“The Reproductive System,” provides a comprehensive overview of human reproduction, focusing on the anatomy, physiology, and hormonal control of both male and female systems.
Male Reproductive System
The primary reproductive organs are the testes, which are situated in the scrotum. The scrotum keeps the testes at a slightly lower temperature than the body, a condition essential for spermatogenesis (sperm production). After production, sperm mature in the
epididymis before being transported through the vas defer
These fluids mix with sperm to create semen, which provides nourishment and a medium for the sperm. The hormone testosterone is crucial for regulating spermatogenesis and the development of male secondary sexual characteristics.
Female Reproductive System
The female reproductive system is responsible for producing eggs (ova) and nurturing a devloping fetus.
An egg is released into the fallopian tube, where fertilization by a sperm typically occurs. The vagina is the passageway for intercourse and serves as the birth canal.
The Menstrual Cycle
A key aspect of female reproduction is the menstrual cycle, a monthly cycle of hormonal and physical changes. This cycle is divided into four phases:
- Menstrual phase: The shedding of the uterine lining, resulting in menstruation.
- Follicular phase: Hormones stimulate the growth of a follicle in the ovary and the rebuilding of the uterine lining.
- Ovulatory phase: The mature egg is released from the ovary (ovulation).
- Luteal phase: The ruptured follicle becomes the corpus luteum, which releases hormones to maintain the uterine lining. If fertilization doesn’t occur, the corpus luteum degenerates, and the cycle restarts.
Fertilization and Hormonal Regulation
This process, known as implantation, marks the beginning of pregnancy. Hormones play a central role in regulating both male and female reproductive systems. The pituitary gland secretes FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone), which control the production of gametes and other sex hormones in both males and females, ensuring the proper timing and function of all reproductive processes.
Exercise
A. MULTIPLE CHOICE TYPE:
1) Which one of the following is the correct route that a sperm follows when it leaves the testis of a mammal?
(a) vas deferens epididymis urethra
(b) urethra Epididymis vas deferens
(c) Epididymis urethra vas deferens
(d) Epididymis vas deferens urethra
Ans: (d) Epididymis vas deferens urethra
2) When pregnancy does not occur, the life of corpus luteum is about-
(a) 4 days
(b) 10 days
(c) 14 days
(d) 28 days
Ans: (d) 28 day
3) In females, after how much time after fertilization, does the fertilized egg get implanted in the uterine wall?
(a) Few months
(b) one month
(c) Three weeks
(d) about seven days
Ans: (d) About seven days
B. VERY SHORT ANSWER TYPE:
1) Name the following:
(a) The body part in which the testes are present in a human male.
(b) The part where the sperms are produced in the testes
(c) The fully developed part of the ovary containing a mature egg
(d) The accessory gland in human males whose secretion activates the sperms
(e) The tubular knot fitting like a cap on the upper side of the testis.
Ans: (a) Scrotum
(b) Seminiferous Tubules
(c) Graafian Follicle
(d) Seminal vesicle
(e) Epididymis
2) When pregnancy does not occur, the life of corpus luteum is about-
(a) 4 days
(b) 10 days
(c) 14 days
(d) 28 days
Ans: (d) 28 days
3) In females, after how much time after fertilization, does the fertilized egg get implanted in the uterine wall?
(a) Few months
(b) one month
(c) Three weeks
(d) about seven days
Ans: (d) About seven days
B. VERY SHORT ANSWER TYPE:
1) Name the following:
(a) The body part in which the testes are present in a human male.
(b) The part where the sperms are produced in the testes
(c) The fully developed part of the ovary containing a mature egg
(d) The accessory gland in human males whose secretion activates the sperms
(e) The tubular knot fitting like a cap on the upper side of the testis.
Ans: (a) Scrotum
(b) Seminiferous Tubules
(c) Graafian Follicle
(d) Seminal vesicle
(e) Epididymis
2) Choose the odd one in each of the following:
(a) Oestrogen; progesterone; testosterone; prolactin.
