Question

Photosynthesis begins in a germinating dicot plant due to
(a) Cotyledon
(b) Endosperm
(c) Embryonic root
(d) Apical meristem
(e) Lateral meristem

Answer 1

Hint: They refer to the important part of the embryo present inside the seed. They are the first and the tender leaf emerges when the seed germinates. It is also called the storage unit of a seed, as it provides nutrients to the various parts of an embryo.

Complete answer:
Cotyledon is the primary leave in germinating dicot plants and starts the method of photosynthesis. In the instance of dicot seedlings whose cotyledons are photosynthetic, the cotyledons are working almost like leaves. However, true leaves and cotyledons are developmentally distinct. Cotyledons are formed during embryogenesis, alongside the basis and shoot meristems, and are therefore present within the seed before germination. True leaves, however, are formed post-embryonically (i.e. after germination) from the shoot apical meristem, which is liable for generating subsequent aerial portions of the plant.

Additional information: The reserve food in cotyledons is utilized to nurture the growing seedling. The embryo axis has two ends, which are the plumule and radicle. They are further enclosed within a protective cover called the seed coat. Cotyledons of the standard dicot embryo are simple structures basically thick and swollen because of storage of food reserves, as they provide nutrients to the different parts of an embryo. Cotyledons are formed in the course of embryogenesis, together with the root and shoot meristems, and are thus found in the seed prior to germination. Cotyledons reserve food in the form of starch and protein. The endosperm is a nutritive tissue of seed and is fed by maturing embryos before seed germination. Embryonic roots are non photosynthetic. Apical and lateral meristems are responsible for primary and secondary growth.
So, the correct answer is ‘(a) Cotyledon’.

Note: The term cotyledon was coined by Marcello Malpighi (1628–1694) Cotyledons are rich in proteins, starch, and fats. The cotyledon of grasses and several other monocotyledons is a largely modified leaf made up of scutellum and a coleoptile. The cotyledons could also be ephemeral, ending only days after origin, or persistent, undergoing a minimum of a year on the plant.