Q.Draw L.S. of an embryo of grass and label its parts.
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🔒 Start your 14-day free trial to unlock the full solution →Part (a)Concept understanding — Seed Structure Terminology
Seed Structure Terminology – A First Look
Think of a seed as a tiny, self-contained survival kit. A plant makes a seed to send its offspring out into the world, equipped with everything needed to travel, wait, and eventually sprout into a new plant. The terminology around seed structure is simply the names we give to the parts of that kit.
The Three Essential Parts
Every seed, from a mustard seed to a mango seed, has three basic components. You can remember them as the baby, the lunchbox, and the coat.
- Embryo – This is the baby plant itself. It is a miniature, dormant plant with tiny leaves (cotyledons or plumule), a tiny stem (hypocotyl), and a tiny root (radicle). When conditions are right, the embryo wakes up and starts growing.
- Endosperm – This is the lunchbox. It is a tissue that stores food (starch, proteins, oils) for the embryo to use when it germinates. In some seeds, the endosperm is consumed by the embryo before the seed matures, and the food is stored directly in the cotyledons instead.
- Seed Coat – This is the coat. It is a tough, protective outer layer that shields the embryo from injury, drying out, and disease. It often has a tiny scar called the hilum where the seed was attached to the mother plant, and a small pore called the micropyle that lets water enter during germination.
The micropyle is a tiny opening in the seed coat. It is not just a scar — it is a functional pore. Water enters through the micropyle to trigger germination, and later, the radicle (the first root) emerges through it.
Why This Matters for Exams
In NCERT textbooks (Class 11 Biology, Chapter 5), seed structure is taught to help you understand how plants reproduce and how seeds are adapted for survival. The key distinction you must know is between two types of seeds based on where the food is stored:
- Albuminous seeds – The endosperm remains present and stores food. Example: castor, coconut, maize.
- Exalbuminous seeds – The endosperm is completely used up during development, and food is stored in the cotyledons. Example: pea, bean, groundnut.
In exalbuminous seeds, the cotyledons become thick and fleshy because they have absorbed the endosperm. In albuminous seeds, the cotyledons remain thin and papery because the endosperm does the job of food storage.
A Simple Way to Visualise
Imagine a packed lunch in a lunchbox inside a backpack. The embryo is the child, the endosperm is the lunch, and the seed coat is the backpack. In an albuminous seed, the lunchbox is still full when the child opens it. In an exalbuminous seed, the child has already eaten the lunch and packed the food into its own pockets (the cotyledons) before the journey begins.
Common Exam Terms at a Glance
| Term | Meaning |
|---|---|
| Radicle | The part of the embryo that becomes the root |
| Plumule | The part that becomes the shoot (stem and leaves) |
Part (b)Concept understanding — Male Reproductive Anatomy
Male Reproductive Anatomy – A First Look
Think of the male reproductive system as a production and delivery line. Its job is to make tiny cells called sperm (the male contribution to reproduction) and then safely deliver them into the female body. Unlike the female system, which is mostly internal, the male system has several parts that are visible outside the body. That’s the first big clue: the system is built for external production and internal delivery.
The Two Main Jobs
The male reproductive system does two things at once:
- Spermatogenesis – making sperm inside the testes.
- Hormone production – making the male sex hormone testosterone, which drives puberty, muscle growth, voice deepening, and sex drive.
These two jobs happen in the same organs, but they are separate processes. Testosterone is made by special cells between the sperm-making tubes, not inside the tubes themselves.
The Key Parts (from outside to inside)
1. The Testes (the factories)
The two testes (singular: testis) are oval organs about the size of a large olive. They hang outside the body in a pouch of skin called the scrotum. Why outside? Because sperm production needs a temperature about 2–3°C lower than normal body temperature. The scrotum can contract (pull testes closer to the body when cold) or relax (let them hang lower when warm) to regulate this temperature.
Inside each testis are about 250–300 coiled tubes called seminiferous tubules. This is where sperm are actually made. Between these tubules are the interstitial cells (Leydig cells) that produce testosterone.
The testes are the primary male reproductive organs – they produce both the gametes (sperm) and the hormone (testosterone). Everything else in the system is a duct, gland, or delivery tube.
2. The Duct System (the conveyor belt)
Once sperm are made, they need to travel. The path is:
Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra
The epididymis is a long, coiled tube stuck to the back of each testis. Sperm are stored here and become motile (able to swim) as they pass through. It takes about 2–3 weeks for a sperm to travel the full length of the epididymis.
The vas deferens (plural: vasa deferentia) is a thick-walled muscular tube that runs from the scrotum up into the abdomen. You can feel it as a firm cord just above the testis – it’s part of the spermatic cord. During a vasectomy, this tube is cut or blocked to prevent sperm from reaching the urethra.
3. The Accessory Glands (the fluids)
Sperm alone are just a tiny fraction of the fluid that comes out during ejaculation. Most of the volume comes from three sets of glands:
- Seminal vesicles – two sac-like structures behind the bladder. They secrete a thick, fructose-rich fluid that provides energy for the sperm. This makes up about 60–70% of the semen volume.
