Reproduction in Humans

The testes are located within the:

1. Penis
2. Scrotum
3. Ureter
4. Urinary bladder

Answer

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.

Amoeba most commonly reproduces by:

1. Budding
2. Regeneration
3. Binary fission
4. Multiple fission

Answer

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.

Which of the following is a stage formed after the fertilisation of the egg by a sperm?

1. Ovule
2. Foetus
3. Embryo
4. Zygote

Answer

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.

Internally, the uterus opens into:

1. Urethra
2. Vagina
3. Oviduct
4. Vulva

Answer

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.

There are many specific cellular structures involved in the process of reproduction in humans, like :

(1) Gametes
(2) Foetus
(3) Zygote
(4) Embryo

Which of these start resembling with the parents?

1. Only 1
2. Only 2 and 3
3. Only 2
4. Only 3 and 4

Answer

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.

Which of the following statements is incorrect?

1. Eggs and sperms are the reproductive gametes.
2. Fertilization occurs before implantation.
3. Epididymis is the highly coiled structure found on the upper side of the testis.
4. Gestation period in humans is 820 days.

Answer

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.

Assertion (A): Reproduction is a kind of life process which is not necessary for the survival of humans in their own life time.

Reason (R): The process of reproduction helps in the continuation of species on earth, not an individual.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

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.

Assertion (A): Budding is a type of asexual reproduction which occurs only in some plants.

Reason (R): Both Yeast and Hydra, reproduce by the process of budding.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

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.

Assertion (A): Only one egg is produced by each ovary in human females every month.

Reason (R): Usually, both ovaries do not release egg in the same month.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

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.

Assertion (A): Sperms are produced in testes and transported to urethra through the fallopian tubes in males.

Reason (R): On their way to urethra, sperms mix with three kinds of fluids released by the male accessory glands to form semen, the reproductive fluid.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

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.

Assertion (A): Growth is the characteristic feature of all living beings which occurs for a limited time in animals and throughout lifetime in plants.

Reason (R): Growth means any type of reversible or irreversible change in the size, shape and weight of an individual during the process of development.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

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.

Arrange the following terms in a logical sequence.

(a) Gestation, Birth, Fertilization, Implantation

(b) Urethra, Epididymis, Sperm duct, Testis

Answer

(a) Fertilization → Implantation → Gestation → Birth

(b) Testis → Epididymis → Sperm duct → Urethra

Choose the odd one out and mention the category to which the remaining terms belong.

(a) Testis, Uterus, Vas deferens, Epididymis

(b) Ovary, Uterus, Seminal vesicle, Oviduct

(c) Vagina, Seminal vesicle, Cowper's gland, Prostate gland

(d) Amoeba, Hydra, Paramecium, Bacteria

Answer

(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

List the structures, in their correct sequence, through which the sperms must pass from the time they are produced in the testes to the time they leave the urethra.

Answer

Testes → Epididymis → Sperm duct → Urethra

Define Fertilization.

Answer

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

Define Implantation.

Answer

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

Distinguish between Egg and sperm

Answer

Difference between Egg and Sperm:

Distinguish between Sexual Reproduction and asexual reproduction

Answer

Difference between Sexual Reproduction and Asexual reproduction

Distinguish between Budding and regeneration

Answer

Difference between Budding and Regeneration

State the reason why testes lie outside the abdomen in a scrotum?

Answer

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.

Why is it important that a very large number of sperms should be present in the semen?

Answer

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.

State the functions of the following:

(a) Ovary

(b) Testes

(c) Fallopian Tubes

(d) Seminal Vesicles

(e) Uterus

Answer

(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.

Given here is a section of the female reproductive system of humans.

(a) Name the parts labelled 1 to 4.

(b) Name the part where fertilisation occurs in the female reproductive system.

Answer

(a) The parts are:

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

(b) Fallopian tube / Oviduct

Draw neat and labelled diagrams of a sperm and ovum. Answer the following questions:

(a) Is a sperm and an ovum unicellular or multicellular ?

(b) Name the organ of the human body where these gametes are produced.

(c) Name the process of the fusion of these gametes.

(d) Name the organ where the fusion of these gametes take place.

(e) What is formed by the fusion of the sperm and ovum ?

Answer

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.

Given below is a diagram of the male reproductive system in humans. Label the parts indicated by numbers 1 to 5, and state their functions.

Answer

• 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.

Draw a neat and labelled diagram showing the reproduction in amoeba. Answer the following questions :

(a) Is reproduction in amoeba of the sexual or asexual kind ?

(b) Name the specific kind of reproduction which occurs in amoeba.

(c) How many offsprings are produced from one division?

(d) What kind of cell division occurs during the reproduction in amoeba?

(e) Give one more example of an organism which reproduces by the same mode of reproduction as that of amoeba.

Answer

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.

Draw a neat and labelled diagram of the human female reproductive system. From the diagram, name the following :

(a) The organ where ovum is produced.

(b) The muscular tube situated between the rectum and the urethra.

(c) A hollow, inverted pear-shaped muscular organ found in the pelvic cavity.

(d) A pair of narrow, muscular long ducts extending from each ovary to the upper part of the uterus.

(e) A small lower constricted part of the uterus.

Answer

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

(a) Ovary

(b) Vagina

(c) Uterus

(d) Fallopian tube

(e) Cervix

Answer the following questions:

(a) What is budding? Define it.

(b) Is it asexual or sexual mode of reproduction?

(c) Mention one example of a plant and one of an animal that reproduce by budding.

(d) Draw and label the diagram of an animal showing the process of budding.

(e) Write the specific locomotory structures of the animal drawn by you in part (d) above.

Answer

(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.

One evening, Abdul spotted a lizard in his room. In an attempt to shoo it away with a broom, the lizard's tail suddenly broke off and kept wriggling on the floor. Abdul got sad, thinking he had hurt the lizard badly. His father explained that many lizards can regrow their tails if they lose them. This ability is called regeneration.
Abdul wondered if this meant a new lizard can grow from the broken tail in the same way some animals reproduce new individuals. However, his biology teacher clarified that regrowing a tail is not reproduction. It only replaces a lost body part. In some simple animals, regeneration can actually produce a whole new organism. But in lizards, regeneration only replaces the lost body part (or tail) and does not create a new lizard.

(a) Name two animals that use regeneration for producing a new organism.

(b) What type of reproduction do the animals named by you above show?

(c) How is this type of reproduction different from how a dog gives birth to puppies?

Answer

(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: