Test: Sexual Reproduction (Old NCERT) - Grade 12 MCQ

• Sexual reproduction is the fusion of male and female gametes, which can be from the same species or different species, resulting in the formation of a zygote with a new combination of genetic traits.
• The male gamete (sperm) fertilizes the female gamete (egg or ovum) to form a zygote, which develops into an embryo and eventually a new individual.
• The fusion of a haploid male (23 chromosomes) and a haploid female gamete (23 chromosomes) produces a diploid (46 chromosomes) egg or a zygote.
  
• This process of reproduction is known as sexual reproduction.

Hence, the correct option is B

NCERT Reference: topic “SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT

• It is difficult to clearly distinguish between the different phases in perennial plants.
• Some plants exhibit unusual flowering phenomena.
• Some plants flower every year, there are some that flower every 10 years and some plants flower every 50 years.
• Neelakurinji is a flowering plant that flowers every 12 years.

Fig: Neelakurinji Blooms

Hence, the correct option is A

NCERT Reference: topic “1.2 SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT

• Monocarpic plants flower only once in its lifetime. They die after flowering.
• Annuals like marigold, wheat, paddy, biennials like radish, perennials like Bambusa tulda which flowers every 50-100 years, fruits and dies.

Hence, the correct option is A

NCERT Reference: topic “SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT

• The most important event of sexual reproduction is fusion of gametes, called as fertilisation or syngamy.
• This process results in the formation of a zygote. If the zygote is not formed then the next generation of organisms are not produced.

Hence, the correct option is D.

NCERT Reference: topic “Fertilisation” of chapter Reproduction in Organisms of NCERT

• Hermaphrodites are those organisms in which both the sex organs are present. The cockroach, ant and termite are monosexual. The male and female reproductive organs are present in different individuals.
• Whereas in the case of earthworm, the testis and ovaries are present in the same individual and are referred to as a hermaphrodite.
• Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites.

Hence, the correct option is B.

NCERT Reference: topic “Gametogenesis” of chapter Reproduction in Organisms of NCERT

• Sexual reproduction is the fusion of the male and the female gamete that forms a single-celled zygote, the process is known as fertilization.
• This process has been divided into 3 events. The pre-fertilization, fertilization and post-fertilization events.

Hence, the correct option is D

NCERT Reference: topic “SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT

The Correct Answer is (D) Heart.
During the development of the body, the first organ to develop from the embryo is the heart. 

• External fertilization occurs mostly in wet environments and requires both the male and the female to release their gametes into their surroundings (usually water).
• An advantage of external fertilization is that it results in the production of a large number of offspring.
• One disadvantage is that environmental hazards such as predators greatly reduce the chance of surviving into adulthood.
• Amphibians and fish, aquatic algae are examples of animals that reproduce this way.

Hence, the correct option is A
NCERT Reference: topic “Fertilisation” of chapter Reproduction in Organisms of NCERT

There are 3 phases in a life cycle:

1. Juvenile phase/ vegetative phase: Period from birth to maturation of reproductive systems.
2. Reproductive Phase: Period when the reproductive systems have matured and ready to produce offspring.
3. Senescence: Period when the organism starts growing old and starts degrading.

Hence, the correct option is D.
NCERT Reference: topic “SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT

• Hormones are chemical messengers that travel through the bloodstream (in case of animals).
• Hormones are responsible for the change in the phases in both plants and animals.
• Hormonal change can be affected by environmental factors too.

Hence, the correct option is B

NCERT Reference: topic “SEXUAL REPRODUCTION” of chapter Reproduction in Organisms of NCERT