Mix Examples-Human Reproduction Questions in English

(A) Genetic recombination is the process by which genetic material is exchanged between different organisms or chromosomes,leading to the production of offspring with combinations of traits that differ from those found in either parent.
$1$. $Meiosis$: During the prophase $I$ of meiosis,specifically in the pachytene stage,crossing over occurs between non-sister chromatids of homologous chromosomes. This physical exchange of $DNA$ segments results in new combinations of alleles.
$2$. $Fertilization$: The fusion of two genetically distinct gametes (sperm and egg) during fertilization brings together two different sets of genetic information,further contributing to the recombination of genes in the zygote.
Therefore,both meiosis and fertilization are essential for genetic recombination in sexually reproducing organisms.

(B) The life cycle of sexually reproducing organisms involves two key processes that maintain a constant chromosome number across generations:
$1$. $Meiosis$: This process reduces the chromosome number by half,resulting in the formation of haploid gametes $(n)$.
$2$. $Fertilization$: This process involves the fusion of two haploid gametes $(n + n)$,which restores the diploid chromosome number $(2n)$ in the zygote.
Thus,the combination of $Meiosis$ and $Fertilization$ ensures that the species-specific chromosome number remains constant.

(D) The female reproductive system produces several hormones that regulate the menstrual cycle and secondary sexual characteristics.
$1$. Progesterone is a steroid hormone involved in the menstrual cycle,pregnancy,and embryogenesis.
$2$. Estrogen is a group of steroid hormones that promote the development and maintenance of female secondary sexual characteristics.
$3$. Estradiol is the most potent and prevalent form of estrogen produced by the ovaries.
Since all three are female hormones,the correct option is $D$.

(A) The correct matching is as follows:
$(a)$ $FSH$ (Follicle Stimulating Hormone) is responsible for the maturation of the Graafian follicle in the ovary $(a-v)$.
$(b)$ $LH$ (Luteinizing Hormone) induces ovulation and stimulates the formation and development of the corpus luteum from the ruptured follicle $(b-iv)$.
$(c)$ Progesterone is essential for maintaining the endometrium and preparing it for the implantation of the embryo $(c-i)$.
$(d)$ Estrogen is responsible for the development and maintenance of female secondary sexual characteristics $(d-ii)$.
Therefore, the correct sequence is $a-v, b-iv, c-i, d-ii$.

(D) The correct matching is as follows:
$(a)$ Oxytocin: It acts on the smooth muscles of the uterus and stimulates their contraction during parturition (childbirth). Thus, $(a-s)$.
$(b)$ Prolactin: It regulates the growth of mammary glands and the formation of milk in them after childbirth. Thus, $(b-r)$.
$(c)$ Luteinizing hormone $(LH)$: In females, it induces ovulation of fully mature follicles (Graafian follicles) and maintains the corpus luteum. Thus, $(c-p)$.
$(d)$ Progesterone: It is essential for the maintenance of the endometrium, which is necessary for implantation and the maintenance of pregnancy. Thus, $(d-q)$.
Therefore, the correct sequence is $(a-s, b-r, c-p, d-q)$.

(C) Adolescence is a transitional phase of growth and development between childhood and adulthood. According to the World Health Organization $(WHO)$ and standard biological definitions,the period of adolescence is generally defined as the age range from $10$ to $19$ years. However,in many educational contexts and textbooks,the range of $10$ to $18$ years is commonly cited as the primary period of adolescence. Given the options provided,$10$ to $18$ years is the most accurate representation of this developmental stage.

(A) Adolescence is a transitional phase of physical and mental development that occurs between childhood and adulthood.
It represents the bridge that connects the period of childhood to the period of adulthood.
Therefore,the correct options are $(ii)$ Childhood and $(iv)$ Adulthood.

(A) The period between $12$ and $18$ years of age is known as adolescence.
Adolescence is a bridge linking childhood and adulthood and is accompanied by many biological and behavioral changes.
It is a phase of rapid growth and development.

