All Free Biology MCQs with Answers

• A. Sperm is viable for only up to 24 hours
• B. Survival of sperm depends on the pH of the medium and is more active in alkaline medium
• C. Viability of sperm is determined by its motility
• D. Sperms must be concentrated in a thick suspension

Explanation: Sperms remain viable for 48 hours to 72 hours.

• A. Both placenta as well as fully developed foetus
• B. Oxytocin released from maternal pituitary
• C. Placenta only
• D. Fully developed foetus only

Explanation: Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and…

• A. High level of circulating FSH and LH in the uterus to stimulate implantation of the embryo
• B. High level of circulating hCG to stimulate endometrial thickening
• C. High levels of FSH and LH in uterus to stimulate endometrial thickening
• D. High level of circulating hCG to stimulate estrogen and progesterone synthesis

Explanation: During pregnancy, placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human…

• A. 14th day
• B. 20th day
• C. 5th day
• D. 11th day

Explanation: The correct option (a) 14th day: In a normal human menstrual cycle, the rapid secretion of luteinizing hormone (LH) typically occurs…

• A. Testicular lobules to Rete testis
• B. Rete testis to vas deferens
• C. Vas deferens to Epididymis
• D. Epididymis to Urethra

Explanation: a) Testicular lobules to rete testis: The testicular lobules are the compartments within the testes where the seminiferous tubules are…

• A. Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilization
• B. The sperm lysins in the acrosome dissolve the egg envelope facilitating fertilization
• C. The acrosome serves as a sensory structure leading the sperm toward the ovum
• D. Acrosome serves no particular function

Explanation: The correct option is: b) The sperm lysins in the acrosome dissolve the egg envelope facilitating fertilisation.Explanation of each…

• A. Fructose and calcium but has no enzymes
• B. Glucose and certain enzymes but has no calcium
• C. Fructose and certain enzymes but poor in calcium
• D. Fructose, calcium and certain enzymes

Explanation: The correct option is: d) Fructose, calcium, and certain enzymes.Explanation of each option:a) Fructose and calcium but has no…

• A. Release of oxytocin from pituitary
• B. Fully developed fetus and placenta
• C. Differentiation of mammary glands
• D. Pressure exerted by amniotic fluid

Explanation: Note: Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus…

• A. Maintenance of the hypertrophical endometrial lining
• B. Maintenance of high concentration of sex hormones in the bloodstream
• C. Retention of well-developed corpus luteum
• D. Fertilisation of the ovum

Explanation: The correct answer is Fertilisation of the ovum, as this process leads to increased levels of hormones such as human chorionic…

• A. At menopause in the female, there is an especially abrupt decrease in gonadotropic hormones
• B. The beginning of the cycle of menstruation is called menarche
• C. During normal menstruation about 40 mL blood is lost
• D. The menstrual fluid can easily clot

Explanation: Note: Menstruation is a process which involves discharge of blood (45 - 100mL), serous fluid, cell debris and mucosal fragments from cast…

• A. Corpus luteum will disintegrate
• B. Progesterone secretion rapidly declines
• C. Estrogen secretion further increases
• D. Primary follicle starts developing

Explanation: If the mammalian ovum fails to fertilize choices, (a) and (b) are obvious.

• A. Luteotropic hormone
• B. Luteinizing hormone
• C. Estrogen
• D. Progesterone

Explanation: The mammalian corpus luteum is a temporary endocrine structure that forms after ovulation.

• A. After entry of sperm before completion of fertilization
• B. After completion of fertilization
• C. Before entry of sperm
• D. Without any relation of sperm entry

Explanation: After the entry of the sperm into the egg, the egg nucleus undergoes its second meiotic division to form the second polar body.

• A. Liver­-cholesterol
• B. Ovary­-estrogen
• C. Testes­-testosterone
• D. Pancreas­-glucagon

Explanation: Leydig cells, also known as interstitial cells, are found in the testes in males and play a crucial role in the production of…

• A. Mitochondria only
• B. Centriole only
• C. Mitochondria and centriole
• D. Nucleus and mitochondria

Explanation: The middle piece of mammalian sperm plays a crucial role in providing the energy required for sperm motility and the structure necessary…

• A. They inhibit gametogenesis
• B. They make uterus suitable for implantation
• C. They inhibit ovulation
• D. They suppress sperm motility and fertilising capacity of sperms

Explanation: The correct answer is: d. They suppress sperm motility and fertilizing capacity of sperms.

• A. LNG­-20
• B. Multiload-375
• C. Lippes loop
• D. Cu7

Explanation: The correct answer is: a. LNG-20 Now, let's explain each of the options and why the correct answer is LNG-20: a.

• A. No sperm occurs in seminal fluid
• B. No sperm occurs in epididymis
• C. Vasa deferentia is cut and tied
• D. All are correct

Explanation: The correct answer is: b. No sperm occurs in epididymis Let's go through each option and explain why the correct answer is b: a.

• A. Uterus
• B. Fallopian tube
• C. Cervix
• D. All of these

Explanation: The correct answer is: b. Fallopian tube Now, let's explain each option and why the correct answer is b: a.

• A. Hormonal contraceptives prevent/retard entry of sperm,prevent ovulation and fertilization
• B. Vasectomy prevents spermatogenesis
• C. Barrier methods prevent fertilization
• D. Intra uterine devices increase phagocytosis of sperms, suppress sperm motility and fertilizing capacity of sperms

Explanation: The correct answer is: B. Vasectomy - Prevents spermatogenesis Now, let's explain each option and why the correct answer is B: A.