Answer: Option C. -> Both a and b
:
C
Decomposition is the natural process of break down of organic matter like dead animal or plant tissue. This process is carried out by invertebrates, fungi and bacteria. Decomposition process helps in the release of chemical energy stored in the bodies of organisms, which is used by the decomposers. The chemicals that are released into the soil are then used up by plants.

Answer: Option A. -> Spermatogonium - 46 chromosomes, Spermatids - 23 chromosomes, Spermatozoa - 23 chromosomes
:
A
Each spermatogonium is diploid and contains 46 chromosomes. Some of the spermatogonia undergo mitotic divisions to form primary spermatocytes, which periodically undergo meiosis. A primary spermatocyte completes the first meiotic division (reduction division) leading to the formation of two equal, haploid cells called secondary spermatocytes, which have only 23 chromosomes each. The secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids with 23chromosomes. The spermatids are transformed into spermatozoa which are also haploid, having23 chromosomes.

Answer: Option A. -> Human chorionic gonadotropin
:
A
Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc.Vasopressin, also known asantidiuretic hormone(ADH), is aneurohypophysial hormonefound in mostmammals.Insulinproduction is regulated based on blood sugar levels and other hormones in the body. Somatotropic hormoneis secreted by the anterior pituitary gland, and stimulates growth in humans.

Answer: Option B. -> Prevent binding of additional sperm
:
B
Soon after the first sperm penetrates the zona pellucida of the ovum, calcium ions diffuse inward through the oocyte membrane triggering multiple cortical granules to be released by exocytosis from the oocyte into the perivitelline space. These granules contain substances that permeate all portions of the zona pellucida and prevent binding of additional sperm.

Answer: Option D. -> Germinal epithelium
:
D
Spermatogenesis occurs in the seminiferous tubules of the testes. The seminiferous tubules are lined by germinal epithelium which is made up of germ cells and sertoli cells.

Answer: Option C. -> Both [A] and [R] are true and [R] is the correct explanation of [A].
:
C
Penis is a cylindrical shaped erectile organ of the male reproductive system with an enlarged tip known as the glans penis.The tissue of the penis is highly vascular, with several sponge like regions known as corpora cavernosa and corpus spongiosum which can hold large amounts of blood. It is from this vascularity that the penis derives its importance as a delivery organ. During intercourse, the corpora cavernosa gets filled upwith blood, causing the penis to expand and become erect.

Answer: Option B. -> Fundus
:
B
Theuterusis a thick walled muscular organ. The uterus has 3 parts - fundus:top of the uterus, above the entry point of the uterine tubes, body:usual site for implantation of the blastocyst, cervix:lower part of uterus linking it with the vagina.

Answer: Option D. -> (iii)
:
D
The parts labelled in the image given are germ cells, sertoli cells, leydig cells and the basal lamina respectively. Among these cells labelled, leydig cells produce androgens such as testosterone.

Answer: Option A. -> Graafian follicle
:
A
After ovulation (release of ovum), the empty graafian follicle forms the corpus luteum that acts as an endocrine gland, because it secretes progesterone hormone for the maintenance of pregnancy. However, in the absence of pregnancy, it degenerates.

Answer: Option A. -> Fructose and calcium
:
A
Seminal plasma is composed of the fluid and sperms from the vas deferens, fluid from the seminal vesicles, fluid from the prostate gland and small amounts of secretions from the mucous gland,and the bulbourethral glandsecretions. It contains calcium, citrate ion, phosphate ion, a clotting enzyme,fructose, citrate, inositol, prostaglandins, several proteins, etc.