How Do Organisms Reproduce? - Class 10 MCQ

The correct answer is:

c) Animals reproduce only by sexual mode of reproduction

Explanation:

• While many animals reproduce sexually, some animals can reproduce asexually. Examples include hydra (budding), planaria (regeneration), and some insects and reptiles (parthenogenesis).
• Therefore, it is incorrect to say that animals reproduce only by sexual reproduction.

Placenta is the part that provides nutrients to the growing fetus inside the uterus.
Explanation:
The placenta is an organ that develops during pregnancy and is attached to the inner wall of the uterus. It acts as a connection between the mother and the fetus, providing essential nutrients and oxygen to support the growth and development of the fetus.
Key Points:
- The placenta is responsible for exchanging nutrients and waste products between the mother's blood and the fetus's blood.
- It allows the transfer of oxygen, glucose, amino acids, vitamins, and minerals from the mother's bloodstream to the fetus.
- The placenta also filters out waste products such as carbon dioxide and urea from the fetus's blood, which are then eliminated by the mother's body.
- It produces hormones that help maintain the pregnancy, such as human chorionic gonadotropin (hCG), progesterone, and estrogen.
- The placenta also acts as a protective barrier, preventing harmful substances from reaching the fetus.
- It continues to grow and develop throughout pregnancy, ensuring a constant supply of nutrients and oxygen to support the fetus's growth.
In conclusion, the placenta plays a crucial role in providing the necessary nutrients for the growing fetus inside the uterus.

Menstruation refers to the shedding of the uterine lining that occurs when fertilization does not occur. The unfertilized egg, along with the thickened uterine lining, is expelled from the body through the vagina during menstruation.
Therefore, the correct answer is A: Menstruation.

Route of Sperm Travel:
The correct route that a sperm takes after being deposited into the vagina is as follows:
Vagina → Cervix → Uterus → Oviduct
1.The sperm is initially deposited into the vagina during sexual intercourse.
2.  The sperm then travels through the cervix, which is the narrow passage that connects the vagina to the uterus.
3.  From the cervix, the sperm enters the uterus, which is a hollow, muscular organ located in the pelvis.  The sperm moves through the uterus towards the oviduct.
4. The sperm travels through the oviduct, where it may encounter and fertilize an egg if one is present. The oviduct is the site of fertilization and the beginning of the journey for the fertilized egg towards the uterus.

(i) They are the sexual reproductive organs.

• True. Flowers are the sexual reproductive organs of most plants. They contain the male (stamens) and female (pistils) reproductive structures, which are involved in the process of pollination and fertilization.

(ii) They are produced in all groups of plants.

• False. Flowers are produced by angiosperms (flowering plants), but not all plant groups produce flowers. For example, gymnosperms (like conifers) do not produce flowers; they produce cones instead.

(iii) Flowers are always bisexual.

• False. Flowers can be bisexual (containing both male and female reproductive parts, i.e., both stamens and pistils), but not always. Some flowers are unisexual, meaning they have either male or female reproductive parts, but not both. For example, in some plants, male and female flowers are separate, like in the case of holly plants.

(iv) After fertilisation, they give rise to fruits.

• True. After fertilization occurs in the flower (when the male gamete fuses with the female gamete), the ovary of the flower develops into a fruit, and the ovules inside the ovary develop into seeds.

Answer:
The ability to reproduce is lost in a female after menopause, which is the permanent cessation of menstruation and the end of the reproductive phase of a woman's life.

• Offspring inherit traits from their parents, leading to similarities such as eye color, hair texture, and height.
• However, genetic variation occurs due to recombination and mutations, resulting in differences like unique features or traits.
• This combination of inherited traits and variations contributes to the genetic diversity of a population.
• Hence, offspring display both resemblances and differences compared to their parents.

The fertilization of the human egg by the sperm takes place in the oviduct, specifically in the ampulla region of the fallopian tube.

The organs that produce the gametes are referred to as the primary sex organs. These are the gonalds, the testicles in the male and the ovaries in the female.

Asexual reproduction is the mode of reproduction in single parent produces offsprings. Amoeba reproduces asexually by binary fission. Asexual reproduction occurs in yeast by means of budding and in banana asexual reproduction occur by means of vegetative propagation from the stem. Thus, the correct answer is option B.

What marks the beginning of the reproductive life of a woman?
The correct answer is B: Menarche.
Explanation:
Menarche is the term used to describe the first occurrence of menstruation in girls. It marks the beginning of the reproductive life of a woman. Here is a detailed explanation:
Menarche:
- Menarche refers to the onset of menstruation in girls, typically occurring between the ages of 10 and 15, although it can vary.
- It is a significant milestone in a girl's life and indicates that her reproductive system is maturing.
- Menarche is accompanied by hormonal changes as the body prepares for potential pregnancy.
- It signifies that the ovaries are starting to release eggs and the uterus is developing a lining to support a possible pregnancy.
Other Options:
- Menopause (Option A) is the end of a woman's reproductive period and refers to the cessation of menstrual periods.
- Fertilisation (Option C) is the process by which a sperm cell combines with an egg cell to form a zygote, which can develop into an embryo.
- Ovulation (Option D) is the release of a mature egg from the ovary, which typically occurs midway through the menstrual cycle.
Overall, menarche is the correct answer as it marks the beginning of a woman's reproductive life by initiating the menstrual cycle.

Where does fertilisation take place?

• Fertilisation: The process in which a sperm cell fuses with an egg cell to form a zygote, which eventually develops into an embryo.


• Location: Fertilisation takes place in the Fallopian tube of the female reproductive system.

Explanation:

• The female reproductive system consists of several organs, including the uterus, vagina, fallopian tubes, and cervix.


• During sexual intercourse, sperm is deposited in the vagina.


• The sperm then travels through the cervix and enters the uterus.


• From the uterus, the sperm continues its journey through the Fallopian tube.


• If an egg is present in the Fallopian tube, fertilisation can occur.


• The sperm penetrates the egg, and their genetic material combines to form a zygote.


• The zygote then implants itself in the uterus, where it develops into an embryo.

Conclusion:

• Fertilisation takes place in the Fallopian tube of the female reproductive system.


• It is the process of sperm fusing with an egg to form a zygote.


• The zygote then develops into an embryo and implants itself in the uterus.

Pollen tube passes from surface of stigma to the lowest part of pistil the ovary where ovules are located.

Leishmania reproduces asexually through the process of binary fission. This method involves the following:

• The organism divides into two equal parts.
• Each part then grows into a new organism.
• This process allows for rapid population increase.

In all of them asexual reproduction takes place e.g., in spirogyra fragmentation, malarial parasite multiple fission and in yeast by budding.

The anther, part of the stamen, produces pollen grains (male gametes).

Meanwhile, the ovary, part of the pistil, contains ovules that produce eggs (female gametes).

The correct answer is B: vas deferens. The vas deferens carries sperm from the testes to the ejaculatory ducts and is an important part of the male reproductive system.

Reduction division occurs during meiosis. Budding is seen in yeast and hydra while amoeba reproduces asexually by binary fission.

Gametes have half the number of chromosome (n) as they are formed by meiosis. After syngamy the (2n) diploidy is restored in zygote.

• Characters passed from parents to offspring are encoded in genes, which are segments of DNA.
• DNA is organized into structures called chromosomes, found in the nucleus of cells.
• Genes determine traits such as eye color, height, and other characteristics of an organism.
• Cytoplasm and protoplasm are cellular components, but they do not carry genetic information.
• Gemmules are outdated concepts and not involved in modern genetics.