- Prostate gland – a walnut-sized gland that surrounds the urethra just below the bladder. It secretes a thin, milky fluid that makes the semen more fluid and slightly alkaline (to protect sperm from the acidic vagina).
- Bulbourethral glands (Cowper’s glands) – two pea-sized glands near the base of the penis. They secrete a clear, slippery fluid before ejaculation that lubricates the urethra and neutralises any leftover urine acidity.
Semen is not just sperm. It is a mixture of sperm (about 1–5% of the volume) plus secretions from the seminal vesicles, prostate, and bulbourethral glands. The sperm themselves are made in the testes; everything else is added along the way.
4. The Penis (the delivery tube)
The penis is the external organ that deposits semen into the female vagina. It contains three columns of erectile tissue that fill with blood during arousal, causing an erection. The urethra runs through the centre of the penis and carries both urine and semen – but never at the same time. A sphincter (a ring of muscle) at the base of the bladder closes off the urine passage during ejaculation.
The tip of the penis is called the glans penis, which is covered by a loose fold of skin called the foreskin (prepuce) in uncircumcised males.
Why This Matters (beyond reproduction) …
Part (a)
L.S. of a grass (monocot) embryo — parts to label:
- Scutellum — the single, shield-shaped cotyledon (lies on one side of the embryonal axis).
- Coleoptile — sheath covering the plumule (shoot tip).
- Plumule — the embryonic shoot.
- Radicle — the embryonic root.
- Coleorhiza — sheath covering the radicle.
- Epiblast — small projection opposite the scutellum. …
- The grass (monocot) embryo L.S. is labelled: scutellum, coleoptile, plumule, radicle, coleorhiza and epiblast.
- The seminiferous-tubule section is labelled: basement membrane, spermatogonia, primary and secondary spermatocytes, spermatids, spermatozoa, Sertoli cells, Leydig (interstitial) cells and lumen.
Note: an actual diagram cannot be drawn here, so each part is described with its position; a student should draw the figure and add exactly these labels.
Part (a)
A grass is a monocotyledon, so its embryo has a characteristic single-cotyledon (scutellum) structure. In a longitudinal section the parts, and where they sit, are:
- Scutellum — the single shield-shaped cotyledon, lying to one side of the embryonal axis; it absorbs food from the endosperm for the growing embryo.
- Embryonal axis bearing:
- Plumule — the embryonic shoot, enclosed and protected by a sheath called the coleoptile.
- Radicle — the embryonic root, enclosed and protected by a sheath called the coleorhiza.
- Epiblast — a small projection on the side opposite the scutellum (a rudimentary second cotyledon). …
Showing the 12 most recent of 65 on this concept.
- CBSE 2026Set V11 markMCQQ.The cells that secrete androgens are(a) Sertoli cells(b) Leydig cells(c) Germ cells(d) Spermatogonia
›Reveal solutionSolution
The interstitial Leydig cells of the testis secrete androgens.
In the testis, the Leydig cells (interstitial cells) lie in the spaces between the seminiferous tubules and synthesise and secrete the male sex hormones called androgens (mainly testosterone). Sertoli cells nourish the de …
- CBSE 2026Set A1 markMCQQ.In which of the following seeds is perisperm not found?(a) Beet(b) Black pepper(c) Wheat(d) Both (A) and (B)
›Reveal solutionSolution
Wheat has no perisperm; beet and black pepper are examples of seeds where perisperm persists.
Perisperm is the residual, persistent nucellus that remains in the mature seed of a few plants. In seeds such as beet (Beta) and black pepper, the nucellus is not fully used up and remains as perisperm. In wheat, the nucellus is co …
- CBSE 2026Set A1 markMCQQ.What is cotyledon called in grass family?(a) Plumule(b) Radicle(c) Hypocotyl(d) Scutellum
›Reveal solutionSolution
In the grass family (Poaceae), the cotyledon is a shield-shaped structure called the scutellum.
Grasses are monocots and have a single cotyledon. In their embryo this cotyledon is highly modified into a shield-shaped structure that lies against the endosperm and absorbs food from it during germination — this is called the scutellum. The plumule is the embryoni …
- CBSE 2026Set A1 markMCQQ.Which of the following cells are found in seminiferous tubules?(a) Sertoli cells(b) Interstitial cells(c) Spermatogonia(d) Both (A) and (C)
›Reveal solutionSolution
Inside the seminiferous tubules are spermatogonia (germ cells) and Sertoli (nurse) cells; interstitial (Leydig) cells lie outside the tubules.
