BIOLOGY ASSESSMENT CLASS IX Chap – 5 Part III ( Seed dormancy and Germination ) GERMINATION Once the seed is ready , it waits for the favourable condition for germination .It can be defined as the The sum total of all the processes by which the dormant embryo of the seed grows out of the seed coats and establishes itself as the independent seedlings is called as Germination. The processof germination is irreversible. Q1.What are the conditions required for germination ? Ans . The following favourable conditions are required for germination are – i. WATER : Germination of seed only starts with intake of water through micropyle. Water intake helps the seed in the following ways- a. It softens the seed coat and causes its rupture letting way to develop plumule and radical. b. It activates protoplasm and increase metabolic activity. c. It help in transporting of soluble food from storage tissue to thedeveloping embryo. ii. OXYGEN : During germination lot amount of energy is required . The oxygen is utilized for oxidation of stored food to produce enough amount of energy for development. The exchange of O2 and CO2 takes place through micropyle. iii.TEMPERATURE : Temperature play a very important role in germination . Seeds of different pant germinate at different optimum temperature. Q2. Into how many categories germination is divided ? Ans. Depending upon the behavior of cotyledons ,the process of germination is divided into two types – i. Epigeal Germination ii. Hypogeal Germination i. EPIGEAL GERMINATION : In this type of germination ,the hypocotyls elongates rapidly and arches upward pulling the cotyledons which move above the soil. Bean , Cotton , Papaya , Gourd , Castor and onions have this trype of germination. ii. HYPOGEAL GERMINATION : When the cotyledons remain under the soil or just on the groung during germination of seed is called Hypogeal germination. It is found in the seed of gram , pea , maize , mango , groundnut etc. Q3. What is Vivipary ? Give three examples Ans. Vivipary is a special type of germination it occurs when seeds or embryos begin to develop before they detach from the parent . This type of germination could be seen in plant growing near the sea shore or in saline marshes. It is found in Rhizopora , Ceriops , Avicennia , Heritiera , Sonneratia etc. Q4. What functions the following parts of the seed plays – Ans . i. Seed coat : It is the outer coat of the seed that protects the embryonic plant. ii. Hilum :It is a scar left by the stalk which attached the ovule to the ovary wall before it become a seed . iii. Micropyle : It is a tiny pore in the testa that lies on the opposite tip of radical . It permit water to enter the embryo before active germination . iv.Cotyledons in pea : In some plants ,this contain high quantities of a starch and provide the source of food to the developing embryo prior to germination v. Cleoptile : The cleoptile is the protective sheath found in the monocot seed of plant . It generally protects the Shoot tips. vi. Coleorhiza : The coleorhiza is the sterile protective sheath found in monocot seed of plant . It generally protects the root tips of plant. vii. Endosperm : In many plants other than cotyledons ,a separate part for storage of starch develops and this is called the endosperm . It is seen in maize and wheat. viii. Plumule : it forms the future shoot . ix. Radicle : It forms the future root. .