Selina Concise Solutions for ICSE Class 9 Biology Chapter 6 Seeds Structure And Germination

Exercise 1

Question 1:
Answer: (c) Maize grain - coleoptile

The coleoptile is a protective sheath that covers the young shoot (plumule) in monocot seeds. It helps the delicate tip push through the soil safely as it grows toward the surface.
Teacher's Tip: Think of the 'Coleoptile' as a protective 'Cap' for the shoot.
Exam Tip: Mention that this structure is specifically found in monocots like maize for full marks.

Question 2:
Answer: (d) do not get enough oxygen

When seeds are buried too deep or are submerged in water, air cannot reach them. Oxygen is essential for the seed to produce the energy required for germination through respiration.
Teacher's Tip: Remember that seeds need to "breathe" just like we do to stay active and grow.
Exam Tip: If asked for conditions of germination, always list oxygen, water, and suitable temperature.

Question B.1:
Answer: (a) F (False). Monocotyledonous seeds contain one cotyledon and dicotyledonous seeds contain two cotyledons.
(b) T (True)
(c) T (True)
(d) T (True)

These statements clarify the basic anatomical differences between the two main types of flowering plant seeds. Understanding these features helps in identifying plants right from their earliest stage of life.
Teacher's Tip: Use the prefix to remember: 'Mono' means one and 'Di' means two.
Exam Tip: When correcting a false statement, always provide the specific biological reason to ensure maximum points.

Question B.2:
Answer: (a) Maize
(b) Pyrogallic acid
(c) Shoot
(d) $Rhizophora$
(e) Aleurone layer
(f) Bean

These terms represent specific plant species, chemical agents, and structural parts involved in seed study. For example, $Rhizophora$ is famous for its unique ability to sprout seeds while they are still attached to the parent tree.
Teacher's Tip: Associate Pyrogallic acid with "Oxygen absorption" in your science experiments.
Exam Tip: Learn the scientific names like $Rhizophora$ as they are often used in "Name the following" sections.

Question B.3:
Answer: (a) plumule, above
(b) Coleorhiza, coleoptile
(c) seed coat, testa
(d) micropyle
(e) starch

The plumule is the part of the embryo that eventually becomes the stem and leaves that we see above the ground. The seed coat, or testa, acts as a tough shield protecting the tiny embryo from external harm.
Teacher's Tip: Remember: 'Radicle' grows into the 'Root' and 'Plumule' grows into the 'Plant' (shoot).
Exam Tip: Using the term "testa" alongside "seed coat" shows a professional scientific vocabulary.

Question B.4:
Answer: (a) Micropyle, 1st male gamete, egg cell, zygote, embryo
(b) Allogamy, fusion of gametes, zygote, embryo, seed
(c) Seed coat bursts, radicle grows downward, hypocotyls form loop above the soil, epicotyls elongate

These sequences show the logical order of biological development from a single cell to a growing plant. In epigeal germination, the hypocotyl creates a loop to safely pull the cotyledons out of the soil.
Teacher's Tip: Visualize the process like a movie: fertilization first, then seed formation, then sprouting.
Exam Tip: For sequencing questions, use arrows to show the direction of development clearly.

Question C.1:
Answer: A seed is a mature ovule after fertilization. It contains a tiny living-plant called the embryo. The embryo within the seed remains in an inactive or dormant state, until it is exposed to favourable conditions, when it germinates.

A seed is essentially a survival package that holds a baby plant and its food supply in a protected shell. Dormancy is a clever trick that allows the seed to wait for the perfect weather before starting to grow.
Teacher's Tip: Think of a seed as a "baby plant in a box" with a lunch packed inside.
Exam Tip: Define a seed specifically as a "mature ovule" to score the structural definition point.

Question C.2:
Answer: Endospermic (albuminous) seeds: E.g. Castor, Maize, Poppy
Non-endospermic (exalbuminous) seeds: E.g. Bean, Gram, Pea

Endospermic seeds store their food in a separate tissue called the endosperm that surrounds the embryo. Non-endospermic seeds have used up the endosperm and store their food directly in the thick cotyledons.
Teacher's Tip: Albuminous seeds are like having a separate pantry (endosperm) for food.
Exam Tip: Memorize at least two examples for each category as they are frequent short-answer questions.

Question C.3:
Answer: Germinated grams are considered highly nutritive because the cotyledon of the seed absorbs food from the endosperm, making it nutritive. It is rich in starch and its outermost layer is rich in protein.

When seeds sprout, they transform their stored energy into vitamins and minerals that are easier for our bodies to digest. This process essentially turns a hard, dry seed into a "superfood" packed with life-giving nutrients.
Teacher's Tip: Sprouting "unlocks" the hidden energy and nutrition trapped inside the hard seed.
Exam Tip: Mention both starch and protein when explaining why germinated seeds are healthy.

Question C.4:
Answer: Maize grain is actually a fruit in which the fruit wall and the seed coat are fused together to form a protective layer. Therefore, we do not use the terms maize fruit and maize seed. Instead, we call such fruits as grains.

In most plants, the fruit is separate from the seed, but in maize, they are permanently joined into one single unit. This fusion creates a very tough and durable structure that protects the embryo inside from pests.
Teacher's Tip: A maize grain is a "two-in-one" package of a seed and its fruit wall.
Exam Tip: Explain the fusion of the "fruit wall" and "seed coat" as the reason for calling it a grain.

Question D.1:
Answer: (a) Seed coat: It protects the delicate inner parts of the seed from injury and the attack of bacteria, fungi and insects.
(b) Micropyle: During germination, micropyle allows water to enter the seed through its pore.
(c) Cotyledons: They contain food for the embryo.
(d) Radicle: It forms the future root.
(e) Plumule: It forms the future shoot.

