Q15 of 43 Page 1

Draw L.S. of an embryo of grass and label its parts.

OR


Draw a diagrammatic sectional view of a seminiferous tubule (enlarged) in humans and label its parts.


• A grass embryo is an example of a typical dicotyledonous embryo.


• It consists of an embryonal axis and two cotyledons.


• The portion of embryonal axis above the level of cotyledons is the epicotyl, which terminates with the plumule or stem tip.


• The cylindrical portion below the level of cotyledons is hypocotyl that terminates at its lower end in the radical or root tip.


• The root tip is covered with a root cap.



OR


• The seminiferous tubule are the site within the male testes where the sperm germinates, matures and gets transported from.


• Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.



More from this chapter

All 43 →
13

When and where do tapetum and synergids develop in flowering plants? Mention their functions.

OR


Where are the following structures present in a male gametophyte of an angiosperm? Mention the function of each one of them.


(a) Germ pore


(b) Sporopollenin


(c) Generative cell


 14

Construct a flow chart exhibiting sequential events of oogenesis.

 16

(a) How does mutation occur?

(b) Differentiate between point mutation and frameshift mutation.


 17

‘‘Use of heavy isotope of nitrogen by Meselson and Stahl demonstrated semi-conservative mode of replication of a DNA molecule.’’ Explain how did they arrive at this conclusion.

OR


Explain the mechanism of translation that occurs in the ribosomes in a prokaryote.