Reproduction MCQ Quiz in मल्याळम - Objective Question with Answer for Reproduction - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is three cells

Explanation:

When the pollen grain is mature it contains two cells, the vegetative cell and generative cell

• The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus.
• The generative cell is small and floats in the cytoplasm of the vegetative cell. It is spindle shaped with dense cytoplasm and a nucleus.
• In over 60 per cent of angiosperms, pollen grains are shed at this 2-celled stage.
• In the remaining species, the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage).

In the mature pollen grain, the male gametophyte contains:

• One Vegetative Cell: Also known as the tube cell, it is responsible for forming the pollen tube during fertilization. This tube cell is larger and plays a significant role in the delivery of sperm cells to the ovule.
• Two Sperm Cells: These are the cells that participate in double fertilization. One sperm cell fuses with the egg cell to form the zygote (which develops into the embryo), while the other fuses with the two polar nuclei to form the triploid endosperm

Key Points

• Outbreeding devices refer to the adaptive methods of plants that prevent self-pollination and encourage cross-pollination.
• This is to prevent continued self-pollination, which may result in inbreeding depression.
• Some of the outbreeding devices are:
  • Self-incompatibility - Pollen germination and pollen tube growth is inhibited on the same plant.
  • Dicliny - It is the production of dioecious or unisexual flowers, where male and female flowers are produced on different plants. It prevents both autogamy and geitonogamy.
  • Protogyny & Protandry - These are processes where pollen and stigma maturity are not synchronized. Pistil develops before anther in protogyny and vice versa in protandry.
  • Heterostyly - Stigma is placed at a higher position than the anthers, so that pollens do not fall on them.
• Production of monoecious flowers means both male and female flowers are borne on the same plant.
• This may prevent autogamy but not geitonogamy, which is also self-pollination.
• Therefore, production of monoecious flowers is not an effective outbreeding device for plants.

Additional Information

Pollination can be divided into 3 types:

• Autogamy -
  • It is the transfer of pollen grains from the anther to the stigma of the same flower.
  • It requires the pollen release and stigma receptivity to be synchronous, to prevent cross-pollination.
  • The anthers and stigma lie close to each other to assure self-pollination.
  • The autogamous flowers can be of 2 types - chasmogamous and cleistogamous.
  • Chasmogamous flowers have normal flowers with exposed anther and stigma.
  • Cleistogamous flowers do not open at all, thus assuring self-pollination and seed set.
• Geitonogamy -
  • It is the transfer of pollen grains from the anther to the stigma of a different flower of the same plant.
  • It is functionally cross-pollination as pollinating agents are involved.
  • It is genetically self-pollination as both male and female gametes come from the same plant.
  • Example - Maize, Castor.
• Xenogamy -
  • It is the transfer of pollen grains to the stigma of different plant.
  • It causes genetic variation and is a type of cross-pollination.
  • It is always found in unisexual plants where male and female flowers are borne on different plants.
  • Example - Papaya.

The correct answer is Frog
Key Points 

• External fertilization occurs when eggs are shed by the female and fertilized by the male outside of the body. This type of fertilization is common in aquatic organisms, such as fish and amphibians.
• Among options (hen, cat, frog, and snake), the frog is an example of a species where external fertilization takes place. The other listed animals - hen (a species of bird), cat (a mammalian species), and snake (a species of reptiles) - practice internal fertilization.

The correct answer is flowers are large and colourful

Explanation:

• Pollination is defined as the transfer of pollen grains from the anther of a flower to the stigma of a pistil.
• Pollination by wind is more common amongst abiotic pollinations.
• Wind pollination also requires that the pollen grains are light and non-sticky so that they can be transported in wind currents.
• They often possess well-exposed stamens (so that the pollens are easily dispersed into wind currents,and large often-feathery stigma to easily trap air-borne pollen grains.
• Wind-pollinated flowers often have a single ovule in each ovary and numerous flowers packed into an inflorescence; a familiar example is the corn cob

Colourful flowers with large size is the need of the plants where pollination occurs by insects and other animals. 