(b) Ovary; fallopian tube; ureter; uterus
(c) Seminiferous tubule; ovum; epididymis; sperm duct; urethra
(d) Sperm; implantation; fertilization; ovum; ovum; after birth.
Ans: (a) Testosterone
(b) Ureter
(c) Ovum
(d) After birth
3) Rewrite the terms in the correct order so as to be in a logical sequence. (a) Sperm duct, penis, testes, sperms, semen
(b) Puberty, menopause, menstrals , menarche, reproductive age.
(c) Graafian follicle, ostium, uterus, fallopian tube.
Ans: (a) Testes→ Sperms→ Sperm duct→ Semen→Penis
(b) Menarche→ Puberty→ Reproductive age→Menstruals→ Menopause
(c) Graafian follicle →Ostium→ Fallopian tube Uterus
4) Write in sequence the regions in which a mature sperm travels from the seminiferous tubules up to the urethral opening in the human male.
Ans: Seminiferous tubule→ Epididymis→ Vas deferens→ Penis
C. SHORT ANSWER TYPE:
1) What is semen?
Ans: Semen is the whitish, fluid released during ejaculation. It consists of:
Sperm (male reproductive cells from the testes).
Purpose: Acts as a medium to transport sperm, boosting their survival and mobility for fertilization.
2) Describe the functions of the following:
(a) Inguinal canal
(b) Prostate gland
(c) Testis
(d) ovary
(e) Oviduct
Ans: a) The inguinal canal is a vital passage in the lower abdomen, differing in function between males and females. Its anatomical significance extends to clinical conditions like hernias, making it an essential area of study in both anatomy and medicine.
(b) Prostate gland – A male reproductive gland that secretes an alkaline fluid which nourishes and protects sperm, forming part of semen.
(c) Testis – Male reproductive organs that produce sperm (spermatogenesis) and secrete testosterone, the primary male sex hormone.
(d) Ovary – Female reproductive organs that produce eggs (oogenesis) and secrete hormones like estrogen and progesterone.
(e) Oviduct (Fallopian tube) – Tubes that transport eggs from the ovary to the uterus; fertilization typically occurs here.
3) What are the secondary sexual characteristics of the human male and female respectively?
Ans: In Males:
Facial and body hair (beard, chest hair)
Deeper voice (due to enlarged larynx)
Broad shoulders and muscular build
Adam’s apple prominence
In Females:
Development of breasts
Wider hips (for childbirth)
Higher-pitched voice
Less body hair compared to males
These traits develop during puberty under hormonal influence (testosterone in males, estrogen in females).
4) What are the accessory reproductive organs?
Ans: In Males:
Epididymis – Stores & matures sperm.
Vas deferens – Carries sperm.
Seminal vesicles, prostate, bulbourethral glands – Make seminal fluid.
Penis – Delivers sperm.
In Females:
Fallopian tubes – Transports eggs.
Uterus – Holds & nourishes embryo.
Vagina – Receives sperm & birth passage.
Mammary glands – Produce milk.
These organs support reproduction but don’t produce gametes.
5) Differentiate between primary and accessory reproductive organs
Ans:
| Primary Reproductive Organs | Accessory Reproductive Organs |
| The primary reproductive organs produce sex cells. | The accessory reproductive organs help in the transfer and meeting of two kinds of sex cells leading to fertilization. |
| The primary reproductive organs do not help in the development of baby. | The accessory organs help in the growth and development of egg up to the birth of baby. |
| Example: Testes in males and ovaries in females. | Example: penis in males, Uterus, vagina in female. |
6) What is hyne?
Ans: A hymn is a sacred song or poem that praises God or a deity, used in worship. It has uplifting lyrics and is often sung in churches or temples. Hymns inspire devotion and bring people together in faith.
