Reproduction MCQ Quiz - Objective Question with Answer for Reproduction - Download Free PDF

Key Points

• Polyembryony refers to the occurrence of more than one embryo in a single seed.
• It is commonly observed in Citrus fruits, such as oranges and lemons.
• In Citrus, polyembryony often occurs due to the development of nucellar embryos along with the zygotic embryo.
• Polyembryony ensures the production of genetically uniform plants, which is beneficial for agriculture.

Important Points

• In plants exhibiting polyembryony, multiple embryos can develop from the same ovule, resulting in more plants from a single seed.
• Polyembryony can be classified into three types:
  • Simple polyembryony: Development of multiple embryos from a single zygote.
  • Adventive polyembryony: Development of embryos from somatic cells of the ovule (e.g., nucellar tissue).
  • Mixed polyembryony: Involves both zygotic and adventive embryos.

Additional Information

• Banana: Bananas are parthenocarpic fruits, meaning they develop without fertilization. They do not exhibit polyembryony.
• Tomato: Tomato plants reproduce sexually, and their seeds usually develop a single embryo. Polyembryony is not observed in tomatoes.
• Potato: Potatoes are propagated vegetatively through tubers. They do not involve seeds and hence do not exhibit polyembryony.

Key Points

• Synergids are two specialized cells located in the embryo sac of a flowering plant.
• They play a crucial role in guiding the pollen tube to the egg cell for fertilization.
• They release chemical signals to attract the pollen tube, ensuring successful fertilization.
• Once the pollen tube reaches the synergids, one synergid degenerates to facilitate the release of sperm cells for fertilization.

Important Points

• The synergids are part of the egg apparatus in the ovule and are located near the micropyle.
• They assist in breaking down barriers so the sperm cells can reach the egg cell and central cell.
• They are necessary for the precise delivery of male gametes to the female gametophyte.
• Synergids also help sustain the pollen tube during its growth process.
• Micropyle: The micropyle is the opening in the ovule through which the pollen tube enters to deliver sperm cells to the egg apparatus.

• Embryo sac: The embryo sac is the female gametophyte in angiosperms, containing the egg cell, synergids, central cell, and antipodal cells.

Key Points

• Appearance of hair on the head of a human embryo typically occurs during the 5th month of pregnancy.
• By the 5th month, the embryo develops lanugo, which is fine, soft hair that covers the body, including the head.
• Lanugo plays a crucial role in helping to regulate the fetus’s body temperature within the womb.
• This hair gradually disappears before birth or shortly after birth, as it is replaced by vellus or terminal hair.

Important Points

• The development of hair follicles begins early in the embryonic stage, but visible hair growth on the head starts during the 5th month.
• The growth of hair is part of the overall development of the fetus, including skin and appendages.
• Lanugo is a temporary protective mechanism for the fetus and is not permanent.
• Proper fetal development during this phase is crucial and can be influenced by maternal nutrition, health, and genetics.

The correct answer is They are fraternal twins.

Concept:

• Twins are classified into two main types: monozygotic (identical) and dizygotic (fraternal).
• Monozygotic twins develop from a single fertilized egg that splits into two embryos, leading to identical genetic material. These twins are always of the same sex.
• Dizygotic or fraternal twins occur when two separate eggs are fertilized by two different sperm cells. As a result, they share approximately 50% of their genetic material, similar to regular siblings, and can be of the same or different sexes.

Explanation:

• They are monozygotic twins: This is incorrect because monozygotic twins are genetically identical and always of the same sex. 
• They are fraternal twins: This is correct. Fraternal twins are the result of two separate eggs being fertilized by two different sperm cells. They can be of different sexes, as in this case, where the twins are a boy and a girl.
• They were conceived through in vitro fertilization: This is incorrect. While in vitro fertilization (IVF) can increase the likelihood of twins, there is no indication in the question that IVF was involved. Twins can occur naturally as well.
• They have 75% identical genetic content: This is incorrect. Fraternal twins share 50% of their genetic material, the same as any other siblings. 