Key Points

• In human, fertilization takes place in the ampullary-isthmic junction of the fallopian tube.
• The zygote undergoes mitotic divisions by a process called cleavage.
• The cells formed after mitotic divisions are known as blastomeres.
• The dividing zygote gradually forms 2, 4, 8 and 16 celled stages.
• The 8-16 celled embryo is called morula, which continues to divide to form the blastocyst.
• The developing embryo, in the meanwhile, keeps moving through the fallopian tube towards the uterine cavity.
• The blastomeres of the blastocyst are arranged into the outer layer of trophoblast and an inner cell mass.
• The inner cell mass later differentiates to form the embryo.
• The trophoblast gets attached to the endometrium as the uterine cells divide rapidly to cover it.
• This process is known as implantation, where the blastocyst gets embedded in the endometrium.
• After implantation, the inner cell mass or the embryo differentiates into 3 germinal layers (as humans are triploblastic animals):
  • Ectoderm - outer layer.
  • Mesoderm - middle layer.
  • Endoderm - inner layer.
• All the tissues and organs present in an adult body are formed from these 3 germinal layers.
• Therefore, morula is an embryonic developmental stage that is formed between zygote and blastocyst.​​​

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Additional Information

• Human pregnancy lasts for about 9 months, which is known as the gestational period.
• It is usually divided into 3 trimesters, each of which shows some characteristic embryonic development.
• The process by which childbirth or delivery of fetus takes place is known as parturition.

Concept:

• Angiosperms or flowering plants are of two types based on the number of cotyledons found in them.
• Monocots such as grasses have one cotyledon in them whereas dicots have two cotyledons in them.

Explanation:

• The endosperm is a nutritive tissue that develops in flowering plants during double fertilization.
• It is formed by the fusion of one of the male gametes with the polar nuclei present in the center of the female gametophyte.
• It provides nourishment to the growing seed.
• Albuminous Seed - 
  • Seeds that contain endosperm at maturity are known as endospermic or albuminous seeds.
  • Food is stored in endosperm in albuminous seeds.
  • For example, castor, wheat, maize, etc.
• Ex-albuminous Seed - 
  • Seeds that do not contain endosperm at maturity are known as non-endospermic or exalbuminous seeds.
  • In these types of seeds, food is stored in cotyledons as endosperm is completely consumed during the seed development.
  • For example, peas, and groundnut.

So, the correct answer is option 3. 

Key Points

• There are three main modes of reproduction observed in animals:

1. Viviparity - 
   • It involves giving birth to young ones directly.
   • Fertilization in viviparous animals takes place internally.
   • Embryonic development takes place inside the mother's body.
   • The embryo is connected to the mother by the placenta.
   • E.g.: Mammals like a horse. Fishes like shark (some species) are viviparous as well.
2. Oviparity - 
   • It involves the laying of eggs by the animal.
   • Embryonic development takes place within the egg.
   • Fertilization can take place internally or externally.
   • E.g.: Birds, some fish, amphibians, etc.
3. Ovoviviparity - 
   • This method involves laying of eggs and then keeping them inside the mother's body till the young are nearly ready to hatch.
   • Fertilization takes place internally.
   • The embryonic development takes place within a thin membranous eggshell in the oviduct.
   • E.g.: Some lizards and snakes.

Explanation:

• House lizard - 
  • ​House lizard belongs to Class Reptilia.
  • House lizards are oviparous.
  • They lay eggs and the development of the young takes place inside the egg.
• Ostrich - 
  • Ostrich belongs to Class Aves.
  • On fertilization, the ostrich lays a fertilized egg within which the young one develops.
  • Ostrich eggs are considered to be the largest egg of all.
  • Thus ostrich is an oviparous.
• Pigeon - 
  • Pigeon belongs to Class Aves.
  • Pigeon is an oviparous.
  • The development of a young one takes place inside the egg.
  • Once the development of the young one is complete at the end of 18 days, eggs are hatched.
• Kangaroo - 
  • ​Kangaroo belongs to Class Mammalia.
  • Kangaroo is a viviparous animal.
  • It gives birth to the immature young one.
  • The young one (joey) born is immature, naked and one inch long.
  • Immediately after birth, it is transferred into the large marsupium (pouch) of the mother.
  • It comes out when it turns four months old.

