Olympiad Test: Reproduction In Animals - 1 - Class 8 MCQ

Answer:
Animal: Earthworm
Explanation:
An hermaphrodite animal is an organism that possesses both male and female reproductive organs. It is capable of producing both eggs and sperm, allowing it to reproduce with itself or with another individual of the same species.
The correct answer to the question is option C: Earthworm. Here is the explanation for why an earthworm is a hermaphrodite animal:
- Earthworms belong to a group of animals known as annelids, which are characterized by having segmented bodies.
- Earthworms have both male and female reproductive organs located in different segments of their body.
- Each earthworm has both testes (male reproductive organs) and ovaries (female reproductive organs).
- During reproduction, two earthworms align themselves with their heads facing opposite directions and exchange sperm.
- The sperm is then stored and used to fertilize the eggs produced by the earthworm.
- This unique reproductive system allows earthworms to reproduce both sexually and asexually.
In conclusion, the hermaphrodite animal among the given options is the earthworm.

Male Reproductive Organs in Human Beings:
- Testes: The testes are the primary male reproductive organs. They are responsible for producing sperm cells and the male sex hormone, testosterone.
- Sperms: Sperm cells are the male reproductive cells produced by the testes. They are responsible for fertilizing the female egg during sexual reproduction.
- Ova: Ova, also known as eggs, are the female reproductive cells. They are not part of the male reproductive organs.
- Ovaries: Ovaries are the female reproductive organs. They produce eggs (ova) and female sex hormones like estrogen and progesterone.
In summary, the male reproductive organs in human beings are the testes and the sperm cells they produce. Ova and ovaries are part of the female reproductive system.

Animals reproduce by:
- Asexual mode: This mode of reproduction involves the production of offspring without the involvement of gametes (sex cells) or the fusion of genetic material from two parents. It is commonly observed in simple organisms like bacteria, fungi, and some invertebrates. Asexual reproduction can occur through various methods such as binary fission, budding, fragmentation, and parthenogenesis.
- Sexual mode: This mode of reproduction involves the production of offspring by the fusion of gametes from two parents. It is the most common mode of reproduction in higher organisms, including animals. Sexual reproduction promotes genetic diversity and adaptation. It involves the formation of specialized sex cells (sperm and eggs) through a process called meiosis, followed by fertilization to form a zygote.
- Both (a) and (b): Some animals have the capability to reproduce both asexually and sexually, depending on the environmental conditions and availability of mates. This flexibility allows them to adapt to different situations and maximize their reproductive success. Examples of animals that can reproduce by both modes include certain species of insects, reptiles, and amphibians.
- Vegetative mode: Vegetative reproduction is a mode of reproduction commonly seen in plants, where new individuals are produced from vegetative parts like stems, roots, or leaves. It does not occur in animals.
In conclusion, animals primarily reproduce through sexual mode, but some species have the ability to reproduce asexually as well.

Turkey and ostrich reproduction:
Introduction:
Turkey and ostrich are two different species of birds. In terms of reproduction, they have some similarities and differences. Let's explore how they reproduce.
Similarities:
- Both turkey and ostrich reproduce by laying eggs.
Differences:
Turkey:
- Female turkeys, known as hens, lay eggs.
- The eggs are usually laid in a nest made by the hen on the ground.
- The eggs are incubated by the hen for approximately 28 days until they hatch.
- After hatching, the young turkeys, called poults, are able to walk and feed within a day.
Ostrich:
- Female ostriches, known as hens, also lay eggs.
- The eggs are laid in a communal nest, which may be shared by multiple hens.
- The eggs are incubated by the dominant female and the dominant male ostrich.
- The incubation period for ostrich eggs is around 42 to 46 days.
- Once hatched, the ostrich chicks are precocial, meaning they are relatively independent and able to walk and forage shortly after hatching.
Conclusion:
Both turkey and ostrich reproduce by laying eggs. However, there are some differences in terms of nesting habits and incubation periods. Turkey eggs are incubated solely by the hen, while ostrich eggs are incubated by both the dominant female and male ostrich.

