that when two individuals with different alleles for a trait are crossed, their offspring will receive one allele from each parent, and the two alleles will segregate during gamete formation.

For example, if we cross a pea plant with yellow seeds (YY) with a pea plant with green seeds (yy), the resulting F1 generation will all have yellow seeds because the Y allele is dominant over the y allele. However, the F1 generation will be heterozygous (Yy) because they received one Y allele from the yellow-seeded parent and one y allele from the green-seeded parent. When the F1 plants self-pollinate, their offspring (F2 generation) will exhibit a 3:1 ratio of yellow-seeded to green-seeded plants, with the green-seeded plants being homozygous recessive (yy).

The following Punnett square shows the possible genotypes and phenotypes of the F1 and F2 generations in a monohybrid cross: