Sporozoite is the infective stage of the malarial parasite. They are present in the saliva of infected female anopheles mosquito.

An age pyramid is a graphic representation of the proportion of various age groups of a population with pre-reproductive at the reproduction in the middle and posts-reproductive at the top. For human population, the age pyramids show age distribution of males and females in the combined diagram. The shape of the age pyramids reflects the growth status of the population. In a declining population the shape of the pyramid is urn- shaped.

The cellular factory responsible for synthesising proteins (peptide synthesis) is the ribosome.

Bisexual flowers which remain always closed are called the cleistogamous and such condition of flowers is called cleistogamy. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in the flowers buds, pollen grains come in contact with stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous.

The superiority of hybrids over either of the parents (dominant or recessive is called hybrid vigour (G. shull). Heterosis is equivalent of hybrids vigour.

Rhizobium leguminosarum is a symbiotic bacteria found in root nodules of legume. This bacterium has nitrogen fix nif gene and fixing N₂, Soybean is a legume. Thus, Rhizobium is used as a biofertilizer for raising soybean crop.

In Marchantia, a bryophyte, the archegonia (female sex organs) are borne on special branches called archegoniophore or female receptacles. Each archegoniophore has rows of archegonia protected by involucre or perichaetium.

The occurrence of more than one embryo in a seed is referred as polyembryony. In many Citrus and mango varieties, some of the nucellar cells surrounding the embryo sac and develop into the embryos in such species each ovule contain many embryos (nucellar polyembryony).

The fallopian tube is about 10-12 cm long and extends from the periphery of each ovary to the uterus. The part closer to the ovary is the funnel-shaped and is called infundibulum. The edges of the infundibulum possess finger - like projections called fimbriae, which helps is a collection of the ovum after ovulation. The uterus opens into the vagina through a narrow cervix.

The testes in humans are situated outside the abdominal cavity in scrotal sacs. This is because the temperature of scrotal sacs is 25^o C less than internal body temperature.