The fusion of sperm and egg leads to the formation of a zygote. Here is a detailed explanation of the process:
1. Sperm and Egg:
- Sperm is the male reproductive cell produced in the testes.
- Egg, also known as an ovum, is the female reproductive cell produced in the ovaries.
2. Fertilization:
- When sperm is ejaculated into the female reproductive system during sexual intercourse, it travels through the vagina, cervix, and into the fallopian tubes.
- In the fallopian tubes, the sperm encounters the egg.
- One sperm successfully penetrates the outer layer of the egg, leading to fertilization.
3. Zygote Formation:
- The fusion of the sperm and egg forms a zygote.
- The zygote contains a combination of genetic material from both the sperm and egg.
- It is the beginning stage of the development of a new individual.
4. Further Development:
- After fertilization, the zygote undergoes cell division through mitosis.
- It travels down the fallopian tube and implants itself into the uterine wall.
- The zygote then develops into an embryo, which is the early stage of prenatal development.
- The embryo continues to grow and differentiate, forming different tissues, organs, and systems.
5. Formation of Placenta:
- While the zygote develops into an embryo, the placenta also forms.
- The placenta is an organ that develops during pregnancy and provides a connection between the mother and the developing embryo.
- It facilitates the exchange of nutrients, oxygen, and waste products between the mother and the embryo.
Therefore, the correct answer is: D. Zygote.

Animals that give birth to babies are called Viviparous.
Explanation:
- Viviparous animals are those that give birth to live young.
- They do not lay eggs like oviparous animals.
- The term "viviparous" comes from the Latin words "vivus" meaning "alive" and "parere" meaning "to bring forth".
- In viviparous animals, the embryos develop inside the mother's body and receive nourishment directly from the mother through a placenta or other specialized structures.
- Examples of viviparous animals include mammals like humans, dogs, cats, elephants, and whales.
- Viviparity is an adaptation that allows the offspring to develop and receive protection from the mother until they are ready to survive independently.
- This reproductive strategy is different from oviparity, where animals lay eggs that hatch outside the mother's body.
- Some animals, like certain reptiles and fish, exhibit a combination of both viviparity and oviparity, known as ovoviviparity, where the eggs develop inside the mother's body, but the young are still born live.
- Viviparity is a common reproductive strategy among mammals but is relatively rare in other animal groups.

Answer:
The correct answer is A: Hydra.
Here is a detailed explanation:
Hydra:
- Hydra is a small, simple aquatic organism that belongs to the phylum Cnidaria.
- It reproduces asexually by a process called budding.
- In budding, a small outgrowth called a bud forms on the parent's body.
- The bud then grows and develops into a new individual, which eventually detaches from the parent and becomes an independent organism.
Amoeba and Paramecium:
- Both Amoeba and Paramecium are single-celled organisms belonging to the phylum Protozoa.
- They reproduce asexually by a process called binary fission.
- In binary fission, the parent cell divides into two daughter cells of equal size.
- The offspring are genetically identical to the parent.
Human:
- Humans are multicellular organisms belonging to the phylum Chordata.
- Humans reproduce sexually, meaning the offspring are formed from the fusion of male and female gametes (sperm and egg).
- The offspring develop inside the female's body and are born as separate individuals.
In conclusion, among the given options, only Hydra grows out of the parent's body through asexual reproduction by budding.

Metamorphosis: The Transformation of Larva into an Adult
Metamorphosis is the process by which a larva transforms into an adult through drastic changes. Here is a detailed explanation of this phenomenon:
1. Definition:
- Metamorphosis is a biological process in which an organism undergoes a distinct change in its body structure and physiology during development.
- It involves a series of stages and transformations leading to the development of an adult organism from a larval form.
2. Types of Metamorphosis:
- There are two main types of metamorphosis: incomplete metamorphosis and complete metamorphosis.
- In incomplete metamorphosis, the larva resembles the adult but lacks wings or other adult structures. It undergoes a series of molts until it reaches adulthood.
- In complete metamorphosis, the larva goes through a dramatic transformation, changing its body structure, behavior, and diet. It passes through distinct developmental stages such as egg, larva, pupa, and adult.
3. Examples of Metamorphosis:
- Insects such as butterflies, moths, beetles, and flies undergo complete metamorphosis.
- The larva of a butterfly, called a caterpillar, hatches from an egg and goes through multiple molts, increasing in size each time. Eventually, it forms a pupa or chrysalis, within which the larva undergoes a complete restructuring of its body tissues to form the adult butterfly.
- Frogs and other amphibians also undergo metamorphosis. The larval stage, called a tadpole, lives in water and breathes through gills. As it develops, it grows legs, loses its tail, and develops lungs to become an adult frog.
4. Importance of Metamorphosis:
- Metamorphosis is crucial for the survival and adaptation of many species.
- It allows organisms to occupy different ecological niches and exploit different resources at different stages of their life cycle.
- The transformation from larva to adult often involves changes in diet, habitat, locomotion, and reproductive organs, enabling organisms to specialize in different functions at different life stages.
In conclusion, metamorphosis is the process by which a larva undergoes dramatic changes to transform into an adult organism. It is a fascinating biological phenomenon that allows organisms to adapt to different stages of their life cycle and occupy various ecological niches.

Onset of sexual maturity in human beings is called
The correct answer is Puberty.
Explanation:
During puberty, a series of physical and physiological changes occur in the human body, marking the onset of sexual maturity. Here is a detailed explanation of the term:
1. Puberty:
- Puberty is the stage of development when a person becomes sexually mature and capable of reproduction.
- It is a natural process that typically occurs during adolescence, usually between the ages of 10 to 14 for girls and 12 to 16 for boys.
- The onset of puberty is triggered by hormonal changes in the body, specifically the increased production of sex hormones called estrogen and testosterone.
2. Physical changes:
- During puberty, both boys and girls experience physical changes such as growth spurts, development of secondary sexual characteristics, and changes in body shape.
- Girls may experience breast development, the onset of menstruation, and widening of hips.
- Boys may experience the growth of facial and body hair, deepening of the voice, and an increase in muscle mass.
3. Psychological changes:
- Along with the physical changes, puberty also brings about psychological and emotional changes.
- Adolescents may experience mood swings, increased sexual feelings and curiosity, and a heightened interest in relationships and sexuality.
4. Reproductive capability:
- One of the main purposes of puberty is to prepare the body for reproduction.
- During puberty, the reproductive organs mature, and individuals become capable of sexual reproduction.
In conclusion, the correct term for the onset of sexual maturity in human beings is Puberty. It is a transformative period characterized by physical, psychological, and reproductive changes.

Answer:

The correct answer is B: Asexual reproduction.

Explanation:
- Asexual reproduction is a type of reproduction that involves the production of new organisms by just one parent.
- In asexual reproduction, the offspring are genetically identical to the parent because there is no combining of genetic material from two different parents.
- Asexual reproduction can occur through various mechanisms, such as binary fission, budding, fragmentation, or spore formation.
- Binary fission is a common form of asexual reproduction in single-celled organisms, where the parent cell divides into two identical daughter cells.
- Budding is another form of asexual reproduction where a small bud or outgrowth develops on the parent organism and eventually detaches to become a separate individual.
- Fragmentation occurs when the parent organism breaks into several pieces, and each fragment develops into a new organism.
- Spore formation involves the production of specialized cells called spores that can develop into new individuals under favorable conditions.
- Asexual reproduction is advantageous in certain environments as it allows for rapid population growth and colonizing new habitats without the need for a mate.
- Examples of organisms that reproduce asexually include bacteria, fungi, plants (through vegetative propagation), and some animals such as starfish and planarians.