7) Define the following terms:
(a) Hernia
(b) Ovulation
(c) Puberty
Ans: (a) A hernia occurs when an internal organ or tissue squeezes through a weakened area in the surrounding muscle or connective tissue. This often results in a noticeable bulge, especially when straining or lifting heavy objects. Common types include inguinal (groin), femoral (upper thigh), umbilical (belly button), and hiatal (upper stomach) hernias. Symptoms may include pain, discomfort, or a heavy feeling in the affected area. In severe cases, surgery may be needed to repair the weakened muscle and prevent complications. Maintaining a healthy weight, avoiding heavy lifting, and strengthening core muscles can help reduce the risk of hernias.
(b) Ovulation – A mature egg is released from the ovary into the fallopian tube for potential fertilization.
(c) Puberty – The shift from childhood to adulthood involving hormonal changes, growth spurts, and sexual development.
8) List any two changes each in human male and female, which occur during puberty.
Ans: Puberty Changes in Males and Females
Puberty is a natural phase where boys and girls undergo physical and emotional changes due to hormonal shifts.
Changes in Males:
Facial & body hair growth (face, chest, underarms).
Deeper voice (may crack temporarily).
Growth spurt (rapid height increase, muscle development).
Broader shoulders and more muscular torso.
Reproductive development (enlarged testes/penis, sperm production, wet dreams).
Changes in Females:
Breast development (starts around 8-13 years).
First period (menarche) (usually between 10-16 years).
Wider hips (curvier body shape).
Body hair growth (underarms, pubic area).
Growth spurt (fast height increase before menstruation).
Common Changes in Both:
Mood swings (due to hormones).
Acne & body odor (oil glands become active).
Increased self-awareness & emotions.
9) Differentiate between the following pairs:
(a) Menarche and menopause
(b) Bulbo-urethral gland and prostate gland
(c) Hymen and clitoris
(d) Uterus and vgia
(e) Efferent duct and sperm duct
Ans:
a) Menarche and Menopause
Menarche: First menstrual cycle in girls (puberty stage).
Menopause: End of menstruation, usually between 45-50 years.
(b) Bulbo-urethral Gland and Prostate Gland
Bulbo-urethral Gland: Releases fluid to neutralize urethra before ejaculation.
Prostate Gland: Produces alkaline fluid to support sperm survival.
(c) Hymen and Clitoris
Hymen: Thin membrane at vaginal opening (may tear during activity).
Clitoris: Sensitive organ for pleasure (no reproductive role).
(d) Uterus and Vagina
Uterus: Houses and nourishes the developing fetus.
Vagina: Birth canal and receives sperm during intercourse.
(e) Efferent Duct and Sperm Duct
Efferent Duct: Carries sperm from testes to epididymis.
Sperm Duct: Transports sperm to urethra during ejaculation.
D. LONG ANSWER TYPE:
1) What is the significance of the testes being located in scrotal sacs outside the abdomen. Can there be any abnormal situation regarding their locations? If so, what is that and what is the harm caused due to it?
Ans: Significance of Testes in Scrotal Sacs:
The testes are placed in the scrotal sacs to maintain a temperature 2–3°C lower than body temperature, which is essential for sperm production. The scrotum adjusts to temperature changes by contracting in cold and relaxing in heat.
Cryptorchidism (Undescended Testes):
When testes stay inside the abdomen instead of descending into the scrotum, it leads to:
Lower fertility or sterility (due to high abdominal heat damaging sperm production).
Higher risk of testicular cancer.
Increased chances of hernia or testicular torsion.
2) Is it correct to say that the testes produce testosterone Discuss?
Ans: The Testes Produce Testosterone – Key Facts
The testes (male reproductive glands) have two main roles:
Sperm production – Occurs in the seminiferous tubules.
Testosterone production – Made by Leydig cells.
Why Testosterone is Important:
Triggers male puberty (deepening voice, muscle growth, facial hair).
3) Suppose a normal woman has never borne a child; How many mature eggs would she have produced in her lifetime? Your calculation should be based on two clues-
(a) Eggs are produced at the rate of 1 egg every 28 days (one menstrual cycle)
(b) A woman’s total reproductive period is 13 – 45 years.
