Govt. Exams
Entrance Exams
Cross: XᶜX × XᶜY produces: XᶜXᶜ (normal daughter), XᶜX (carrier daughter), XᶜY (color blind son), XᶜY (normal son). 50% of sons are color blind.
Sex-linked genes are located on sex chromosomes, particularly the X chromosome. X-linked traits show different inheritance patterns in males and females.
The classical dihybrid cross ratio is 9:3:3:1, following Mendel's Law of Independent Assortment for two independently assorting genes.
Antipodal cells (typically three) are located at the chalazal end and are vegetative in nature, containing vacuoles for nutrient storage. They eventually degenerate.
Gram (chickpea) is a legume with a monocarpellary ovary showing marginal placentation where ovules are attached along the ventral suture.
Protandry is when anthers mature and release pollen before the stigma of the same flower becomes receptive, preventing self-pollination and encouraging cross-pollination.
The generative cell typically divides after pollination (not before pollen release) to form two sperm cells. In some plants it divides before release, but this is not the general pattern.
Date palm pollen can remain viable for several months under room temperature due to low moisture content and thick protective wall. This is unusual compared to most angiosperms.
In marginal placentation, ovules are attached along the ventral suture (margin) of the carpel. This is characteristic of legumes and many other families with unilocular ovaries.
Synergids secrete attractants and guide pollen tubes. One synergid nucleus disintegrates on pollen tube entry, controlling the number of sperm cells entering the embryo sac.