(B) The correct matches are as follows:
$(A)$ Mons pubis is a part of the female external genitalia.
$(B)$ Antrum is the fluid-filled cavity present in a mature Graafian follicle.
$(C)$ Trophectoderm is the outer layer of the blastocyst that helps in embryo formation and implantation.
$(D)$ Nebenkern is a structure formed by the aggregation of mitochondria in the middle piece of a sperm.
Therefore,the correct sequence is $A-(iii), B-(iv), C-(i), D-(ii)$.

(A) : During the follicular phase,$FSH$ secretion increases.
Follicular phase (proliferative phase) usually includes cycle days $6-13$ or $14$ in a $28$-day cycle.
The follicle-stimulating hormone $(FSH)$ secreted by the anterior lobe of the pituitary gland stimulates the ovarian follicle to secrete estrogens.

(A) The correct option is $A$.
In the provided figure,$A$ represents a secondary follicle,while $B$ represents the corpus luteum.
The corpus luteum is a temporary endocrine gland formed from the remnants of the Graafian follicle after ovulation.
It primarily secretes large amounts of progesterone,which is essential for the maintenance of the endometrium during pregnancy.
If fertilization does not occur,the corpus luteum degenerates into a corpus albicans after about $14$ days.

(B) The correct answer is $(B)$.
The female reproductive system includes the ovaries,a pair of oviducts (Fallopian tubes),uterus,cervix,vagina,and the external genitalia.
In the provided diagram:
- $(I)$ represents the endometrium (the innermost glandular layer of the uterus).
- $(II)$ represents the myometrium (the middle thick layer of smooth muscle).
- $(III)$ represents the infundibulum (the funnel-shaped part of the Fallopian tube closer to the ovary).
- $(IV)$ represents the fimbriae (finger-like projections at the edges of the infundibulum that collect the ovum after ovulation).
- $(V)$ represents the cervix (the narrow neck of the uterus that opens into the vagina).
- $(VI)$ represents the vagina.
Therefore,the set $(III)$ infundibulum,$(IV)$ fimbriae,and $(V)$ cervix is correctly identified.

(C) The reproductive cycle in female mammals is categorized into two main types: the menstrual cycle and the oestrus cycle.
$1$. The menstrual cycle occurs in primates,such as humans,monkeys,and apes.
$2$. The oestrus cycle occurs in non-primate mammals,such as cows,sheep,rats,deer,dogs,and tigers.
Since rats are non-primate mammals,they exhibit the oestrus cycle.

(D) The provided figure shows a cross-section of the seminiferous tubules.
$X$ points to the large,elongated cells extending from the periphery of the seminiferous tubule towards the lumen.
These are the Sertoli cells,also known as nurse cells.
Their primary function is to provide nutrition to the developing germ cells (spermatids/spermatozoa).
Interstitial cells are located in the interstitial space between the tubules,while spermatogonia are the immature germ cells located at the periphery.

(D) The correct matches are as follows:
- $(A)$ Myometrium: It is the middle thick layer of smooth muscle in the uterus wall. Thus,$(A-4)$.
- $(B)$ Mons pubis: It is a cushion of fatty tissue covered by skin and pubic hair. Thus,$(B-1)$.
- $(C)$ Acrosome: It is a cap-like structure on the sperm head containing enzymes that help in the fertilization of the ovum. Thus,$(C-5)$.
- $(D)$ Prostate gland: It is a male accessory gland. (Note: The provided options focus on the correct combination of $A$,$B$,and $C$).
Comparing these with the given options,the pair $(A-4), (B-1), (C-5)$ is correct.