Every part of the seed has a specialized job to ensure the survival and growth of the next generation of plants. From the protective outer shell to the tiny pore for drinking water, the design is highly efficient.
Teacher's Tip: Link the part to its future: Radicle = Root, Plumule = Plant (Shoot).
Exam Tip: List these parts and functions clearly in a vertical format to help the examiner read them easily.

Question D.2:
Answer: Aim: To prove that a suitable temperature is necessary for germination.
Apparatus: Two beakers, wet cotton wool, refrigerator
Procedure:
1. Take two beakers and label them as A and B.
2. Place some gram seeds on wet cotton wool in each of the beakers.
3. Keep beaker A at ordinary room temperature and beaker B in the refrigerator.
4. In 1-2 days, the seeds in beaker A will germinate, showing the importance of a suitable temperature for germination. Seeds in beaker B may not show the signs of germination or may germinate after several days, though not to the extent as the seeds in beaker A.
Inference: Seeds require a suitable temperature for germination.

This experiment demonstrates that warmth acts as a signal to the seed that it is safe to start growing. Cold temperatures slow down or stop the chemical reactions that happen inside the living embryo.
Teacher's Tip: Think of the refrigerator as a "pause button" for the seed's life cycle.
Exam Tip: Always include the Aim, Procedure, and Inference headings in your science lab reports.

Question D.3:
Answer: Yes, we call it germination because all the changes leading to the formation of a seedling collectively constitute germination. During germination, either the epicotyl or the hypocotyl elongates.

Germination is the entire journey a plant takes from being a tiny dormant embryo to becoming an independent young plant. It involves a series of complex physical and chemical changes that transform the seed into a seedling.
Teacher's Tip: Germination is simply the process of a seed "waking up" and starting its life.
Exam Tip: Mention the elongation of the "epicotyl or hypocotyl" to provide a complete scientific answer.

Question D.4:
Answer: (a) Epigeal germination and Hypogeal germination
Epigeal germination: 1. Cotyledons are pushed above the ground. 2. Hypocotyl elongates.
Hypogeal germination: 1. Cotyledons remain underground. 2. Epicotyl elongates.

(b) Coleorhiza and Coleoptile
Coleorhiza: 1. Protective sheath of radicle. 2. Present towards the pointed end of embryonic region.
Coleoptile: 1. Protective sheath of plumule. 2. Present towards the upper broader side of the embryonic region.

(c) Bean seed and Maize grain
Bean seed: 1. Two cotyledons. 2. No endosperm.
Maize grain: 1. One cotyledon. 2. Large endosperm present.

These comparisons highlight the diverse ways plants have evolved to survive in different soil conditions. For instance, some keep their food safe underground, while others lift it up to start catching sunlight as soon as possible.
Teacher's Tip: 'Epi' means above (above ground) and 'Hypo' means below (underground).
Exam Tip: Use a clear table format to present "Distinguish Between" questions for better marks.

Question D.5:
Answer: Germination: When the embryo in the seed becomes activated and begins to grow into a new plant, then it is known as germination.
Vivipary: Vivipary is known as the germination of seed within the fruit, while it is still attached to the parent plant.

Standard germination happens in the soil, but vivipary is a specialized trick used by plants like mangroves to survive in salty water. By sprouting while still on the tree, the young plant is strong enough to survive when it finally falls into the mud.
Teacher's Tip: Think of vivipary as "live birth" for plants instead of "laying eggs" (seeds).
Exam Tip: Mention the parent plant in the definition of vivipary to highlight the key difference.

Question D.6:
Answer: A fruit is the enlarged ripened ovary in which the ovarian wall forms the fruit wall and encloses the seed. The fruit protects the seed and helps in seed dispersal. The maize grain is regarded as a ‘one-seeded fruit’ because the fruit wall and the seed coat are fused to form a protective layer. Such a fruit is called grain.

A fruit's main job is to act as a protective container and a vehicle for getting seeds to new places. In grains, this protection is extremely efficient because the seed and the fruit are physically bonded together into one shell.
Teacher's Tip: Remember: Fruit = Ripened Ovary. Seed = Mature Ovule.
Exam Tip: Use the term "fused" to describe the relationship between the fruit wall and seed coat in grains.

Question D.7:
Answer: Germination of a seed which takes place above the ground is called epigeal germination. In epigeal germination, the hypocotyl grows forming a loop above the soil. It then straightens pushing the cotyledons above the ground.

In this type of growth, the plant uses its stem like a biological hook to pull the seed leaves out of the earth. This allows the plant to start photosynthesizing very quickly after the first part of the stem reaches the air.
Teacher's Tip: Imagine the plant making an "n" shape as it pushes up through the dirt.
Exam Tip: Identify the "hypocotyl" as the part that forms the loop in epigeal growth.

Question D.8:
Answer: (a) The ‘micropyle’ serves two important functions:
Allows absorption of water and makes it available to the embryo for germination.
Enables diffusion of respiratory gases for the growing embryo

(b) The embryo of the seed grows into the seedling.

(c) Structure of embryo: [Labels: Epicotyl, Plumule with two rudimentary leaves, Tegmen, Testa, Hypocotyl, Radicle, Cotyledon]

(d) The cotyledons of the seed provide nutrition for the growing seedling or the embryo.

The micropyle acts like a tiny "door" that lets in the life-giving water and air needed to wake up the embryo. Once growth starts, the embryo uses the energy stored in its cotyledons until its own green leaves are ready to make food.
Teacher's Tip: The Micropyle is a "Micro" sized "Pipe" for water and air.
Exam Tip: Label the radicle as the "future root" and the plumule as the "future shoot" for extra detail marks.