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Solutions for Biology, Class 8, ICSE
Write about different parts of the male reproductive system of human beings.
The male reproductive system of human beings consists of a pair of testes, sperm ducts, urethra, penis and accessory glands. Each of them is briefly described below:
Explain the process of fertilization in human beings.
In human beings, fertilization takes place in the fallopian tubes or oviducts inside the female body. The sperms from the male received by the vagina swim up to the oviduct for fertilization. An ovum is fertilized by a single sperm. It results in the formation of a single cell called zygote. Since the zygote is formed as a result of the fusion of sex cells from the father and mother, it has the chromosomes and genes from both of them. Thus, the new individual inherits characteristics from both the parents. Zygote moves from the oviduct to the uterus and gets implanted in it for further development. The below diagram shows the process of fertilization in human beings:
Explain the process of development of a zygote into a foetus.
The formation of an individual from the zygote is called development. In human beings, the zygote undergoes continuous cell division to form a ball of cells. The ball gets implanted in the uterine wall for further development. The implanted ball of cells undergoes many cell divisions. The cells change their size, shape and function to become different types of cells such as nerve cells and blood cells. From these, tissues and organs develop and get organized into various organ systems of the baby. From the third week of development till the end of the second month, the developing organism is referred to as the embryo. From the third month until birth, it is called foetus.
What is placenta? How is the placenta beneficial to the foetus?
The structure which connects the foetus to the uterus and helps the foetus to get oxygen and nutrients from mother is called placenta. Placenta is an organ attached to the lining of the uterus.
The placenta is beneficial to the foetus in following ways:
Define fertilization.
The fusion of male and female gametes i.e. sperm and ova, either inside or outside the body of the female is called Fertilization.
Name the male reproductive organs of human beings.
The male reproductive organs of human beings are
Name the male reproductive organ through which sperms are released.
Penis is the male reproductive organ through which sperms are released.
What is semen?
The mixture of the sperms and secretions from the accessory glands is called semen.
Which part of the human body produces ova?
Ovaries produce ova.
Name the organ where the fertilization of an ovum by the sperm takes place.
Fallopian tube or Oviduct.
What do you mean by foetus?
From the third month of development until birth, the developing organism in the uterus is known as Foetus.
What is placenta?
The structure which connects the foetus to the uterus and helps the foetus to get oxygen and nutrients from mother is called placenta.
A ............... is formed as a result of fertilization.
A zygote is formed as a result of fertilization.
The male gametes are called ............... .
The male gametes are called sperm.
The sperm travel through the sperm duct or vas deferens to reach the ............... .
The sperm travel through the sperm duct or vas deferens to reach the urethra.
The ............... are almond-sized oval glands situated in the pelvic or hip region.
The ovaries are almond-sized oval glands situated in the pelvic or hip region.
The cervix is narrow and opens to the outside through a muscular tube called the ............... .
The cervix is narrow and opens to the outside through a muscular tube called the vagina.
Human fertilization occurs in the ............... and the baby develops in the ............... .
Human fertilization occurs in the fallopian tube and the baby develops in the uterus.
The foetus is connected to the uterus by a structure called ............... .
The foetus is connected to the uterus by a structure called placenta.
............... fluids acts like a cushion and protects the developing foetus in the uterus.
Amniotic fluid acts like a cushion and protects the developing foetus in the uterus.
From the third week of development till the end of the second month, the developing organism is referred to as the ............... .
From the third week of development till the end of the second month, the developing organism is referred to as the embryo.
The time period between fertilization and birth is called ............... .
The time period between fertilization and birth is called gestation.
Complete the following table by filling in the blanks numbered 1 to 5.
| Sl. No. | Structure | Function |
|---|---|---|
| 1. | ovaries | 1 |
| 2. | uterus | 2 |
| 3. | 3 | produces sperm |
| 4. | fallopian tubes | 4 |
| 5. | 5 | foetus is connected to the placenta through this |
The completed table is shown below:
| Sl. No. | Structure | Function |
|---|---|---|
| 1. | ovaries | produce eggs (1) |
| 2. | uterus | zygote developes into baby in uterus (2) |
| 3. | Testes (3) | produces sperm |
| 4. | fallopian tubes | Fertilization and transfer of zygote to the uterus (4) |
| 5. | Umbilical cord (5) | foetus is connected to the placenta through this |
Some of the parts of the female reproductive system are marked incorrectly. Write the correct names in the space provided.
oviducts → ovaries
uterus → fallopian tube or oviduct
vagina → uterus
ovary → vagina
Ovulation
Ovulation — The release of a mature egg from an ovary is called ovulation.
Menstruation
Menstruation — Discharge of blood along with the broken lining of uterine tissues in females is called Menstruation.
Fertilization
Fertilization — The fusion of male and female gametes i.e. sperm and ova, either inside or outside the body of the female is called Fertilization.
