Chapter 9 : Seeds: Structure and Germination - Frank Solutions for Class 9 Biology ICSE

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Chapter 9 - Seeds: Structure and Germination Exercise 78

Question 1
Define the following:
(a) Seed
(b) Germination
Solution 1
(a) Seed is defined as a fertilized mature ovule which possesses an inactive embryo and reserve food for its further development.
(b) The process by which the dormant embryo of the seed resumes active growth and forms a seedling is known as germination.
Question 2
Explain the following terms:
(a) Albuminous seed
(b) Dormancy
(c) Hypogeal germination
(d) Epigeal germination
Solution 2
(a) Albuminous seed - In some dicotyledons and monocotyledons, the
food is stored mainly in the endosperm. Such seeds are called albuminous seeds. Example - Seeds of castor, cereals and grasses.
(b) Dormancy - Seed dormancy is a condition of plant seeds that prevents germination under optimal environmental conditions. Here the seed is in a state of apparent inactivity and will not grow even if favorable conditions are provided, until a definite time has elapsed.
(c) Hypogeal germination - In this germination, the seed remains inside the soil since epicotyl elongates faster than hypocotyl. Hence the cotyledons remain inside the soil. Example - Wheat, rice, pea, mango.
(d) Epigeal germination - It is a type of germination in which cotyledons are pushed above the soil into the air and light. This occurs due to rapid growth and elongation of the hypocotyl.  Example - Bean, cotton, castor, papaya, onion, tamarind.
Question 3
A seed is provided with all the conditions necessary for germination. Yet it fails to germinate. Explain.
Solution 3
This is because the seed is in a state of dormancy. In this case, even if all the favorable conditions are provided, the seed remains in a state of apparent inactivity and only germinates after a definite time has elapsed.
Question 4
Give the functions of the following:
(a) Seed coat (b) Micropyle
(c) Endosperm (d) Cotyledons
Solution 4
(a) Seed coat is the outer covering of seed. It protects the inner contents of the seed.
(b) Micropyle allows entry of water into the embryo.
(c) Endosperm contains stored food mostly as starch.
(d) Cotyledons store food material for the embryo.
Question 5
Name the following:
(a) The part of the seed which gives out the shoot.
(b) The protective sheath covering the radical in the maize grain.
(c) The part of castor seed that stores food.
(d) The small opening through which water enters the seeds.
(e) What is formed from radical and plumule?
(f) In which part of the maize-seed food is stored?
(g) The type of germination in which the cotyledons come above ground.
(h) The type of germination in which the cotyledons stay below the ground.
(i) Lightest seed.
(j) Largest seed.
Solution 5
(a) Plumule
(b) Coleorhiza
(c) Endosperm
(d) Micropyle
(e) Root and shoot
(f) Endosperm
(g) Epigeal germination
(h) Hypogeal germination
(i) Orchis seed
(j) Seed of Lodoicea moldivica

Chapter 9 - Seeds: Structure and Germination Exercise 79

Question 1
Differentiate between:
(a) Coleorhiza and Coleoptile.
(b) Albuminous seed and Exalbuminous seed.
(c) Epigeal germination and Hypogeal germination.
Solution 1
Question 2
Give two examples each of:
(a) Dicotyledonous albuminous seeds.
(b) Monocotyledonous albuminous seeds.
(c) Dicotyledonous non-endospermic seeds showing hypogeal germination.
(d) Monocotyledonous endospermic seeds showing hypogeal germination.
Solution 2
(a) castor, papaya
(b) grasses, wheat
(c) pea, mango
(d) wheat, rice
Question 3
Briefly, explain the factors that are necessary for germination.
Solution 3
The factors necessary for germination are:
(i) Water - Water is essential for seed germination since protoplasm becomes active only when saturated with water. Water facilitates the necessary chemical changes in food material. Also enzymatic reaction occurs only in the water medium. Water when imbibed by the seed coat makes it soft and swollen. Then the seed coat bursts open, helping the embryo come out easily.
(ii) Temperature - A suitable temperature is essential for seed germination since many physiological processes occur within the seed during germination. Seeds fail to germinate below 0?C or above 45?C. Optimum temperature for seed germination is 15-30?C.
(iii) Oxygen - During germination, embryo resumes growth and for this energy is required. This energy comes from the oxidation of food material stored in the endosperm or cotyledons. This process requires oxygen.
Question 4
Describe three beans experiment. What does it demonstrate?
Solution 4
Apparatus required for three beans experiment are beaker, bean seeds and wooden piece.
The air-dried seeds are attached to a piece of wood, one at each end and one in the middle. This is then placed in a beaker and water is poured into it till the middle seed is half immersed in it. The beaker is then left in a warm place for a couple of days. From time to time, water is added to maintain the original level.
It is observed that after a couple of days that the bean in the middle germinates normally since it has sufficient water, oxygen and temperature. The bottom seed gets sufficient water and temperature but not oxygen hence it may develop a radicle but doesn't grow further. The upper seed gets oxygen and temperature but not water and hence fails to germinate.
This experiment shows that water, temperature and oxygen are essential for seed germination and that germination will not occur if any one of these factors are absent.
Question 5
Explain, why seeds sown in too deep in the soil fail to germinate.
Solution 5
If the seeds are sown too deep in the soil, they may not get sufficient oxygen required for respiration and hence will fail to germinate.
Question 6
Describe the structure of a seed by suitable diagram.
Solution 6
Question 7
Every question has four options. Choose the correct answer:
(i) Food is stored in the seeds of castor
(a) in radicle
(b) in plumule
(c) in cotyledons
(d) in endosperm
(ii) Caruncle is present in
(a) wheat
(b) maize
(c) paddy
(d) castor bean
(iii) Essential condition for germination is
(a) water
(b) oxygen
(c) temperature
(d) all the above
(iv) Hypogeal germination is present in
(a) pea
(b) bean
(c) castor
(d) maize
(v) Largest seed is
(a) double coconut
(b) coconut
(c) heartnut
(d) walnut
(vi) The collective term for the stages that lead to the formation of seedling from a seed is
(a) dormancy
(b) germination
(c) viability
(d) none of these
Solution 7
(i) (d) in endosperm
(ii) (d) castor bean
(iii) (d) all the above
(iv) (d) maize
(v) (a) double coconut
(vi) (b) germination
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