The lining of each seminiferous tubule is made of two types of cells: the male germ cells or spermatogonia, which undergo meiosis to form sperm, and the Sertoli cells (nurse cells), which provide nourishment to the developing germ cells. The interstitial cells (Leydig cells), which secrete testosterone, are lo …
- CBSE 2026Set A1 markMCQQ.In which structure of sperm are the enzymes present which help in fertilisation of the ovum?(a) Middle piece(b) Neck(c) Nucleus(d) Acrosome
›Reveal solutionSolution
The acrosome, a cap over the sperm head, holds enzymes that help the sperm enter the egg.
The head of a sperm is covered by a cap-like structure called the acrosome. It is filled with hydrolytic enzymes (such as hyaluronidase) that digest and break down the outer coverings of the ovum (the zona pellucida), allowing the sperm to penetrate and fertilise the egg. The middle piece contains mit …
- CBSE 2026Set BOTANY1 markMCQQ.In a developing monocot embryo, _____ is often called the scutellum.(a) plumule(b) cotyledon(c) radicle(d) root cap
›Reveal solutionSolution
In a developing monocot (e.g. grass family) embryo, the single cotyledon is specialised into a shield-shaped structure called the scutellum, which absorbs nutrients from the endosperm.
A mature dicot embryo has two cotyledons, a plumule (embryonic shoot) and a radicle (embryonic root). A mature monocot embryo, in contrast, has only a single cotyledon. In grasses (Poaceae) such as maize, rice and wheat, this single cotyledon is large, shield-shaped, and pressed against the endosperm; it is given the special name scutellum. The scutellum's main function is absorptive - during seed germination it secretes enzymes (like amylases, under gibberellin control) that digest the stored starch of the endosperm and absorb the resulting nutrients to nourish the growing embryo. The embryonal axis o …
- CBSE 2026Set ANNUAL1 markMCQQ.Acrosome is found in which part of the human sperm?(a) Tail(b) Middle piece(c) Head(d) Neck
›Reveal solutionSolution
The acrosome is an enzyme-filled cap over the sperm's head that helps the sperm penetrate the egg's outer coverings.
A human sperm has a head, neck, middle piece and tail. The head contains an elongated, haploid nucleus, the anterior portion of which is covered by a cap-like structure called the acrosome, filled with enzymes (such as hyaluronidase) that facilitate fertilisation by digesting t …
- CBSE 2026Set ANNUAL1 markMCQQ.Which of the following is not a part of male reproductive system?(a) Ampulla(b) Prostate(c) Foreskin(d) Bulbourethral gland
›Reveal solutionSolution
Prostate, bulbourethral (Cowper's) glands and the foreskin are all male reproductive structures; the ampulla belongs to the female oviduct.
In the male reproductive system, the accessory glands (prostate, seminal vesicles, bulbourethral glands) add secretions to semen, and the foreskin (prepuce) covers the glans penis. The ampulla, by contrast, is the wide distal part of the female fall …
- CBSE 2026Set ANNUAL1 markMCQQ.Leydig cells are found :(a) in liver(b) in testes(c) in kidney(d) in uterus
›Reveal solutionSolution
Leydig cells (interstitial cells) are found in the testes, between the seminiferous tubules.
Inside the testis, in the interstitial spaces between the seminiferous tubules, are small clusters of glandular cells called Leydig cells (interstitial cells). They are steroidogenic cells that synthesise and secrete the male sex hormone testosterone (androgen), which controls the development of secondary sexual characters in males …
- CBSE 2026Set ANNUAL1 markMCQQ.In a grass family, the cotyledon is called(a) plumule(b) radicle(c) embryo(d) scutellum
›Reveal solutionSolution
The scutellum is the specialised, shield-shaped single cotyledon characteristic of grass-family (monocot) embryos.
In the embryo of members of the grass family (Poaceae), the single cotyledon is highly modified into a shield-shaped structure known as the scutellum, situated laterally, one side pressed against the endosperm. It functions to absorb and transfer nutrients from the endosperm to the growing embryo axis during germination. The plumule (a) an …
- CBSE 2026Set ANNUAL1 markQ.In which part of the body is the male reproductive system located?
›Reveal solutionSolution
The human male reproductive system is located in the pelvic region.
Concept: The male reproductive system comprises the testes, accessory ducts (rete testis, vasa efferentia, epididymis, vas deferens), accessory glands and the external genitalia. …
- CBSE 2026Set ANNUAL1 markMCQQ.The testes in humans are located outside the abdominal cavity within a pouch called the scrotum. This positioning helps in :(a) avoiding compression by internal organs.(b) maintaining a temperature slightly lower than the body temperature for sperm formation.(c) protecting the testes from physical injury during movement.(d) helping in the storage of urine before excretion.
›Reveal solutionSolution
The scrotum keeps the testes cooler than the body core, and this lower temperature is required for sperm production, so (b) is correct.
In the CBSE/NCERT Human Reproduction chapter, the testes lie outside the abdomen in the scrotum. Spermatogenesis (sperm formation) proceeds normally only at a temperature 2-2.5°C below core body temperature. The scrotal sac provides exactly this cooler environment. If the testes are retained inside the abdomen (cryptorchidism), the higher temperature impairs sperm formatio …
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