Question
In some plants thalamus contributes to fruit formation. Such fruits are termed as [NEET (Oct.) 2020]
(a) false fruits
(b) aggregate fruits
(c) true fruits
(d) parthenocarpic fruit
Answer/Explanation
Ans. (a)
A fruit in which floral parts other than ovary, like thalamus, base of sepals, petals, etc., fuse with pericarp and contribute in fruit formation is called false fruit or pseudocarp. Apple, mulberry and strawberry are false fruits.
Question
Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? [NEET (National) 2019]
(a) Zygote develops into embryo
(b) Central cell develops into endosperm
(c) Ovules develop into embryo sac
(d) Ovary develops into fruit
Answer/Explanation
Ans. (c)
The statement that “ovules develop into embryo sac is incorrect. Correct information about the statement is as follows. During post-fertilisation event, ovule develops into seed. On the other hand, embryo sac is a multicellular structure which is derived from the megaspore. Rest statements regarding post-fertilisation development in flowering plants are correct.
Question
Seed formation without fertilisation in flowering plants involves the process of [NEET 2016, Phase I]
(a) budding
(b) somatic hybridisation
(c)apomixis
(d) sporulation
Answer/Explanation
Ans. (c)
Apomixis is a special mechanism found in flowering plants to produce seeds without fertilisation. It is a type of asexual reproduction which mimics the sexual reproduction and is commonly found in Citrus varieties.
Question
The coconut water from tender coconut represents [NEET 2016, Phase I]
(a) fleshy mesocarp
(b) free-nuclear proembryo
(c) free-nuclear endosperm
(d) endocarp
Answer/Explanation
Ans. (c)
Coconut milk represents free-nuclear endosperm where the division of primary endosperm nucleus is not followed by formation of cell walls (cytokinesis) thus all nucleus remain free in liquid form. It is rich in plant hormone cytokinin.
Question
Cotyledon of maize grain is called [NEET 2016, Phase I]
(a) coleorhiza
(b) coleoptile
(c) scutellum
(d) plumule
Answer/Explanation
Ans. (c)
Large, shield shaped cotyledon of grass family is called scutellum. Coleorhiza is a sheath protecting the root of germinating grass. Coleoptile is a sheath covering emerging shoot. Plumule is rudimentary shoot of an embryo plant.
Question
The wheat grain has an embryo with one large, shield-shaped cotyledon known as [CBSE AIPMT 2015]
(a) epiblast
(b) coleorrhiza
(c) scutellum
(d) coleoptile
Answer/Explanation
Ans. (b)
The grain of wheat, maize or rice is a caryopsis. The embryo in such grains lies laterally near the base of the grain. The embryo consists of an upper large, shield shaped cotyledon known as scutellum.
The scutellum is closely pressed against the endosperm and helps in the translocation of nutrients from endosperm to the growing embryo at the time of germination and seedling growth.
Question
Coconut water from a tender coconut is [CBSE AIPMT 2015]
(a) immature embryo
(b) free nuclear endosperm
(c) innermost layers of the seed coat
(d) degenerated nucellus
Answer/Explanation
Ans. (b)
The coconut water from tender coconut that we are familiar with, is nothing but free nuclear endosperm (made up of thousands of nuclei) and the surrounding white kernel is the cellular endosperm. In the most common type of endosperm development, the Primary Endosperm Nucleus (PEN) undergoes successive nuclear divisions to give rise to free nuclei. This stage of endosperm development is called free-nuclear endosperm.
Question
Non-albuminous seed is produced in [CBSE AIPMT 2014]
(a) maize
(b) castor
(c) wheat
(d) pea
Answer/Explanation
Ans. (d)
Non-albuminous or non-endospermic seeds are those in which cotyledons are usually smaller and less developed like in pea. Such seeds are seen when most or all of the endosperm is used up much before germination.
Question
Nucellar polyembryony is reported in species of [CBSE AIPMT 2011]
(a) Gossypium
(b) Triticum
(c) Brassica
(d) Citrus
Answer/Explanation
Ans. (d)
Nucellar polyembryony is reported in species of Citrus. Occurrence of more than one embryo in a seed is referred to as polyembryony. In many Citrus and mango varieties, some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into the embryos.
Question
Apomictic embryos in Citrus arise from [CBSE AIPMT 2010]
(a) synergids
(b) maternal sporophytic tissue in ovule
(c)antipodal cells
(d) diploid egg
Answer/Explanation
Ans. (b)
Apomictic embryos in Citrus arise from maternal sporophytic tissue (e.g. nucellus or integuments) in ovule. Apomixis is the formation of new individuals directly through asexual reproduction without involving the formation and fusion of gametes.
Question
Endosperm is consumed by developing embryo in the seed of [CBSE AIPMT 2008]
(a) coconut
(b) castor
(c)pea
(d) maize
Answer/Explanation
Ans. (c)
Endosperm is consumed by developing embryo is the seeds of pealPisum sativum). These seed are called non-endospermic seeds. Other examples are gram, beans, orchids, etc.
Question
The scutellum observed in a grain of wheat or maize is comparable to which part of the seed in other monocotyledons? [CBSE AIPMT 2010, 06]
(a) Cotyledon
(b) Endosperm
(c) Aleurone layer
(d) Plumule
Answer/Explanation
Ans. (a)
In wheat or maize (family-Poaceae), the scutellum is thought to be a modified cotyledon or seed leaf.
Question
In angiosperms, triple fusion is required for the formation of [CBSE AIPMT 1996]
(a) embryo
(b) endosperm
(c) seed coat
(d) fruit wall
Answer/Explanation
Ans. (b)
In angiosperms, triple fusion is required for the formation of endosperm. Triple fusion refers to the vegetative fertilisation, i.e. the fusion of nucleus of a male gamete with the two polar nuclei or the diploid secondary (fusion) nucleus. Triple fusion converts central cell into triploid primary endosperm cell which forms the endosperm, a nutritive tissue.
Question
Study of formation, growth and development of new individual from an egg is [CBSE AIPMT 1993]
(a) apomixis
(b) embryology
(c)embryogeny
(d) cytology
Answer/Explanation
Ans. (b)
Embryology (Gr. en – in; bryo – swell; logos – study) is the study of formation growth and development of embryo. It includes sporogenesis, fertilisation and embryogeny, i.e. the overall process starting from formation of gametes, fertilisation, zygote and embryo formation and development of new individual.
Question
Nucellus embryo is [CBSE AIPMT 1989]
(a) amphimictic haploid
(b) amphimictic diploid
(c) apomictic haploid
(d) apomictic diploid
Answer/Explanation
Ans. (c)
Nucellus embryo is apomictic haploid. Nucellus is a parenchymatous, haploid nutritive tissue of the ovule of phanerogams. The phenomenon of formation of embryo or new individual directly through asexual reproduction or adventitiously from a cell other than egg, i.e. nucellus, integuments, etc., is known as apomixis. Nucellus embryo is thus, known as apomictic embryo.