Ans: A woman’s reproductive period typically spans from ages 13 to 45 (32 years). With one egg released every 28 days (menstrual cycle), she has about 13 cycles per year (365 ÷ 28 ≈ 13).
Total mature eggs = 13 cycles/year × 32 years ≈ 416 eggs in her lifetime.
Final Answer: ~416 eggs.
E. STRUCTURED / APPLICATION / SKILL TYPE:
1) Given below is a diagram of two systems together in the human body
(a) Name the systems
(b) Name the parts numbers 1-10
(c) Describe the functions of the parts 3, 4, 5 & 6.
(a) Systems Shown:
Left side: Male reproductive system
Right side: Female reproductive system
(b) Labeling Parts 1–10:
Testis – Produces sperm and testosterone.
Scrotum – Protects and holds testes.
Vas deferens – Transports sperm.
Seminal vesicle – Secretes seminal fluid for sperm nourishment.
Prostate gland – Releases alkaline fluid to protect sperm.
Urethra – Passage for urine and semen.
Ovary – Produces eggs and hormones.
Fallopian tube – Site of fertilization.
Uterus – Supports fetal development.
Vagina – Birth canal and menstrual passage.
(c) Functions of Parts 3, 4, 5 & 6:
3.The vas deferens is a thick, muscular tube in the male reproductive system. It carries sperm from the testes (where sperm is produced) to the urethra during ejaculation. This tube plays a crucial role in fertility by ensuring sperm is delivered effectively for fertilization.
Function: Transports sperm from testes to urethra.
Importance: Essential for sperm delivery during ejaculation.
4. Seminal vesicle – Provides nutrients for sperm motility.
5. Prostate gland – Neutralizes vaginal acidity for sperm survival.
6. Urethra – Releases urine and ejaculates semen.
2) The following diagram represents the vertical sectional view of the human female reproductive system.
(a) Label the parts indicated by the guidelines 1 to 8
(b) How does the uterus prepare for the reception of zygote?
(c) What happens to the uterus, if fertilization fails to take place?
Ans: (a) Label the parts indicated by the guidelines 1 to 8
Based on a standard diagram, the labels are:
1.Oviduct (or Fallopian Tube)
2.Funnel (or Infundibulum)
3.Uterus (or Womb)
4.Endometrium
5.Cervix
6.Vagina
7.Ovary
8.Uterine wall (or Myometrium)
(b) How does the uterus prepare for the reception of zygote?
The uterus builds a thick, blood-rich lining called the endometrium. This provides nourishment and a site for the embryo to attach.
(c) What happens to the uterus if fertilization fails to take place?
The prepared uterine lining (endometrium) breaks down and is shed from the body.
3) Given below is the schematic diagram of the sectional view of the human male reproductive system.
(a) Name the parts numbered 1-11
(b) State the functions of the parts numbered 1, 2, 3, 5, 8 and 11
Ans:
(a) Labeled Parts
1.Scrotum
2.Testis (plural: testes)
3.Epididymis
4.Vas Deferens (Sperm Duct)
5.Prostate Gland
6.Seminal Vesicle
7.Ejaculatory Duct
8.Urinary Bladder
9.Pubic Bone
10.Urethra
11.Penis
(b) Functions of Key Parts
Scrotum: A skin pouch that holds and temperature-regulates the testes for healthy sperm production.
Testis: Produces sperm and the hormone testosterone.
Epididymis: A coiled tube for sperm maturation and storage.
Prostate Gland: Adds a fluid to semen that nourishes and activates sperm.
Urinary Bladder: Stores urine (part of the urinary system).
Penis: Delivers sperm during intercourse and also passes urine.