Hence, the correct answer is option 4.

Key Points

• Outbreeding devices refer to the adaptive methods of plants that prevent self-pollination and encourage cross-pollination.
• This is to prevent continued self-pollination, which may result in inbreeding depression.
• Some of the outbreeding devices are:
  • Self-incompatibility - Pollen germination and pollen tube growth is inhibited on the same plant.
  • Dicliny - It is the production of dioecious or unisexual flowers, where male and female flowers are produced on different plants. It prevents both autogamy and geitonogamy.
  • Protogyny & Protandry - These are processes where pollen and stigma maturity are not synchronized. Pistil develops before anther in protogyny and vice versa in protandry.
  • Heterostyly - Stigma is placed at a higher position than the anthers, so that pollens do not fall on them.
• Production of monoecious flowers means both male and female flowers are borne on the same plant.
• This may prevent autogamy but not geitonogamy, which is also self-pollination.
• Therefore, production of monoecious flowers is not an effective outbreeding device for plants.

Additional Information

Pollination can be divided into 3 types:

• Autogamy -
  • It is the transfer of pollen grains from the anther to the stigma of the same flower.
  • It requires the pollen release and stigma receptivity to be synchronous, to prevent cross-pollination.
  • The anthers and stigma lie close to each other to assure self-pollination.
  • The autogamous flowers can be of 2 types - chasmogamous and cleistogamous.
  • Chasmogamous flowers have normal flowers with exposed anther and stigma.
  • Cleistogamous flowers do not open at all, thus assuring self-pollination and seed set.
• Geitonogamy -
  • It is the transfer of pollen grains from the anther to the stigma of a different flower of the same plant.
  • It is functionally cross-pollination as pollinating agents are involved.
  • It is genetically self-pollination as both male and female gametes come from the same plant.
  • Example - Maize, Castor.
• Xenogamy -
  • It is the transfer of pollen grains to the stigma of different plant.
  • It causes genetic variation and is a type of cross-pollination.
  • It is always found in unisexual plants where male and female flowers are borne on different plants.
  • Example - Papaya.

The correct answer is 24 and 36

Explanation:

Pollen Mother Cells and Chromosome Number:

• Pollen mother cells undergo meiosis to produce haploid pollen grains (gametophytes).
• Given that the pollen mother cell has 24 chromosomes, the resulting pollen grains will have half this number, i.e., 12 chromosomes.

Root Cells and Chromosome Number:

• The root cells of the female plant are somatic cells and are diploid.
• Therefore, the female gametes (egg cells) produced will also be haploid with 12 chromosomes, because they come from a diploid cell with 24 chromosomes undergoing meiosis.

Embryo Formation:

• The sperm cell from the pollen grain (12 chromosomes) fuses with the egg cell (12 chromosomes).
• The resulting zygote (embryo) will hence have 12 + 12 = 24 chromosomes (diploid).

Endosperm Formation:

• The other sperm cell fuses with the two polar nuclei in the central cell of the ovule.
• Each polar nucleus is haploid with 12 chromosomes, so two polar nuclei together have 12 + 12 = 24 chromosomes.
• The fusion will result in a triploid endosperm with 12 (sperm cell) + 24 (two polar nuclei) = 36 chromosomes.
• The process is called triple fusion as three haploid nuclei are involved in the fusion.

As two fusions, i.e. syngamy and triple fusion occur in an embryo sac. This phenomenon is known as double fertilisation. 

The correct answer is Ampulla

Explanation:-

• Fertilization of the human egg most often takes place in the fallopian tube, specifically in the ampulla region of the fallopian tube.
• After ovulation, the egg is released from the ovary into the fallopian tube. Sperm cells travel through the female reproductive tract and meet the egg in the fallopian tube. The ampulla, which is the widest part of the fallopian tube, provides an ideal environment for fertilization to occur.
• Once fertilization occurs in the ampulla, the resulting zygote begins to divide and develop as it moves down the fallopian tube towards the uterus, where it eventually implants into the uterine lining for further development during pregnancy.

Conclusion:-Fertilization of human egg most often takes place in the ampulla.