INTRODUCTION All sexually reproducing organisms exhibit sequential events and processes which are grouped into three distinct stages, namely, the pre-fertilization, fertilization and the post-fertilization events. Pre-fertilization Events:- They occur prior to the process of fertilization. The two main prefertilization events are gametogenesis and gamete transfer. (a) Gametogenesis:– It refers to the process of … Read more
female reproductive system parts and functions The female reproductive system consists of a pair of ovaries, a duct system consisting of a pair of fallopian tubes (oviducts), a uterus, cervix and vagina. A pair of mammary glands are accessory genital glands. Ovaries The ovary produces ova and secretes the female sex hormones, estrogens and progesterone … Read more
Features of sexual reproduction are:– Two fusing gametes can be produced by same individual or different individuals. So it can be both uniparental as well as biparental (mostly). Offsprings produced are not identical to parents or amongst themselves because organisms produce inherits chromosome/genetic material contributed from two different gametes. So we can say it produces … Read more
male reproductive system The male reproductive system is located in the pelvic region. It includes a pair of testes along with accessory ducts, glands and external genitalia. The testes are situated outside the abdominal cavity within a pouch called the scrotum helps in maintaining the low temperature of the testes (2-2.50C )lower than the normal … Read more
As there is involvement of only one parent so it is uniparental. It can occur with or without gamete formation but gametic fusion is absent. The individuals produced are exact copies of each other and their parents because the new organisms produced inherit all of its chromosomes from one parent. Such a group of morphologically … Read more
pregnancy and embryonic development Embryonic development includes cleavage, blastulation, implantation, gastrulation and organogenesis. Cleavage:- First cleavage is completed after 30 hours of fertilization. Cleavage furrow passes from animal- vegetal axis as well as centre of zygote (Meridional plane). It divides the zygote completely into two blastomeres (Holoblastic cleavage). Second cleavage is completed after 60 hours … Read more
Introduction It is common step of both types of respiration which takes place in cytoplasm. Glycolysis (Greek glycon- for sugar and lysis- for splitting)means up of sugar. This scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and often referred to as the EMP Pathway. In plants, the glucose is … Read more
Establishment of sex through differential development in an early stage of life is called sex determination. Sex of human beings and insects like grasshopper, firefly, Drosophila etc. is determined genetically. Chromosomal basis of sex determination:- The foundation of this type was laid down by Henking (18999). He traced a specific nuclear structure all through spermatogenesis … Read more
The reproductive cycle in the female primates (e.g. monkeys, apes and human beings) is called menstrual cycle. The first menstruation begins at puberty and is called menarche. In human females, menstruation is repeated at an average interval of about 28/29 days, and the cycle of events from one menstruation till next is called the menstrual … Read more
In flowering plants, male and female gametes are non-motile, therefore, they have to be brought together for fertilization. The transfer of pollen grains to stigma is called pollination. Pollination types:- Depending on the source of pollen, pollination is of three types:- Autogamy:- The transfer of pollen grain from the anther to the stigma of the … Read more