Mendel’s laws

Gregor Mendel mainly used the garden pea plant, Pisum sativum, to investigate how contrasting traits are inherited. Peas were useful because they have clear observable features, a relatively short generation time, and can undergo self-pollination as well as controlled cross-pollination. Therefore option A is correct. Wheat, mango, and neem were not the principal organism associated with Mendel’s classic inheritance experiments.

Gregor Johann Mendel used the garden pea plant, Pisum sativum, to investigate how traits are inherited. Pea plants were suitable because they have several clear contrasting characteristics, a short generation time, and can undergo self-pollination as well as controlled cross-pollination. By comparing parental and offspring generations, Mendel identified regular patterns of inheritance. Therefore option A is correct; the other listed plants are not the classic organism used in his foundational experiments.

In a Mendelian cross, a dominant trait is expressed in the heterozygous first-generation offspring, whereas a recessive trait can remain hidden. Let T represent tallness and t represent dwarfness. A pure cross TT × tt produces F1 offspring with genotype Tt; because T is dominant, all F1 plants are tall. Therefore option A, tallness, is correct. Dwarfness is the contrasting recessive trait, and seed shape or colour is unrelated to this cross.

A monohybrid cross follows one pair of contrasting traits. For example, crossing two heterozygous plants, Tt × Tt, gives TT, Tt, Tt and tt in the second generation. Three offspring show the dominant trait and one shows the recessive trait, so the usual phenotypic ratio is 3:1. Therefore option A is correct. The other ratios do not represent the standard Mendelian phenotypic result.

The governing concept is Mendelian dominance. A dominant trait is expressed in the phenotype when its allele is present in either a homozygous or a heterozygous condition, so it can appear even when a contrasting recessive allele is also present. For example, Mendel observed tallness as dominant over dwarfness in pea plants. Therefore option A is correct; a dominant trait is not necessarily acquired and is not restricted to fossils.

Gregor Mendel is famous for establishing the basic laws of heredity through carefully controlled experiments with pea plants. By tracking contrasting traits across generations, he described predictable patterns of segregation and independent assortment. Thus option A is correct and Mendel is widely called the father of genetics. Darwin is chiefly associated with evolution by natural selection, while Newton and Einstein are known mainly for physics.

Mendel mainly used the garden pea plant, Pisum sativum, in his heredity experiments. Peas were suitable because they had several clear contrasting traits, a relatively short generation time, and could undergo self-pollination or controlled cross-pollination. Therefore option A is correct. Mango, wheat and neem were not the principal experimental plant associated with Mendel’s classic laws of heredity.

The governing concept is segregation of alleles in a monohybrid cross. If the F1 hybrids are Tt, the cross Tt × Tt produces TT, Tt, Tt and tt in a 1:2:1 genotypic ratio. Because TT and Tt are both tall while tt is dwarf, the phenotypic ratio is three tall plants to one dwarf plant, or 3:1. Therefore option A is correct.

In Mendel’s pea experiments, plant height was studied as a character with two clearly different forms: tall and dwarf. Such alternative forms of the same character are called contrasting traits. They are not identical, are not produced merely by practice or experience, and are not fossil traits. Hence option A correctly identifies the relationship between the two forms.

The prefix mono means one, so a monohybrid cross examines the inheritance of one contrasting pair of traits. The prefix di means two, so a dihybrid cross follows two contrasting pairs simultaneously, for example seed shape and seed colour. Therefore B is correct. A refers to only one trait, while C and D are different biological topics rather than types of Mendelian crosses.