Tag: life processes in living organisms- part 2

Parthenogenesis is a type of asexual reproduction in which the embryo grows and develops from egg without fertilization. Apogamy is a type of reproduction in which sporophyte develops from a gametophyte without fertilization. Parthenocarpy is the phenomenon of development of fruit without fertilization. In this, fruits are seedless. Pseudogamy is a form of reproduction in which the embryo develops from egg following the stimulus of pollination but without fertilization. It involves activation of egg by sperm but does not involve nuclear fusion. 

• Secondary sexual characters are those that appear at the time of puberty while the primary sexual characters are present from the time of birth. 
• These secondary sexual characters are caused by hormones released at the time of puberty.
• Beard growth starts in the male at the time of puberty in the male because of increased secretion of testosterone.

Fertilization can be internal or external. When the fertilization occurs inside the female body, then it is internal fertilization (e.g., most reptiles, some birds, some fishes.)
Fertilization in dogfish, shark is internal. While in catfish, toads and some frogs, it is external fertilization.
Hence, the correct answer is option (C).

Testes are the organs that produce the germ cells and scrotum is the pouch that contains the testes. The evolution of the scrotal sacs in mammals has been mysterious and there exist many hypotheses to explain the probable function of the scrotum. Primarily they provide a space, that isolate and serves to provide a temperature, lower than the body; essential for the production, maturation, and storage of sperm cells. Bats in this respect are unique and exhibit testicular migration between abdomen and scrotum, while the cauda epididymis is permanently in the scrotal sacs.

the functions of the following hormones are:

FSH is responsible for the growth of the Graafian follicle in the ovary. It also promotes the growth of follicles and promotes the secretion of oestrogen in the ovary.
Oestrogen is the female sex hormone. It is responsible for the endometrial thickening and it also helps in the healing of the wall of the uterus.
LH is the Leutenizing hormone and is responsible for the ovulation that takes place on the 14th day of the menstrual cycle.

• The follicular phase of the menstrual cycle is defined as the first day of menstruation until ovulation.
  
• It is initiated by a rise in follicle-stimulating hormone levels on the first day of the cycle. Produced by the hypothalamus.