(C) Based on the anatomical structure of the human female reproductive system:
$1$. $Z$ points to the innermost glandular layer of the uterus,which is the $Endometrium$.
$2$. $Y$ points to the thick middle layer of smooth muscle,which is the $Myometrium$.
$3$. $X$ points to the narrow passage leading from the uterus to the vagina,which is the $Cervix$.
However,looking at the provided options,there seems to be a slight mismatch in the labeling sequence provided in the options versus the standard diagram. Re-evaluating the labels in the diagram:
- $Z$ is the $Endometrium$.
- $Y$ is the $Myometrium$.
- $X$ is the $Cervix$.
Given the options,option $C$ $(Cervix - Myometrium - Ampulla)$ is partially incorrect as $Z$ is $Endometrium$. Let's re-examine the diagram labels: $X$ is the $Cervix$,$Y$ is the $Myometrium$,and $Z$ is the $Endometrium$. If the question asks for $Z-Y-X$,it should be $Endometrium-Myometrium-Cervix$. Since this exact sequence is not present,we identify the most accurate anatomical labels provided in the options. Option $C$ identifies $Cervix$ $(X)$ and $Myometrium$ $(Y)$. Therefore,$C$ is the most appropriate choice.

(D) The correct matches are as follows:
$1$. $(a)$ Parturition: It refers to the process of delivery of the foetus from the uterus, which corresponds to $(r)$.
$2$. $(b)$ Gestation: It is the period of development of the embryo, i.e., the duration between pregnancy and birth, which corresponds to $(s)$.
$3$. $(c)$ Ovulation: It is the process of the release of the secondary oocyte (egg) from the Graafian follicle, which corresponds to $(q)$.
$4$. $(d)$ Implantation: It is the process of the attachment of the blastocyst (embryo) to the uterine endometrium, which corresponds to $(p)$.
Therefore, the correct sequence is $a-r, b-s, c-q, d-p$.

(A) Based on the standard diagram of the human ovary provided in the $NCERT$ textbook:
- $a$ points to the blood vessels entering the ovary.
- $b$ points to a primary follicle.
- $c$ points to a tertiary follicle,characterized by the presence of an antrum.
- $d$ points to a mature Graafian follicle.
- $e$ points to the released ovum (secondary oocyte).
- $f$ points to the corpus luteum,which is formed after ovulation.
Therefore,the correct sequence is $a$ - Blood vessel,$b$ - Primary follicle,$c$ - Tertiary follicle,$d$ - Graafian follicle,$e$ - Ovum,$f$ - Corpus luteum.

(B) Statement $(1)$ is True: The fusion of a male gamete (sperm) and a female gamete (ovum) is defined as fertilization.
Statement $(2)$ is True: $A$ rapid secretion of Luteinizing Hormone $(LH)$ during the mid-cycle,known as the $LH$ surge,induces the rupture of the Graafian follicle and thereby leads to ovulation.
Statement $(3)$ is False: The embryo with $8$ to $16$ blastomeres is called a morula. An $8$-celled stage is typically referred to as an early morula,but the term 'morula' is specifically applied to the $8-16$ cell stage.
Statement $(4)$ is True: The fallopian tube (oviduct) in humans is approximately $10-12 \, cm$ long,but $8-10 \, cm$ is often cited in various standard textbooks as the approximate length range.
Therefore,all statements are considered correct in the context of standard biological curriculum.

(A) The process of fertilisation involves several key biological events:
$(1)$ Fertilisation marks the final step of oogenesis,as the secondary oocyte completes its second meiotic division only upon the entry of a sperm.
$(2)$ The entry of the sperm induces the completion of the second meiotic division,resulting in the formation of a haploid ovum and a second polar body.
$(4)$ Fertilisation prevents the degeneration of the corpus luteum,which continues to secrete progesterone to maintain the endometrium for pregnancy.
$(5)$ The fusion of the male and female gametes results in the formation of a diploid zygote.
Statement $(3)$ is incorrect because the corpus luteum does not degenerate upon fertilisation; it persists to support the pregnancy.
Therefore,the correct statements are $(1)$,$(2)$,$(4)$,and $(5)$.

