Reproduction in Humans

Scrotum

Reason — Sperms are produced in the testes. A pair of testes lie outside the abdominal cavity in a sac called the scrotum.
The penis is the external male reproductive organ used for copulation and urination. It does not contain the testes. The ureter is a tube that carries urine from the kidneys to the urinary bladder. The urinary bladder is a storage organ for urine before it is excreted.

Binary Fission

Reason — Binary fission is the most common method of reproduction in single-celled organisms. In Amoeba, it results in the division of the parent amoeba into two daughter amoebae.
In budding, a small outgrowth (bud) develops on the parent and later detaches. This is seen in organisms like yeast, not Amoeba. Regeneration is the ability to regrow lost body parts (e.g., in Planaria). It is not the usual method of reproduction in Amoeba. In multiple fission, one organism divides into many daughter cells at once (seen in some conditions in Amoeba and in organisms like Plasmodium), but it is not the most common method.

Zygote

Reason — A zygote is a fertilised egg. The zygote is formed when the male gamete (sperm) and female gamete (egg) fuse. It is formed when a sperm fuses with an egg in one of the fallopian tubes. The zygote grows by cell division and produces an embryo. An ovule is the female reproductive cell (egg) before fertilisation. It is not formed after fertilisation. A foetus is a later stage of development in humans, after the embryo stage, when body parts are more developed. An embryo is formed after the zygote divides multiple times. It is an early developmental stage, but not the immediate result of fertilisation.

Vagina

Reason — The uterus is a hollow, inverted pear shaped muscular organ which opens to the outside through a long, muscular tube called the vagina, situated between the rectum and the urethra.
The urethra is a tube that carries urine from the bladder to the outside. It is part of the excretory system, not connected to the uterus. The oviduct (fallopian tube) connects the ovaries to the uterus. It opens into the uterus, not the other way around. The vulva is the external part of the female reproductive system, not an internal structure connected directly to the uterus.

Only 2

Reason — The foetus is the developmental stage where the body structures and organs are well formed, and it starts resembling the parents. Gametes, zygote and embryo do not resemble the parents in appearance.

Gestation period in humans is 820 days.

Reason — Gestation period in humans is 280 days.
Eggs (female gametes) and sperms (male gametes) are involved in reproduction. Fertilization (fusion of sperm and egg) occurs in the oviduct, and then the zygote moves to the uterus for implantation. The epididymis is a coiled tube where sperms mature and are stored.

Both A and R are true and R is the correct explanation of A.

Explanation — A is true as humans can live without reproducing in their own lifetime.
R is true as reproduction helps in the continuation of species on Earth.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

A is false and R is true.

Explanation — A is false as Budding does not occur only in plants. It is also seen in organisms like Yeast and Hydra. R is true as budding occurs in both plants and animals. Both yeast (a fungus) and Hydra (an animal) reproduce by budding.

Therefore, A is false and R is true is the correct option.

Both A and R are true and R is the correct explanation of A.

Explanation — Only one egg is produced by an ovary alternatively every month.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

A is false and R is true.

Explanation — A is false as sperms are produced in testes and transported to urethra through the sperm ducts in males.
R is true as moving towards the urethra, sperms mix with fluids from male accessory glands (seminal vesicles, prostate gland, etc.) to form semen.

Therefore, A is false and R is true is the correct option.

A is true and R is false.

Explanation — A is true as in animals, growth occurs only up to a certain age (after maturity, growth stops). In plants, growth continues throughout life due to meristematic tissues. R is false as growth means any type of irreversible increase in the size and weight of an individual during the process of development.

Therefore, A is true and R is false is the correct option.

(a) Fertilization → Implantation → Gestation → Birth

(b) Testis → Epididymis → Sperm duct → Urethra

(a) Odd term: Uterus
Category: Male reproductive parts

(b) Odd term: Seminal vesicle
Category: Female reproductive parts

(c) Odd term: Vagina
Category: Male accessory glands

(d) Odd term: Bacteria
Category: Eukaryotic organisms

Testes → Epididymis → Sperm duct → Urethra

The fusion of the male gamete (sperm) and the female gamete (ovum) to form a zygote is called fertilisation.

The process of fixing of the fertilized egg (embryo) to the wall of the uterus is termed implantation.

Difference between Egg and Sperm:

Difference between Sexual Reproduction and Asexual reproduction

Difference between Budding and Regeneration

Testes lie outside the body because the normal body temperature does not allow the maturation of the sperms. In such an arrangement, the testes are at a temperature which is 2-3°C lower than that of the body. This is the most suitable temperature for sperm production and development.

Semen contains a very large number of sperms because out of the millions of sperms released into the vagina, only a few of them are able to reach up to the upper parts of the oviducts. Some die on the way and are absorbed. Only a few of them reach the ovum. Thus, to increase the chances of fertilisation, a very large number of sperms should be present in the semen.

(a) Ovary — The ovaries have two main reproductive functions in the body. They produce eggs and secrete the reproductive hormones, Oestrogen and Progesterone.

(b) Testes — The two main functions of testes are to produce sperms and to secrete the male reproductive hormone testosterone.

(c) Fallopian Tubes — Fallopian Tubes transfer the egg from the ovaries to the uterus.

(d) Seminal vesicles — They produce a secretion which serves as a medium for the transportation of the sperms.

(e) Uterus — The embryo grows and develops in the Uterus.

(a) The parts are:

• 1 → Ovary
• 2 → Fallopian tube
• 3 → Uterus
• 4 → Vagina

(b) Fallopian tube / Oviduct

Labelled diagrams of a sperm and ovum are shown below:

Sperm

Ovum

(a) A sperm and an ovum are unicellular.

(b) In males, the testes produce male gametes (sperms), and in females, the ovaries produce female gametes (eggs).

(c) Fertilisation.

(d) The fusion of male and female gametes in humans takes place in the fallopian tube.

(e) Zygote is formed by the fusion of the sperm and ovum.

• 1 → Seminal vesicle — Produce a secretion which serves as a medium for the transportation of the sperms.
• 2 → Prostate gland — Pours an alkaline secretion into the semen as it passes through the urethra.
• 3 → Testes — To produce sperms and to secrete the male reproductive hormone testosterone.
• 4 → Urethra — Carries either urine or semen.
• 5 → Sperm duct — Carries the sperms from the epididymis to the urethra.

Labelled diagram showing the reproduction in amoeba is shown below:

(a) Reproduction in amoeba is asexual.

(b) Amoeba reproduces by binary fission.

(c) Two offsprings are produced from one division.

(d) During the reproduction in amoeba, the type of cell division that occurs is mitosis.

(e) E. coli also reproduces by binary fission.

Labelled diagram of the human female reproductive system is shown below:

(a) Ovary

(b) Vagina

(c) Uterus

(d) Fallopian tube

(e) Cervix

(a) Budding is a form of asexual reproduction in which a small outgrowth, called a bud, grows from the parent body and develops into a new individual.

(b) Budding is an asexual mode of reproduction.

(c) Budding is seen in Yeast and Hydra. Yeast is a fungus, Hydra is an animal.

(d) The labelled diagram below shows the process of budding in Hydra:

(e) The specific locomotory structures of Hydra, which reproduces by budding, are its tentacles.

(a) Two animals that can produce a new organism by regeneration are Planaria and Hydra.

(b) These animals show asexual reproduction. In this process, a new organism develops from a single parent without the involvement of gametes.

(c) This type of reproduction is different from reproduction in a dog: