Reproductive system in humans - class-X

Statement (i) is true as the middle piece contains mitochondria (powerhouse). Statement (ii) is false because the vas deferens joins the seminal vesicle duct to form the ejaculatory duct, not vasa efferentia. Statement (iii) is true as semen is a mixture of fluids from these glands and sperm.

Ovaries are the primary female sex organs that produce the female gamete/germ cell ovum and several steroid hormones such as estrogen and progesterone also called ovarian hormones. Each ovary is about 2-4 cm in length and is connected by ligaments to the pelvic wall and the uterus.  Each ovary is whitish in colour and located alongside the lateral wall of the uterus and the other side points downwards attached to the uterus via the ovarian ligament.

Females have two oviducts (or Fallopian tubes). Each oviduct has three regions, infundibulum, ampulla and isthmus. Isthmus is the narrow part closest to uterus, while infundibulum is the first part of oviduct that is encountered by released ova.

The seminiferous tubule is present in the testicular lobule and is highly coiled and produces sperms. The seminiferous tubule opens into the vasa efferentia (small ducts) through the rete testis (a network of interconnecting tubules where the straight seminiferous tubules empty). The enlarged part of the penis or the male genitalia is called the glans penis or head of the penis (sensitive bulbous structure at the distal end of the human penis) and is covered by a foreskin (prepuce) a double-layered fold of smooth muscle tissue, blood vessels etc, to protect the glans penis and urinary meatus. 

The testes are the primary male reproductive organs responsible for the production of both sperm cells and testosterone. Seminal vesicles, the urinary bladder, and Cowper's glands secrete seminal fluid or store urine, but do not produce sperm.

The assertion is true because human sex determination is based on the sperm carrying either an X or a Y chromosome. The reason is false because sex determination in humans is chromosomal (XX/XY), not polygenic.

Humans reproduce exclusively through sexual reproduction, which involves the fusion of male and female gametes. Asexual, vegetative, and parthenogenetic reproduction are not methods used by humans.

The acrosome of the sperm contains enzymes that digest the outer layers of the egg, allowing it to penetrate the membrane. The option 'Tears a hole' is a simplified way of describing this enzymatic penetration.

Blastula differentiate into various regions and cells (blastomeres) of a particular region form a particular part of adult body, hence these areas are called presumptive areas and at this stage if cells of a particular area removed the adult lacks a particular part from its body.

In microlecithal eggs or alecithal eggs, the cleavage results in the production of closely packed blastomeres. The stage in which solid mass of blastomeres appears is said to be morula, whereas blastula is hollow with a cavity known as blastocoel.

In spite of their morphological, anatomical and physiological differences, the fundamental events in sexual reproduction are the same. These events can be categorized as follows:

The hypothalamus is a small region of the brain. It's located at the base of the brain, near the pituitary gland. It secretes hypothalamic hormone such as the GnRH or Gonadotropin stimulating hormone which further has effects on the pituitary gland. The acrosome is the anterior covering on the head of the sperm that consists of enzymes called lysins that can lyse the ovum membrane to penetrate and fertilize it. A Graafian follicle is a developed tertiary follicle and is responsible for the ovulation that occurs as a result of the surge in FSH and LH levels responsible for estrogen production. Leydig cells in the seminiferous tubules are responsible for the secretion of androgens such as testosterone. Parturition is the process of the delivery of the fetus and during this process, Relaxin is a hormone produced by the ovary and the placenta with important effects in the female reproductive system and during pregnancy. 

Parturition is the delivery or childbirth of baby from the uterus. Gestation is the period of development during the carrying of an embryo or fetus inside viviparous animals and the duration between pregnancy and birth. Ovulation is the process of release of the ovum from the Graafian follicle as it ruptures. Implantation is the process of attachment of the zygote to the endometrial lining of the uterus. Conception refers to the post-fertilization fusion of the egg and sperm into the zygote.