(D) $1$. Implantation: The process of attachment of the blastocyst to the uterine wall (endometrium) is called implantation,which leads to pregnancy.
$2$. Chorionic villi: After implantation,finger-like projections appear on the trophoblast called chorionic villi,which are surrounded by uterine tissue and maternal blood.
$3$. Parturition: The process of delivery of the foetus (childbirth) is called parturition.
$4$. Since all the given statements are scientifically accurate,the correct option is $D$.

(A) In mammals,the egg is alecithal (containing very little yolk) or microlecithal.
Due to the minimal amount of yolk,the cleavage process involves the entire zygote.
This type of cleavage is known as holoblastic cleavage.
Since the blastomeres formed are of approximately equal size,it is specifically termed as holoblastic equal cleavage.

(A) The correct answer is $A$.
$1$. The $Corpus luteum$ is a temporary endocrine structure in the ovary that develops from the ruptured $Graafian follicle$ after ovulation. Both are stages in the ovarian cycle related to the same follicle.
$2$. $Sebum$ is an oily secretion from sebaceous glands, while $Sweat$ is a watery secretion from sweat glands; they are distinct.
$3$. The $Bundle of His$ is a part of the cardiac conduction system, whereas the $Pacemaker$ $(SA node)$ is the initiator of the heartbeat; they are different.
$4$. Vitamin $B_7$ is $Biotin$, while $Niacin$ is Vitamin $B_3$; they are different vitamins.

(D) Based on the anatomical structure of the human female reproductive system:
$A$ represents the Endometrium (the inner glandular layer of the uterus).
$B$ represents the Myometrium (the middle thick layer of smooth muscle).
$C$ represents the Infundibulum (the funnel-shaped part of the fallopian tube).
$D$ represents the Fimbriae (finger-like projections at the end of the infundibulum).
$E$ represents the Uterine cavity.
$F$ represents the Cervix.
Comparing these with the given options,option $D$ correctly identifies $B$ as Endometrium,$C$ as Infundibulum,and $D$ as Fimbriae.

$(B)$ Mons pubis is a cushion of fatty tissue covered by skin and pubic hair, which is a part of the female external genitalia $(A-3)$.
$(B)$ Antrum is the fluid-filled cavity present in the Graafian follicle $(B-4)$.
$(C)$ Trophectoderm (or Trophoblast) is the outer layer of the blastocyst that helps in embryo attachment and formation of the placenta $(C-1)$.
$(D)$ Nebenkern is the mitochondrial spiral found in the middle piece of the sperm $(D-2)$.
Therefore, the correct matching is $A-3, B-4, C-1, D-2$.

(B) The correct answer is $B$.
$1$. $LH$ and $FSH$ levels actually increase gradually during the follicular phase,not decrease.
$2$. $LH$ surge induces ovulation,but it occurs from the Graafian follicle,not the fallopian tube.
$3$. $LH$ acts on Leydig cells (interstitial cells) to stimulate androgen synthesis and secretion.
$4$. $FSH$ acts on Sertoli cells to stimulate the secretion of some factors which help in the process of spermiogenesis.

(A) The sex of a fetus can be determined by amniocentesis,a procedure where amniotic fluid is collected.
In female mammals,one of the two $X$ chromosomes is inactivated and condensed into a structure known as a $Barr$ body,which can be observed in the nuclei of somatic cells.
Since males have only one $X$ chromosome,they do not possess $Barr$ bodies.
Therefore,the presence of $Barr$ bodies in the cells of the amniotic fluid indicates a female fetus,while their absence indicates a male fetus.

(C) Oogonia are referred to as gamete mother cells.
$A$ represents a primary follicle.
$B$ represents a tertiary follicle.
$C$ represents a Graafian follicle,which is a mature follicle that ruptures to release the secondary oocyte during ovulation.
$D$ represents the corpus luteum,which is formed from the remains of the Graafian follicle after ovulation.
$A$ large number of primary follicles degenerate during the phase from birth to puberty,a process known as follicular atresia.
Therefore,option $C$ is the correct identification and description.