The correct answer is 1 Meiosis and 3 Mitosis

Concept:

• In angiosperms, female gametophyte development begins with the differentiation of the megaspore mother cell (MMC) within the ovule. The MMC undergoes meiosis to produce a linear tetrad of haploid megaspores.
• Out of the four megaspores formed, typically only one survives, while the other three degenerate. This surviving megaspore develops into the mature female gametophyte (embryo sac) through a series of mitotic divisions.
• The mature female gametophyte (embryo sac) contains seven cells arranged in three groups: one egg cell, two synergids, three antipodal cells, and a central cell with two polar nuclei.

Explanation:

• Step 1: Meiosis - The megaspore mother cell undergoes a single meiotic division to produce four haploid megaspores. Out of these, only one remains functional, and the other three degenerate.
• Step 2: Mitosis - The functional megaspore undergoes three rounds of mitotic divisions, resulting in eight nuclei within a single cell. These nuclei are then arranged into seven cells, forming the mature female gametophyte (embryo sac).

Thus, the process involves one meiosis followed by three mitotic divisions.

The correct answer is Male gamete.

Key Points

• Sperm or spermatozoa is a gamete (sex cell) produced in the male reproductive system.
• It is a mobile cell with one goal - to fertilize a female egg.
• Each sperm contains the entire genome of the male that produced it.
• Combined with the female genome contained in the egg, a zygote is formed - a single pluripotent stem cell containing the fused male and female genomes.
• Sperm cells were first described in the late 17th century by Antonie van Leeuwenhoek.

Additional Information

• Isogamete:
  • Isogamete is a gamete that is similar in shape, size, and behavior to another gamete with which it can produce a zygote.
  • They are also known as homogametes.
• Female gamete:
  • Female gametes are produced in the ovary. It is called an egg or egg.
  • Each month, the female produces one egg during her menstrual cycle.
• Gamete:
  • A gamete is a haploid cell that fuses with another haploid cell during fertilization in sexually reproducing organisms.
  • Gametes are reproductive cells of an organism, also known as sex cells.

The correct answer is Vascular plants.Key Points

• The sporophyte stage is the dominant phase in vascular plants, which includes all plants except bryophytes (mosses, liverworts, and hornworts).
• In bryophytes, the gametophyte stage is the dominant phase, while the sporophyte is dependent on the gametophyte for survival. 
• Algae do not have a well-defined alternation of generations, and their life cycles can vary greatly depending on the type of algae.
• Pteridophytes, which include ferns and horsetails, have a dominant sporophyte stage that is independent of the gametophyte.
• The dominance of the sporophyte stage is characterized by the fact that it is the stage that produces the spores, which give rise to the next generation of plants.

Additional Information

• Bryophytes are small, non-vascular plants that grow in damp habitats.
  • They do not have true roots, stems, or leaves and rely on diffusion to transport water and nutrients.
• Algae are a diverse group of aquatic organisms that can range from single-celled organisms to large seaweeds.
  • They are not considered to be true plants because they lack specialized tissues and organs.
• Pteridophytes are vascular plants that reproduce by spores instead of seeds.
  • They have true roots, stems, and leaves, and can range from small herbaceous plants to large tree ferns.
• The alternation of generations is a life cycle that includes both a haploid (n) gametophyte and a diploid (2n) sporophyte stage.
  • In plants, the gametophyte produces gametes (eggs and sperm), which fuse to form a diploid zygote that develops into the sporophyte.
  • The sporophyte produces spores, which give rise to the next generation of gametophytes.

The correct answer is Testes.

Key Points

• Testosterone is the only male sex hormone present in the human body, which causes physical changes in puberty, increases bone density and muscle mass, growth of facial, pubic, and body hair, deepening of the voice, and also responsible for sexual and reproductive development.
• Testosterone is the main sex hormone in men, which is naturally produced in the testes and in small amounts by the adrenal glands.
• Testosterone belongs to a class of male hormones called androgens, which are also known as steroids.
• The production of male sex hormones is mainly controlled by the hypothalamus and pituitary gland.
• The testosterone levels gradually decrease with age, which results in impotence, shrinking of testes, low sperm count, depression, mood swings, irritability, etc.

Additional Information

• The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing.
  • It is referred to as the body's 'master gland' because it controls the activity of most other hormone-secreting glands. 
  • The pituitary gland is a small gland that sits in the sella turcica, a bony hollow in the base of the skull, underneath the brain and behind the bridge of the nose.
• Adrenal glands, also known as suprarenal glands, are small, triangular-shaped glands located on top of both kidneys.
  • Adrenal glands produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress and other essential functions.
• The ovary is an organ found in the female reproductive system that produces an ovum.
  • When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm.
  • There is an ovary found on each side of the body.

