Evaluate the statements concerning lactation and colostrum:
(I) The mammary glands of females undergo differentiation during pregnancy and start producing milk toward its end. (II) The milk produced during the initial few days of lactation is known as colostrum. (III) Colostrum is completely devoid of antibodies, making breast-feeding optional for resistance development. (IV) Breast-feeding during the initial period of infant growth is strongly recommended by doctors.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because colostrum contains several antibodies (primarily IgA) that provide passive immunity to the newborn.
Question 32 of 100
📘 CLASS XII
Analyze the statements regarding the blastocyst structure and its differentiation:
(I) The blastomeres in a blastocyst are arranged into an outer layer called the trophoblast. (II) The inner group of cells attached to the trophoblast is known as the inner cell mass. (III) The trophoblast layer gets directly differentiated to form the embryo. (IV) The inner cell mass contains certain stem cells with the potency to give rise to all tissues and organs.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because the inner cell mass differentiates into the embryo, whereas the trophoblast contributes to implantation and placental development.
Question 33 of 100
📘 CLASS XII
Read the following statements concerning the menstrual cycle's follicular phase:
(I) During this phase, primary follicles in the ovary mature into a fully developed Graafian follicle. (II) Simultaneously, the endometrium of the uterus degenerates through active apoptosis. (III) These uterine and ovarian changes are induced by changes in the levels of pituitary and ovarian hormones. (IV) Gonadotropin (LH and FSH) secretions decrease drastically to prevent premature ovulation.
Explanation: Statements (I) and (III) are correct. Statement (II) is incorrect because the endometrium regenerates through proliferation, rather than degenerating. Statement (IV) is incorrect because LH and FSH secretions increase gradually during the follicular phase.
Question 34 of 100
📘 CLASS XII
Evaluate the statements concerning the spermatid transformation process:
(I) Spermatids are transformed into mature spermatozoa by a process called spermiation. (II) Following this transformation, sperm heads become embedded in the Sertoli cells. (III) The subsequent release of sperms from the seminiferous tubules is called spermiogenesis. (IV) Both transformation and release are highly regulated endocrine events beginning at puberty.
Explanation: Statements (II) and (IV) are correct. Statements (I) and (III) are incorrect because the terms are interchanged. The transformation of spermatids into spermatozoa is called spermiogenesis, while their release from the seminiferous tubules is called spermiation.
Question 35 of 100
📘 CLASS XII
Regarding primary and secondary oocytes, identify the correct statements:
(I) Primary oocytes are formed within the fetal ovary and are temporarily arrested in prophase-I. (II) Secondary oocytes are haploid cells produced after the completion of the first meiotic division. (III) The secondary oocyte retains only a tiny fraction of the cytoplasm of the primary oocyte. (IV) A primary oocyte completes its first meiotic division within the primary follicle stage.
Explanation: Statements (I) and (II) are correct. Statement (III) is incorrect because the secondary oocyte retains the bulk of the cytoplasm. Statement (IV) is incorrect because the first meiotic division is completed in the tertiary follicle, not the primary follicle.
Question 36 of 100
📘 CLASS XII
Examine the structure of a human sperm and choose the correct combination:
(I) A plasma membrane covers only the head region of the sperm. (II) The anterior portion of the sperm head is covered by a cap-like acrosome. (III) The middle piece contains centrioles but is completely devoid of mitochondria. (IV) The tail's motility is powered by energy produced in the middle piece.
Explanation: Statement (I) is incorrect because the plasma membrane covers the entire sperm. Statement (II) is correct. Statement (III) is incorrect because the middle piece contains numerous mitochondria. Statement (IV) is correct because ATP generated by these mitochondria powers tail movement.
Question 37 of 100
📘 CLASS XII
Concerning fertilization and the block to polyspermy:
(I) Fertilization takes place in the infundibulum region of the fallopian tube. (II) Contact of sperm with the zona pellucida layer induces changes in the membrane to block additional sperm entry. (III) This membrane alteration ensures that only one sperm fertilizes the ovum. (IV) Acrosomal secretions allow the sperm to enter the cytoplasm of the ovum.
Explanation: Statement (I) is incorrect because fertilization normally occurs in the ampullary region of the fallopian tube. Statements (II), (III), and (IV) are correct.
Question 38 of 100
📘 CLASS XII
Read the statements below regarding the male accessory sex glands:
(I) The secretions of paired seminal vesicles, a prostate, and paired bulbourethral glands constitute seminal plasma. (II) Seminal plasma is rich in glucose, sodium, and certain lipid-digesting enzymes. (III) The secretion of the bulbourethral glands helps in the lubrication of the penis. (IV) All accessory glands are single, unpaired structures in the male pelvis.
Explanation: Statements (I) and (III) are correct. Statement (II) is incorrect because seminal plasma is rich in fructose, calcium, and certain enzymes. Statement (IV) is incorrect because the seminal vesicles and bulbourethral glands are paired, whereas only the prostate is unpaired.
Question 39 of 100
📘 CLASS XII
Identify the correct statements concerning the germ layers formed after implantation:
(I) The inner cell mass differentiates into ectoderm and endoderm almost immediately. (II) A middle layer called mesoderm appears between the ectoderm and endoderm. (III) These three germ layers give rise to all tissues and organs in the adult. (IV) The ectoderm alone forms 100% of the internal mucosal organs.
Explanation: Statements (I), (II), and (III) are correct. Statement (IV) is incorrect because all three germ layers contribute to the formation of tissues and organs, and the ectoderm alone does not form all internal mucosal organs.
Question 40 of 100
📘 CLASS XII
Analyze the human female breast structure and select the correct statements:
(I) Each glandular tissue contains 15–20 mammary lobes. (II) The cells of alveoli secrete milk, which is stored in the cavities (lumens) of the alveoli. (III) The tubules of each mammary lobe join to form a lactiferous duct directly. (IV) Several mammary ducts join to form a wider mammary ampulla connected to the lactiferous duct.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because the tubules of each mammary lobe join to form a mammary duct, not directly a lactiferous duct.
