Reproduction (Plants) – Special modes- apomixis: NEET MCQs with Answers

15 free questions on Reproduction (Plants) – Special modes- apomixis for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Special modes- apomixis, parthenocarpy, polyembryony

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Question 1

Previous-year question
Which one of the following fruits is parthenocarpic? [AIPMT 2015]
  1. Jackfruit
  2. Banana
  3. Brinjal
  4. Apple
Show answer
Answer: (B) Banana
Explanation: Parthenocarpic fruits develop from the ovary without fertilisation and are therefore naturally seedless. Banana is the classic example of a natural parthenocarpic fruit.

Question 2

Previous-year question
Apomictic embryos in Citrus arise from [AIPMT 2009, 2010]
  1. synergids
  2. maternal sporophytic tissue in ovule
  3. antipodal cells
  4. diploid egg
Show answer
Answer: (B) maternal sporophytic tissue in ovule
Explanation: In Citrus the apomictic embryos develop from maternal sporophytic tissue of the ovule, i.e. from the nucellus or the integuments. Since no gamete fusion is involved, these embryos are genetically identical to the mother plant.

Question 3

Previous-year question
Nucellar polyembryony is reported in species of [AIPMT 2011]
  1. Gossypium
  2. Triticum
  3. Brassica
  4. Citrus
Show answer
Answer: (D) Citrus
Explanation: Polyembryony is the occurrence of more than one embryo in a seed. In many varieties of Citrus and mango some nucellar cells surrounding the embryo sac divide, protrude into it and develop into additional embryos — this is nucellar polyembryony.

Question 4

Previous-year question
What is common between vegetative reproduction and apomixis? [AIPMT 2011]
  1. Both are applicable to only dicot plants
  2. Both bypass the flowering phase
  3. Both occur round the year
  4. Both produce progeny identical to the parent
Show answer
Answer: (D) Both produce progeny identical to the parent
Explanation: In apomixis the embryo develops from a diploid cell of the ovule without gamete fusion, and in vegetative reproduction the new plant arises from a somatic part of the parent. In both cases meiosis and fertilisation are absent, so the progeny are genetically identical to the parent.

Question 5

Previous-year question
Which of the following statements is not true about somatic embryogenesis? [NEET 2013]
  1. A somatic embryo develops from a somatic cell
  2. The pattern of development of a somatic embryo is comparable to that of a zygotic embryo
  3. Somatic embryos can develop from microspores
  4. Somatic embryo is induced usually by an auxin such as 2, 4-D
Show answer
Answer: (C) Somatic embryos can develop from microspores
Explanation: The statement about microspores is not true for somatic embryogenesis. Somatic embryos, by definition, arise from somatic (vegetative) cells or groups of cells not normally involved in embryo formation; embryos formed from microspores are androgenic (haploid) embryos, not somatic embryos.

Question 6

Previous-year question
Seed formation without fertilisation in flowering plants involves the process of [NEET 2016, Phase II]
  1. budding
  2. somatic hybridisation
  3. apomixis
  4. sporulation
Show answer
Answer: (C) apomixis
Explanation: Apomixis is a special mechanism by which some flowering plants produce seeds without fertilisation; it is a form of asexual reproduction that mimics sexual reproduction. NCERT cites some species of Asteraceae and grasses, and nucellar embryos of Citrus and mango as examples.

Question 7

Previous-year question
Nucellar polyembryony is reported in species of [2010]
  1. Triticum
  2. Citrus
  3. Brassica
  4. Gossypium
Show answer
Answer: (B) Citrus
Explanation: Citrus and mango are the classical examples of nucellar polyembryony, in which several embryos of nucellar origin accompany the zygotic embryo within one seed. Horticulturists value it because the nucellar seedlings are true to type and free of virus.
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Question 8

Previous-year question
Apomictic embryos in citrus arise from [2008]
  1. antipodal cells
  2. synergids
  3. a diploid egg
  4. maternal sporophytic tissue in the ovule
Show answer
Answer: (D) maternal sporophytic tissue in the ovule
Explanation: The apomictic embryos of citrus develop from nucellar cells, which are diploid sporophytic tissue of the mother plant. This is the basis of the uniformity of citrus rootstocks raised from seed, since such seedlings are genetically identical to the parent tree.

