Question

Seminal plasma of humans is rich in
A. Fructose and certain enzymes, poor in $Ca^{2+}$
B. Fructose, $Ca^{2+}$ and certain enzymes
C. Fructose, $Ca^{2+}$ but no enzymes
D. Glucose, certain enzymes but no $Ca^{2+}$

Answer 1

Semen is a mixture of sperms and seminal fluid, which is the liquid portion of semen that consists of secretions of the seminiferous tubules, seminal vesicles, prostate gland and bulbourethral glands. The average volume of semen in an ejaculation is 2.5-5 ml, with a sperm count (concentration) of 200 to 300 million sperms.

Complete answer:
The composition of semen contains following secretions:-
1. Seminal vesicles: These are paired, tubular, coiled glands situated behind the bladder. They secrete viscous fluid which constitutes the main part of the ejaculate. Seminal fluid contains fructose, citric acid, inositol and prostaglandins.

2. Prostate gland: The alkaline secretions of prostate gland help the sperms to become active and counteract any adverse effects that the urine may have on the sperms. The prostatic fluid provides a characteristic odour to the seminal fluid. Prostate gland secretes citrate ions, calcium, phosphate ions and profibrinolytic.

Let us match this with given options:-

Option A: the seminal plasma contains secretion of glands present in male reproductive system. Calcium is secreted by prostate gland. Thus, seminal plasma has calcium present in it.

Option B: the secretion of the gland of male reproductive system secrete fructose from seminal vesicle, calcium from prostate gland and enzymes from bulbourethral gland. Thus, this option is correct.

Option C: the secretion of bulbourethral gland contains some enzymes so seminal plasma has enzymes present in it. So, this option can not be correct.

Option D: seminal plasma with glucose and certain enzymes also has calcium which is secreted by the prostate gland. Thus, this option can not be correct.

Hence, the correct answer is option (B).

Note: Semen has somewhat alkaline pH of 7.2-7.7, due to the higher pH and larger volume of fluid from the seminal vesicles. The secretion of prostate gland gives semen a milky appearance whereas the fluids from the seminal vesicles and bulbourethral glands give it a sticky consistency. Semen provides sperms with transportation medium and nutrients. It neutralizes the hostile acidic environment of the male urethra (due to presence of urine) and the female vagina.