(D) The Assertion is incorrect because $Hyaluronidase$ is an enzyme found in the acrosome of the sperm,not the ovum. It helps the sperm penetrate the layers surrounding the ovum during fertilization.
The Reason is also incorrect. Mammalian eggs are $alecithal$ (or $microlecithal$ in some contexts,but not $telolecithal$). $Telolecithal$ eggs,such as those of birds and reptiles,have a large amount of yolk concentrated at one pole. Mammalian eggs contain negligible amounts of yolk due to their placental development.
Therefore,both the Assertion and the Reason are incorrect.

(C) Males generally have a greater stature than females after puberty due to the action of the male sex hormone,testosterone,which is secreted by the testes.
Testosterone secretion begins at puberty under the influence of Luteinizing Hormone $(LH)$ from the anterior pituitary gland.
Testosterone promotes secondary sexual characteristics in males,including bone growth,calcium retention,and the closure of epiphyseal cartilage,which contributes to increased height and bone density.
$hCG$ (Human Chorionic Gonadotropin) is a hormone secreted by the placenta during pregnancy,not a hormone responsible for stature.
Therefore,the Assertion is correct,but the Reason is incorrect.

(A) The correct sequence of events in human reproduction is as follows:
$1$. Gametogenesis: Formation of gametes (sperm and ovum).
$2$. Gamete transfer: Insemination (transfer of sperm into the female reproductive tract).
$3$. Syngamy: Fertilization (fusion of male and female gametes to form a zygote).
$4$. Zygote: The single-celled diploid structure formed after fertilization.
$5$. Cell division (Cleavage): The zygote undergoes mitotic divisions to form a morula and blastocyst.
$6$. Cell differentiation: The cells of the embryo organize into specific layers and tissues.
$7$. Organogenesis: The development of organs from the differentiated tissues.

(N/A) No,the number of eggs produced by an oviparous mother is generally much higher than the number of young ones produced by a viviparous mother.
In oviparous animals,the development of the embryo occurs outside the mother's body. These eggs are highly vulnerable to environmental hazards and predators.
To compensate for this high mortality rate and ensure the survival of the species,oviparous organisms produce a large number of eggs.
In contrast,in viviparous organisms,the development of the embryo takes place within the protected environment of the mother's body.
Since the offspring are shielded from external threats,their survival rate is significantly higher,which is why fewer young ones are produced.

(N/A) Humans reproduce sexually.
$(b)$ Humans are viviparous.
$(c)$ Fertilization is internal in humans.
$(d)$ Male and female gametes are haploid.
$(e)$ Zygote is diploid.
$(f)$ The process of release of the ovum from a mature follicle is called ovulation.
$(g)$ Ovulation is induced by a hormone called the luteinizing hormone $(LH)$.
$(h)$ The fusion of the male and the female gametes is called fertilization.
$(i)$ Fertilization takes place in the fallopian tube (ampulla).
$(j)$ The zygote divides to form blastocyst,which is implanted in the uterus.
$(k)$ The structure which provides vascular connection between the fetus and uterus is called placenta.

(N/A) Corpus luteum: It is formed from the ruptured Graafian follicle. It secretes progesterone hormone during the luteal phase of the menstrual cycle. High levels of progesterone inhibit the secretion of $FSH$ and $LH$,thereby preventing further ovulation. It also maintains the endometrium for embryo implantation.
$(b)$ Endometrium: It is the innermost glandular lining of the uterus. It undergoes cyclic changes during the menstrual cycle to prepare itself for the implantation of the embryo.
$(c)$ Acrosome: It is a cap-like structure present in the anterior part of the sperm head. It contains hydrolytic enzymes (like hyaluronidase) that help the sperm penetrate the egg membrane during fertilization.
$(d)$ Sperm tail: It is the longest part of the sperm that facilitates motility,allowing the sperm to move through the female reproductive tract.
$(e)$ Fimbriae: These are finger-like projections at the ovarian end of the fallopian tube. They help in the collection of the ovum released from the ovary after ovulation.

