The concept “Test cross is a back cross, but a back cross is not necessarily a test cross” highlights differences in genetic approaches. A test cross unveils genotype by breeding with a homozygous recessive individual. It observes phenotypic ratios in offspring. A back cross mates an organism with a parent or a genetically similar individual. … Read more
After syngamy, the zygote becomes active and starts dividing. 1. Cleavage: Cleavage is the initial mitotic division of the zygote, forming a hollow multicellular blastula. Blastomeres, the cells produced, decrease in size with each cleavage due to the absence of a growth phase. As size reduces, metabolic rates increase, leading to faster successive cleavages. This demands … Read more
Fertilization is the amazing process of combining male and female gametes to form a diploid zygote, crucial for human reproduction. This complex event usually happens in the ampulla of the fallopian or uterine tube, paving the way for the embryo’s development in the protective environment of the uterus. Sperm Movement towards Egg: The journey commences … 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
Characteristic Zygote Embryo Developmental Stage Initial single-cell stage after fertilization Advanced stage after several cell divisions; multicellular Structure Single cell containing the full set of chromosomes Multicellular with basic structures and organs starting to form Duration Starts at fertilization Follows the zygote and lasts until about the eighth week in humans
Characteristic Blastula Gastrula Structure Hollow ball of cells, often with a blastocoel Three-layered structure with ectoderm, mesoderm, and endoderm due to gastrulation Cellular Differentiation Initial differentiation, cells maintain a more uniform appearance Significant cellular differentiation, forming distinct cell types and tissues within germ layers
The external genital organs in females include: Mons Pubis Labia Majora Labia Minora Clitoris Vaginal Opening These structures collectively form the external genitalia or vulva in females.
Fertilization, the fusion of the sperm and egg, typically occurs in the fallopian tube. Implantation usually occurs within the endometrium, the inner lining of the uterus.
Seminal vesicles (fructose), Prostate (enzymes & proteins), and Bulbourethral Glands (lubrication) all pour fluids into semen.