EXERCISE. 2 A. MULTIPLE CHOICE TYPE:
1) In humans, the fertilization takes place in:
(a) Uterus
(b) Oviduca funnel
(c) Fallopian tube
(d) vagina
Ans: (c) fallopian tube
2) The middle piece of sperm provides:
(a) energy
(b) food
(c) gene
(d) chromosomes
Ans: (a) energy
3) The normal gestation period in humans is:
(a) 270 days
(b) 290 days
(c) 280 days
(d) 295 days
Ans: (c) 280 days
B. VERY SHORT ANSWER TYPE:
1) Name the following:
(a) The fluid surrounding the developing embryo
(b) The body part in which the embryo develops.
(c) The membrane which protects the foetus and encloses a fluid
(d) The canal through which the testes descend into the scrotum just before birth in a human male child.
Ans: (a) Amniotic fluid
(b) Uterus
(c) Amniotic membrane
(d) Inguinal canal
2) Choose the odd one in each of the following:
(a) Sperm; implantation; fertilization; ovum; afterbirth
(b) Relaxin; cervix dilated; amniotic sac ruptures; child birth; follicle.
Ans: (a) Sperm
(b) Follicle
3) Rewrite the terms in the correct order so as to be in a logical sequence:
(a) Implantation→ Ovulation→ child birth→ gestation→ fertilization.
(b) coitus→ ovum → Sperm → sperm duct→ urethra → Vagina.
Ans: (a) Ovulation→ fertilization→ implantation→ gestation child birth
(b) Sperm→ sperm duct→ urethra → coitus→ vagina→ ovum
4) Give appropriate terms for each of the following:
(a) The onset of reproductive phase in a female.
(b) Rupture of follicle and release of ovum from the ovary.
(c) Monthly discharge of blood and disintegrated tissues in human female
(d) Process of fusion of ovum and sperm
(e) Fixing of developing zygote (blastocyst) on the uterine wall.
Ans: a) Menarche
(b) Ovulation
(c) Menstruation
(d) Fertilization (or Syngamy)
(e) Implantation
5) Match the items in column I with those in column II and write down the matching pairs (some may not match)
| column I | column II |
| (a) Acrosome | (i) An embryo which looks like human baby |
| (b) Gestation | (ii) Luteinizing hormone |
| (c) Menopause | (iii) ovum producing cells |
| (d) Foetus | (vi) complete stoppage of menstrual cycle |
| (e) Oogenesis | (v) spermatozoa |
| (f) Ovulation | (vi) Complete stoppage of menstrual cycle. |
| (vii) Time taken by a fertilized egg till the delivery of baby |
Ans:
| column I | column II |
| (a) Acrosome | (v) spermatozoa |
| (b) Gestation | (vii) Time taken by a fertilized egg till the delivery of baby |
| (c) Menopause | (vi) Complete stoppage of menstrual cycle. |
| (d) Foetus | (i) An embryo which looks like human baby |
| (e) Oogenesis | (iii) ovum producing cells |
| (f) Ovulation | (ii) Luteinizing hormone |
C. SHORT ANSWER TYPE:
1) (a) State whether the following statements are TRUE (T) or FALSE (F):
(i) Fertilisation occurs in vagina
(ii) Uterus is also known as birth canal
(iii) Nutrition and oxygen diffuse from the mother’s blood into the fetus’s blood through amnion.
(iv) Gestation period in humans is about 380 days.
(b) Rewrite any two of the wrong statements by correcting only one word either at the beginning or at the end of the sentences.
Ans: (a) (i) False
(ii) False
(iii) False
(iv) False
(b)
(i) Fertilization occurs in the fallopian tube.
(ii) Vagina is also known as the birth canal.
(iii) Nutrition and oxygen diffuse from the mother’s blood into the fetus’s blood through the placenta.
(iv) Gestation period in humans is about 280 days.
2) Complete the following table by writing the name of the structure or the function of the given structure:
| Structure | Function |
| 1. Corpus luteum | 1. …………… |
| 2. . ……………. | 2. Produces male gametes in mass |
| 3. Placental disc | 3. …………………….. |
| 4. . ……………. | 4. Increases the force in uterine contractions during child birth |
| 5. Umbilical cord | 5. …………………. |
| 6. Fallopian tube | 6. ………………… |
Ans:
| Structure | Function |
| 1. Corpus luteum | 1. secretes progesterone & other hormones to prepare the uterine wall for the receival of the embryo. |
| 2. Testes | 2. Produces male gametes in mass |
| 3. Placental disc | 3. supplies oxygen and nutrients to embryo |
| 4. Oxytocin | 4. Increases the force in uterine contractions during child birth |
| 5. Umbilical cord | 5. connects placenta with foetus |
| 6. Fallopian tube | 6. The site of fertilization for the sperm and ovum |
3) Given below are the names of certain stages/substances related to reproduction and found in the human body. Answer the questions related to them.
(a) Foetus.
• Where is it contained?
• How does it differ from embryos?
(b) Hyaluronidase
• Is it an enzyme or simply a protein?
• What is its function?
(c) Morula.
• What is this stage?
• Name the stage which comes next to it?
(d) Amniotic fluid.
• Where is it found?
• What are its functions?
(e) Gestation
• What is its meaning?
• How long does it normally last?
(f) Placenta
• What are the two sources that form placenta?
• Name any two main substances which pass from foetus to mother through placenta
• Name any two hormones it produces
(g) Implantation
• The development stage that undergoes this process
• The approximate time after fertilization, when it occurs.
Ans: ( a) Foetus
Where is it contained? It’s contained and grows inside the uterus( womb).
How does it differ from an embryo? The developing baby is called an embryo for the first eight weeks after generality. After that point and until birth, it’s appertained to as a foetus.
(b) Hyaluronidase
Is it an enzyme or simply a protein?
It’s an enzyme. You can think of all enzymes as specialized proteins that act as biological catalysts, meaning they speed up specific chemical reactions in the body.
What is its function?
This enzyme is located in the head of a sperm cell. Its crucial job is to break down the protective outer layers surrounding the egg. In essence, it clears a path so that a single sperm can penetrate and fertilize the egg.
(c)Morula.
It is a solid ball of 16 to 32 cells, and its name comes from its resemblance to a mulberry.
The stage that follows is the blastocyst. In this phase, the cells reorganize to form a hollow, fluid-filled structure. This change is essential for the next step: implanting into the uterine wall to begin a pregnancy.
d) Amniotic fluid
Where is it set up? It’s the liquid contained inside the amniotic sac, which encases the developing foetus.
What are its functions? It acts as a defensive bumper against bumps and jolts and helps maintain a stable temperature for the baby.
e) Gestation
What’s its meaning? It’s the entire duration of a gestation, from the moment of generality to the birth of the baby.
How long does it typically last? In humans, a typical gravidity period lasts about 40 weeks, which is roughly nine months.
(f) Placenta
What are the two sources that form the placenta?
The placenta is a unique organ because it develops from tissues of two different individuals: the mother (from the lining of her uterus) and the foetus (from its outer cell layer).
Name any two main substances which pass from foetus to mother.
Waste products from the foetus are passed to the mother’s bloodstream for disposal. Two primary examples are carbon dioxide and urea.
Name any two hormones it produces.
The placenta acts as a temporary hormone factory, producing several vital hormones, including progesterone, estrogen, and human chorionic gonadotropin (hCG).
(g) Implantation
The development stage that undergoes this process The blastocyst is the stage that implants into the uterine wall.
The approximate time after fertilization, when it occurs This pivotal event happens about one week after fertilization.
D. LONG ANSWER TYPE:
1) Differentiate between:
(a) Semen and sperm
(b) Implantation and pregnancy
(c) Follicle and corpus luteum
(d) Amnion and allantois
(e) Impotency and sterility
(f) Prostate gland and cowper’s gland (the nature of secretion)
(g) Identical twins and fraternal twins
Ans: (a) Semen and Sperm
Semen is the fluid discharged during male ejaculation. It is a complex mixture of fluids from the testes, seminal vesicles, prostate gland, and Cowper’s glands. It contains various substances that nourish and protect sperm. Sperm are the male reproductive cells (gametes) that are suspended within the semen.