(A-D) Androgens are produced by Sertoli cells. (False) Androgens are produced by Leydig cells found in the interstitial spaces of the testis.
$(b)$ Spermatozoa get nutrition from Sertoli cells. (True)
$(c)$ Leydig cells are found in ovary. (False) Leydig cells are found in the interstitial spaces of the testis.
$(d)$ Leydig cells synthesise androgens. (True)
$(e)$ Oogenesis takes place in corpus luteum. (False) Oogenesis takes place in the ovary.
$(f)$ Menstrual cycle ceases during pregnancy. (True)
$(g)$ Presence or absence of the hymen is not a reliable indicator of virginity or sexual experience. (True)

(A) human ovary typically releases $1$ egg per month during the menstrual cycle.
In the case of identical (monozygotic) twins,only $1$ egg is released,which is fertilized by a single sperm to form a single zygote. This zygote later splits into two embryos,resulting in identical twins.
If the twins are fraternal (dizygotic),the answer changes because fraternal twins are produced when $2$ separate eggs are released by the ovaries and fertilized by $2$ separate sperms. Therefore,for fraternal twins,$2$ eggs would have been released.

(N/A) Reproduction is a biological process that ensures the continuity of a species by passing genetic material from one generation to the next. In this process,the genetic material of a single cell is doubled and transmitted.
Humans are sexually reproducing and viviparous organisms. The reproductive events in humans include the formation of gametes (gametogenesis). The transfer of sperm into the female genital tract is known as insemination. The fusion of male and female gametes is called fertilization,which leads to the formation of a zygote.
Following fertilization,the zygote undergoes cleavage to form a blastocyst,which attaches to the uterine wall (implantation). This is followed by embryonic development (gestation) and the delivery of the baby (parturition).
These reproductive events occur after puberty. There is a significant difference between reproductive events in males and females; for example,sperm formation continues even in old men,whereas the formation of ova (oogenesis) ceases in women around the age of $50$ years.

(N/A) The differences between male and female reproductive characteristics are as follows:
$1.$ External reproductive characteristics:

Male	Female
$(1)$ Mammary glands are rudimentary.	$(1)$ Mammary glands are well-developed.
$(2)$ Beard and moustache are present.	$(2)$ Beard and moustache are absent.
$(3)$ Muscles are generally stronger.	$(3)$ Muscles are comparatively weaker.
$(4)$ Voice is deep (low pitch).	$(4)$ Voice is sharp (high pitch).

$2.$ Internal reproductive characteristics:

Male	Female
$(1)$ Primary sex organs are testes.	$(1)$ Primary sex organs are ovaries.
$(2)$ Testes are located outside the abdominal cavity in the scrotum.	$(2)$ Ovaries are located inside the abdominal cavity.
$(3)$ Produce sperms.	$(3)$ Produce ova.
$(4)$ Produce male sex hormone,testosterone.	$(4)$ Produce female sex hormones,estrogen and progesterone.

(A)

Testis	Ovary
$(1)$ Testis is an egg-shaped gland with a length of $5 \ cm$ and a diameter of $2.5 \ cm$.	$(1)$ Ovary is an almond-shaped gland with a length of $3 \ cm$,width of $2 \ cm$,and thickness of $1 \ cm$.
$(2)$ It produces the male sex hormone,testosterone.	$(2)$ It produces female sex hormones,estrogen and progesterone.
$(3)$ Testes are located in the scrotum,outside the abdominal cavity.	$(3)$ Ovaries are located inside the abdominal cavity on both sides of the uterus.

Sperm cell	Ovum (egg) cell
$(1)$ Sperm cell is motile.	$(1)$ Ovum is non-motile.
$(2)$ It consists of a head,middle piece,and a tail.	$(2)$ It is a spherical cell structure surrounded by a zona pellucida layer.
$(3)$ Production continues throughout the male reproductive life.	$(3)$ Production stops after menopause (around $50$ years of age).

(N/A) Differences between Spermatogenesis and Oogenesis:

Spermatogenesis	Oogenesis
$(1)$ Occurs in the testes of males.	$(1)$ Occurs in the ovaries of females.
$(2)$ Meiosis of primary spermatocytes results in two equal haploid secondary spermatocytes.	$(2)$ Meiosis of primary oocytes is unequal,resulting in a large haploid secondary oocyte and a small first polar body.
$(3)$ Secondary spermatocytes undergo meiosis $II$ to produce four haploid spermatids.	$(3)$ The secondary oocyte undergoes meiosis $II$ to form an ovum and a tiny second polar body.
$(4)$ Spermatids undergo spermiogenesis to become mature spermatozoa.	$(4)$ The ovum does not require a maturation process like spermiogenesis.

Differences between Embryo development and Foetus development:

Embryo development	Foetus development
$(1)$ The stage from fertilization up to the first $8$ weeks is called the embryo.	$(1)$ The period from $8$ weeks after fertilization until parturition is called the foetus.
$(2)$ Characterized by rapid cell division (cleavage) and early differentiation.	$(2)$ Characterized by the growth and development of various organs and organ systems.
$(3)$ The placenta produces hormones like $hCG$,$hPL$,estrogen,and progesterone to support early development.	$(3)$ As birth approaches,hormones like oxytocin and prostaglandins are produced to facilitate parturition.

(N/A) Differences between oestrus and menstrual cycles:

Oestrus Cycle	Menstrual Cycle
$(1)$ Occurs in non-primates like cows,dogs,and rats.	$(1)$ Occurs in primates like monkeys,apes,and humans.
$(2)$ Characterized by a short period of heat or oestrus.	$(2)$ Characterized by a menstrual phase involving bleeding.
$(3)$ The endometrium is reabsorbed if fertilization does not occur.	$(3)$ The endometrium is shed and expelled through the vagina.

Differences between ovipary and vivipary:

Ovipary	Vivipary
$(1)$ Organisms lay fertilized or unfertilized eggs.	$(1)$ Organisms give birth to young ones.
$(2)$ Development of the embryo occurs outside the female body.	$(2)$ Development of the embryo occurs inside the female body.
$(3)$ Example: Birds,Reptiles.	$(3)$ Example: Mammals (except monotremes).

(A) $(1)$ Bulbourethral gland:
Location: This gland is situated on either side of the urethra,posterior to the prostate gland.
Function: Its secretion acts as a lubricant for the urethra and neutralizes acidic urine.
$(2)$ Corpus luteum:
Location: It is a temporary glandular structure that develops from the ruptured Graafian follicle in the ovary after ovulation.
Function: It secretes the hormone progesterone,which is essential for maintaining the endometrium during pregnancy.

(N/A) $(1)$ Placenta:
Location: It is a structural and functional unit between the developing embryo (foetus) and the maternal body,connected via the umbilical cord.
Function: It facilitates the supply of oxygen and nutrients to the embryo and removes carbon dioxide and waste materials produced by the embryo. It also acts as an endocrine tissue and produces several hormones like $hCG$,$hPL$,estrogens,and progestogens.
$(2)$ Acrosome:
Location: It is a cap-like structure located at the anterior part of the sperm head.
Function: It contains hydrolytic enzymes (collectively called sperm lysins,such as hyaluronidase) that help in the penetration of the ovum during fertilization.

(GAMETOGENESIS, INSEMINATION, FERTILISATION, IMPLANTATION, GESTATION, PARTURITION) The correct sequential order of events in human reproduction is: Gametogenesis $\rightarrow$ Insemination $\rightarrow$ Fertilisation $\rightarrow$ Implantation $\rightarrow$ Gestation $\rightarrow$ Parturition.
Detailed explanation of the processes:
$(1)$ Gametogenesis: The process of formation of gametes (sperms in males and ova in females).
$(2)$ Insemination: The transfer of sperms into the female reproductive tract.
$(3)$ Fertilisation: The fusion of male and female gametes to form a zygote.
$(4)$ Implantation: The attachment of the blastocyst to the uterine wall.
$(5)$ Gestation: The period of embryonic development inside the uterus.
$(6)$ Parturition: The process of delivery of the foetus (childbirth).

(A) $(a - 3), (b - 4), (c - 1), (d - 2)$
Explanation:
- Mons pubis is a cushion of fatty tissue covered by skin and pubic hair,which is part of the external female genitalia.
- Antrum is the fluid-filled cavity present in the Graafian follicle.
- Trophoblast is the outer layer of the blastocyst that attaches to the endometrium and is involved in embryo development and placenta formation.
- Mitochondria are present in the middle piece of the sperm cell to provide energy for motility.

$(A)$ The correct matches are as follows:
$(a)$ Placenta produces hormones like Human Chorionic Gonadotropin $(hCG)$. Thus, $(a)-(ii)$.
$(b)$ Zona pellucida is the outer glycoprotein layer of the ovum. Thus, $(b)-(iii)$.
$(c)$ Bulbo-urethral glands secrete a fluid that helps in the lubrication of the penis. Thus, $(c)-(iv)$.
$(d)$ Leydig cells (interstitial cells) present in the testis produce male sex hormones called androgens. Thus, $(d)-(i)$.
Therefore, the correct sequence is $(a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)$.

(A) The correct matches are as follows:
$(a)$ Corpus luteum is formed from the ruptured Graafian follicle after ovulation $(a - 3)$.
$(b)$ Testis descends from the abdominal cavity into the scrotum during development $(b - 1)$.
$(c)$ Myometrium is the middle thick layer of smooth muscle in the wall of the uterus $(c - 4)$.
$(d)$ Penis is the external male genitalia located at the anterior part of the scrotum $(d - 2)$.
Therefore,the correct sequence is $(a - 3), (b - 1), (c - 4), (d - 2)$.

$(A)$ Testis and ovary are the primary sex organs that produce germ cells (gametes). Thus, $(a - 3)$.
$(b)$ Clitoris is a sensitive erectile structure associated with sexual response. Thus, $(b - 4)$.
$(c)$ Oviduct (Fallopian tube) is the part of the female reproductive system that transports the ovum (germ cell). Thus, $(c - 1)$.
$(d)$ Scrotum and labia majora are fleshy folds/pouches that protect the reproductive organs and surround the urogenital region. Thus, $(d - 2)$.
Therefore, the correct match is $(a - 3, b - 4, c - 1, d - 2)$.

(D) Puberty is the period during which an adolescent reaches sexual maturity and becomes capable of reproduction.
In human females,the onset of puberty typically occurs between the ages of $10$ and $14$ years.
This phase is marked by the development of secondary sexual characteristics and the onset of the menstrual cycle (menarche).
Therefore,the range of $10-14$ years is the most accurate representation of the onset of puberty in females.

(D) In human reproductive anatomy,homologous structures are those that share a common embryonic origin.
$1$. The $Clitoris$ in females is homologous to the $Penis$ in males,as both develop from the same embryonic tissue (genital tubercle).
$2$. The $Bartholin's$ $gland$ in females is homologous to the $Cowper's$ $gland$ (bulbourethral gland) in males,as both are accessory glands that secrete lubricating fluids.
Therefore,both $A$ and $B$ represent structures that have male counterparts in the female reproductive system.