Foetus
Foetus — From the third month of development until birth, the developing organism in the uterus is known as Foetus.
External fertilization and internal fertilization
| Sl. No. | External fertilization | Internal fertilization |
|---|---|---|
| 1. | When the sperm fuses with the ovum outside the female body it is called external fertilization. | When the sperm fuses with the ovum inside the female body it is called internal fertilization. |
| 2. | It is seen in aquatic habitat, for example fish and frog. | It is found in mammals, birds and reptiles. |
Testes and Ovary
| Sl. No. | Testes | Ovary |
|---|---|---|
| 1. | Testes are part of the male reproductive system. | Ovaries are part of the female reproductive system. |
| 2. | Testes are located outside the abdomen in a sac-like structure called scrotum. | The ovaries are situated in the pelvic or hip region. |
| 3. | Sperms are produced in testes. | Eggs (ova) are produced and released by ovaries. |
Sperm and ovum
| Sl. No. | Sperm | Ovum |
|---|---|---|
| 1. | The male gamete is called sperms. | The female gamete is called ovum. |
| 2. | Sperms are formed in testes. | Ovum is formed in ovaries. |
| 3. | Sperm pass through sperm duct. | Ovum moves through fallopian tube. |
| 4. | Sperms have oval head and long tail. | Ovum is generally spherical and is full of yolk. |
When an ovum fuses with a sperm outside the body, it is called ............... fertilization.
When an ovum fuses with a sperm outside the body, it is called external fertilization.
Testes produce male sex hormone called ............... .
Testes produce male sex hormone called testosterone.
Fertilization of the ovum takes place in the ............... .
Fertilization of the ovum takes place in the fallopian tubes.
The females have 28 day-long reproductive cycle called ............... .
The females have 28 day-long reproductive cycle called menstrual cycle.
The embryo is attached to the uterus by a structure called ............... .
The embryo is attached to the uterus by a structure called placenta.
Given alongside is the outline of the cross-section of the male reproductive system.
| Sl. No. | Column A | Column B |
|---|---|---|
| 1. | gestation | the lower part of the uterus |
| 2. | testosterone | the time period between fertilization and birth |
| 3. | sperm | when a sperm fuses with an ovum inside the female body |
| 4. | internal fertilization | the male sex hormone produced by the testes |
| 5. | cervix | the male reproductive cells in human beings |
| Sl. No. | Column A | Column B |
|---|---|---|
| 1. | gestation | the time period between fertilization and birth |
| 2. | testosterone | the male sex hormone produced by the testes |
| 3. | sperm | the male reproductive cells in human beings |
| 4. | internal fertilization | when a sperm fuses with an ovum inside the female body |
| 5. | cervix | the lower part of the uterus |
Number the process in the correct sequence of their occurrence.
| implantation, embryonic development, fertilization, birth, ovulation |
|---|
The Correct sequence is as follows:
Can menstruation and ovulation occur till the birth of the baby during pregnancy.
No, menstruation and ovulation does not occur during pregnancy. As the embryo gets implanted into the uterus, the uterine wall is not shed so menstruation does not occur. Also, ovary does not release a new egg during pregnancy so ovulation does not occur.
External fertilization occurs mostly in
frogs
Reason — External fertilization is seen in aquatic habitats, for example in fishes and frogs.
Sperms are produced by
testes
Reason — Sperms are produced in a pair of special reproductive organs called testes.
Testes are present in a sac called
scrotum
Reason — Testes are located outside the abdomen in a sac-like structure called scrotum.
The sperms reach the urethra by travelling through the
sperm duct
Reason — The sperms travel through the sperm duct or vas deferens to reach the urethra.
The release of an egg from an ovary is called
ovulation
Reason — The release of a mature egg from an ovary is called Ovulation.
In human females, fertilization of egg takes place in
fallopian tubes
Reason — Fertilization takes place in the fallopian tubes or oviducts of the human females.
From the third week of development till the end of the second month of pregnancy, the developing organism is called
embryo
Reason — From the third week of development till the end of the second month of pregnancy, the developing organism is called embryo. From the third month until birth, it is called foetus.
The female sex hormones secreted by the ovaries are
progesterone and oestrogen
Reason — The two main functions of ovaries are to produce eggs or ova and secrete female sex hormones progesterone and oestrogen.
Sexual reproduction involves the fusion of an egg and a spore.
False
Corrected Statement — Sexual reproduction involves the fusion of an egg and a sperm.
The ovum is carried from the ovary to the uterus by the vas deferens.
False
Corrected Statement — The ovum is carried from the ovary to the uterus by the fallopian tubes or oviduct.
Oestrogen is a female sex hormone.
True
Normally, two eggs are released from one of the ovaries every month.
False
Corrected Statement — Normally, one egg is released from one of the ovaries every month.
The formation of an individual from the zygote is called development.
True