(b)Pregnancy refers to the entire period of fetal development, which spans from the time of successful implantation until childbirth. It encompasses all the stages of growth, from the embryo to the fully developed fetus, and typically lasts for about nine months in humans.
(c) Follicle and Corpus Luteum
A follicle is a fluid-filled sac in the ovary that contains and protects a developing egg. It secretes the hormone estrogen. The corpus luteum is a temporary endocrine structure that forms from the remnants of the ruptured follicle after the egg has been released during ovulation. It primarily secretes progesterone to maintain the uterine lining for a potential pregnancy.
(d) Amnion and Allantois
The amnion is a protective membrane forming a fluid-filled sac around the embryo, cushioning it. The allantois is another extra-embryonic membrane that contributes to the umbilical cord and assists in waste storage and gas exchange.
(e) Impotency and Sterility
Impotency refers to the inability of a male to achieve or maintain an erection for sexual intercourse. It is a physical condition that affects sexual performance but does not necessarily prevent the man from producing viable sperm. Sterility is the inability to reproduce, meaning an individual (male or female) cannot produce viable sperm or eggs, thus making conception impossible.
(f) Prostate Gland and Cowper’s Gland (Nature of Secretion)
The prostate gland secretes a milky, slightly acidic fluid that makes up a significant portion of semen. This fluid contains enzymes and citrate, which help activate sperm motility. The Cowper’s gland (or bulbourethral gland) secretes a clear, alkaline mucus-like fluid just before ejaculation. Its main purpose is to neutralize any residual acidity in the urethra from urine and to lubricate the passage for sperm.
(g) Identical Twins and Fraternal Twins
Identical twins (monozygotic) develop from a single fertilized egg that splits into two embryos early in development. Because they originate from the same egg and sperm, they share nearly identical DNA and are always the same sex.
2) Name and describe very briefly the stages in the development of human embryo.
Ans: The development of a human embryo is a remarkable journey from a single cell to a complex organism, progressing through several key stages. It begins with the formation of a zygote after fertilization, which rapidly divides without increasing in size to form a solid ball of cells called the morula. This morula then transforms into a hollow structure, the blastocyst, which implants itself into the uterine lining. Once implanted, the cells of the blastocyst rearrange to form three distinct germ layers in a process called gastrulation. These layers then differentiate and specialize to form all the major organs and body systems in a process known as organogenesis.
3) Describe the functions of (a) Amnion (b) placenta
Ans:
(a) Amnion
This sac is filled with fluid to cushion the embryo from physical shocks, allow for movement to aid development, maintain a constant temperature, and prevent the fetus from adhering to the sac.
(b) Placenta
The placenta is a temporary organ connecting the mother and fetus. Its key roles are to supply oxygen and nutrients to the fetus, remove its waste products, produce essential pregnancy hormones (like hCG, estrogen, and progesterone), and transfer antibodies from the mother to provide initial immunity.
E. STRUCTURED / APPLICATION / SKILL TYPE:
1) The diagram below represents two reproductive cells A and B. study the same and then answer the questions that follow:
(a) Identify the reproductive cells A and B
b) Name the specific part of the reproductive system where the above cells are produced.
(c) Where in the female reproductive system do these cells unite?
(d) Name the main hormones secreted by the (1) ovary (2) testes
Ans: Part a)
Based on the diagram, cell A is the ovum, or egg cell. It is the female gamete and is relatively large and non-motile. Cell B is the sperm cell, which is the male gamete. It is much smaller and has a tail (flagellum) that allows it to swim.
Part b)
Cell A, the ovum, is produced in the ovaries, which are part of the female reproductive system. Cell B, the sperm cell, is produced in the testes, which are the primary reproductive organs in males.
Part c)
For a new individual to be formed, these two cells unite through a process called fertilization. This event most commonly occurs in the fallopian tube (also known as an oviduct) of the female reproductive tract.
Part d)
(1) The ovary is an endocrine gland that primarily secretes the hormones estrogen and progesterone.
(2) The testes secrete the primary male sex hormone, known as testosterone.
2) The diagram given alongside is that of a developing human foetus in the womb. Study the same and answer the questions that follows:
(a) Name the parts ‘1’ to ‘5’ indicated by guidelines
(b) What term is given to the period of development of the foetus in the womb?
(c) How many days does the foetus take to be fully developed?
(d) Mention two functions of the parts labeled ‘2’other than its endocrine function
(e) Name (any one) hormone produced by the part labelled ‘2’
Ans: (a) Naming Parts ‘1’ to ‘5’
- 1: Uterus
- 2: Placenta
- 3: Umbilical cord
- 4: Amniotic fluid
- 5: Fetus
b) Period of Development
The entire amazing journey, from a single fertilized cell to a fully formed baby ready for birth, is called pregnancy or the gestation period.
c) Development Time
For humans, this development typically takes about 40 weeks, which is roughly nine months. This time is usually grouped into three-month phases known as trimesters.
d) Functions of the Placenta
The placenta isn’t just a simple filter; it’s a complex organ that acts as the baby’s life-support system, handling jobs the baby’s own organs aren’t ready for yet:
Breathing for the Baby: It works as the baby’s lungs, picking up oxygen from the mother’s blood and passing it over, while simultaneously taking carbon dioxide waste from the baby to be removed.
Providing Nourishment: All the nutrients, vitamins, and minerals the baby needs to grow—sourced from the mother’s food—are transferred through the placenta into the baby’s bloodstream.
Handling Waste: The placenta acts as the baby’s kidneys, filtering out waste products created by the baby’s metabolism and passing them back to the mother’s body for disposal.
Offering Protection: It provides the baby with a first line of defense by transferring the mother’s disease-fighting antibodies, giving the newborn some temporary immunity.
e) Hormone from the Placenta
This hormone is famous because it’s what all home pregnancy tests detect. Its most important job in early pregnancy is to send a signal to the mother’s body to continue producing progesterone, which is essential for maintaining the pregnancy and preventing a menstrual period.
3) Given below is a portion of the diagram to show the diagrammatic highly magnified view of a single human sperm. Complete the diagram to show its normal structure.
Ans: A human sperm cell is a tiny, remarkable structure designed for a single, crucial purpose: to deliver the father’s genetic material to the mother’s egg. It is a microscopic cell, but it is packed with specialized parts that allow it to swim a tremendous distance relative to its size.
The Head: The Command Center
The head is the front section of the sperm and functions as its command center. Its distinct oval shape is dominated by the nucleus, which securely packages the father’s 23 chromosomes—the complete set of genetic instructions needed to create a new human life. Capping the front of the head is a specialized structure known as the acrosome. Think of it as a tool kit; it’s filled with powerful enzymes that will later be released to dissolve the outer layers of the egg, allowing the sperm to tunnel inside and achieve fertilization.
The Middle Piece: The Powerhouse
These mitochondria work like tiny batteries, generating a constant supply of energy in the form of ATP. This energy fuels the intense activity of the tail, providing the power necessary for the long and arduous journey.
The Tail: The Propulsion System
The tail is the longest part of the sperm, essentially a long, whip-like flagellum. Its sole job is movement. This swimming ability, known as motility, is absolutely essential. Without the relentless driving force of the tail, the sperm would never be able to navigate the challenging path to reach and fertilize the waiting egg.
4) The figure given alongside represents the female reproductive system of a mammal.
(a) Name the parts labelled A – D
(b) What will happen if the part B on both sides gets blocked?
Ans: (a) The labeled parts are:
A: Uterus
B: Fallopian Tube
C: Ovary
D: Cervix
(b) Blockage in both fallopian tubes causes infertility. It prevents the sperm and egg from meeting. A partial blockage can lead to a dangerous ectopic
5) Given below is the outline of the male reproductive system. Name the parts labelled 1 to 5.
Ans:
