Class 8 Science Chapter 9 MCQ

In option [C], sperm is a male gamete, a part of male reproductive system, whereas the other three terms are related to the female reproductive system. As there is a mismatch, this option is an incorrect combination. This is because it has parts of both male and female reproductive system. In option [A], all four terms are related to male reproductive system, and in option [B] and [D], all four terms are related to female reproductive system. As there is no mismatch, these options are correct combinations.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Asexual reproduction is the simplest method of reproduction. It takes only in those animals whose bodies have a simple structure. In asexual reproduction the young one or offspring produced is an exact copy of the parent. Asexual reproduction is a method producing generally identical off-springs.

Hen is the odd one because it is the only one which lays eggs (oviparous), that is it shows oviparity. Humans, cow and dog are viviparous, i.e., they give birth to young ones. All four organisms show internal fertilization, none of them fertilizes externally, except one.

Ovary is the structure that occurs in the reproductive system of flowering plants as well as of humans. In both of them, it produces female gametes called egg.

Budding is an asexual method of reproduction. In budding, a small part of the body of the parent organism grows out as a “bud” which then detaches and becomes a new organism. The asexual reproduction by budding is observed in animals like Hydra, sponges, coral, sea-anemones etc.

In Hydra, reproduction take place by budding. A small part of the body of an organism grows as “bud” which then detaches and becomes a new organism. The other options Amoeba, Paramecium and bacteria reproduce asexually by binary fission.

Testes are the oval shaped organs which lie outside the abdominal cavity of man. A man has two testes. Testes are the real reproductive organs in man. The male sex cells called sperms are made in testes. Thus, testes make male gametes called sperms or millions of sperms are produced in the testes.

Fertilization in humans take place in the female body. The sperms of men are introduced by penis into female’s body through vagina. The sperms then pass through the uterus and reach to oviducts. It is here, that sperms combines with egg to forms zygote (i.e. fertilization occurs).

The aquatic animals in which fertilization takes place in water, lay unfertilized eggs and fertilization takes place when male gametes, already present in water, float up to them and fuse. Thus, these animals are oviparous as they lay eggs, and exhibit external fertilization as the fusion of male and female gametes takes place outside the body of an organism.

Here, all the statements are correct. Hence, your answer will be option [D].

The immediate product of fertilization, formed by the fusion of male and female gametes, is called a zygote. After fertilization zygote is formed. All the multicellular animals start their life from a single cell called “Zygote”. Ovum is the unfertilized egg. Zygote, on division develops into an embryo, which gets implanted in the maternal uterus. Foetus is the stage when all body parts of the baby are recognizable and appear similar to the adult beings.

In humans, the ovaries alternatively release one mature egg cell every month into the oviducts or fallopian tubes.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Embryo grows and becomes a foetus in which all the main body features of the baby animal have formed. And foetus grows and develops to form a new baby animal.

Here, all the statements are correct. Hence, your answer will be option [D].

The hen is a bird. Internal fertilization take place in hen also. But a hen does not give birth to chicks (like human beings). As fertilization take place inside the body of hen and after that it travels down the oviduct, many protective layers are formed around the embryo. The hard shell that we see in hen’s egg, is the outermost protective layer. After the hard egg shell is formed around the developing embryo, the hen finally lays the egg. The hen then sits on the eggs to provide sufficient warmth to the eggs for the development of the embryo into the chicks. The embryo takes about 3 weeks or 21 days to develop into a complete chick. And after the chick is completely developed, the egg shell breaks open automatically and the chick comes out of it.

The fertilization which takes place outside the female body is called external fertilization. In external fertilization the female animal eggs are fertilized by sperm outside her body. External fertilization is very common in aquatic animals such as frog, fish and star-fish etc. Animals exhibiting external fertilisation produce a large number of gametes to ensure better chance of fertilisation.

Unicellular organisms also can reproduce. But their methods are different. There are many different ways in which new organisms are produced from their parents. Some organisms like Amoeba just splits into two parts to produce new Amoebae, some organisms like Hydra grow out of the parent’s body in the form of a bud.

The development of fertilized egg take place in the uterus or womb. The embryo gets embedded in the wall of the uterus for development by implantation. Implantation is the attachment of the blastocyst to the uterine wall. It occurs after 7 days of fertilization. The portion of the blastocyst where the inner cell mass is located lies against the endometrium of the uterus.

Option [B] and [C] are true. Menstruation occurs every 28 days and during every menstrual cycle, one mature ovum will be released by the ovary.

The process by which the division of the nucleus takes place during the cell cycle is known as karyokinesis. It is usually followed by cytokinesis. It can take place by mitosis, meiosis, and amitosis. Mitosis is an equational division, meiosis is a reductional division while amitosis, is an indirect division of nucleus. Cytokinesis refers to the division of the cytoplasm to form two separate daughter cells immediately after mitosis. Hence, the correct answer is option [A].

In human beings, the process of reproduction starts by the formation of male and female gametes respectively in the male and female reproductive systems. This is followed by the fusion of these gametes inside the female body, a process called fertilization. The fertilized product of this process is termed as a zygote. The fusion forms a zygote, which divides repeatedly to form the embryo. The embryo gets implanted in female uterus for further development to form foetus. Thus, the correct sequence is gamete formation, fertilization, zygote and embryo. Hence, your answer should be option [A].