The correct answer is Option 4, i.e Carpel.

• Carpel is NOT a part of an anther.
• Pollen grains, Anther lobs, and Filament are the parts of the anther.
• Anther is the part of a stamen that contains the pollen.
• The stamen is the male reproductive organ of a flower.
• The stamen has two parts: Anther and stalk (filament).
• Collectively the stamens form the androecium.
• Carpel is the female reproductive organs in a flower, composed of an ovary, a style, and a stigma.

Key Points

• The placenta is an organ that develops in the uterus during pregnancy.
• It facilitates the supply of oxygen and nutrients to the embryo.
• It removes carbon dioxide and excretory/waste materials produced by the embryo.
• Placenta acts as an endocrine tissue and produces hormones:
  • Human chorionic gonadotropin (hCG)
  • Human placental lactogen (hPL)
  • Estrogens
  • Progestogens
• These hormones work together to control the growth and development of the placenta and the fetus.
• They act on the mother to support the pregnancy and prepare for childbirth.
• Placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.

Explanation:

• Androgen is the male sex hormone that is secreted by the Leydig cells of the testis in males.
• It plays an important role in spermatogenesis process.
• It also helps in developing male secondary sexual characters.

Hence, the correct answer is option 3.

Key Points

• The occurrence of more than one embryo in a seed is referred to as polyembryony.
• It is commonly found in citrus fruits like lemon and orange.
• Ways of forming polyembryonic seeds:
  • Developing of cells like synergids, cells of the nucellus, cells of integument into the embryo.
  • Formation of more than one embryo sac in an ovule.
  • Formation of more than one egg in an embryo sac.

Additional Information

According to Webber, polyembryony is classified into three different types :

1. Cleavage Polyembryony: In the case of this type, a single fertilized egg gives rise to a number of embryos.
2. Simple polyembryony: In this type, a number of embryos develop as a result of the fertilization of several archegonia.
3. Rosette polyembryony: Additional embryos develop from the rosette cells in certain gymnosperms, this type of polyembryony is termed rosette polyembryony.

The correct answer is asexual reproduction.Key Points

• Asexual reproduction is a type of reproduction in which offspring are produced by a single parent without the involvement of gametes or fertilization.
• In asexual reproduction, the offspring are genetically identical to the parent, as there is no genetic recombination or mixing of genetic material from two parents.
• Examples of asexual reproduction include binary fission in bacteria, budding in yeast, and fragmentation in starfish.
• Asexual reproduction is advantageous in stable environments, as it allows for rapid reproduction and the ability to colonize new habitats quickly.

Additional Information

• In vitro fertilization (IVF) is a type of assisted reproductive technology that involves fertilizing an egg with sperm outside of the body and then transferring the resulting embryo into the uterus.
  • IVF is used in cases of infertility or genetic disorders. 
• External fertilization is a type of sexual reproduction that occurs outside of the body, such as in aquatic animals like fish and amphibians.
  • The eggs and sperm are released into the water, where fertilization occurs.
• Sexual reproduction involves the fusion of gametes from two parents to produce offspring with genetic diversity.
  • This type of reproduction is common in animals, plants, and some fungi.
  • It allows for genetic variation, which can be advantageous in changing environments.

Concept:

• Vigorous contraction of the uterus at the end of pregnancy causes expulsion/delivery of the foetus. This process of delivery of the foetus (childbirth) is called parturition.

Explanation:

• Foetal Ejection reflex - 
• The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex.
• This triggers the release of oxytocin from the maternal pituitary.
• Oxytocin then acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates the further secretion of oxytocin.
• The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions.
• This leads to the expulsion of the baby out of the uterus through the birth canal – parturition.

Additional Information

• Prolactin: It is also called lactotrophic hormone. It regulates the growth and milk formation of mammary glands.
• Estrogen, or oestrogen: It is a sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics.
• Relaxin as the name suggests is used to keep the smooth muscles of the uterus relaxed. It is secreted in large amounts during parturition.

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.

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.