Question 9

Previous-year question
The formation of a gametophyte directly from the sporophyte without meiosis is [1988]
  1. parthenogenesis
  2. apospory
  3. amphimixis
  4. apogamy
Show answer
Answer: (B) apospory
Explanation: In apospory a gametophyte arises from a vegetative cell of the sporophyte without spore formation, so it is diploid rather than haploid. Apogamy is the reverse, a sporophyte developing from the gametophyte without gametic fusion, and amphimixis is normal sexual reproduction.

Question 10

Previous-year question
The development of an organism from the female gamete or egg without fertilisation is [1989]
  1. parthenocarpy
  2. adventive embryony
  3. parthenogenesis
  4. polyembryony
Show answer
Answer: (C) parthenogenesis
Explanation: Parthenogenesis is the development of an unfertilised egg into a new individual, as in the drones of the honey bee. Parthenocarpy is the formation of fruit without fertilisation and yields seedless fruit, and adventive embryony is the development of an embryo from sporophytic tissue of the ovule.

Question 11

Why would it benefit farmers if high-yielding hybrid varieties could be made apomictic?
  1. Apomixis would add new useful genes to the hybrid in each generation
  2. Apomictic seeds would form without any embryo, so storage would be easier
  3. Hybrid characters would not segregate in the progeny, so seed could be saved and resown
  4. Apomictic seeds would need no water for germination
Show answer
Answer: (C) Hybrid characters would not segregate in the progeny, so seed could be saved and resown
Explanation: Seed collected from ordinary hybrids gives progeny in which the hybrid characters segregate, so fresh and costly hybrid seed must be bought every year. Apomictic seed forms without meiosis and gametic fusion, so the embryo is genetically like the parent. The hybrid traits would therefore be retained generation after generation.

Question 12

A hybrid plant is heterozygous at two unlinked genes (AaBb). If it is selfed, what fraction of the progeny will be AaBb? If instead all its seeds carried apomictic embryos arising from nucellar cells, what fraction would be AaBb?
  1. 1/4 and 1/2
  2. 1/16 and 1/4
  3. 1/4 and all of them
  4. 1/2 and 1/2
Show answer
Answer: (C) 1/4 and all of them
Explanation: On selfing, each gene segregates independently and gives one-half heterozygotes, so AaBb progeny form 1/2 x 1/2 = 1/4 of the total. Nucellar cells are diploid maternal cells, and embryos arising from them involve no meiosis or gamete fusion, so every embryo is AaBb. This is why making hybrids apomictic would let farmers reuse hybrid seed without segregation of characters.

Question 13

In a diploid plant, embryo P develops from an egg formed after normal meiosis, and embryo Q develops from an egg formed without reduction division. Neither egg is fertilised. What are the ploidy levels of P and Q?
  1. Both are diploid
  2. Both are haploid
  3. P is haploid and Q is diploid
  4. P is diploid and Q is haploid
Show answer
Answer: (C) P is haploid and Q is diploid
Explanation: Normal meiosis gives a haploid egg, so development without fertilisation produces a haploid embryo. If the reduction division is skipped, the egg stays diploid and forms a diploid embryo. Only this diploid route preserves the full genotype of the mother plant.

Question 14

A Citrus seed contains five embryos. One arose from the fertilised egg, and the other four arose from nucellar cells. What can be expected of the seedlings grown from these embryos?
  1. Four are genetically like the seed parent, and one carries genes of both parents
  2. All five are genetically identical to the seed parent
  3. One is identical to the seed parent, and four carry genes of both parents
  4. Four are haploid, and one is diploid
Show answer
Answer: (A) Four are genetically like the seed parent, and one carries genes of both parents
Explanation: Nucellar cells are diploid sporophytic cells of the mother plant, and they form embryos by mitosis without fertilisation. The four nucellar embryos are therefore genetic copies of the seed parent. Only the zygotic embryo combines maternal and paternal genes.

Question 15

Both apomixis and parthenocarpy occur without fertilisation. What is the key difference between them?
  1. Apomixis forms a seedless fruit, while parthenocarpy forms a seed with a viable embryo
  2. Apomixis needs a pollen tube, while parthenocarpy needs two male gametes
  3. Apomixis occurs only in dicots, while parthenocarpy occurs only in grasses
  4. Apomixis forms a seed with a viable embryo, while parthenocarpy forms a fruit that is usually seedless
Show answer
Answer: (D) Apomixis forms a seed with a viable embryo, while parthenocarpy forms a fruit that is usually seedless
Explanation: Apomixis is a form of asexual reproduction that mimics sexual reproduction, so its product is a seed holding a viable embryo. Parthenocarpy concerns the fruit: the ovary enlarges without fertilisation, giving seedless fruit as in banana.

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