Mendel’s success in his experiments with pea plants can be attributed to several factors: 1. Choice of Organism: Pea plants (Pisum sativum) were an excellent choice due to their easily observable traits, short generation time, and ability to self-pollinate or cross-pollinate. 2. Controlled Experiments: Mendel meticulously controlled the breeding of the pea plants, ensuring purebred … Read more
Pleiotropy refers to a genetic phenomenon where a single gene influences multiple, seemingly unrelated traits or characteristics. The phenotypic ratio is 1:2 instead of 3:1 because of the death of recessive homozygote. The disease, sickle-cell anaemia, is caused by a gene Hbs . Normal or healthy gene HbA is dominant. The carriers (heterozygotes HbA/Hbs ) … Read more
The Law of Segregation, proposed by Gregor Mendel, states that during the formation of gametes (sex cells), the two alleles for a gene separate (or segregate) from each other into different gametes. As a result, each gamete carries only one allele for each gene. This principle also embodies the idea of the purity of gametes … Read more
This table outlines the dominant and recessive forms of each trait that Mendel studied in pea plants. Trait Dominant Form Recessive Form Seed shape Round Wrinkled Seed color Yellow Green Pod shape Inflated Constricted Pod color Green Yellow Flower position Axial Terminal Plant height Tall Short Flower color Purple White
One classic example of complete sex linkage is the gene for hemophilia, a blood clotting disorder. The gene responsible for hemophilia is located on the X chromosome. Since the gene is recessive and located on the X chromosome, its expression is more prevalent in males. If a male inherits one copy of the hemophilia gene, … Read more
Budding is a form of asexual reproduction commonly observed in various animals like coelenterates such as Hydra and corals, as well as some colonial ascidians. In Hydra, a small outgrowth emerges at the basal end of the body, developing into a bud. This bud grows, forms tentacles, and eventually matures into a new individual. Upon … Read more
Three Devices Encouraging Cross-pollination in Angiosperms: 1. Dioecy: Separate male and female flowers on different plants, preventing self-pollination. Examples: Willow, spinach, hemp. 2. Dichogamy: Timing mismatch between pollen release and stigma receptivity. 3. Hermaphroditism with Structural Barriers: Physical separation of male and female parts within the same flower. Examples: Hibiscus, iris, snapdragon. Bonus: Self-incompatibility: Genetic … Read more
Incompatibility refers to a suite of pre-zygotic barriers in plants that prevent fertilization between genetically incompatible individuals. This mechanism essentially serves as a natural “bouncer” system, promoting outbreeding and enhancing offspring fitness.
The statement that pollination and seed formation are crucial for fruit formation is absolutely correct. Here’s why: Pollination: Triggers fruit development: Pollination acts as the initial signal for the ovary of the flower to start developing into a fruit. Provides genetic diversity: Pollen grains typically carry male genetic material from another plant, which, upon fertilization, leads to the … Read more
Polyembryony’s commercial potential lies in its ability to produce multiple identical plantlets from a single seed. Here’s how it’s exploited: Reduced seed cost Clones of desirable plants Rootstocks for grafting Disease-free plantlets Faster breeding programs